MonteCarloSS.com
MonteCarloSS.com

CELEBRATING 20 YEARS!

Previous Thread
Next Thread
Print Thread
Page 4 of 5 1 2 3 4 5
#1064815 - 01/18/20 08:51 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: May 2002
Posts: 4,060
MAP Offline
15+ Year
MAP  Offline
15+ Year
Member

Joined: May 2002
Posts: 4,060
Yuma, AZ
Hi Bob,

As a rule of thumb, if the spring is a true helix of constant pitch, made of a wire of isotropic material properties and consisting of constant diameter, it will be linear (i.e., possess constant stiffness) nearly to the point of coil-bind.

Other things being equal, the latter two qualities are usually essentially true, so spring linearity can usually be deduced from wind geometry alone. HTH.

For a deeper dive, go here:

https://www.engineersedge.com/spring_comp_calc_k.htm

For springs that aren't simple helices, like the rear springs of an A/G body, you can approximate net spring behavior by dividing the spring into representative sections that are individually linear, and then adding the compliances (= reciprocal stiffness) of the sections to get the compliance of the whole spring. Then invert the expression for summed compliance to get the total stiffness.

Best,
MAP

Last edited by MAP; 01/18/20 08:59 PM.
#1064822 - 01/19/20 04:44 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Thanks Mark. Have a pretty good understanding of the linear springs. What I'm trying to understand is how these nonlinear spring will behave.
A linear will, should, show the same rate from a little preload, to it's rated load compressed length. And actually should show the quoted rate to coil bind.

Even though the two non-linear, progressive or dual rate, as some call them, springs I'm testing have different rates, wire diameter, OD, number of coils low and high rate from end to end is it the distance between the coils causing the progressive rate, coil bind in the few close coils is assumed the cause to transfer to the higher rate. I need to see how they transitions from a lower to a higher rate. Need to see that happening and at what compressed length the rate change and is it gradual. Knowing how and when that happens timed with the droop and compression caused by body roll is how UMI/Drago and the engineers at Hyperco/Ridetech came up with how many coils to make close together and how many not to. Now you factor in the sprung load which can change from from car to car, producing what compressed length, at what ride height, to try and find that point that the progressive spring rates change. Making an inexpensive tester will give me the visual this blind guy need to see.

40 years ago installed Moog Cargo Coils on my 69 C10 pickup. I get progressive springs. Back then I didn't care about the effect on body roll, it was about overloading a 1/2 ton pickup truck. Now I'm trying to figure out how they may help cornering in my case, or as some say cause unpredictable handling. Unfortunately the sellers of non-linear rear springs for our cars to improve handling, Ridetech, BMR, Hotchkis, Eibach, UMI, aren't much help with the math, talked to them all. What I need to know will come from my trial and error.

Months ago when i started to over think this project part of that was due to that coil spring engineer at Hyperco and our discussion about spring rate and body roll effect. Hyperco makes Ridetech's "dual rate" rear G spring, which was collaboration between those two companies. If Ridetech is one of the companies at the forefront of G handling why an expensive "dual rate" spring in the rear. Yes they would like to see coilover on your G but they spent the time and effort to deal with Hyperco to produce their 11324799, which is rear spring for their Street Grip package.
https://www.ridetech.com/products/s...etgrip-dual-rate-rear-coil-springs-pair/

A note on the pic of that spring, it not a pic of the 11324799 spring which is double pigtail. You would think Ridetech would have the correct spring pictured.
Another note on the Ridetech, if installed at 12" free length, no shimming, my car would be 1" lower in the rear. To low for the roads I travel. But if the car was solely a parking lot cone dodger it would be a good height. There is a one inch shim at each spring used to raise ride height. How does that effect transition of rate at my ride height.

This UMI spring is not a G spring, it's a 3rd-4th Gen F spring and it's non-linear, progressive also. Because it's not engineered for the G seeing how it transitions is also needed.
https://www.umiperformance.com/home/product/1993-2002-gm-f-body-lowering-springs-rear-1-5-lowering/

Even though my math skills are pretty good visually seeing something work is what make me tic.

