Body Roll

[85/Silverado]

I get body roll but the steering stays true. It was hard to control If I hit a dip on the freeway.
All new suspension,
Coilovers
4 Link
Ford 9"

[The Rocknrod]

Have you checked your sway bar and end links?

[85/Silverado]

Here is a photo of rear. Which bar? I just bought the truck.

[The Rocknrod]

That is a track bar, the sway bar goes from right to left side of the front and rear (one or the other or both if installed). Here is a link and a pic - http://67-72chevytrucks.com/vboard/s...ad.php?t=72338

[theastronaut]

First thing- check the alignment. As much caster as possible (looks like you have stock front suspension so no worries about going too far), -.5 camber, and 1/16" toe in is a good starting point.

Check the bushings in the four link, track bar, and sway bar ends.

The "coilovers" are just coil springs over a regular shock, not actual coilovers. They're mounted wayyy inboard, probably for clearing wide tires? Mounting them that far in gives the body a lot more leverage on them, so it's harder for them to control body motion and may be part of the problem you're describing. Since it's a separate shock you could pull it out and try a shock with firmer valving if the alignment and bushings check out. Mounting the springs and shocks outboard of the frame would be ideal.

[SCOTI]

Originally Posted by theastronaut

First thing- check the alignment. As much caster as possible (looks like you have stock front suspension so no worries about going too far), -.5 camber, and 1/16" toe in is a good starting point.

Check the bushings in the four link, track bar, and sway bar ends.

The "coilovers" are just coil springs over a regular shock, not actual coilovers. They're mounted wayyy inboard, probably for clearing wide tires? Mounting them that far in gives the body a lot more leverage on them, so it's harder for them to control body motion and may be part of the problem you're describing. Since it's a separate shock you could pull it out and try a shock with firmer valving if the alignment and bushings check out. Mounting the springs and shocks outboard of the frame would be ideal.

If I may add to the above....

The 4-bar looks to be 'in-board' as well. With the shocks & locating links all within the frame rails vs. out side it's going to require more effort than normal to keep it stable vs. the same exact truck w/the links & C/O's out-board of the frame rails.

[85/Silverado]

tires are MT P315/60R 15 rears. As soon as I transfer the title I'll take it too a suspension shop and have them look it over.

[SCOTI]

Originally Posted by 85/Silverado

tires are MT P315/60R 15 rears. As soon as I transfer the title I'll take it too a suspension shop and have them look it over.

Definitely appears to be more of a 'pro-street' set-up intended for straight line performance/usage.
Inboard springs/shocks are going to make controlling body roll @ speed on a tall vehicle difficult to say the least.

[Kudzupatch]

Agreed with the comments and about this 4 link not being ideal for cornering.

But I will add that sway bars can make a huge difference properly sized and installed and are probably the most bang for the buck. Assuming the suspension is not worn or damaged.

It has stock suspension in good condition other than a lowering kit. Spindles, springs and read axle flip but it is still stock parts, just relocated. I added better shocks and replaced the worn out sway bar bushings with high density ones.

For a Suburban it corners surprisingly flat and still rides well. It always impressed me how well it corners. No sports car obvious but FAR from a typical Suburban or pickup. It rarely falls to impress people who ride with me. I see them bracing when I go into a corner faster than you should in a truck and they always are like wow.

[PGSigns]

Needs a good alignment for sure. A front sway bar is a must. Next measure the rear springs as the sit compressed. This will tell you how much sag is in the spring and if it may be to soft. The way that four link is set up is a pro street design for sure. The better the shock the better it will do. A cheap or worn shock will give you a lot of body roll.
Jimmy

[85/Silverado]

There is no sway bar on the front as you can see and the passanger front wheel is positive camber that I can see just by looking at the front of the truck.
. Also why are there so many adjustment holes on the 4link?

[SCOTI]

Originally Posted by 85/Silverado

There is no sway bar on the front as you can see and the passanger front wheel is positive camber that I can see just by looking at the front of the truck.
. Also why are there so many adjustment holes on the 4link?

