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#1073697 - 04/20/22 04:46 AM Re: Front sway bar project [Re: mmc427ss]  
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Funny it was only a short time ago when I was playing with the B tall spindle on this car trying to figure out how to change the steering arm angle to improve Ackermann. I had bought a second set of B spindle from Paul B, whacked off the steering arm on the left spindle and tack welded it back together with a MIG to explore the Ackermann possible gain. My homemade alignment rack/turnplates and accurate gauges make alignment/Ackermann easy to check in the shop.

The whole time going through the PITA of the steering arm project it was always the same final question. "Would I be willing to bet my life on the fact the steering arms could be bent or reattached safely?"
I found no one was going to give me that guarantee.
Yep, back in the day many would just get out the torch, cherry red the arms on those old cast iron Ford spindles for the street rod. My TIG guy said he had done a few back in the day. Would he do it today, nope. Today it's called liability.

I had found a 2nd Gen Camaro racer/parts vender who was re-popping the B-spindle with a mod to the steering arm angle, arm length, Made in USA and a high quality part. After buying a set from him and doing the whole math, alignment, measurements the gain was near zero over the stock, 9C1, 1987 cop car donors i ran for 20+ years. The things I did learn from all that was 17" or bigger wheels are need to get the steering arm end outboard enough to have an Ackermann improvement. My tack welded steering arm contacted the edge of the 16" GTA wheels at the time limiting any Ackermann gain possible.
One of the reasons I now run a 17x9" GTA wheel. May revisit that steering arm idea again some day.

The other thing learned from that project is the same question asked of the sway bar project. Would I feel safe?
And I agree that as usual I overthink, try to engineer a part without the proper paper work to say I'm qualified, but have learned if you don't try you won't fail.

Last night sat with my TIG guy and explained the process we will go through to weld these thing together. A 500 preheat with a slow cool down, maintain 500-550 through the interpass heat cycling. I really think the crack formation shouldn't be an issue from welding if done correctly.
Also think the size of the arm section area is strong enough with out a tempering procedure. It was always my concern with the brittleness and possible cracking at the edge of the welds as the possible failure point.

Another piece of the strength puzzle is the arms have two 42 degree bends with welds at both bends. The offset of the arms is 3 13/16" which is a lot of offset and contributes more stress to the arm.
Calculations of possible load on the arms to link attachment point with this bar/arm setup says 1200 with 1" of travel on the link. Total suspension travel at the link in compression is about 1 1/3" on this car, not measured yet but a very accurate guesstimate, so may see 1600 lb of force at the tip of the arm. It's always difficult to get a feel for what 1600 lb of pressure feels like, how much force is that really. But when I put the floor jack under the front crossmember of the car and know it's lifting about 2200 lbs off the ground and also know, that's heavy. That potential 1600 to the arm links is a working pressure, a + and - pressure, pulling and pushing as the car is leaned over side to side at high speed.

Also on another suspension project a spring rate checker was made to try and find a little help for the rear suspension in the car. Numerous rear springs were compressed to 1000 lb on that homemade spring rater. That gave me more respect for what 1000 lb of pressure is.
Ya just gotta have some respect for what happens there at possible 1600.

Lots of little things will get in the way of getting the arms welded up this week, overly busy with my side gig, and yard work that needs to be caught up on, the green thing is happening to my little splice of the pie. But if can't be ignored. The supposed to be awesome Honda mower engine just got it's second new carb today, but at least now it will mow again.

Pulling the LCAs to weld the link's bottom mount to the arm may actually get started by weeks end. I need the bay the car is sitting in now to service the other vehicles in the "fleet", it Spring here. Once those mounts are attached to the LCA, the LCA reinstalled, the car is back in streetable trim, can drive it at any time even without a front sway bar. That would put the pressure back on getting the arms powdercoated, as in ALL DONE.
Bob

#1073701 - 04/21/22 01:35 PM Re: Front sway bar project [Re: mmc427ss]  
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Bob, I'll toss my opinion as well, without referring to handbooks and material science textbooks etc... I'll bet a nickel that the potential failure points are going to be the splines and the pivot point for your linkage. That steel is thick enough, you could use annealed A36 and you wouldn't have major issues on the arms (just the splines potentially). Didn't you say aluminum is the other option? Based on that, keep the cracking potential down with some preheat as discussed (assuming your 4130 assumption is accurate), cool it slowly, and you will be fine. Honestly, I could make a case that you don't want it heat treated due to the higher likelihood of catastrophic failure (a weld splitting with little/no warning due to a brittle fracture) vs a slow bending failure that you would pick up on, I'm sure.