Found a free bottle jack to use on the rate checker instead of the floor jack. Tomorrow snow is gone, life back to normal. Will inventory the steel laying around the shop and layout the pieces to the be cut. Nice to be retired, you have time for silly projects.
Bob

#1064893 - 01/23/20 09:25 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Some may wonder why go to all the trouble of taking a quality progressive rear spring with an as advertised dual rate of 150/250, Ridetech, and the progressive UMI F-body spring and build a rate checker to test them. As mentioned it was the discussion with the Hyperco engineer about the theory behind the "dual rate" that made this inquiring mind want to see for himself. For the type of driving the 86 is used for, mostly a touring car, and the need to fix the "loose in" rear without cutting up the frame or body, playing with springs is an option.

Again here is the read from Hyperco about the who and why of progressives.

https://www.hypercoils.com/tech-tips/linear-vs-progressive-rate-suspension-springs/

Below is the pertinent paragraph,
"The second type of progressive rate suspension springs, the dual-rate spring with two linear rates connected with a rate transition range is a much more sophisticated suspension spring. The design is much more focused on the specific use for the spring. These types of springs are used primarily in road racing and high performance street and GT applications where the vehicle trim package will stay in a very predictable range. These springs are easily identified by having a few closely wound coils at one end and then wider, equal spaced coils at the other end. They have rates described as 200/425lb/in. This means that the spring has an initial rate of 225lb/in through some range of deflection and then the rate transitions to 425lb/in through a deflection range of 1”-1.5.” The big advantage of these springs is that they can provide “roll control” in addition to roll control provided by sway bars."

The transition of rates, an inquiring mind wants to know when. Did I mention a pair of Ridetech springs weights 19 lbs. Both the UMI (100/200) and old Global West (130) rear springs are 9 lbs, A PAIR, a lot more steel in the Ridetech. Was able to check the 1" to 2" compressed range on all three springs on the bathroom scale checker prior, Global was 1"= 130, 2nd inch = 129, UMI 100-100, and Ridetech 100-100. Another reason to do a recheck of the Ridetech on the new checker, should have been 150-150. Did I mention there is not a lot of help out on the information highway. Lots of videos on shocks, springs, advertisements, car mag stories, builds, but really not much on progressives. Most all the susp parts venders sell a progressive somewhere in their coil spring options, front or rear or some sell progressive for both ends of the car.

After a day of playing with the old antique horizontal band saw to get it to cut straight got it working satisfactorily. After a few trips to various places to find a new blade ended up at Eastwwod which is a little more than a well struck golf ball with my driver from my house. They sell the same saw I have, just re-branded it. Walked in, 10 minutes later walked out with a new blade. Bingo.
Making the rater out of 1 1/4" x 2" x .080" wall tubing recycled from a piece of work out equipment along with some angle iron and 1/4" x 4" flat. Should be more than substantial to run up to 800 lb, and have safety figured in so the springs don't pop out under load. An old 3 ton bottle jack sourced from my brother for free keeps the material costs to zero. Just had to buy the Sherline gauge. All 15 pieces of the rater are now cut, and fitted, just need to find some good glasses so I can see while MIG ing. Should have it all glued together by the weekend.
Bob

#1064898 - 01/24/20 02:09 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Apr 2011
Posts: 989
Hunter79764 Offline
Member
Hunter79764  Offline
Member

Joined: Apr 2011
Posts: 989
Grand Prairie, Tx
This reminds me a lot of something my grandfather would have done in his retirement. "If a man built it, another man can figure it out" and build one himself. Maybe one day I'll have the work room and the scrap pile to take on some stuff like this.

Keep up the good work, Bob!


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
#1064899 - 01/24/20 03:45 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
Posts: 6,080
SSLance Offline
10+ Year
SSLance  Offline
10+ Year
Member

Joined: Dec 2007
Posts: 6,080
Peoria, AZ
I was working on sway bar rates last night and got to thinking about how I could use my 4 post lift and my scales to check the rates on the 3 different holes on my rear bar...and it hit me that this might also work to check spring rates...

Use lowering the lift to squeeze the spring down onto the scale. Just have to be careful it doesn't pop out is all right?


