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#1066767 - 06/11/20 06:35 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Has been awhile since an update. Project has not fallen by the way side, just collecting data from the steering linkage modeling for Ackermann improvement when time permits. Can say it's been almost three weeks of tweaking on the linkage model to make it more accurate to get solid number on why these cars can't produce a lot of Ackermann. That's right, hard to increase Ackermann no matter what you do to the linkage. I'll get into it more later concerning the "why not".

Being I'm itching to drive the car and the modeling told me it's a waste of my time to change steering arm angle, and the shorter the steering arm the less the gain, the old spindles will go back on the car, unmolested. Will realign the front end to the old spindles and make a trip to the computer rack to verify the Ackermann numbers my turnplates and the modeling tell me.

Both the G and B spindle only had about 1 degree outboard angle on the arms. Because G's came with a 14 and 15" wheel the 1 degree was necessary to not hit the wheel, any farther outboard was a collision. The B spindle was used on the 15" wheels, same problem even though the B arm is shorter.

As steering arms get shorter less Ackermann can be produced, the G at 6 3/4" produces the most.
Moving either the G or B arm outboard nets minimal gains. The G body linkage itself is the problem.
The Ackermann gains left and right are not the same, the G centerlink is not symmetric causing the slight difference.
Moving the centerlink reward will net more Ackermann. But more than 1" rearward would be necessary and would only net a little increase. The left inner tie rod will hit the frame if the centerlink is move rearward much less than an inch. Moving forward produces less.
Moving the steering arms outboard, 13 or 14 degrees, may also cause the tie rods to possible hit the LCA at full lock, 30 degrees, and the strain on the linkage at that angle is much more.

The linkage model will stay intact on a bench for awhile, just so I can see if there is something I missed.
Being the important thing about Ackermann is how it behaves when in a high speed roll angle. I know the modeling only shows what grandma would have when trying to park at Wally World with no roll. I have seen those special mechanical suspension analyzers where they can produce and monitor every aspect of suspension travel, pretty cool but can't be done in my shop. So stuck will single plane modeling of the linkage, but I think the result tell the story, more pro-Ackermann is hard to obtain and has minimal gains with any mods.

Bob

#1066778 - 06/12/20 05:11 AM Re: Rear spring options for handling [Re: mmc427ss]  
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The B spindles ran for 20 years are back on the car tonight. Tomorrow will settle the suspension, roll it back on the turnplates, put zero toe on it and reset the caster-camber to 9.6 and -1.25, then add 5/32" toe out. I've heard there is the local "cars and coffee" Sat morning which I usually attend. So now need to get the car all done and wash the turd to make the event. Pressure!

Will further tweak the results from the steering linkage modeling and put together some numbers.
Bob

#1066820 - 06/15/20 04:21 AM Re: Rear spring options for handling [Re: mmc427ss]  
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The car is off the rack, ended up with L -1.20/9.6, R -1.25/9.6 and 5/32" toe out. The drive showed the steering wheel is ever so low left, will add a little more toe out to the left side to correct. Took forever to wash the dust, pollen off late Fri night.
10 am Sat first coffee and car locally for this year, about a 100 cars and everyone was socially correct. Got to see some of the car people not out since last fall. There were a few cars/people you never see, they're just happy to go somewhere in their pride and joy..

Put about 30 miles on the car Sat getting a feel for the front end again. Have nothing bad to say about it, just wish the Ackermann project would have worked out. The good thing is the old B spindles are still untouched and back on the car. The new Protouringf-body spindles I'll find a home for them for 1/2 price. The donor B spindle that had their arms cut of, for now will find a place on the floor in the mezz. Who knows maybe I missed something and a revelation will appear to me, doubt it. Just don't see any way to improve pro Ackermann on a B spindle on a G to make it worth it. Was looking for 4 degrees increase, 1 isn't enough. Was never crazy about having a cut and welded cast steel steering arm on the car. Can't say I didn't try.

Will post some Ackermann numbers of the different combos of steering arm angle and length and tie rod lengths later. The winner was the 6 3/4" G arm with 14 degree steering arm angle, but it only gained about 1 1/2-2 degrees at 20 degrees over the 1 degree angle stock location. The shorter the arm, 6.25, 6 and 5.80 the less gain.

Next is a trip to the computer rack to see how my alignment numbers match up with the computer rack. Should be able to get real world Ackermann number at 20 and 30 degrees, will see how my toe out numbers using an old school toe gauge measure up, and be able to lift the front end 1" at a time and get droop bump numbers. All that info will tell if my rack alignment is good and if I need to revisit the bump again. Thrust angle was dialed in last time on that rack, will have the wrenches with me to tweak it if necessary. Something else you get with the computer rack besides the trust angle is camber and toe of the rear which was good last time looked at.