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
#1073712 - 04/23/22 02:38 AM Re: Front sway bar project [Re: mmc427ss]  
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Time will tell the story of arm strength. Just trying not to make a fatal mistake of just being ignorant to potential flaws in the thinking. The spline in the arm, the 1/2" hole out at the end of the arm, maybe, we'll see.

Last year got a new not to expensive four burner gas grille.Used it dozens of time and it was the usual mess after a year. Decided it needed a cleaning so it can be a portable preheat oven for my project.
Today, maybe a high 60s ambient, a spotless gas grille and a large scrap of the arm material clamped to the welding jig for the arms were placed on the warming rack in the top section of the grille and heated to 525. On both the jig's flat surface and the side of the fat piece of scrap arm steel a 1"x1" area of Krylon 1200 degree flat black stove paint was applied earlier in the week. To get a more accurate temperature reading with the infrared gun a flat black surface is best.

In about 1/2 hr of preheat, all four burners on high temp the grille's temp gauge in the top of the hood was 550. The laser temp on the black paint confirmed 525-550. Turned off the grille, lid closed and occasionally lifting to check for temp drop. From this determined the core of the fat steel piece was heated to 550 and the trick is to take your time to completely heat soak the parts to 500. And of course i can preheat the parts to most any temp up close to 600 if I want to with the grille. With just this simple procedure this will be my preheat oven and with very little effort on managing the temp of parts during welding. And also may have better control of of the temp than just using a rosebud on a torch. I now can see us getting this welded with a 500 preheat. It's no big deal to throw the grille in the back of my van and haul it over to this shop. It can be set up close and I can be doing all the pre and post heat while he gets the TIG done.

Interestingly the 3/4"x 2"x 3" piece of scrap and the three 1/8"x 2" x 2" mild steel angle iron welded to the 1/2" thick base of the jig turned a pretty blue from the 500+ preheating. That pretty blue color of the steel indicates I was in that 550 heat range. Will shoot for 500 to help keep the pretty from turning dark blue.

Torqued the front lug nuts yesterday, front wheels were off both sides a couple times for arm fitting/checking. A couple other cars need to occupy the shop bay the 86 hogs up, and will get it out to warm up the old tires that need to be used up this year. Pulling the front LCAs off the 86 to weld the link mounts on can take a little time, the daily drivers always take precedent over the toy car. Two weeks and the grandkids have a car show to attend, in the 86.
Bob

#1073736 - 04/26/22 09:27 PM Re: Front sway bar project [Re: mmc427ss]  
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Finally got in touch with the engineer at the shop that produced the sway bar arm blanks that I've cut up to have welded. He was on vacation fishing for trophies in the Gulf for 2 weeks and unavailable.
He verified that the arm's steel is a 4130, that my procedure to weld should include a 500 degree preheat, some gas apply time to stay on the weld for a few seconds after welding, and a post heat process with cooling as long as possible. He basically confirmed the process that I had thought was necessary to weld the arms. All good to know info.
Lots of other stuff on my plate this week but intend to get this part of this long painful construction process over with.
Bob

#1073798 - 05/01/22 03:50 AM Re: Front sway bar project [Re: mmc427ss]  
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Today. Gas grille taken to the weld shop, arms preheated to 500. With 8 sections, near 20", needing root welded and filled It took a while switching between sections and arms to try and keep steel temps not excessively hot, 800+. Whole process maintaining 500 and not overly hot at 800 with pieces going back and forth to the 500 degree oven (gas grille) took less than 2 hrs. Once we we were satisfied with the amount of filler both arms went back a 550 oven and the process of dropping the temp back to 100 degrees was began.

A 30 lb block of steel I had laying around at the shop was set on the cast crates in the grille as a large heat sink, Between the arms, that chunk of steel, the heavy steel production jig and the cast crates it took several hours to drop the temp down to 100 degrees 4 hours later.
The gas grille is now safely back at my house and ribeye after the yard work the agenda for tomorrow. Will clean up and finish the prep to get the arms to the powdercoater on Tues.
Did I mention I'm tired of this project.
But, almost done.
Bob

#1073800 - 05/01/22 04:07 PM Re: Front sway bar project [Re: mmc427ss]  
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It's going to be SO worth it!!!