Lance
1985 Monte Carlo SS Street Car
#1064902 - 01/25/20 06:10 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
I'd be a little leery about dropping the lift down onto the spring, you need to be a little careful and anchor the top and bottom of the spring. Also it would be hard to measure the decreasing length accurately. The good thing about a linear spring is you only need to measure about 2" of compression. So a 600 lb front spring becomes 1200 + a little prelaod, it like a bomb ready to go off.
Rear springs usually much less rate, 200 or less. With the rear springs I'm testing will need to do upwards of 800-900 lb max because needing to do 5"+ ofcompression on the progressive springs. .Safeguards have been done to the rater to prevent that bomb from going off. By changing the 1000 psi gauge to a 2000 the rater will be able to check a 700 front spring to 2" compression, 1400 lb load. The rater will be able to check my 700 front springs if I every need to tear the front end apart again, hoping not.

Yep, have thought about what it would take to check sway bar rate while using the tongue weight gauge I bought. It can be done, just don't have the energy to think about that right now. When I bought my adj Pro Tour bar from Marcus we talked about what it's rates were, Those number have slipped through the cracks in my brain, but do know at it's softest setting it's WAY more rate than a stock bar attached to the LCA. There are calculators on the web to calculate the rate given measurements.

Got the MIG out today and found out my eyes are bad, had a hell of a time seeing the weld. Will need to fix that problem before proceeding. My self-darkening lens gave me fits last time I had to weld, switched to just a lens. A trip to the store tomorrow to get a #5, just kidding, will try a 10. Stopped by my local chassis guys shop tonight, he said bring it by next week and he'll TIG it. Wanting to build the rater in house, cheap, strong, and all done on my bench I hope the ego doesn't get in the way of good welds. Would love to have it TIGed, but why did I buy an expensive Miller.
Bob

#1064913 - 01/26/20 04:57 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Tied to find a #10 lens for the welding helmet today, Eastwood, Lowes and Depo no go. Sat my local welding supply is closed. Back to the shop and recharged the auto darkening #10 lens I removed awhile ago thinking it wasn't working right, These lens need to be charged via the photo cells, guess the batteries were low. Removed the gold #12 lens from the helmet that I couldn't see with, installed the auto-dark lens, bingo, I can see again.
Laid the rater parts out on the bench, clamped it together, welded it up, done. Not that hard when you can see.

Was getting late in the day but decided the need to see it in action was more important than diner. Ran some tests on the lower rate UMI springs to get an understanding of how to get good numbers. What I found was the 3 ton bottle jack, got for free, doesn't have a long enough stroke, 5 1/2", which I knew may be a problem.
Knowing that the distance between the frame and rear's spring mount at full droop is about 14" the rater is then setup to have that length with no preload on the spring. The two springs when tested are installed in the rater with the top and bottom cushions or spacers that gave the correct right height when they were installed in the car. The spring is then compressed to get a little preload on the spring, about 25 lb. Then going one inch at a time the rate for that is measured until i ran out of stroke on the bottle jack. Using that method I was only able to get readings to 9 1/4" compressed, the goal is 7". At that 9" rate was 600.
Preloaded the spring 2" using the screw height adjuster on the top of the bottle jack piston to increase the total compressed spring length but was now starting at 12" installed spring length instead of the 14". Was now able to compress to 8", which netted 760 lbs. But you lost the ability to easily, accurately, compress the spring from that 14' number to the 8" without readjusting the usable range of the jack. Not an accurate enough method.

So next is find a double ram high lift jack to do the complete travel I'm looking to get. Found this one on ebay tonight, a quality Ford jack. Can't believe i said that. But it's range of operation is exactly what's needed. Will double check that tomorrow before buying it.
Previously when drag racing and having to change rear tires to slicks, and autox installing Hoosiers, had to carry a scissors jack to events. My Lincoln floor jack is WAY to heavy to leave the shop. That F250-F350 ebay jack would replace that scissors jack, hmm, another reason to buy it.

https://www.ebay.com/itm/NEW-OEM-Ford-4-Ton-Yellow-Bottle-Jack-10-Stroke-F250-F350-Super-Duty-Truck-Van/174067546899?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D20131231084308%26meid%3Dc7878e9c77534366ad1e7466132472c7%26pid%3D100010%26rk%3D1%26rkt%3D12%26mehot%3Dpp%26sd%3D352609259376%26itm%3D174067546899%26pmt%3D1%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100010.m2109

Progress made. The coming week should be able to get some numbers from these springs now. Don't you just love it when a plan comes together.
Bob

#1064926 - 01/27/20 02:58 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Apr 2011
Posts: 989
Hunter79764 Offline
Member
Hunter79764  Offline
Member

Joined: Apr 2011
Posts: 989
Grand Prairie, Tx
Don't be too hard on Ford, even the bling squirrel finds a nut now and then... They got the '32 body right, Model T assembly, the 9" and 8.8" rear ends, Starter Relays, and apparently a good bottle jack. Not bad for over a century of operating a 2nd class engineering group... wink

But seriously, you have me looking at trying to find one or two of those yellow jacks for use around (and under) my house.