Anything you do to caster will effect bump number. As caster goes up the outer tie rod moves upward, effecting bump. Being the inside front tire in a corner is in droop a little toe out in droop on the inside tire will help the Ackermann. Last time I check bump the toe out in droop was very good, .030" out at 3". Toe out in compression was also present and more than I'd like, .080" at 1 1/2".
Bump in at droop has always been the singularly HUGE problem with the B spindle swap on a G, an inch toe change from ride height to full droop possible. The tires would squeal as you lifted the car on a smooth floor. Certain off camber corners needed your full attention, quick rises and falls in a straight away at high speed another that told you bump was BAD. Again the main reason to condemn the B swap.
Suffice it to say making an inner tie rod relocation 10 years ago and running 9 1/2 degrees caster now has improved the bump to being a non-factor now. So for the foreseeable future will drive this front end setup.

So next up is drive the car as much as possible. This post started as a rear spring option for handling. The cut to fit BMR F body 200 lb springs have been in for a while now, just not a lot of miles on them. I can say yesterday's 30 mile cruise around the countryside with the 200 springs in the back even with the medium settings on the DA Viking's was not objectionable. Only on an old country lane with a lot of undulations at 30 mph did you know it wasn't your dad's boat. My wife is a ride quality critic, she likes the SS ride least of all, or is it not at all. Oh well.

As an early part of this rear spring project Viking's new triple adjustable shock was an option on the table. Two reasons to have a set on the car. First the Viking DA on there now are a little to long for the travel available. Shortening a 7 year old shock is not cost effective. Second the triple has low and high speed compression and rebound control. Kinda like having your cake and eating too. On the street you can run a very soft low speed and take some of the harshness of ride out. I can do that now by backing off the compression on the DA but then you run into very nearly bottoming the shock out on compression on that big dip in the road. A very small tie wrap around the shaft of the rear shocks tells the whole story. Shorter shocks needed and triple would be nice.
Guessing I'll be again talking to Viking soon.
Bob

#1066825 - 06/15/20 12:56 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Shoot, I'd consider making a longer lower shock mounts first before putting new shocks on it.

Glad to hear it got to get out and stretch its legs again though. Its good for the soul.


Lance
1985 Monte Carlo SS Street Car
#1066861 - 06/17/20 01:20 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi Folks,

Bob - you can probably sort-out Ackermann with sufficient accuracy by looking at the problem from only two dimensions instead of three. Assume the tie rods and centerlink conform to a plane, and pick the points of intersection of the kingpin axes with that plane. Ditto the inner axes of the Pittman arm and idler arm.

You can steer the car virtually by rotating the Pittman arm and watch how the whole geometry reacts. Just use your compass as a set of dividers to conserve lengths.

The challenge, however, is picking the best Ackermann correction to use. If you use the one that works in the low-speed limit, i.e., where both wheels turn to the same center located on an axis extending from the rear axle, then the correction will be too great at higher speeds. As you know, the higher the speed in a turn, the less Ackermann you need, and for some cars with sufficient front-end grip, the requisite correction could even become negative. But one way or another, you need to pick your sweet spot...

As a starting point, I would establish the center of revolution of the wheels assuming 100% correction at the low-speed limit, then advance that center 1/2-car length forward. This corresponds to roughly 50% Ackermann correction, and equal angles of slip at all four wheels (which never happens in real life, but again, this is an exercise in compromise.)

I always wondered why every production car I'm aware of has fixed Ackermann. In my opinion, it should be dynamically variable or at least statically adjustable.

Last edited by MAP; 06/17/20 01:25 AM.
#1066867 - 06/17/20 05:05 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi Mark.

The modeling of the steering linkage was full scale two dimensional with all 12 pivot points accurately located and variable, + and - 35 degree scales for each steering arm. The only thing I would do different the next time would be use 1/8 x 1 flat stock for all the pieces to allow very precise hole locations. The first model made 10 years ago was 1/8 x1 for everything but the centerlink. It was 1/4" plastic sheetstock with multiple locations for the inner tie rod, in, out, forward, rearward. From that model learned the inner tie rods are condemned to their location on the centerlink both side to side and front to rear. But up and down could help correct the bump which is something you don't learn from an Ackermann model.