Lance
1985 Monte Carlo SS Street Car
#1073833 - 05/05/22 08:26 PM Re: Front sway bar project [Re: mmc427ss]  
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Monday put the grinder and all the other metal finishing processes in the shop to use and got the arms prepped for the powdercoater. Dropped off the arms Tues morning, he called Weds morning, done, picked up today and staged a couple pics of how intense, time consuming, and costly getting a set of powdercoated arm to fit my car was. This puts an end to the long evolution to make arms that will fit the frame, not touch anything and hopefully hold up to possible 2000 lb of force. The pile of plywood and alum arms represent more than a dozen efforts to make something I'm happy with.
What amazed me most was how expensive and difficult to buy all the nickel and dime stuff was.
Time will tell how well they hold up to the abuse they will get.

Next is pull the LCAs, locate the link lower bracket and weld the brackets to the arms. Already have a very good idea of how the links, the arms and the LCAs will articulate. Expecting no complications on that part of the sway bar install.

One of the benefits of doing the entire three piece bar the way if was done is the old 36mm bar or any one piece G bar can go back in the car with only a little wrenching to remove the new bar. Only the bar bushing frame mounts would remain and they are in the way of nothing. Another is by just changing the bar on this new three piece bar virtually any rate lower than the current installed rate can be done with simple a bar change. And if an even higher bar rate is desired some rate can be added to the 1200lb/in going in the car.

Can't wait to see how this project pans out. Having put a few hundred miles on the car with no front bar at all and just 700 springs and DA shocks on my street setting and find it's better than just OK. Drives very well but roll in a fast corner I know that 36mm is not there.

My 275x40x17 Falken RT660 tires are sitting in the corner of this computer room were they hid from the cold for the past Winter. They need to find there way back to the shop for true Summer duty.
They also need to go on the car for final check of clearance between the sidewall and the new location of the bar/arm spline area. My old street tires, 255/50x16 when turned to full lock show enough clearance to the location. The RT660 have a wider section width, also 17" wheels slightly different offset than the 16" and so sidewall clearance needs to be checked.The stockish LCAs have adjustable stops to allow adjusting the tire sidewall to sway bar clearance. A goal of the project was to not reduce the turning radius anymore than I already have done.

As a side note to that whole relocate the sway bar rearward from the stock location reasoning. If a three piece bar was to go into the stock location tire sidewall clearance was one of the big issues. A three piece bar needs it's arms located outside the frame rails, tires need that space too.The turning radius would need to be reduced or you can't run a big fat tire up front due to excessive rubbing. Big fat sticky tires up front improve our cars.
The other reason to not use the stock location is the shape and working length of the arms requires a huge thickness bar when going to a three piece.
My old 36 mm bar with 12.5" arms is the fattest one piece bar available, guesstimate is 550 rate. A couple aftermarket one piece may be a tad higher rate, and just a silly milometer smaller in OD. Because the length of the one piece arm is near double my 7.75" arm a HUGE OD one piece bar would need to be made to even approach 1000.

I'm told I will be happy with the new setup. The old antique cars i see trying to make something work from something that is, outdated, they run fat bars, fat tires and young guys behind the wheels. Hoping two out of three ain't bad.

Will be registering for a June autox in the coming week.
Bob

#1073836 - 05/06/22 02:10 PM Re: Front sway bar project [Re: mmc427ss]  
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Get er done already!!!


Lance
1985 Monte Carlo SS Street Car
#1073838 - 05/06/22 09:21 PM Re: Front sway bar project [Re: mmc427ss]  
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^^ X2!

Bob, I know the frustration here, but when this thread is finished, I propose you call it, "How to Build a Sway Bar In Only 314,159,265,358,979,32,846,264,338,327,950,288,419,716,939,937,510,582,097,494,459,230,781,640,628,620,899,862,803,482,534,211,706,792 easy steps. Operators standing by. Batteries not included, items sold separately." Or, "How The Federal Government Would Build a Sway Bar So They Could Double The National Debt."

(I've been designing and building my next gen of satellite speakers for only 7 years now, so I know what OCD is all about.)

Last edited by MAP; 05/06/22 09:32 PM.
#1073840 - 05/07/22 12:05 AM Re: Front sway bar project [Re: mmc427ss]  
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^^ That's gold lmao


Enjoy life, family first!
#1073841 - 05/07/22 12:20 AM Re: Front sway bar project [Re: mmc427ss]  
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Ya know when I was working full time for a living i had a lot more free time. When I was retired near 6 years ago, retreaded as I call it, I was told everyday had become a Saturday. Well, have yet to get past Thurs, kinda stuck there, Hump Day, did get over that hump. But find way to many things now get in the way of getting anything done quickly. Hell, spent hours this week just sitting in doctor's offices.