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
#1064928 - 01/27/20 05:52 PM Re: Rear spring options for handling [Re: Hunter79764]  
Joined: May 2007
Posts: 4,773
Buick Runner Offline
10+ Year
Buick Runner  Offline
10+ Year
Member

Joined: May 2007
Posts: 4,773
Dharma station 1 the Hydra
Originally Posted by Hunter79764
Don't be too hard on Ford, even the bling squirrel finds a nut now and then... They got the '32 body right, Model T assembly, the 9" and 8.8" rear ends, Starter Relays, and apparently a good bottle jack. Not bad for over a century of operating a 2nd class engineering group... wink

But seriously, you have me looking at trying to find one or two of those yellow jacks for use around (and under) my house.


Their Panther platform is pretty good.


SBC powered 1987 Regal with TES headers, ZZ4 intake, ZZ4 PROM chip, mini starter, THM2004R, 2500 stall converter, 2040 cam, CCC system, and 3.73 posi rear.

2008 ex NPS P71 Crown Victoria, cop motor, cop shocks, cop brakes.

Never argue with an idiot.
They will just drag you down to their level and beat you with experience.
#1064934 - 01/28/20 01:29 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Ordered the Ford bottle jack last night, should have by the end of the week. Not having the necessary travel needed with the old jack put a hold on the project.
But did throw the Ridetech 150/250 springs on to get a quick look at the rates and the first thing noticeable was the first three inches were 100 psi per inch, same numbers I got from the bathroom scale method I used earlier. Hmmm, not 150?

When the new jack arrives it will give the ability to log rate from full droop spring length, 13" and 12", to a compressed length of less than 6" without changing the setup in the middle of a spring's test. And be able to log it 1/4" at a time. Repetitive runs and logging hopefully will show just where the transition of rates happens, the reason for building the rater.

Sent Lance a pic of the rater as it sits currently with the old jack, maybe he will post that pic.
Bob

#1064948 - 01/29/20 05:22 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
Posts: 6,080
SSLance Offline
10+ Year
SSLance  Offline
10+ Year
Member

Joined: Dec 2007
Posts: 6,080
Peoria, AZ
Check this out!!

[Linked Image]


Lance
1985 Monte Carlo SS Street Car
#1064950 - 01/29/20 06:59 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Mar 2012
Posts: 777
MC96 Offline
Member
MC96  Offline
Member

Joined: Mar 2012
Posts: 777
St. Johns MI
Nice! Looks just like the one dads childhood buddy gave us. A National Dirt Late Model Hall of Fame inductee!


86 SS
400SBC, 4l80e, MSD Atomic injection/trans controller, Tilt glass clip, all tubular arms, corvette brakes, 9" rear
In progress
#1064952 - 01/30/20 05:27 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Yea, mine is kinda a copy cat to a DECO sold by Speedway.
https://www.speedwaymotors.com/DECO-Hydraulic-Coil-Spring-Rater-0-1000-Lbs-,231.html

Of the four raters available, Longacre, Intercomp, DECO and Larson none had the stroke necessary without mods to do 7" of compression. To check the progressive springs I have you need extra stroke, 4" and 5" isn't enough. Some aren't wide enough to do a 6.75" OD G body stock rear spring. All would require adapters to be made to do double pigtail springs.
So making a rater to do A,B,G, F-bodies front and rear up to 15" free length had to be done. It would have been nice to be able to find a digital scale to use but the tongue weight scale from Sherline will be lent out to a few guys I know that trailer, so that 130 bucks wasn't a waste. The hydraulic gauge setup will give me the info I need, just maybe not 2% accurate like the digital,
The material costs were 130 for the Sherline, 40 bucks for an Ebay bottle jack, and 10 bucks for all the steel/5 bolts/can of Rustoleum. So 180 bucks for the new toy.