Did a lot of reading on Pro, parallel, anti Ackermann and when it helps or hurts you, scrub radius, tire slip angle, all that stuff that muddies the waters for what you think you need. Fifteen years ago just wanted a good touring car that was going to get road course time very locally when the promised track was done. Drove past there twice yesterday, the Liberty Bell Motorsports Park sign is still up but paint is fading. Numerous times went with my son autocrossing his car and I finally realized it was time to make the effort to do that and do OK when I went, road course days gone, 100 passes at the drags, over it.

Mark as you said it's about the use of the car, all forms of racing require different setup. I knew insufficient pro Ackermann wouldn't be an issue if I could live my dream and beat the car up for an hour or two on an open track day a time or two a year. That bubble broken by no road course and getting old, the past year or more getting around a cone very quickly seems like the only legal fun available. More Pro Ackermann was the goal of this project, would be beneficial for me at autox. But unfortunately it appears the possible gains are minimal for my suspension setup via steering arm realignment.

When on the computer rack bump in droop will be serious looked at. From those numbers may be able to see if getting more toe out in droop will create some cheater Ackermann. Bump correction was done the first time 10 years ago. If necessary another bump correction will need to wait until being a Winter project. Today having a little more knowledge for the correction and better tools for measuring bump the results should be much better, and may be able to help the inside tire as a result.

Today had the car out a few times for toe and steering wheel level checks. Wheel level now and 3/16" toe out. Will check again a few times before hitting the computer rack. Takes less than 5 minutes to check it with my old school toe gauge. I always check it at the spindle centerline height. Things get in the way, front sway bar, scattershield, long tips on the gauge can reach the centerline accurately.

Next up is gets some miles on the car. The goal of 2K miles a year will be a challenge this year. We still have a yellow light in PA. But the car is together and very driveable and will stay that way for a while.
Bob

#1066868 - 06/17/20 06:42 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi Bob,

IIRC the spindle is nodular iron, so welding it is possible, but definitely a challenge. Have you thought about trying another spindle (from another B-body?) where you just weld a steering arm end in a different position based on your best estimate of correctness?

Another problem with the A/G body front end is that steering inputs change the relative height between the centerlink and the tie rod ends, because the spindles and the Pittman/idler arms axes are very much not parallel viewed in plan. I don't remember whether this misalignment aids or hurts Ackermann, but it definitely has to cause a varying bump steer response depending on steering angle. What a mess GM designed! But still, since the low-performance, skinny, soft tires back in the day hid so many design shortcomings, it's obvious they took all the liberties they could.

Best,
MAP

#1066879 - 06/17/20 08:23 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Actually the spindles are cast steel, not nodular. Welding them can be done but is a procedure, preheat, weld, bury immediately in something to allow them to cool as slowly as possible.

Yes I fully understand the limitations of the G steering linkage, the suspension inadequacies, and the shortcuts GM did to produce grandma cars of the day. And how suspension travel in any direction was a make it fit and "we ain't racing this thing, it's just a driver". I did all the chalking/lines of the points necessary to see what it would take to get bump to something OK and why the inner tie rods were dropped 11/16" on the centerlink to move them to reduce bump. It will never be great, you just make it tolerable.

So many things on the G chassis are a compromise. You just keep picking something to improve and hope you can re-engineer it.
Bob

#1066881 - 06/17/20 10:57 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi Bob,

Actually, it was a former GM engineer that told me nodular iron. In any event, they have similar welding challenges.

At some point, I think we have to take a big step back from the whole mess and say, "You know, better to start with a clean sheet of paper." And it's not just the front-end design by any means. Everything structural/mechanical/electrical about these cars sorely needs to benefit from several decades of engineering advancement. Even in 1978 when the A/G body design was brand-new, it was still based on old ideas, old technologies, and old methodologies. Basically, they just took the cheapest means possible to cut 700-800lb weight out of the previous generation of cars as a knee-jerk reaction to the 1975 Middle East oil crisis. (Fuel economy goes roughly as the reciprocal square root of mass.) How extraordinarily unimaginative. But those were the days right before the imports came and ate GM's lunch...

Bob, my guess is that you feel too much water has gone under the bridge to start afresh. That's understandable but I don't have the patience for that. Me, I'd start afresh if I just had the chance.

Anyway, good luck with tweaking.

Best,
MAP

Last edited by MAP; 06/17/20 11:04 PM.
#1066895 - 06/18/20 03:42 PM Re: Rear spring options for handling [Re: MAP]  
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Originally Posted by MAP
Hi Bob,

Actually, it was a former GM engineer that told me nodular iron. In any event, they have similar welding challenges.

