TJM

This a C4 but don’t ’run away .. C5/6 are fundamentally the same.

We have replaced the front drive train suspension frame [ “cradle” whatever term you might call it] with a 1992 version and used a ZO7 [ FHB] front spring.

No shims were present between the old Z51 [ BMB ] on the original ’84 Drive train frame. None are installed now.

The F.S.M. is no great intellectual aid here, but does specifies a certain amount of shim according to spring color code on BOTH sides. Not exactly the formula to raise one side???

BUT the motor mounts are not level. The driver side is lower by one half inch+. I don’t see any geometry OTHER than spring shims [ driver side] that could affect this?



I have looked at the end links 20 times, they are symmetrical.

There are spacers that go under the Shock towers, and I suppose that could affect rebound? But it’s hard to understand how this what affect the motor leveling issue??

Is there anything in the install of the lower A arms that could possibly affect this [ all new Energy Poly bushings]

We did not “Lower” the front by lobbing off the cushions or spring bearings.

TJM

TJM

?? Nobody knows? Or nobody checks trim height??

froggy47

IIRC from when I changed springs on my 1996, the # shims used was based on a color dot on the spring used and was only to set "correct" factory ride height.

So you are not concerned with factory ride height & can add/remove shims as desired, I always pulled the shims to lower the car.

They were (again IIRC) equal on both sides of the spring.

Not sure at all what how this relates to motor mounts?

FWIW.

TJM

Thanks!

Always something bizarre. The Cross frame perches on the sping. Balance right to left should be the same. It's not?


The lack of other comment confirms the Bizarre nature.

I think I will get a set of scales. If there is more weight on the driver tire than the passenger, then maybe I really have a problem?

If no, then I'll just shim the motor to level and give it a go in August?

TJM

Crepitus

What do you see if you compare the old to the new cradle?

froggy47

IMO if you try at this point to mount / shim the motor or the springs to get corner balanced I wouldn't do that. Those attachments are not where you should get involved with corner balance.

It could even be, and I'm not saying it is, but could be the motor is designed, from the factory, to have a "tilt" to it. Who knows.

I think more research is needed. Wish I could be more helpful.

TJM

Responding is a help. Just happen to have a C4 Garage Queen!! I believe I will toss a level on it!

TJM

Sold the old cradle for more than paid for the new!!

Hot Rodders are crazy for the C4 parts.

The folks that are least aware of that are the guys "Parting" out.

They will almost give away a stripped sub frame.

Crepitus

I am wondering if the front frame rail mounting points are the same early vs late C4.

TJM

Holes are in the same location, there is a little bit different geometry, but that would be consistent side to side? Went together very easy.

I emailed Rippie to see if he could shed any wisdom.

Been on the track and it runs well, and handles ok, but that is a relative assessment? Much better than the stock, mild 1989?

But we spun twice, both times it was a small diameter spin, as if front had brakes and backs broke loose? Have a bias spring so I had hoped this would resolve to much right foot input?


Driver blames himself for being to aggressive... I have doubts, though. If planted harder on one tire than the other, certain corners will be great others not so good?

Actually this is a good advertisement for coil overs isn't it?