Was only going to paint only the welds to prevent rusting but shot and whole thing today satin black. The steel tube was already powdercoated but painted over it anyway. New bottle jack hoping to have Fri. Had a nice very old alum 18" ruler that got re-purposed, bent so it wraps around the side of the rater, attached with black duct tape, and allows accurately checking compressed distance. That required some time to make that ruler straight again after braking the edge, it was a hard alum. Using duct tape allows zeroing the starting compression point for any spring length.

So rater is done, next find out what those two progressive springs really are all about.

That stainless steel sink in the background, 100 bucks at the scrapyard 25 years ago, great for washing tires and a hundred other things.
Bob

#1065008 - 02/04/20 06:49 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Spent a bunch of time with the rater running numerous compression cycles on the two progressive springs. About ten runs on each spring from 13" to 7" compressed length by 1/4" increments. First 5 runs were to insure that the method/procedure would give accurate results. A digital scale would have been much easier to get the dead on numbers. But the analog 1000 lb gauge even with markings at 20 lb was pretty easy to get good numbers to 5 lb.

Once I had numbers for the two progressive springs one of the old Global West 129 lb linear springs was pulled from the car and ran on the rater to see if the results mimic a 129 linear rate. They were ran three times from 13 1/4" to full compressed at 7" and being linear were very close to stated rate of 129 per inch. First run was 128, second 126, and third run 126 average per inch of compression. So with those numbers verifying the accuracy of the rater and I can say the numbers got for the two progressive springs are probably very accurate, + or - maybe 2%. Can't see it from my house.

Next is to find unsprung weight to determine compressed length of each spring. After some on the car measurements of the old Global spring at ride height, then running that spring on the rater set at that installed compressed length it was determined that the spring is seeing 575 lbs of load. This was the same number I had estimated before starting the rater project, 575. The 575 number can now be used to look at the progressive springs at 575 and then figure out how they transition between rates.

Should note here that there is a world of physical difference between the UMI 100/200 spring and the Ridetech 150/250 springs. UMI has a smaller OD wire, has small coil ID, weighs 4 1/2 lb, has three low rate coils, four high rate coils. The Ridetech has larger OD wire, larger coil ID, weighs 9 lb, has 5 low rate coils, has 3 high rate coils. So the Ridetech should be a hefty spring compared to the UMI.

What is funny is the UMI compressed rates was higher than the Ridetech from the starting point of 13" all the way to almost 8" compressed height before the Ridetech's 250 high rate took off. Another thing funny is the Ridetech checks in at 100-115 rate for the first 3" of compression before it starts to rate climb. The UMI is also 100-105 for the first 2" then goes to 125 for the third inch. The Ridetech spring doesn't catch up to the UMI rate until almost 8" then it goes sky high. The rater's gauge only goes to 1000 lb. At 7" the Global 129 is 825 lb, the UMI 100/200 at 7" is 930 lb, the Ridetech would bury the scale on the gauge and was limited to 7 1/2" compression and was 940. Projected to be 1080 lb at 7". All the rate on the Ridetech is got in the last two inch of travel.

My rating of these two spring from the numbers I get are the UMI is a 100/165 spring. the Ridetech is a 100/250-275 spring.

After getting all the data points made a graph plotting their rates at given compressed length for the UMI, Ridetech and old linear Global 129 spring.
Knowing now unsprung is about 575 lb, compressed length of the Global installed is 9 1/8" at ride height, that point on the graph can be located and then try and figure out each springs rate change impact before and after that point. That next on the list. Trying to figure out if either of those progressive springs will do what I want.

There are other options for rear progressive springs to look at, BMR and Moog in particular. Also thinking with now an in to Hyperco could have a set made to order.

Spent a week making the rater, pretty much done with it now, will tuck it away on a shelf somewhere later in the week. By just installing a 2000 gauge in the unit can do linear front coil springs to 700-800 rate in the future. Oh boy.
Bob

#1065013 - 02/04/20 02:51 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
Posts: 6,080
SSLance Offline
10+ Year
SSLance  Offline
10+ Year
Member

Joined: Dec 2007
Posts: 6,080
Peoria, AZ
I'm curious where in travel the RT springs hit the really stiff rate? Like actual fender height... That has to be almost like hitting a bumpstop.