At some point, I think we have to take a big step back from the whole mess and say, "You know, better to start with a clean sheet of paper." And it's not just the front-end design by any means. Everything structural/mechanical/electrical about these cars sorely needs to benefit from several decades of engineering advancement. Even in 1978 when the A/G body design was brand-new, it was still based on old ideas, old technologies, and old methodologies. Basically, they just took the cheapest means possible to cut 700-800lb weight out of the previous generation of cars as a knee-jerk reaction to the 1975 Middle East oil crisis. (Fuel economy goes roughly as the reciprocal square root of mass.) How extraordinarily unimaginative. But those were the days right before the imports came and ate GM's lunch...

Bob, my guess is that you feel too much water has gone under the bridge to start afresh. That's understandable but I don't have the patience for that. Me, I'd start afresh if I just had the chance.

Anyway, good luck with tweaking.

Hey Map,

I have to say you hit the nail on the head with these cars and the history.

With Bob I think he has much time being retired and this is his hobby. It's a cheap hobby when you look at it with test after test and measurement after measurement while documenting processes in a long drawn out fashion. It passes the time and keeps him involved with something he enjoys which is cool. Will all this work pay off on a G body, for sure not. But he is happy and enjoying tinkering with his SS. My cars aren't the best in any aspect and I'm the same way, I do it for something to do more times than not. The end result is always the same... Someone has a faster better car and they keep making faster better cars until we are commuting like the Jetsons.

Best,
MAP


Last edited by 1 Slow SS; 06/18/20 03:43 PM.

Enjoy life, family first!
#1066898 - 06/18/20 04:26 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Yeah, I think the constant challenge of tweaking the next thing is what keeps hot rodding going (as opposed to sports cars or racing, where the answer is almost always to start fresh with the latest and greatest any time you can). To me, hot rodding is taking what you have, what you have available, and the time and energy and spare cash you have as resources and modifying for improvement. None of us can make our Monte's better in every regard than something like a new Corvette or Ferrari. Shoot, I can't even get mine to be better than a new base model Malibu in more than 3-4 areas. But we pick the aspects we care about, and go for the best bang-for-the-buck we can get. At least I do, when I can, and the rest of the time I try to think of what I'd do if I had the time or the money to act.


Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1066900 - 06/18/20 05:47 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Talking with Dave, owner of Protouringf-body where I bought his new B spindle to see exactly what he had done to the B spindle for his 2nd Gen F-body group, his new spindle is made of a higher quality of cast steel than the previous GM cast steel spindles, per Dave.

As for polishing the 35 year old turd, it's what old people do. Would I like to have a C8, sure, who wouldn't. But it's the challenge of making something better and not the huge price tag of the hot cars available today. Yes you can buy cheaper performance cars with already great handling packages but that takes the fun out of the build, or lack of a build. Just write a check, as I call them, "check book cars". Most of those owners don't even know where the dipstick is. For the past 50 years have been playing with these low tech, heavy, slow, fat, whatever, cars and enjoy the results, although some time minimal. That's what hot rodding is all about.
Bob

#1066917 - 06/19/20 03:58 PM Re: Rear spring options for handling [Re: mmc427ss]  
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I had a boss with a Maserati that he was quite proud of. We had a company car show that he and I both entered. Mine had a steady stream of onlookers, most cringing at things like a red wire used as a ground, and laughing at my use of HVAC 24VAC relays on a 12V DC system (they work great, are very reliable, and have up to 3 independent NO/NC circuits with plenty of current capacity, and we literally threw dozens of them away each day). He pulled up and spent 20 minutes trying to figure out how to pop the hood. He had the car for 2 years and never even tried. I'm sure he could have smoked me in any kind of race, and it is certainly a much nicer car than anything I've got, but I was a lot more proud of what I had that day.
I quit reading Hot Rod magazine since I couldn't afford anything they did anymore, and I get a lot more kicks from actual real-world builds and repairs and tweaks than what the OEM's and the high end shops are doing. I like the work Matt Happel does (Sloppy Mechanics), although he is getting more and more new stuff these days. Guess we all have our own tastes.

Anyway, I'm still enjoying the ride of following the work you're doing.

Last edited by Hunter79764; 06/19/20 03:58 PM.

Shawn

'85 MC with budget 5.3L swap, TH350 with stock 2.14 rear end
It ain't much off the line, but it's nice on the highway
#1066970 - 06/23/20 06:32 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi 1SlowSS, Hunter, Bob,

Those are all great answers. Even though I tend to write from the theoretical point of view, I deeply relate to and appreciate all that you (collectively) are saying. I know we all wind up finding our most comfortable compromise scenarios and then make the best of it. That's why I don't criticize you at all with following the path you're following, Bob. Furthermore, you can't put a price tag on the sense of satisfaction you get from making your own discoveries and advancements that turn the car into something the original designers never envisioned, even if it's not a C8.