As far as 7 quad zillion millions posts to arrive at simple sway bar arm doing what ya want it to do there's a couple reasons for pounding the keys to add to the encyclopedia of stupid knowledge only a few will ever need. I monitor the post hit count on subjects, this sway bar posts is near 12,000 "looks" in a little over 6 months, average of 2000 monthly somebodies are looking at it beside the couple hundred posts I've hacked out on the subject.
My thinking on the hit count for this subject on our forum is that the overwhelming number of people that look at, read, this post are not members on this forum. They are doing the same thing I am, searching for tidbits of info on a project and finding very little info out there. Forums were the info highway, storage platforms of info for car guys , audio guys, backyard engineers, they are all but gone now. Now replaced by social media which is only about today.
I still follow more than a dozen car forums, little new content, activity on par to here.

Secondly, for me posts are a notepad, diary be it, to store my thoughts on a current project. I look forward to criticism and critiques, it makes doing the project easier. Today it's hard to get any constructive backlash on anything. Many times I will wonder "what the hell was I thinkin". Recently I went back to the first days of posting this project to read my initial thoughts about this huge bar idea, that was June 2021. Again the logic of writing stuff down to compare notes later allow a fresh look at the end results.

And as we know finding any info on doing a three piece bar is all but known existent. If even only one guy has one brain fart from something he reads here, SUCCESS, that's what our forum is for.

Oh, by the way i hate one word answers. Even more so is a guy with a grotesque IQ with, Yeh, as the answer to a question. Can't even say Yes anymore.

Got spacers made for the lower mount's welding process. Mounts are 1/2" bolt, double shear, the width of the opening needs to be held at a specific width so the rod end and two rod end spacers fit snugly after welding. The welding spacer just insures that width doesn't change after heating.

Before LCAs are removed need to know the height relationship between the LCA -frame and sway bar arm- frame. Once the car is on jackstands at the #2 body bushing, the wheels, brakes, shocks, springs are remove and the spindle is again attached to the UCA and LCA you need to be able to raise the LCA to the ride height level.

At ride height two reference point needed between the LCA and frame or other location. One from the top of the frame to the bottom edge of the LCA. This looks like a reliable place. Second is from the top of the lower ball joint stud to a specific spot on the inner wheelhousing, 16 1/2". A wood dowel was fitted and marked at the well so it can go exactly the same location later.
Also before the jackstand install, sitting at ride height , the sway bar arm installed and the link end set to 0.00 degrees a marker is used through the 1/2" link bolt hole to make a point on the frame. No mater what the change in frame attitude/angle that point is used as the level arm at ride height reference.
With both the bar arm to frame and LCA to frame locations easy found the link length and the link's location on the LCA is pretty easy.

Will be able to measure and factor in the correction for angle change from ride height to jackstand height. Could be 10 degrees.

In the end the exercise is about optimizing link angle changes as all the pieces move in different direction from full compression to full droop. Once the procedure to located the lower link mount is understood, learned, calculated the rest is just some dirty fingers. One thing obvious as the birthdays add up is labor causing dirty fingers is harder to get inspiration for. Procrastination is easy.

I know, to many words again.
Bob

#1073843 - 05/07/22 02:49 AM Re: Front sway bar project [Re: mmc427ss]  
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Bob, just having fun, and, believe me, cheering you on!

#1073844 - 05/07/22 01:04 PM Re: Front sway bar project [Re: mmc427ss]  
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Some of the 2,000 clicks a month on this thread are from the people that I send here when they ask me on social media how I put a stiffer front sway bar on my G body. There have been quite a few actually as it comes up quite a bit.


Lance
1985 Monte Carlo SS Street Car
#1073847 - 05/07/22 03:35 PM Re: Front sway bar project [Re: mmc427ss]  
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Thanks Lance for the incentive to keep pluggin away on this tedious project. Have done dozens of projects, car, home, shop, at work that were off the beatin' path and required as much thinkin' as this one. Never one to turn down a challenge. The only difference is the complication that age has in gettin things done.

Never had typing in HS, they were to busy trying to learn me Trig, Latin, Spanish and other lessons I thought i would never need. The hunt and peck typing was soon replaced when I found some people, including me, actually were looking for help with car stuff. That was back in the last millennium when email mailing lists were the ticket. Forums that anyone could read replaced those "member only" reads. Now we are back full circle again and social media limits readership, and of course, content. And forums will fall to the way side, as the World Book, Colliers, Wikipedia, and most others have done. No need to save knowledge in print form, we are all enlightened now and what's for breakfast tomorrow is more important.

