Calling all Rear Suspension Experts

[RussMcB]

Originally Posted by Starman

<snip> ... the spring adjustment bolts are drivers side all the way up, passenger side all the way down - this is over a 4" difference side to side and still the driver's side is not at stock ride height.

Clarifying question: Is this with the wheels and tires "hanging" (unloaded)?

Are you able to take pictures (symmetrical, from the rear) and post them here?

[Starman]

Russ, with the tires and wheels on and everything still connected, the drivers side hung down over a half inch more than the passenger side.

The interesting view before I took it apart, the drivers side spring was almost flat and the passenger side had a nice bow down to the wheel.

Here is a photo of current state.

The one thing that was odd that I recall, was that no matter how much I adjusted the passenger side, it did not seem to move much. The struts, now disconnected from the spindles are pretty hard to move.

I've lowered four C4s and this is the first that I could not get adjusted perfect. Note, I'm not trying to lower this car, just make it look and drive right. Above 60 mph, the driver's rear wheel seems to be hopping - very bumpy.

[Z51JEFF]

How did the sway bar get bent? I was going to say bad spring until the sway bar issue came up. Wouldn't even deal with trying to fix the sway bar,once you heat it to straighten it out it's now junk.

[RussMcB]

Originally Posted by Starman

Russ, with the tires and wheels on and everything still connected, the drivers side hung down over a half inch more than the passenger side.

The interesting view before I took it apart, the drivers side spring was almost flat and the passenger side had a nice bow down to the wheel.

I would think the rear leaf spring should look the same on both sides. The "flat" driver's side sounds suspicious.

Usually, I don't worry about asymmetrical measurements when suspension is just hanging. I suppose that might provide a clue, but you really only care about things when the springs are holding the full weight of the car.

My earlier quest for the symmetrical picture - I was thinking of a picture taken from the area under the license plate, facing forward. That might provide clues about what is different on one side compared to the other. For instance, are the camber adjustments similar from side to side (same orientation)?

I see you have the tie rod unhooked in your picture above. Anything going on there? Unhooked on the other side, too?

Originally Posted by Z51JEFF

How did the sway bar get bent? I was going to say bad spring until the sway bar issue came up. Wouldn't even deal with trying to fix the sway bar,once you heat it to straighten it out it's now junk.

I don't notice any unusual bends in the ARB in the picture. I seem to remember that's what mine looks like, too.

[mike100]

Every C4 Ihave seen lately is a 1/4" lower on the d/s rear. I have had discussions with knowledgeable people on this matter, but nobody can put their finger on it for sure. Bill B. (aka ZFDoc) once surmised it could be the bushing and/or alignment of the batwing mounting.

I can tell you that you are most likely barking up the wrong tree thinking the spring is weaker on one side. I have an aftermarket rear spring too, and though to test that theory... I flipped it 180 and the d/s still sets a touch lower. In the end, I just cranked a couple of turns on the adjusting bolt to help offset the weight of the driver and to get the level look.

[Starman]

Thanks for the input so far guys. To be clear, the sway bar is not bent and perfectly symmetrical from side to side. Shocks seem to be OK, both require a cheater bar to move and have an even smooth motion on the extend.

Like Russ, I generally would not care about the droop position of the suspension, other than looking for binding. Given the high adjustment difference on the spring, going to call Hyperco and get their input. May also do the spring flip, but hate to put it all back together just for practice.

The camber adjusters are close and the measurement along the strut rod is identical. The alignment is to stock and I'll have it rechecked when the car is back together.

I'll keep you guys posted, not going back together until fixed.

[Starman]

OK - learned something today. Kudos to Al at Hyperco and Paul at VanSteel. Although not apparent at a glance, the ends of the strut rods (from differential to bottom of spindles) are not symmetrical. One end is bent at a slightly greater angle and guess what, the suspension binds when installed wrong. One side of the rod has a KAE and long number cast on it. The other side has RH or LH and an 8 digit number.

Can someone who has a car the rides correctly or better yet has never been disassembled, take a look and let me know what number faces the rear of the car on both sides? The RH/LH or the KAE(s).

Thanks

[tpepmeie]

On my 93, the pass side has the "KAE..." facing the rear. On the drv side, the "LH..." faces the rear.

hope this helps.

[Hib Halverson]

I skimmed through this entire thread and no where did I see that the trim height of this car is being measured the way the Service Manual says to do it, so, if it were me, I'd do that before anything else.

Also, I read one post saying urethane bushings were installed in the rear.

Bad idea.
C4 trailing and lateral arms need to be able to twist somewhat as the suspension moves. Urethane won't allow them to twist that will bind the suspension at the far ends of the travel.

Now, that's ok for a track car on smooth tracks but a bad idea for a street car.

You either need to go back to rubber or change to spherical bearings.

[George Maz]

Thank you so much Hib.

I'm also in need of some guidance as to why the handling and ride comfort is so different for each of my cars. One feels planted, straight, and confident. The other quite frankly is all over the place, see-saws, wanders.
A few days ago we had to pull over cruising home from dinner, from all the bouncing around. My other car doesn't do that. Next day, same road in my girlfriend's '07 Honda Accord, we enjoyed a smooth ride...so something is way off.
Back to basics, gotta spend some time reading the manual.