So Bob, have fun. And I mean that 100.000000000000% sincerely.

Best,
MAP

PS: I'm curious to learn how Dave's B-body spindle might vary geometrically from the original design (hopefully it makes bumpsteer and Ackermann a bunch better - two things which a relocated steering-arm end can nicely fix.)

Last edited by MAP; 06/23/20 06:35 AM.
#1066979 - 06/24/20 04:27 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Mark, Dave's new B spindle was made for two reasons. First the old B spindle is hard to find these days so Dave had a company in ILL reproduce them with a few subtle changes. The 2nd gen F spindle was a tall spindle but had an 11" rotor and different mounting for a smaller caliper. Swapping the B spindle into a 2nd gen allows the 3rd Gen F 12" 1LE rotor and better selection for larger B calipers, can even go 13" on the B spindle. So for the 2nd Gen guys potential for bigger brakes and not a big expense
Dave's other market is the A body guys and one of the roundy-round classes that allows spindle mods. I was one of the first G cars to buy the spindles and somewhat of a guinea pig. No problem.

As far as the what Dave has done with the spindle's specs. The KPI he offers in 10 and 8. The B spindle is 10 degrees. Being last years suspension project was moving the LCA pivot points and that was all setup using my old 10 KPI B spindle. The reason for staying with the 10.
Nothing was changed as far as spindle height, ball/tie rod tapers, spindle stub shaft is standard B sizes, just nicely done.

The one big change he made was in the location of the outer tie rod in the steering arm. A stock B spindle length is 6.25", his new length is 5,800" , 7% faster steering. This he said would appeal to the A-body crowd because their overall ratios are slow due to linkage ratios limitations. And to his 2nd Gen autox guys looking for quicker steering.
The tie rod hole is also moved outboard about 3/16". This implied to improve Ackermann. When measured comparing a stock B at just under 1 degree outboard angle the relocation of his hole is about 2 1/2 degrees. My modeling found that change to be insignificant for an Ackermann improvement for a G, Also the shorter length arm reduces the gains. Might improve the Ackermann on an F or A car due to different steering linkage, but didn't see any real gain either on the model or installed on my car.
One other change on his steering arm was the height of the machine tie rod surface and tapered hole, it was 1/8" lower than the old spindles. This would effect bumpsteer and did when the new spindles were installed on the car, made bump in droop worse.

So for my car and my front suspension mods the new spindle was no improvement. How it would work on any other car but mine I can't say.
Bob

#1067020 - 06/26/20 11:31 PM Re: Rear spring options for handling [Re: mmc427ss]  
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Hi Bob,

How about modifying the LCA to move the LBJ about half an inch forward? I know this is simple in principle but there are significant side issues to solve to make this happen correctly, like changing the fundamental shape of the LCA. Even so, it's within reach of some cutting and welding.

And/or:

Re-weld that steering arm end about 1/2" outboard of where it is now, and change height at the same time to fix bumpsteer. There's got to be someone not far from you that can do that right, no?

Best,
MAP

#1067021 - 06/27/20 03:32 AM Re: Rear spring options for handling [Re: mmc427ss]  
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Mark, moving the LCA pivot points was exactly the mod done a little more than a years ago. Total was 11/16" each ball joint moved forward with zero change outboard. At the same time the alignment of the pivot centerlines was fixed, a little tweaking of the antidive but I stayed close to what GM built in, just made that angle equal each side. If you followed Lance's front suspension blueprinting i just took what Lance and Ron were doing and applied it to my setup.

The reason for that 11/16" movement were many. First, no one made a LCA for coil springs that moved the ball joint forward, coilovers yes, coils no. So me using basically a stock LCA the only way to move the ball joint foreword is at the pivot points.
Wanting to run high castor numbers requires moving the lower ball joint forward on our cars. The B spindle and correct Global West UCA previously maxed out at 6 to 7 degrees caster and the fat front tires were rubbing the inner well at 3 o'clock. 6 degrees caster was the max.

With the lower ball joint now at 11/16" forward several thing happen.The goal was high caster, 9 1/2 range , the logic is when caster and KPI marry thing get a lot better with camber gain, and they do. I've been running 9.6 degrees for more than a year now. Shim stacks are .200" to 400" with the exception of that right rear stack that is always fat. UCA frame mount at that location is usually crooked from the conception, thus one shim stack can be huge. So normal shims stacks thickness worked out great.
Tire clearance at 3 o'clock is outstanding, could even add more caster and would be good to go. The tire is now closer to the plastic inner fender extension at 9 o'clock but not an issue.
Camber gains that's another topic. Now adding or subtracting caster can be used to adjust the gains.