The soap box is cheap Chinese cardboard these days, can't stand on it to long.
Bob

#1073851 - 05/07/22 11:28 PM Re: Front sway bar project [Re: mmc427ss]  
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Bob, go easy on the soap box made from Chinese carboard if you break it might be backordered for months before you can get a new one.

#1073855 - 05/08/22 03:19 AM Re: Front sway bar project [Re: mmc427ss]  
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The past two days have been cold, wet, dreary, the first possible car show was today, a washout. Also today was a birthday party for three of us, my 9 year old, my wife and I at my daughter's home. There was conflict, car show-party-car show -party, how do you juggle that. The driving force to do the car show was the 9 year old. That was part of his birthday present, he rides shotgun in the 86 due to child restraint laws. I like when he rides shotgun, the smiles on his face have been priceless for years. You can't jump on the throttle enough, he may be a problem when he's older.

So after we watched an 80:1 win the Kentucky Derby I was sitting behind the kids new steering wheel for the Xbox. Finally they replaced a joystick with a steering wheel, it has paddle shift, and even three pedal on the floor. The steering response was nonexistent, at speed you couldn't control it. The first car I wrecked, destroyed, was one of Ken Blocks. Then the 9 year old goes into the program and changes the car for me. A ridiculously fast black 88 Monte SS with a Goodmark and black wheels. After just burning the tires off of it and tagging a guardrail a 100 times i was done with the Xbox.
The steering was poor at the very best but i think there is something in the reprogramming that can fix that.
https://www.e-pxn.com/products/racing-wheel/pxn-v9

Reason I mention spending time on a kids racing simulator is the technology is here and being used to breed race car drivers, has been for years. During the no racing NASCAR season cool simulators were "driven", "raced", in a competitive environment.
I wanted one of them armchair cockpits from the first time I saw one more than a decade before NASCAR raced them on TV.
So when my grandkids finally got a steering wheel for me to try I can see now i will need to help fix that crappie thing. Not sure if it needs a bigger sway bar at the front but can see there may be a tweak of the software that's helps.

Oh, that new toy steering wheel is much smaller than I'd like, but does have blue tape at 12 o'clock. My car doesn't have that tape, hmmm.
Bob

#1073875 - 05/09/22 11:55 PM Re: Front sway bar project [Re: mmc427ss]  
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Couple of pictures from start to finish on Bob's arms, it's quite amazing too me, hope he doesnt mind me posting them.

[Linked Image]

[Linked Image]

#1073885 - 05/10/22 01:42 AM Re: Front sway bar project [Re: mmc427ss]  
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That's a cool set up, the arms look great. When do we get the finished install pics?


Enjoy life, family first!
#1073886 - 05/10/22 06:00 AM Re: Front sway bar project [Re: mmc427ss]  
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The shop bay to do the rest of the bar install was freed up today. Bill's Tacoma was oil changed and tires rotated. Next the 86 is taken back to ride height for a couple measurements and then onto stands for the LCA removal. The goal is one week down time, Was over to see my TIG guy yesterday and warned him I will be back in his face by weeks end.

With knowing what the LCA, sway bar arm and link relationships are will be pretty simple be able to locate the LCA link mount and measure it's angles fore/aft and in/out of car centerline. Being the arms working length is relatively short, 7 3/4", it's necessary to check angle change through full range of LCA motion. This is easily done with only UCA, spindle and LCA to move, and they are on Delrin bushings, you could do it by hand on this car. Being both LCA need to be removed for link mount welding both sides will be checked to see if they mirror. Not that optimistic as these G suspension/frame are hardly mirrored.

Over the years this front suspension has been modified several times, nothing really stock anymore. Several years ago when the LCA frame pivot locations were moved to obtain high caster, this netted a very good camber gain numbers, the purpose of the project. Another benefit of high caster is the steering arm angle changed very favorable for bumpsteer.
Prior to that LCA relocation many years ago a new steering centerlink was made that lowered the inner tie rods with the intent of reducing horrendous bumpsteer when a B spindle is swapped into G-body. That centerlink mod was a big success at the time reducing bump from horrendous to acceptable.

When the LCA relocation was done after that centerlink mod the two changes to the steering linkage together made a very good bump curve, "plot" for a street car. So good in fact I had to make a very accurate bumpsteer gauge to check bump through full articulation, on just the right side of the car at that time.