Lance
1985 Monte Carlo SS Street Car
#1065024 - 02/04/20 11:58 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Lance I'll email you a couple pics of the rate measurements and the graph. What I see is the Ridetech is the least rate of the three springs all the way until about 1/2" compressed from ride height. It has less rate than the UMI and even the 129 linear during droop. I'm still trying to figure all this out.

I know you four corner scaled your car, have you ever guesstimated the sprung weight at the rear tires. My car scaled at 782 left rear and 786 right rear several years ago. My guesstimate is 575 sprung weight per side.

Today stopped at Buckwalter's shop where they do the 1/4 midget cars and larger dirt cars to show Tim Buckwalter the home built rater. This is the shop I stopped at 2 months ago hoping they had a rater I could use. His spring rater couldn't do anything but a coilover spring for midgets, they are short, not large OD and all are linear so his rater works for him, wouldn't work for me.. Except now he's looking to do a complete coilover shock, (spring and shock) and be able to compress much more than the 4" his rater does. This way he can setup coilovers in the shop before the race. He asked it I could build him a rater to do a 20" coilover. rater. Oh boy.
There is a coilover rater available.
https://www.intercompracing.com/coil-over-spring-rater-p-117.html

Don't think i have the interest in building another rater although it's just a matter of heim joints at each end and a bigger rater to handle +20" of shock length.
Bob

#1065027 - 02/05/20 01:01 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Mar 2012
Posts: 777
MC96 Offline
Member
MC96  Offline
Member

Joined: Mar 2012
Posts: 777
St. Johns MI
"Smashers"
Accuforce has the best one going right now.

Dirt late models dont corner scale any more, they just get thier smash numbers correct and bolt them on and race.


86 SS
400SBC, 4l80e, MSD Atomic injection/trans controller, Tilt glass clip, all tubular arms, corvette brakes, 9" rear
In progress
#1065050 - 02/06/20 08:02 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
No wonder Buckwalter asked if I could make him one, Smashers aren't cheap. Looked at several of those Smashers and videos and yep, ain't cheap. But makes coilover setup for the roundy-rounds much easier.

Being the need to know guy I am just got off the phone with BMR Suspension and ordered a set of SP092 rear springs used in 3rd-4th gen F body. They are a stated progressive 100-210 spring. Free length is a tad longer than I'd like at 13.625" but the nice thing about the tangential top on the F springs is they can be shortened. Will run them through the spring rater and see where they transition from the low to high rates. Already having the upper F-body seat they are a drop in for the SS. Will install them and see how they sit for ride height.

At the start of this spring quest the intent was to increase rear spring rate when the rear compresses and decrease rate going into droop. The rater was built for the purpose of finding that crossover and verifying the stated rates of the springs sold. What i found was stated and actual rates are different. And no one can tell you were the crossover point is.
So another set of springs is on the way to test.

May need to have a yardsale to thin out the coil spring and swaybar pile.
Bob

#1065052 - 02/06/20 08:34 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
Posts: 6,080
SSLance Offline
10+ Year
SSLance  Offline
10+ Year
Member

Joined: Dec 2007
Posts: 6,080
Peoria, AZ
I should send you one of my TJ rear Jeep springs to test...


Lance
1985 Monte Carlo SS Street Car
#1065061 - 02/07/20 06:20 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Not a problem, you know where I live. They were on before the coilovers? Any idea what the free length and rate are?
Bob

#1065086 - 02/12/20 12:58 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Mar 2012
Posts: 777
MC96 Offline
Member
MC96  Offline
Member

Joined: Mar 2012
Posts: 777
St. Johns MI


86 SS
400SBC, 4l80e, MSD Atomic injection/trans controller, Tilt glass clip, all tubular arms, corvette brakes, 9" rear
In progress
#1065091 - 02/12/20 11:05 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Thanks Mason.

BMR Susp. SP092 rear springs showed up yesterday. These are their progressive spring,1 1/4" drop for a 3rd-4th Gen F-body, a rate of 100-210, and a free length of 13 5/8".
https://www.bmrsuspension.com/?page=products&productid=1684&superpro=0


Today servicing my 25 year old Astro got in the way of not having much more than 10 minutes to play with them. Yep, 13 5/8" free length, add another 3/4" for cushion and the F insulator, 14 3/8" installed. A little long to fit easily in the 14" space without removing a shock.

