Vibrations,rear wheels hop,inconsistent steering.HELP!

[a3ternus]

Hello to everyone reading this! :)
Sorry for the long post.
I m really at a loss here.I really really need your help and insight.
I have no clue whatsoever as to what my next step should be.

Last month my mechanic did the following work to the car:
1.Changed all four rims.Same size,same tyres as before.BBS Replicas 15".
2.Changed Rear axle cos it was bent (thanks to a motherfucker who
tried to take out the old Rubber mountings with a sledgehammer).
3.Changed right rear Trailing arm cos it was bent a bit,too.
(this was on the car since I bought it and made the trantition from
drum to disk brakes in the back and was on my to do list for 6 months).
4.Changed the guibo and the rear axle Rubber mountings plus the front Set rubber mounting f wishbone.
5.Balanced all four rims and tyres 2 times.The second shop told me that
the first shops machine was un calibrated.I guess I m unlucky.


After all these I decided to drive the car hard again down a fast twisty
road I know too well and to my horror I noticed that:

1.The car is still vibrating a LOT sometimes at around 85mph (135-140km/h).
I feel the vibration in the steering wheel.WTF? I need tyre balancing AGAIN?!?

2.The steering gets REALLY light and vague at the same speedand above.
Checked and corrected the tyre pressure all around.Still the same.Bad vibrations.
Front rubber mounting f wishbone are new.

3.The rear wheels hop a lot when doing a flying start.Thats new too.
Be it wet or dry,smooth asphalt or not,the car still does that,
fortunately less after correcting the tyre pressures all around.
I ve recently changed the guibo but not the CSB (Center Support Bearing).
Maybe thats what causing this? My rear suspension was measured at
78% left and right during my recent MOT.Bilstein Sports.Almost as new.

Could I correct all of the above simply by changing the CSB (Center Support Bearing)
and try checking/balancilg the front wheels again? :(

4.The braking is not ok at all.When I brake hard the car shifts to the right a lot I d say.Did a brake bleeding all around.Now the pedal is firmer but still
I cant brake in a straight line.Maybe the front caliper is getting stuck or something?

Please people I need good advice.I dont know what to check next.
N.

[a3ternus]

Anyone? I begin to think that the ride/steering thing is cos of the new rims.
The ride was awfull since I put these on...vibrations and everything...
N.

[KenC]

Sounds suspension related. How old are the rear trailing arm bushings, subframe bushings, and rear shock mounts?

You definitely have a caliper that isn't functioning properly, also.

[a3ternus]

Subframe bushings=you mean part number 3? These are brand new!
Top mounts in the back also no more than a year old.Almost as new.

What part is the rear trailing arm bushings? No9?
Sorry,I m just not so good with the terminology and I d like to be sure.
Would that made such a big difference to the way the car rolls or accelerates?

What if the rims are bent in the first place? :(
They were dirt cheap,bought them from a friend.Lots of track action with those wheels and had to fix one of them alreay.
N.

[KenC]

You should definitely check to make sure the wheel is round.

How old are your rear shocks? And rear shock mounts? The "hopping" on hard accel is weird.

Yes, #9 is the rear trailing arm bushing. If they're severely worn, they can cause a lot of issues.

[jlevie]

1.The car is still vibrating a LOT sometimes at around 85mph (135-140km/h).
I feel the vibration in the steering wheel.WTF? I need tyre balancing AGAIN?!?

A vibration that you feel in the steering wheel is from the front tires/suspension. The cause could be any, or a combination, of out of balance or out of round tires, bent wheel, worn suspension (control arms, tie rods, upper strut bearings), or worn shocks.

While it won't be a problem with OE wheels, aftermarket wheels that aren't hubcentric or whose centering rings are a poor fit the hub will cause problems. They can be used, but will probably require on the car balancing.

2.The steering gets REALLY light and vague at the same speedand above.
Checked and corrected the tyre pressure all around.Still the same.Bad vibrations.
Front rubber mounting f wishbone are new.

Most of the above can cause nervous steering.

3.The rear wheels hop a lot when doing a flying start.Thats new too.

If the wheels are actually hopping, the cause is most likely to be bad shocks, perhaps aggravated by bad rear trailing arm bushings. However, if you feel a thumping from uder and towards the rear of the car under acceleration, the cause can be a bad CSB, which is in turn caused by a bad drive shaft.

[AndrewBird]

Here is a quick, easy way to check for bent or out of round wheels. Put the car up on jack stands so you can spin the wheels. Get a box or jack stand or what ever that is roughly tall enough to come up to the center of the wheel. Now tape something pointy like a pencil to the box and place the point of it lined up with the edge of the wheel. Then spin the wheel slowly. If there is a bend, you will be able to see the wheel pull away from the pencil as the bent part passes by it.

Do this with the pencil perpendicular to the wheels (sticking out from them) and as flush with the face of the wheel as you can (tire will be in the way slightly).

[a3ternus]

I REALLY REALLY appreciate all your input here! :up:

All these turned out to be incorrect wheel balancing and alignment. :roll:

I went back to shop to bust their balls and this time got lucky.
By lucky I mean they decided to do a thorough inspection
and balance the wheels right finally. :crazy:
The guy who got this was the older of their employees and took the time to adjust everything the right way.The fact that I went back again and again just talks volumes for their (lack of) professionalism I guess. :???:
I payed once 70$ and refused to give another cent.
A quick sprint up and down the local E75 revealed that every vibrations and wheel hoping and loose steering was gone.

I was getting desperate for a moment there.
E30s can do this to you. ;)
N.