As with most projects I do need to end the drudgery at some point and get the car back on the road for the driving season here. That LCA relocation was that way, get it done and move on. But months later after you have had the front suspension on my alignment rack a couple times you realize there may be some more improvement to be had in the only negative I have left of the B spindle swap. Lack of Ackermann.

Looking at doing bump checks on both side of the car, and will now plot bump change as the car goes through compression and droop. My car shows near zero bump through compression and very tolerable until 3" of droop when checked in the straight ahead wheel position.. I will check bump now when the steering angle each side is 20 degrees, in, and out,and at full compression, and at 3" droop. The goal would be to see if Ackermann gain, more toe out, can be obtained at 3" droop and remain near zero toe change through compression. Possible will need to make another centerlink and adjust the inner tie rod height again.

All of that part of the sway bar project has been on my mind since knowing the LCA will be off for like the tenth time. Have been thinking about that Ackermann improvement for a long time. Was never happy about the 1 1/2-2 degrees at 30 degrees i would see as static Ackermann on my rack. As a rule an autox car/street car will benefit with more Ackermann. Road course cars, drag racing, generally don't need much Ackermann. Oval cars use Ackermann to their benefit.

It's not a big deal after the sway bar link LCA mount is welded in to do bump through all the necessary movements. I already have another used steering centerlink sitting, ready and willing to cut up and play with new inner tire rod locations. Once you have done one centerlink mod the second time is easier. The guy that TIGed the new sway bar arms did the centerlink welding like 10 years ago. Deja vu.

Oh, when the DA Viking shocks went in the adjustments required fingers of very little size to get on the knobs to adjust Comp and Rebound. The shock holes of the stock LCA arm were opened up a little but this fat fingered person always had issues with making quick, easy adjustments to the front shocks. Laying under a lowered car, making those adjustments, difficult. So will look at removing more material at that location and maybe even adding some reinforcement so the access is much better. Just another mod with purpose.
Bob



Last edited by mmc427ss; 05/10/22 06:06 AM.
#1073891 - 05/11/22 06:33 AM Re: Front sway bar project [Re: mmc427ss]  
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Today had very little time to play with the car but enough time to formulate the process needed to get done quickly.

As the first baby step tomorrow the Falken 275/40x17 RT660 need to be installed on the car because everything done to the car going forward will be done to their specs and the wheel backspacing/offset. The 255/50x16 BFG Comp 2 tires are old, slightly smaller, slightly taller and slightly different offset, and the current any day street tires. The Falkens are the autox tires., fatter, shorter and sticky.

So as this final stage of the sway bar install is at hand the check the bumpsteer/Ackermann thorn in my side now needs to have due process to put it to rest. Need a plan of attack to do an accurate plot of how those apply to my car through full suspension articulation. Yes I watch to many videos of suspension junk and find there just isn't enough easily digested info out there to help. So another live and learn session.

Hard for me to do but, the CliffsNotes version.

Tires changed to Falkens, car rolled back and forth to ride height, ride height gauge measured and noted on fender both sides.

Toe angle measured using my toe plate method and noted. Car should show 3/32" toe out. Checked and changed several times but run a toe out as Cheater Ackermann. Knowing toe out set before anything is done to the car is important. Bump and Ackermann are toe changes while in motion.

Next is make solid blocks to hold the frame at ride height at the #2 body mount. Mine are 6 5/8 for the R side and 6 7/8" for the L side of the car. They will be used later to do bumpsteer gauge measurement but need to be fitted before any other playing.

Next car goes on my alignmnet rack, ride height set, current setup and the caster and camber is noted. Should be pretty even each side, +9.5 and - 1.25. Also max turning angle and each tires angle can be measured and compared L to R while on the turnplates.

All that data and process the car has gone through a couple times now. In the shop once the alignment rack is leveled not much worse time or effort than taking your car to a computer rack, and as accurate. But all that info is just "Static" info at ride height. You can watch camber gain, see steering angles but not what is happening at 3 degree body roll when the inside corner is at 3" droop and the outside corner is 1 1/2" compressed.
Same with bumpsteer, it's checked as the tires are pointed forward.

Jack the front of the car up and install jackstands, pull shocks, calipers, springs, LCA and get that lower link mount install done so you can paint it and back onto the car. Gotta get done with the bar project. Don't really expect anything more than optimizing link angle and how to weld the mount to the arm. No big deal, just a PITA.