The quantity of holes is to dial in the amount of 'bite' for the track surface when racing. By adjusting up or down it allows tuning for the track conditions so you can plant the power. That's a main difference between a '4-link' (track use) vs. a '4-bar' (street use).

You'll want a front sway bar for sure if it's a street truck. It will help the body roll issue you've described. Prob has a factory alignment w/POS camber (spec is +.5°). You'll want them to target zero to NEG .5° camber.

[PGSigns]

All the holes are to adjust the instant center. That is what determines how the suspension hits the tire. The setup you have is more of a pro street 4 link compared to a full race 4 link. Where it is set now is not going to hit the tire real hard. You may want to do some reading on 4 links and how they work and what the adjustment do to the way the truck will drive under acceleration.
Jimmy

[lolife99]

That 4-link is mounted extremely close to the ground.
I’m not sure why it hangs below the frame rails so far.
Do you have any side shots of the truck?

[lolife99]

That 4-link looks like an old setup from Competition Engineering.
They used the same shock brackets and external coil spring.

[SCOTI]

Originally Posted by lolife99

That 4-link is mounted extremely close to the ground.
I’m not sure why it hangs below the frame rails so far.
Do you have any side shots of the truck?

I thought the same thing. Not sure why it was attached so low other than ' because it was easier'.

[PGSigns]

Here,s my take on the position. Most pro street setups are done on cars and the ride height is 5 to 6 inches. The truck was not built to the normal car height or even close to it. When they built it they were shooting the the lower bar to be close to level and ended up with it close with the truck still being a foot or more off the ground. Going by the bump stops in the pictures of the front the has no been lowered much. Not the way I would do it but it got who ever built it what they were looking for.
Jimmy

[85/Silverado]

Side View from this weekend

[SCOTI]

Originally Posted by PGSigns

Here,s my take on the position. Most pro street setups are done on cars and the ride height is 5 to 6 inches. The truck was not built to the normal car height or even close to it. When they built it they were shooting the the lower bar to be close to level and ended up with it close with the truck still being a foot or more off the ground. Going by the bump stops in the pictures of the front the has no been lowered much. Not the way I would do it but it got who ever built it what they were looking for.
Jimmy

Agreed 100%.

[85/Silverado]

Went for a 100 mile drive Saturday with a passenger for the first time, and the truck handled like a dream.
Had the front end aligned today and no change. I'm going to try adjustable coil-overs on the rear next so I can drop the rear a couple inches.

[PGSigns]

Coil overs have a set installed that put them in the middle of the travel. The adjuster id there to allow you to get to that point with the springs that are used. The height adjustment is done with the lower bracket. Yours are welded to the housing pretty high up. You could have them dropped a few inches.
Jimmy

[Backpayne]

Get a front sway bar. It will help tremendously.

[85/Silverado]

There are alot of choices for front sway bars, Is there a kit someone can recomend?

[gmc684x4]

Stock one from a c30 truck

[HAULIN' IT]

There is quite a bit of odd stuff going on there (including what appears to be the fuel cell mounted backwards). My first thought is to measure the "installed height" of the rear springs as they are now with the weight on them...bottom of upper spring mount to the top of the lower spring mount. This distance won't change unless you add or subtract weight from the rear of the truck. Make yourself some type of holder (square tube with the holes drilled to mount, a 4x4 block of wood cut to length, whatever). This way you can adjust the truck with a jack under the frame to where you want it & work from there.
Keep in mind, as you lower the truck, the front 4-link bracket is going with it!

What puzzles me is how high the spring brackets are vs. how low the front 4-link bracket is...clearly the person that installed the kit didn't have good forethought. By the time you get the truck down where it looks "correct", that lower mount will sitting on the ground. There are rather simple ways to fix what is going on there but will involve cutting the spring mounts off the housing, lower the truck to where you want it (or the front bracket hits the ground) then put the spring adapter closer to the center of the number of holes & weld it back on the housing.
Upfront, cut the bracket off that goofy mount & slide it up so the bottom hole is level to the lower hole on the rear end at your new, desired ride height then cut off all of that crap hanging down under the truck! My Two Cents, Lorne