Make it handle

[skorpioskorpio]

Something I haven't seen in this thread, or any other for that matter, is any experience with dual rate springs on the coilovers. Bikes have been running dual rate and even triple rate springs for years, decades even, just curious why they seem to be a rarity in automotive applications. Concept is simple enough, dedicate about 70% of your spring length to the primary spring rate and the remaining 30% to either a softer initial spring or a firmer final rate, the former being intended to soften up the typical ride and the latter intended to prevent bind on a hard compress. The 2 springs are stacked on top of each other.



The image shows the Eibach spring stack with a progressive soft initial spring and a linear constant rate main spring, would these not be adaptable to the typical Ridetechs?

[keepitsimple]

There isn't much travel for the springs on most old trucks to utilize something like that. I would also add that all you will improve upon would be ride quality.
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[bdiamond]

I was about to do my alignment. I probably have 6* of camber with the original shim stack in it. Rather than adding 3/4" of shims would it be better to just shorten the lower arm 1/2"-a3/4"? I don't see it affecting the RC much if the lower arm is level, would it?

[skorpioskorpio]

Originally Posted by keepitsimple

There isn't much travel for the springs on most old trucks to utilize something like that. I would also add that all you will improve upon would be ride quality.
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5-6" non binding travel from a 10x2.5" ID spring on a Ridetech isn't particularly limited travel, that's more than enough to run dual rate springs with a 2.5" soft spring and a 7.5" main. As far as only improving ride quality, dual rate springs have been used in just about every form of racing from MotoGP to F1 to LMP to Baja, not to say that they wouldn't maybe be useful to improve ride quality but traditionally they have been used almost exclusively in very high performance racing applications, so I guess I'm not sure you're going with this?

[INSIDIOUS '86]

Originally Posted by skorpioskorpio

5-6" non binding travel from a 10x2.5" ID spring on a Ridetech isn't particularly limited travel, that's more than enough to run dual rate springs with a 2.5" soft spring and a 7.5" main. As far as only improving ride quality, dual rate springs have been used in just about every form of racing from MotoGP to F1 to LMP to Baja, not to say that they wouldn't maybe be useful to improve ride quality but traditionally they have been used almost exclusively in very high performance racing applications, so I guess I'm not sure you're going with this?

Can you find a spring that can fit 67-87? I would imagine a spring like this wouldn't be universal as the nose weight and cross weight would differentiate the spring needs.
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[INSIDIOUS '86]

Originally Posted by robnolimit

Lately we have been experimenting with "Tread Width". Meaning, the total width, outside-to-outside of the tire track. This is a bit different than "Track width" which would be center of the tire tread-to-center of the tire tread.
For our testing we are using the HellBoy, which runs a 315/30/18 on all four corners. So the difference between the front and rear tread width is the same as the track width difference.
At the moment, the front total width is 73" and the rear is 71". So the front is 2" wider than the rear.
The truck has a slight push on corner entry, and can sometimes be loose on the corner exit.
So, here is the question. (we can adjust the width very easily) We can set up in 5 tread width stances. they are:
A. Front 2" wider
B. Front 1" wider
C. Even front/rr
D. Rear 1" wider
E. Rear 2" wider
To be fair, this testing will take a few weeks, We need to compile multiple lap times under somewhat similar conditions. So here is the question, What do you think will happen, and why?

I would imagine that going wider up front will kill the push some and still be loose on the exit and that wider on the rear will make more push but more planted on exit. I would imagine going wider in the rear will be better and changing how you enter a corner and exit will make the difference
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[agtractorjoe]

i just did a hotchkis full TVS and its awesome !

[skorpioskorpio]

Originally Posted by INSIDIOUS '86

Can you find a spring that can fit 67-87? I would imagine a spring like this wouldn't be universal as the nose weight and cross weight would differentiate the spring needs.
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I was refering to coilovers which are somewhat standard, dual rate springs on a stock type suspension would be complicated if it can work at all. On a dual rate spring the spacer between the 2 springs rides on the shock body and prevents the 2 springs from binding against each other. On a stock type spring there is no center support to ride against.

[midnight340]

I promised some update photos on the Chev truck arm conversion I have done to my F-1. (some of my cell phone shots may be not as sharp as I like, but you can get the idea...)

My frame is boxed back to cab mounts (Volare front suspension), stock substantial Ford cross-member that I braced the rear to. I added the very stout trailing arm crossmember, frame is boxed over c-notch, plus I added the tubular rear cross-member where coil-overs/panhard mount, and the angled bracing to triangulate the rear frame. Should be fairly stiff at this point.

Many thanks to Rob and other contributors for comments and photos!

Stock set of arms
U-bolts from way2lo2 from the forum here..... fast, fair. Thanks!
Cross-member came from Performance Online (very nice unit!)
Axle saddles/arm bushings from Brothers Trucks
5" PRO coil-overs w/ 185# 10" springs (decided to start here)
Speedway Motors 1-1/8" o.d. chromoly panhard

All brackets home-made. My welds are a bit "farmer" style (a little rough, but good penetration and a bit over-welded. Frame angle bracing done with 3/4" gas line since weight is a good thing. Tubular crossmember and panhard angle brace done with steel tube I had on hand. Boxing and c-notches were done when the truck was originally built (3/16" plate boxing):

[INSIDIOUS '86]

Originally Posted by skorpioskorpio

I was refering to coilovers which are somewhat standard, dual rate springs on a stock type suspension would be complicated if it can work at all. On a dual rate spring the spacer between the 2 springs rides on the shock body and prevents the 2 springs from binding against each other. On a stock type spring there is no center support to ride against.