Put the spring on the rater just cause I had to. Made a couple very quick passes from 14" compressing to about 8 1/2", the gauge was heading to the 900. Hmmm This spring is 5/8" longer than any of the three springs I have now, two 13" and one is 12". So on the rater set at 14" it already has a fair amount of preload where as the shorter springs require compression before they have preload depending on the spring. It appears the 100 low rate may be 100 and the high rate does appear to be 200 or so.
The quick test of how this spring will fit my car for installed ride height is pretty easy. Install the spring in the rater, compress it to 575-600 and look at the scale. That ride height number is 9 1/8", that is the distance from the seat of the rear's mount, to the seat area on the frame, with the car at my 27" ride height.

Two very quick pulls on the gauge at 9 1/8" and the BMR was way over my 575-600 lb, can't remember just how high it was, surprised, 150-200, my first thought was did I have cutoff discs so I can shorten this thing a 1/2".

Might get back to the shop tonight to run several passes to get accurate numbers on this spring. I do know it's installed length needs to be shorter or come up with a thinner insulator for the top of the spring. Cutting the spring to adjust ride height probably will be done. That cutting is done on the top low rate coils, so removal effects that kick in point also.

More fun.
Bob

#1065110 - 02/14/20 05:05 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Ran the numbers on the BMR spring and they show a 100-200 rate, within my 2%. error range. Being a longer spring at 13 5/8" using the same spacer/insulator setup as the UMI 13.1" spring the BMR is about 140 lb higher at that 9 1/8" compressed height. Had to back off the compressed length by 1/2" to get to that 575-595 load rate at ride height , so spring is about 1/2" to long.

Pulled the Global spring out of the left rear today, stuck the BMR in, yep 1/2" higher.

Next up is a cutoff wheel. Cut 2" off the open end of that spring, pop it right into the rater and see the change. Don't have to install in the car. Nip it again and repeat. A final trim or shim can dial in the 27". Because the cutting is done on the low rate end this will effect the timing of when the high rate starts to kick in. The BMR spring along with the others are sacrificial, not having any remorse cutting a never used good spring. On the plus side the BMR spring shows the best overall highest rate increase from ride height to 1 1/2" of compression before the meaty Ridetech spring catches it. But it also has the highest of the 4 springs rates from ride height to 2" droop, not by much but still the highest.

Once the BMR is trimmed and able to be dropped in with the appropriate insulators for the 27" ride height it will be the fourth spring that is can be easily installed and all will sit at 27". Bingo.

Created a graphed and plotted the pound readings by 1/4" compressed length for the four springs. Now you can see each spring's uniqueness, they are all different. The Global West spring is a linear 129 lb rate (Moog 5401) so it's plots a straight line, compress it 1/4" adds 32 lb. That spring is good representative of all other linear rear springs, a straight line, it's my standard to compare other springs to.
And I had that Global West spring in the car for almost 20 years, A hundred passes at the track, a 1/2 dozen autox, 25K daily driver, and another 35K as Bob's toy. The Global springs and I are well acquainted.

Need to analize, yep spelled correctly, the data and bring it to the real world. Several things do stand out. Being progressive springs for essentially the same application they are vastly different from one another and their plot's shows that. Which one is the one I need, the verdict is not in yet.

Hoping to get the BMR spring length dialed in so I can drive them, weather permitting here in the NE. Had the car out on Weds, needed the bay for my Astro servicing. That 86 doesn't like cold days, neither do I, Softer coils in the rear, hmmm.