Moved the rear end back 1/8" several years ago to compensate for a blocksaver plate at the scattershield. Then moved the lower balljoints forward 11/16".
Wheelbase for an SS is 108.1, + 11/16" + 1/8", stretches the wheelbase close to 109".

Bump, made a correction 10 years ago via inner tie rod height. That corrected 60% of the terrible B spindle's toe change. As parts of that recent ball joint project a bump gauge was made and the numbers said leave it alone for now, it's actually pretty good. So not at the top of the list as projects right now but certainly something for a cold Winter;s night.

When adding caster the steering arm's tie rod location raises. Even while making a moderate change in caster. So at 9 1/2 degrees the arm came up a good bit.
The car will be on the computer rack soon, I hope, and can see what the bump is for droop. Raise car 1" at a time and record the numbers.
Go from there. You will never get great bump from full compression to full droop, the linkage and geometry doesn't allow it. You try to use toe in or out to your advantage when it happens. Hard to do, it's a compromise.


Mark, the weld the steering arm thing is a touchy subject for most shops, liability thing. I had that minor detail covered, just found sacrificing a good pair of B spindle with nothing to be gained Ackermann wise was silly. I can make another centerlink and adjust bump at the inner tie rod. Easier the second time around, already have the donors. The centerlink is forged by the way, easier to weld than a cast steel spindle.
Bob

#1067187 - 07/07/20 04:02 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
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mmc427ss Online content
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mmc427ss  Online Content
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Pottstown, Pa
Not much to add to this other than have a few hundred miles on the car the past month or so.
Toe was set to 1/4" out several weeks ago to get a feel for that much toe. Will be backing it off to 5/32" soon. Was hoping to get the car on the computer rack to see what their numbers show but time on the rack has been limited and Thur evening is the opportune time for me there, just haven't been free for them or me the past weeks. Have had to spend maintenance time on the rest of the fleet the past few weeks, it seems ABS problems on old cars eats up the time. My Astro van needed a LF ABS harness and a water pump and it's left gasket replacement. My daughter's Pontiac GTP needed the supercharger oil changed, RF ABS harness, LR ABS sensor/hub replaced, steering rack leak, cabin filter, LR outboard brake pad came off it's backing plate, and several other service items. All just eat up shop time.
This Thurs is another round of surgery on a bum leg, that puts things on the back burner for a few days.

A friend bought a new open car trailer a few weeks ago. He always refused to drive his 69 Camaro with 4.11s long distance to race the car, now he can load it up and go. The Sherline tongue weight scale I bought to use with my homemade coil spring rate checker was used to setup the tongue weight for his new trailer. Pretty cool and worked great. We set the tongue height to the what the towing height would be and used to gauge to measure tongue weight with the car in different positions on the trailer, then marked the centerlines on the wheels and what the weight was at the tongue. Now he can position the car on the trailer and haul it around, and then add or subtract tongue weight to improve the handling.
From my experiences most people are clueless of tongue weight, must be OK, i didn't crash.
A few weeks ago a Dodge Dually was pulling a 4 car trailer with one missing on the top front. it was sitting in the grass at the cloverleaf, they formed a cool looking V. To fast on the nasty off ramp and tongue weight was not good. Very lucky truck driver with soiled underwear.

The suspension goals for the car right now is DRIVE IT. Ever year my goal is 2000 road miles, don't really need to go anywhere, just drive it. Only at a little over 700 right now and half way thru the year. Most all the events I planned on doing this year were hit with the RONA, and being one of those "compromised" types that lives with a compromised type and most of your senior car friends have been hiding it hard to find opportunities to beat on the car.

Replacing the rear DA Vikings with their triple adjustable rear shock is still on the table. Pro and cons. First the con, $600 bucks to replace a perfectly good $400 set of DA shocks. Only thing wrong with them is they should be 3/8" shorter. The compression setting on the DA needs to be mid point or higher to prevent almost bottoming out the shocks with just some aggressive hilly back roads. A taller rear axle bumper would help limit compression travel, that would be the cheap fix, just hate to loose suspension travel anywhere.

A Pro of the triple would be a shorter shock by 3/8" out of the box, yes less droop travel, but our cars have a lot of droop travel. The Ridetech rear spring is short, less droop travel along with a few other mods and it could be a street spring for me. It requires a 1" spacer to obtain my desired rear height now. A shorter shock would help hold that spring setup in place better.

