LR shock and spring setup

[n4cgrt]

What are guys running on the lr of a blue gray rocket. I heard some guys trying a longer and softer spring any truth to that? What length and spring rate? What are the pro vs cons

[CCHIEF]

80-125# Barrel Spring, car bars up without having to "whip" it up on to the bars. ...Doesn't play nice with short LR upper bar.

[Punisher88]

Some are also running the big 5" 50 pound swift spring.

[CCHIEF]

A call to Rocket Parts Dept will get you on the right stuff.

[Kromulous]

A 50 lb spring? wow thats crazy.

I seen some guys with a spring with a large end on it, one side was normal, the other was 5" thought it must be a really light rate.

[MasterSbilt_Racer]

A 50 lb spring? wow thats crazy.

I seen some guys with a spring with a large end on it, one side was normal, the other was 5" thought it must be a really light rate.

I been using a 75# effective rate for years.

[Twenty-Five]

What effect does the type of limiter chain cushion have when your on a super soft lr spring? Rubber vs a spring ect.

[RaceEngineer]

What effect does the type of limiter chain cushion have when your on a super soft lr spring? Rubber vs a spring ect.

Regardless of LR spring, you need travel to be consistent, you need momentary tire slip to not cause a large change in vertical wheel location, and you need some kind of cushion at all times. Many ways to get there.

[fastford]

I been using a 75# effective rate for years.

your talking stacked , not single right?

[fastford]

Regardless of LR spring, you need travel to be consistent, you need momentary tire slip to not cause a large change in vertical wheel location, and you need some kind of cushion at all times. Many ways to get there.

you are correct RE , i like my home made stop on my under slung frame and no chain pretty well.....

[MasterSbilt_Racer]

your talking stacked , not single right?

Correct. But all the divider does is help with bowing over a single spring.

[Twenty-Five]

Regardless of LR spring, you need travel to be consistent, you need momentary tire slip to not cause a large change in vertical wheel location, and you need some kind of cushion at all times. Many ways to get there.

So how do we go about determining if we have the right cushion? Ideally something that gets close to but never bottoms out ie. coilbound??

[hucktyson]

RE is right if it goes up easy it also comes down easy .... even from a momentary tire slip .... unless you do something to stop it

[CCHIEF]

And now you know why shocks..and driver are so important now days

[billetbirdcage]

What effect does the type of limiter chain cushion have when your on a super soft lr spring? Rubber vs a spring ect.

I'm going to take some liberties here to make this simpler: Lets say that only the traction of the LR tire and it's force on the bars is what is making the car hike and hit the limiter.

So if you induce some wheel spin then you lose some of that force to the bars and the car may drop some, but if you have a cushion on the chain that was compressed some then it is also going to pull the car down (effectively shortening the chain).

Say that the chain cushion was compressed .25" and to do so was a force of 250#, so if you induced wheel spin and lose 250# of force it would uncompress the cushion that .25" and make car drop.

With all that said (again liberties being used): There is an inherent difference in how things rebound. Lets say that cushion was something like memory foam (like bed material), where you press down with your hand and if you remove it quickly you still see a dent in the material and can remove your hand away from it with out it pushing your hand back. Now granted if you move your hand slow enough, the material will push back on you hand but only if you do it slow enough.

It's travel over time or distance over time, that has to be considered. Take a steel spring, it rebounds so fast that it's pretty much impossible to move you hand fast enough to not have the spring touch or push on you hand. So if I move my hand at 100" per second, then the spring will always be pushing on my hand in a rebound matter. However something like a rubber/foam/etc, may only rebound at 10" per second so if I move my hand at that speed or faster then there really isn't any force on my hand pushing it up.

So, you can see that if you have a material that rebounds at a slow rate then it will have a tendency to not pull the car down as easy if I only break traction for a .1 of a second as it doesn't have enough time to rebound the whole amount to uncompress the cushion the whole amount it was compressed.

Example: fictitious but say the same rates and compression amount for both types of cushions just a different rebound rate of distance vs time. Both compressed .25" and 250# to get it there.


Steel spring rebounds at 100" per second so that rebounds .25" in .0025 secs

Memory foam rebounds at 10" per second so that rebounds that .25" in .025 seconds

So if you lose traction and lose 250# of force on the bars for .01 seconds, then the spring will pull the car down the full .25" but if you have the memory foam, then it will only come down a small % of that say like 30% for a travel of .075".

Hopefully that is simple enough that it makes sense.

[sidewinder69]

my real question is why would you want progressive or digressive left rears,,, i understand pro uses the bottom spring to set ride height, and top coilover is setting the extension load.... while digressive it is opposite. but still can arrive at same point. so what is the difference?? and how do you know the extension load you need to be at for a condition

[fastford]

billet , do you think the load applied to the rubber on a chain is equal , load wise , to the rear hitting the rubber on my under slung ? just wandering because this might be where something could be learned with a spring smasher and some rubber......

[hucktyson]

It would depend how much contact area you have on each. For instance you the rubber piece was 2.5” with a 2.5” steel washer trying to compress it the rate would be much stiffer and if a rib from you side bell was trying to crush the same
Piece of rubber. But if you had the same
Surface area it would be the same either way

[billetbirdcage]

billet , do you think the load applied to the rubber on a chain is equal , load wise , to the rear hitting the rubber on my under slung ? just wandering because this might be where something could be learned with a spring smasher and some rubber......

Load is load, so if you got a similar rate and travel/time then yes on a chain or under the rear end would be the same. However like Huck said, it would need to be tested and adjusted to get them actually the same if you knew one that worked perfect.

To be clear, I wasn't saying one is better then the other but they are different and you can get some, a lot, or almost no noticeable change felt on the cars.

Just because I tried explaining something, doesn't mean I actually know what is best. (grins and shrugs)

[Twenty-Five]

Load is load, so if you got a similar rate and travel/time then yes on a chain or under the rear end would be the same. However like Huck said, it would need to be tested and adjusted to get them actually the same if you knew one that worked perfect.To be clear, I wasn't saying one is better then the other but they are different and you can get some, a lot, or almost no noticeable change felt on the cars.Just because I tried explaining something, doesn't mean I actually know what is best. (grins and shrugs)

Thanks for the great response billet! Given the fact that theres a ton of options for limiters available today, how would you go about picking one and then what sort of tendencies would you expect it to exhibit on the track when it's tuned properly? In other words if you watch a video of the limiter on the car what would you want to see?