Now with no springs, shocks or sway bar, only the LCA, UCA, spindle, rotor and steering linkage the car now get set on the two blocks near the #2 body mounts. This puts the car back at ride height sitting solidly on the blocking. A bottle jack under the lower ball joint, and front suspension can be raised to ride height. Install the bumpsteer gauge, zeroed it at ride height, bump is now checked at the straight ahead position. Some only check bump for a couple inches in each direction from ride height. This is how it's done typical and numbers are produced. On this car last time checked it was .020" out at 4" droop and .078" out at 1 1/2" compression. That was one side, double it and add 8% because of tire OD and numbers become .043" out droop total and .168" out total compression. In anybodies book very good numbers for any car, let alone what has been achieved with a B spindle.. The plot on paper of bump on a G-body steering linkage is not straight, it's an arc. You can manipulate the arc plot but you can't straighten the arc.

Once the straight ahead bump is recorded the next steep is try and measure bump while at 20 inboard and outboard at each wheel while moving from 1 1/2" compression to 4" droop. This will indicate what change has happened to the toe under those condition. I'm sure others have gone to this extreme but there ain't no U-Tube video on that. Getting and logging that data will tell me if my last remaining mod for a B spindle into a G is a go or a no go.
It's just a piece of unfinished business, the B spindle swap i did near 25 years ago and have been trying to fix since near day one.

Should be able to get all that done in short order, most of the thinking is done. Still think i may have the arms back from the welding by the weekend.
Bob

#1073892 - 05/11/22 12:49 PM Re: Front sway bar project [Re: mmc427ss]  
Joined: Dec 2007
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SSLance Online content
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SSLance  Online Content
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Peoria, AZ
I have done a similar excersize with the front springs pulled Bob. It really gives you the total picture of what's going on dynamically.

I wouldn't worry about 3 degrees of roll though, 2 degrees will be a lot for you going forward. laugh


Lance
1985 Monte Carlo SS Street Car
#1073896 - 05/11/22 09:02 PM Re: Front sway bar project [Re: mmc427ss]  
Joined: May 2002
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MAP Offline
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Yuma, AZ
Hi Bob,

Just a few quick thoughts: assuming a stock front track width of 58.5", 3 deg of roll in the suspension will give you 3" difference in L/R ride heights. With 3 deg of body roll, something like 1 deg of that will come from differing L/R tire compressions, so you're looking at roughly 2 deg in the suspension. 3" of droop on one side and 1.5" of compression on the other (implying a very non-linear suspension stiffness btw,) come closer to 4.4 deg of suspension roll, or about 5.4 deg of total body roll.

About bumpsteer, the arcuated trace comes from errors in linkage lengths. The overall inclination of the arc comes from errors in the heights of linkage pivot points. Both can be corrected if you're sufficiently determined.

As you know, Ackermann is always a loosey-goosey thing that varies dynamically and is never perfect for all driving scenarios. Too little Ackermann at low speeds can be too much at high speeds, but everyone agrees the stock A/G body design has too little at all speeds. Of course, with the car's original billowy tires and the prevalent gentle driving habits back in the day, it really didn't matter...

HTH

Last edited by MAP; 05/11/22 09:16 PM.
#1073900 - 05/12/22 06:30 AM Re: Front sway bar project [Re: mmc427ss]  
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Yes the 3 degrees of body roll was just a number I threw out there. Would think even with the old bar it wasn't 3 degrees.

About bumpsteer and steering linkage. The location of most all the moving parts of the lineage will not allow correcting. The steering box/pitman arm and the idler are not mirroring each other, and never can be. .
The centerlink is not symmetric, this to compensate for the pitman -idler misalignment. One side of the linkage doesn't move exactly like the other side.
The steering centerlink needs to be moved rearward to help fix the Ackermann, the crossmenber gets in the way.
A small diameter wheel doesn't allow the spindle steering arm (outer tie rod) to be located outboard enough to get Ackermann. Minimum of 17" wheel needed to gain tie rod clearance.
Location of all the tie rods contributes to never being able to make it close to perfect.
They also are the reason the plot of the bumpsteer will always be an arc. You can tweak the decrease of bump as in reduce it, you can move the crossover point of the arc up or down on the plot, but you will never make it a straight line plot and not an arc.

Today ordered a Moog DS909 centerlink and one Moog lower ball joint. The sway bar mount to the LCA is going to be close to the ball joint, and the boot. Removing the boot for welding should be done but boot damage is possible. The Moog lower ball joint on the left LCA has been a leaker since I installed it less than 4 years ago. Will most likely install the new Moog there now that the arm will be out of the car.
The new centerlink needs to be on hand if I'm so possessed to think i need to cut and install tie rod slugs in it, for bump adjustment.