Another Pro and the real reason to try the triple was to see if having a high and low compression speed settings that it really did make a difference in ride quality without sacrificing handling. The BMR rear springs in the car now do ride harsher than the previous Global West spring when set at mid range settings for comp and rebound. Softening up the compression setting to full soft does improve the ride, but at the expense of bottom out the shock if compress rapidly at higher speeds. I'm told by Viking that the triple is a fix, better ride quality at slow speed compression, adjustable, and still have total control of high speed compression, adjustable.

I feel the need to call Viking and see how business has been and help them with a purchase. On the other hand it's nice having that cash in the checkbook for the rainy days ahead. The lack of events to participate in and being confined to quarters doesn't help either.
Bob

#1067348 - 07/18/20 12:42 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
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mmc427ss Online content
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mmc427ss  Online Content
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Reduced the toe out from 1/4" to 1/8" more than a week ago but only got the car out yesterday for a drive to check steering wheel level and any change in turn in response. Can't say I noticed much difference, car still has very good turn in. Will use the 1/8" toe out setting as the street setup norm.

The state inspection stickers on the 86 expire the end of July. The plan is stickers and the computer 4 wheel alignment rack to verify last alignment on my rack. Won't make adjustments, other than thrust, on that rack. Should also be able to gets some accurate Ackermann numbers at 20 degrees and full lock L and R. Also bump from ride height to full droop. Mostly need to know my in shop rack is accurate.

Not much happening here as with most of the country. Last weekend was the local downtown car show with 400+ cars. I was still on the mend from some surgery and didn't attend. But the local governing body was appalled by the lack of distancing and masks after they gave approval for the event. Most likely that will be the last one for this year.

Only autox events scheduled that I would think about attending already have 120 cars registered, it's 80 miles away. This weekend and the next. Just not possible to make either of them, and they will be over a 100 degrees in those parking lots. Mostly kids in little cars, nothing even registered for Classics.
Bob

#1067463 - 07/30/20 03:16 AM Re: Rear spring options for handling [Re: mmc427ss]  
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mmc427ss Online content
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Short update.

State inspection and 4 wheel alignment check on the computer rack Thurs, finally. Not going to adjust, change, settings on the front end alignment i did on my rack, just comparing the caster, camber, toe out number that I set to the computer numbers. But will be able to look at the Ackermann and camber gain numbers I got and see what the 4 wheel says. Something a computer rack does well. Most interested in the Ackermann, and bump from ride height to full droop while watching the computer screen. Only thing I may tweak would be thrust angle in the rear. Last time on that rack thrust was .09 degrees, that was in the Spring of 2018. Nothing has changed 4 link wise in the rear since then.

Called Viking today and ordered their new triple adj shock for the rear. Hoping it works as advertised.

UMI King of the Mountain event is Aug 21-22, booked a room for those two days last week. Been to lots of racing venues, attended KOTM last year and put that at the top of my list of racing experiences without driving a car. The autox cars, and drivers running for that 10K prize are top notch. This year's event will be as good if not better. And I will be more prepared to take cars apart with my eyeballs and a camera. Just a must go event for me.

It's about a 600 mile road trip for the 86, hoping the new Viking rear shocks show up before leaving. It would be a good test of tuning adjustable ride quality in the rear. Not the primary reason for a triple but could be a big plus. Currently with the new rear BMR spring and the double adj Viking set mid range for both Comp and Rebound ride quality could be called harsh. Backing way down on the Comp and quality is much better, but the shocks get close to bottoming out if you dump a lot of compression load on the springs. Being able to control shock rates at low and high should fix that.
Also went with a slightly shorter shock this time, looking to move the shocks working range closer to the middle of the shock's stroke.

Happy motoring
Bob

#1067524 - 08/04/20 06:42 AM Re: Rear spring options for handling [Re: mmc427ss]  
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mmc427ss Online content
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Thurs two new stickers on the windshield, blue and red this time, gotta love Pa. When I arrived was told inspection not a problem, rack time not looking good. Think Jeff, owner, was just playing with me. Waited my turn and drove it on the rack. The plan is touch nothing. Just get numbers. Once the sensors and machine is dialed in it's time to see what the just installed software update last week by Hunter can do.

Rolled the car in the first time and got numbers. rolled it out and then back in again to confirm numbers. Caster, camber the same both times, only a thrust angle change. Toe on the second roll in we changes to inches instead of degrees. I set toe in inches.
One of the goals was to see how my alignment in the shop compared to latest and greatest.