Yah I figured it was for coil overs. Unfortunately there is no simple bolt on coil overs for any of our trucks
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[robnolimit]

We have some good finding on our Track Width testing. Let me start with a good description.
Tread width - This is the total width of the tires footprint, from the outside of the tread on the left side to the outside of the tread on the right side.
Track width - This is measured from the center of the tires footprint, from one side to the other.
Naturally, Tread width will always be wider than Track width. Both of these can be adjusted with tire size and wheel offset.
**** Now, a though about getting through a corner at speed. For a car or truck to reach it's max ability in a corner, it has to "rotate" through the corner. Just driving through wont be fast enough. Four tires don't rotate, three tires do. Now, I'm not saying you need to carry one wheel, but three tires need to be REALLY stuck, and one needs to slip a little. On corner entry and through the middle, You need to be on the two front tires, and the outside rear. On corner exit, this changes to the two rear, and the outside front. The transition happens as throttle is applied, and the steering starts to 'unscrew', and this is all a balancing act.
** One more thing, the effects of track width on lower speed handling, are NOT the same as they are on high speed corners

What we found on the track was what expected, but may seam backwards.
*When we set the truck up a wider rear track width (compared to the front) the truck was 'loose' - or the back would slide outward in the corners, mostly on corner entry, but also was not so hooked up on the exit. This is because when the tires are farther apart, it is harder to get the leverage of the chassis to push them into the pavement.
*When we made the rear narrower, we got the reverse, it developed a severe 'push' on corner entry and through the corner, the only time it cleared up was on the corner exit, under throttle. As the tires get closer, they are more planted to the pavement, and it's hard for one to slip, and let the truck rotate.
*Both of these conditions are multiplied when using a posi type of rear axle. Driving both rear wheels.
*In all set-ups, we worked to get the best laps we could. Shock valving, springs, sway-bars, tire pressure, caster/camber/toe.
Now, most would think that a neutral or balanced track width would be the best, but, not so. At the end of the day, it turned out that our balance point was a bit to the narrow side. Our best laps were ran with the rear track width set at 1/2" less than the front. Now, as per our theory, this would lean towards being 'tight' or a 'push'. But, because trucks are nose heavy, and tend to be naturally 'loose', we are simply using the adjusted track width to balance that out.

[robnolimit]

Originally Posted by bdiamond

I was about to do my alignment. I probably have 6* of camber with the original shim stack in it. Rather than adding 3/4" of shims would it be better to just shorten the lower arm 1/2"-a3/4"? I don't see it affecting the RC much if the lower arm is level, would it?

what was changed to have so much - camber?

[robnolimit]

Originally Posted by agtractorjoe

i just did a hotchkis full TVS and its awesome !

congrats, good lookin truck

[bdiamond]

Originally Posted by robnolimit

what was changed to have so much - camber?

The change was from worn out at stock height to rebuilt with poly bushings , spindles and 1 coil cut 6102's. I threw a square up against it and theres only really about 1/2" difference top to bottom, but the toe is out too, so maybe some will go away. I did the caster mod 3/4"

[robnolimit]

Originally Posted by bdiamond

The change was from worn out at stock height to rebuilt with poly bushings , spindles and 1 coil cut 6102's. I threw a square up against it and theres only really about 1/2" difference top to bottom, but the toe is out too, so maybe some will go away. I did the caster mod 3/4"

Do you have the concave&convex spacer set on the uper control arm studs?

[bdiamond]

Originally Posted by robnolimit

Do you have the concave&convex spacer set on the uper control arm studs?

Yeah. they are still there.

[CSGAS]

Originally Posted by robnolimit

....This is because when the tires are farther apart, it is harder to get the leverage of the chassis to push them into the pavement....

This is with a rear sway bar hooked up, right? Without one, the weight should transfer to the other side and work more like a common lever arm (with the inside tire as the pivot point). Still, when you are turning both ways (Autocross) using the sway bar gives you a far more consistent reaction for turning in both directions.

I haven't stopped learning yet, so if you've found something else seems true you won't hurt my feelings :-)

[CSGAS]

...Scratch that...the inner tire is only the pivot point if the suspension is bound up (on bumpstops, springs or shocks damaged, Go-Kart style suspensions, etc)

When suspensions are doing their job, the pivot point for the lever arm will move around. Predicting it involves Calculus ( )

I'd still be curious to see what the effects are of the additional factor--wider rear end with or without the rear sway bar

[bnelson]

Whew, that was a lot of reading, but I feel like I've gotten a great education on suspension. Rob or Nate (or anyone else who has some input), what do you think about using stock car style weight jack buckets for the rear springs (not my idea, found it on this site). Seems like a cheap way to get a couple extra inches of drop while keeping the spring taller and preserving more travel, plus it's adjustable. Is there any downside to using something like this?

[robnolimit]

When compared to a short spring, this is a better choice. I'm in favor of longer, softer springs that require more static spring compression at ride height. Weight jacks (threaded spring adjusters) can also be added to allow fine tuning of ride height and weight balance. I say go for it.

[Conundrum]

I've been away for quite sometime. Is leaning the spindle 1-1/4" still a good idea or has there been a change in the amount? I'm wanting to get back on the front suspension of my 74 GMC.

[robnolimit]

The 1 1/4" offset, from the lower to the upper ball joint, is still a goos number. we usually move the lower forward 1", and then modify the upper to get the last part.

[Conundrum]

Thank you for the reply Rob

I have already centered my wheels when I did the Z, so I figure i'll do 5/8" forward on the lowers and 5/8" reward on the uppers so that they stay centered.

Does anything need to be done as far as ball joint angle is concerned?

[robnolimit]

Ball joints are fine. Sounds like your on the right track.

[robnolimit]

Catch the airing of the Optima OUSCI qualifier thursday, oct 31, yes, on candy day, on Mav TV. A few fast trucks made the grade here.