Need to call Viking, they said call back at the middle of the Feb about their new triple availability. When I change that left rear spring today looked at the tie wrap indicator on the shock shaft, it was all the way up. COMP setting on the shock is 6, time for a shorter shock. Asked Buckwalter about shortening the Viking DA shocks I have now, to much work, buy new. Just have to justify almost 600 bucks for the triples.
Bob

#1065117 - 02/16/20 07:38 AM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Jan 2000
Posts: 4,565
mmc427ss Offline
20+ Year
mmc427ss  Offline
20+ Year
Member

Joined: Jan 2000
Posts: 4,565
Pottstown, Pa
Fri afternoon waisted to much time and abused my air compressor cutting 2" off a BMR spring. I knew it wasn't enough from the get-go but just thought I needed to see the results in the rater. Yep didn't do much at all, still way to much load on the spring at ride height.
Sat made the trip and got some new 4" cutoff wheels for the angle grinder and made quick work of cutting another 4" off the spring. So 6" off, 1/2 coil is about 7".
Back in the rater at 9 1/6" nets 612 lbs average for the now two cut BMR springs. Installed both in the car and they are just a tad long yet, will trim about 1" more off.

With 4 sets of springs close to being dialed in to the 27" ride height I ran all 8 springs with their appropriate package of shims, insulators through the rater in short order. The Global being the control spring was ran first it's rated at 129 by Moog. Rater said one spring's average for 6" of compressed travel was 128.3, other spring was 125.8.
This tells me the rater is pretty accurate and the 20 year Global West spring is very close to that 129 Moog rate,

Next is the Ridetech 150-250 advertised spring. It shows average of 105 for the first 3" compressed travel on both springs tested and at 1" of compression from ride height 270 one spring and 265 the other.
In comparison to the other three springs it is by far the softest spring in droop which is surprising with all the steel in this set of springs. At 1" compression from ride height it has the highest lb readings of the four springs. It also appears to have the rate transition point closer to ride height. An interesting spring.

Funny thing testing the two UMI springs is not to far off of the linear Global spring's numbers. It's a little softer than the Global in the first 3" of compression, 113.3 on both UMI springs tested and at 1" compressed from ride height it's rate 160 and 165 on the other UMI spring. So I'd call these springs a 113-165 spring. This spring is said to be a 100-200, would like to have seen those 160-165 number much higher for that first inch of compression. From 1" to 2" compression they fall off from there to a less than 160 rate.

The other shining star is the BMR springs. Once I cut 6" off the springs and ran them on the rater you could see they have a good progressive rate curve. For their first 3" of compression they both averaged 103.3 lbs per inch. Because the BMR at 13.5" are a much longer spring than the Ridetech at 12" they build lbs quicker in the droop area. But are a close second to the Ridetech in that 1" droop to ride height transition area. In the ride height to 1" compressed one spring is 190 the other 205. These are an advertised 110-210 spring. From 1" compressed to 2" compressed they still show a good rate number of 190 ish for both springs. only the Ridetech spring showed a little more rate in that 1"-2" zone. Liking these springs so far.

Something i did find was for each set of spring there seemed to be one a little weaker than the other. You can see it as you run up the compression on each spring
and compare recorded numbers. Might mean the lighter spring may go in the right rear, opposite the driver.

Next is all four sets of springs get driving around the block to settle them and then get a ride height measurements, Will tweak spring spacers to get that 27" number. The BMR will be the last set checked so I can leave then in for a while. They are the only set I don't have 10 miles on yet.
Bob

#1065122 - 02/17/20 06:14 PM Re: Rear spring options for handling [Re: mmc427ss]  
Joined: Dec 2007
Posts: 6,080
SSLance Offline
10+ Year
SSLance  Offline
10+ Year
Member

Joined: Dec 2007
Posts: 6,080
Peoria, AZ
I'm interested to see if the rates change once they have settled with weight being on them for a while.

Sounds like the RT spring is pretty abrupt between soft rate and stiff rate right?


Lance
1985 Monte Carlo SS Street Car
Page 4 of 5 1 2 3 4 5

Random Images
504/thumbs/IMG_0114.JPG
by MC87SS
500/thumbs/Dsc00249.jpg
by Aeroaddict
500/thumbs/parking_4.jpg
by montess406
500/thumbs/cowl_hood_003.jpg
by GearedSS
857/thumbs/interior_small.jpg
by 86SSmonte350
Help MonteCarloSS.com


Recent Contributors
finallySS
Authorized Vendors
Tell them you saw it
on MonteCarloSS.com!


CustomMonteSSParts.com
Dixie Monte Carlo Depot
GSI Interiors
HRpartsNstuff
Mikes Montes
Savitske Classic & Custom
Powered by UBB.threads™ PHP Forum Software 7.6.0