The computer rack:

Left side---------Right side
Camber -1.5-- Camber -1.5
Caster 10.0---- Caster 9.4
Toe out .02"--- Toe out .08"
Total toe out .100"

Left rear-------Right rear
Camber -.6 --- Camber -,7
Toe .03" ------ Toe .03"
Total toe .05
Thrust .00"

Aligned on my shop rack was set:

Left and Right the same
Camber -1.25
Caster 9.6
1/8" toe out, steering wheel level out on the highway at 60.

So first off very happy with the rear specs, not bad for a 35 year old 8 1/2. Got .03 degree thrust the first time, .00 the second, no need to touch the LCA, done.

Toe deviation of .025" tells me I'm ok setting it with a 50 year old tweaked toe gauge. Good to go.
Camber being 1/4 degree high both sides, that's questionable. Besides the hub gauge a digital gauge off the wheel flange says my hub gauge is a little light, but, not a 1/4 degree.
Not concerned about running 1.5 degrees if that's what it is. Tires are aging, need to use them up.

The right caster 9.4 doesn't concern me, 9.6 would be great but, who's error.
The left caster at 10.0 was a surprise. Both roll in said 10.0 caster. Will recheck soon on my rack.

The shop rack is still laying at the side of the bay. Not a big deal dropping the car back on it just to see if I missed something. Every time it gets setup, leveled, tweaked it gets more accurate. The turnplates have their own install shims now.

The next computer rack check was seeing how easily you could crank accurate 20 degrees left. 20 right, full lock left, full lock right, and see each wheels angle As expected it's lousy, that's being kind. Ackermann was only 1/2 to 1 degree at all points. Saw 30 dgrees max I was being optimistic on my turnplates and saw 1 degree. So not surprised at all this Ackermann sucks. Would make a good road course setup though.

Didn't bother with checking droop bump, bummed by poor Ackermann results, know what it is anyhow, and not hard to get realistic numbers on the shop floor. I know bump needs adjusted again. And there may be some poor mans Ackermann to be had with a new centerlink. A Winter project.

Running out of time we scrolled through the new software menu. Wheelbase said 108.9 on the right side, the same as I know it is, and the left side is shorter, about 1/8", Scrub radius we scrolled through, didn't see the number but appeared to be not terrible from the diagram. Several front-rear angle and setback modeling available, We ran out of time. There will be a next time when the bump is changed again. And I'll know more about the new rack's capabilities.

But I got what I needed to get done, window stickers and a no adjustment alignment.

Oh, and a mini stater that hiccuped on Thurs as i got ready to pull onto the rack. Today that PowerMaster starter got pulled and refreshed for the second time. Three minis for this car in 20 years, and didn't go anywhere. Not the most fun day pulling the starter, checking all 153 teeth on the ring gear and knowing it the T56 comes out to R&R 3/4 a new ring gear is in order. Just more fun for a later date.
Bob


.

#1067526 - 08/04/20 02:46 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
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SSLance Offline
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SSLance  Offline
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Ah... Fun with cars. smile

Those specs are fine for what you do with the car, now just go enjoy it some before the snow flies again.


Lance
1985 Monte Carlo SS Street Car
#1067527 - 08/04/20 07:28 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
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mmc427ss Online content
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Pottstown, Pa
Guess I need to practice my kick starting procedure in case the starter leaves me sitting somewhere. Was at a car show Sat night and had to park with the rear pointed downhill. Had my fingers and toes crossed that the starter didn't leave me looking for a push to kick start it. Lucky me.

Schedule for autox events to the west of me are still in limbo land, nothing scheduled yet in the near future. Hope to do at least one this year. May have to be satisfied with a couple ride-a-longs at UMI KOTM.

Was able to get a few miles on the car this past week with some fast corners and and it actually feels pretty good. Will just drive the car and put as many miles on until the snow flies now. Goal is 2000 a year, only at 750 now, UMI trip will add 600 more that weekend, which is coming up quickly.
Bob

#1067535 - 08/05/20 09:59 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Sep 2007
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1 Slow SS Offline
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Small town KY
Hey Bob,

2000 miles should be easy to do. Load up the trunk and take a road trip the corvette museum and back. I went last month and seen the Ed Roth exhibit, it was real cool to see the car collection I used to read about in hot rod as a kid. Heck if you travel more I bet you could put 20 plus K on it a year.

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Last edited by 1 Slow SS; 08/05/20 10:43 PM.

Enjoy life, family first!
#1067536 - 08/05/20 10:52 PM Re: Rear spring options for handling [Re: 1 Slow SS]  
Joined: Sep 2007
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1 Slow SS Offline
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1 Slow SS  Offline
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The end... of a couple corvettes.... lmao

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Enjoy life, family first!
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