Limiting rear suspension travel?

[Samckitt]

After installing lowered rear coil springs I have noticed that raising the body with a jack just a small amount will allow the springs to easily come out. Now, not that I am playing the Dukes of Hazard or anything, but have heard that doing some track time with a similar car caused one side spring to come out when taking a corner hard. So do you do anything to limit rear suspension travel, or do anything to keep rear coil spring in place if rear travel is big enough to allow it to fall out?

[Bryce]

If the shock can take the loads you could use a shorter shock to prevent droop. or limiters from competition engineering or just steel wire with some type of custom brackets.

offroad guys use nylon straps.

[justasquid]

this is way out of my realm, so I may be way off. But couldnt you fab a tab that overhangs the coil so it can't pop out of the pocket? Not tight, so the coil can still rotate, but just not lift out. But the limiter strap idea sounds good too. Although a suspension doesnt have any drop will probably ride pretty crappy, plus loose traction over rougher roads. I'd be careful with it.

The other thing that might be a concern is just driving down the road. Hitting a pot hole or even just a bumpy road could make your suspension extend enough to pop the spring out.

[JRouche]

Out of my realm also, but Ill take a poke. I think the spring is wrong for the suspension.
Meaning the suspension has more travel than the spring can accommodate. If you are able to slightly raise the the body off the springs and the suspension still has alot of travel then the spring is too short.

You could do a band-aid fix and try to hold the spring in its pocket during rebound. But I dont think that is a correct use of a spring.

During hard turns you still want the unloaded tire to have some contact if possible. And if the spring is fully extended and not pushing the tire down at all it is useless in the turn. The inside tire will be floating on the road surface with just its weight and not contributing to the traction needed for the turn.

So its on the rear that you are talking about, all the loading will be one the outside tire. I mean ALL the loading, instead of a portion of it like you want if the spring is still forcing the inside tire down like it should be.

Jack the rear of the car up so the tires are still at ride height, the jack is raising the axle housing so the tires are about five inches off the ground. Put some blocks under one of the tires, release the jack a lil at a time. And with a protractor on a level section of the axle housing (digital protractor makes it easy to see degrees) lower the car to where you get 5* of rotation on the rear end. 5* of body roll is a good starting point for maximum body roll. You may have to press on the opposite side of the rear end to get it to drop, and if you have a roll bar you should release one of the links to allow it to drop.

If the spring (on the dropped side) is loose and you can grab it and see that its loose then its useless in a turn. What you see on that 5* rotating of the axle housing is pretty close to what the suspension is doing on a turn (big turn). And 5* of rotation is just a number that I have seen for a standard amount of body roll on a street car. Its not a set number. It can be lower, say 3.5* or higher, 6-7*.

But if you are really curious you can find out exactly where the spring drops out. If its any lower than 3* then I would say the spring is wrong for the car. Actually, Id like to see a drop out of no less than 6* myself for a street car. 3* might be good for a track car. 5* and your car is really turned over in a turn.

If the spring is dropping out of use before 5* of rotation I would look for a different spring. There are so many out there.

A progressive spring was, IMO designed for just this. Needing a longer travel but not a stiffer ride or tall ride hight. Weak spring at the top just to keep the tire in contact with the road surface and progressively stiffer as it came into its loaded ride height. They do accomplish what they were designed to do really.

And a longer weak, non-progressive spring will mimic the progressive spring in a way. But it will still have a "long weak" spring feel. You wont get alot of control from a long weak spring. It will keep the rear suspended, will keep the tire planted. But it will be weaker on the rebound VS the progressive spring. But longer weak springs are easier to find then progressive springs.

So in summary... I think a longer, weaker spring is in order. Because in actuality Im not sure whats available for your car in terms of a progressive spring. JR

[montessaj]

JR, there is like nothing in terms of a progressive spring for G-bodies.

Sam I have the OPG 2" drop springs, are these the same ones you have? I have a slight problem with them being loose when the car is jacked up also.

[BillyShope]

Early Corvettes used a couple of fabric loops that looked like they were made from the belts of WW II Army uniforms.
http://www.racetec.cc/shope

[Samckitt]

Andy, I am not sure what springs I have in the back. They were given to me & I cut 3/4 off to make it a little lower. Maybe I need to look for some different springs, I agree with JR that progressive springs would be best. Surely someone makes them, I think A body springs are the same.

Maybe saying "slightly raising" it is exaggerating a bit.

[funbnme]

the top of the coil over assembly should have a 'hat' that sits on top of the spring. You're supposed to zip tie the spring to the hat. That way, if the spring does bounce due to suspension travel, it will stay properly seated in the hat.

Failure to do this can blow-out the shock. If the spring winds up sitting crooked on the hat, then it's possible that the spring could rub the shock body and break it.

This happened to me because I didn't know you're supposed to zip tie it.

The spring hat should have some holes for the zip ties to go through.

Use the thickest zip tie you can fit and make a point to check them when you do oil changes.

[Samckitt]

Dan - I'm not using coilovers.

[funbnme]

Oh..sorry about that. I saw coil springs and assumed coil-overs.

I had a shelby cobra replica that used limiting straps. They have to be long enough so you don't limit normal travel, but want them to keep the suspension from going fully loose.

Here's a link to a site with some product details.
http://www.offroad-engineering.com/limiting-straps.html

[T-CHRGD]

The GNX had that problem when power-braking. The body/frame would rise UP, and sometimes cause the spring to come out of its mount. They solved the problem by welding a small steel tube to the perch on the axle tube, to extend the center of the mounting plate up into the spring. Problem solved....also made it harder to get the springs in or out.

[b-man]

Would it be possible to modify the lower spring seats on the axle housing to allow the use of a clamp plate to retain the spring?

This type of rear spring retention was used on the '64 -'66 GM A-body cars.

I had the later model '71 Buick 8.5 10-bolt modified so that I could use the early spring clamp plates, to prevent the springs from coming out since I'm using shorter lowering springs.

Tubular spring locator has been cut off the spring mount:



Flat plate welded in place to accept the '64 -'66 A-body clamp plate for spring retention:

[monteboy84]

The G-body rear 4-link allows too much drop-out, with stock-length shocks, though as JRouche was saying, I believe your springs are too short as well. Follow his directions to figure out how tall your springs need to be, then determine what shock length (eye-to-eye) you need to retain them. Call up your favorite shock builder with this dimension and order some shocks that will limit your suspension drop-out.

[Twisted Minis]

Oh..sorry about that. I saw coil springs and assumed coil-overs.

I had a shelby cobra replica that used limiting straps. They have to be long enough so you don't limit normal travel, but want them to keep the suspension from going fully loose.

Here's a link to a site with some product details.
http://www.offroad-engineering.com/limiting-straps.html

This is what I was going to suggest. I think limiting straps are the way to go. I use them a lot and I like them. You can get them from Poly Performance, or Kartek as well.

[monteboy84]

Limiter straps would work, probably better than using shocks for tie-down as well.