Did a tire toe check first thing at the car this morning and it was 1/16" toe out. Less than I thought but know after the last autox on those tires last year i reduced the toe out because i didn't like the way the RT660 tracked on these crappie Pa highways, it didn't help. Some toe in instead of toe out if the car would just be for the street would track better. Excessive static toe out nets good results on this car, cheater Ackermann. Gaining Ackermann via cheater bumpsteer instead of toe out is the current thinking and seeing if it's possible, and worth the trouble.

Today got the four fun tires installed on the car. You kinda forget there's a little maintenance on the rear drum setup that needs to be attended too. It's a once a year thing, scuff the inners of the alum drums with some 80 then a spray rinse of the drums and that black dust on the rest of the brakes back there. Blow dry and lacquer thinner the linings and drum inners. Black dust is from the lining I've run for years, Praise Dyno, now Muscle Car Brakes, a good rear brake package starts with good brake material. Just swapping out the rear tires today became a chore, but done for a while now.

Next is set the car down onto my home brewed alignment rack after all four tires are on the car and air pressure is 32 x 4. It's some what tedious setting the car up on the turnplates and the 2 X 12 x 36" plywood rolling surfaces. As picky as I am about measurements it take many roll-in, roll-out onto the turnplates until I'm happy with the setup. Once you have the plates as close as possible mirroring the car front wheels level in two planes and symmetric and you can you mark the turnplate location precisely on the floor and starting checking the camber, caster, camber/caster relationship. Not planning to change anything before tearing the springs and shocks and LCA out of the car.

Visited my TIG guy tonight. I took him a gift, he broke his 25 year old Smith Argon Flowmeter on his TIG bottle. I got him a brand new one for very reasonable. Also he wanted to see the arms after they were powdercoated. We both agree i should have had him fill a few small voids in the surface after my grinding/finishing process. I do feel the touchup welds would only be of cosmetic, not strength benefit. Everyone seems to think the arms heft is more than ample, should be fine.

Weighed the complete arms, 1/2" rod end links, bolts, spacers, washers and nuts and lower mount going on the LCA, 10.25 lb. Calculated the weight of the sway bar weight in car now and it's 12.5 lb. Another lb for the bar's frame mount and total for this new bar is 23.75 lb. Weighed the 36 mm bar removed and everything associated with it's install at 17.25 lb. Yippee, just added 6 1/2 lb to the front end of this already fat front suspension. At least it's moved 5 3/4" rearward at it's new location.

Onward.
Bob

#1073901 - 05/12/22 08:01 PM Re: Front sway bar project [Re: mmc427ss]  
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MAP Offline
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Yuma, AZ
About correcting arcuation and arc tilting: to quote myself, "...both can be corrected if you're sufficiently motivated." That encompasses even going so far as trashing the entire OE front end, which I don't believe would be a bad thing to do and probably would have saved you time and money in the long run.

#1073902 - 05/13/22 03:46 AM Re: Front sway bar project [Re: mmc427ss]  
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You would think there would be a bolt in rack and pinion that would be better than the present stock system. Unfortunately there isn't, why, for the same reason the stock system isn't very good, the crossmember would need to be moved back to make room for a rack. There is a way to fix that problem, Schwartz and Roadster Shop fixed it, an entirely new design chassis with no stock parts and a price tag to go along with it.

Got all the static alignment numbers from the car today. Virtually the same left and right. And what i set almost 4 years ago when I did the LCA relocation. That tells me the mods and welds and all that thinking back then has stood the test of time and near 10K miles.
Toe was 1/16' out.
Camber - 1 1/4, Caster +9 3/4
Camber at 20 degrees in -3 1/2
Camber at 20 degrees out +3 1/2
Ackermann at 30 degrees is only +1 degrees to the inside wheel. This is the area I'm looking at to improve.

Got to the point tonight of the left side coil spring is out and new sway bar arm and link hanging on the bar, Tomorrow will pull the right side apart then it's set the car back at ride height and locate the link lower mount to the LCA. Moving the suspension through full travel is easy now, can really see how the link angles are going to move. Should have both the LCAs out, paint removed from mount areas and hoping to have a plan to build up the arms to accept the mounts. Once the LCA are laying on the bench for mount work the rest is easy.
About time, I know.
Bob

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