front end wobble

[long tall eta]

my sons 87 eta has a severe front end wobble between 55 and 65mph that stops as soon as the brakes are applied. the tires are also wearing on the outside of both fronts.
possible causes?????

[jlevie]

There are several things this could be, but check for bent or out of round/balance wheels, check front toe, and inspect the suspension:

To check control arm ball joints, squeeze the joint with a large (as in 24") pair of channel locks and pry on the joint. Any motion whatsoever in a ball joint is cause for replacement. Check rubber bushings by prying on them with a 24" pry bar. More motion than there should be (this is where experience comes in play) or any cracks are cause for replacement. On the front control arms I prefer the OE M3 offset bushings. That increases caster and yields better high speed stability.

Changing the control are bushings is really a press job. There are DIY ways to get the old bushing out and force in the new bushing. But for me that is an option of last resort. I prefer having a shop use their press. It is about a 15-20 minute job and if you make an appointment ahead of time you’ll be in and out quickly.

It is important to wait to lock down the control arm bushing brackets or the rear trailing arm bushing until the car is resting on the wheels. I use soap as a lube for the pin of the control arm and get the car on the ground and lock down the bushing bracket before the soap can dry.The rear suspension of an E30 isn't adjustable. Worn trailing arm bushings or bad subframe bushings will result in improper alignment of the rear wheels. In addition to degraded handling, problems there will accelerate wear of the rear tires.

With the car up in the air, grab each front wheel at 9 & 3 o'clock and try to wiggle the wheel. Motion along that line will be worn tie rods. Not the that there is an inner (under the dust cover) and outer tie rod ball joint. Either or both can be worn. Motion when wiggling the wheel at 6 & 12 o'clock will be bearings or control arm ball joints. Spin each wheel and listen for roughness in the bearings. If the brakes drag, remove the pads or caliper (and on the rear wheels the parking brake shoes) to eliminate sounds from dragging brakes. Any roughness when spinning the wheel is cause for bearing replacement.

Although only front toe is adjustable on an E30, a four wheel alignment will tell if there are camber or caster errors. Those errors can be the result of worn parts, bent parts, or frame damage. A single curb strike can result in damage.

[long tall eta]

There are several things this could be, but check for bent or out of round/balance wheels, check front toe, and inspect the suspension:

To check control arm ball joints, squeeze the joint with a large (as in 24") pair of channel locks and pry on the joint. Any motion whatsoever in a ball joint is cause for replacement. Check rubber bushings by prying on them with a 24" pry bar. More motion than there should be (this is where experience comes in play) or any cracks are cause for replacement. On the front control arms I prefer the OE M3 offset bushings. That increases caster and yields better high speed stability.

Changing the control are bushings is really a press job. There are DIY ways to get the old bushing out and force in the new bushing. But for me that is an option of last resort. I prefer having a shop use their press. It is about a 15-20 minute job and if you make an appointment ahead of time you’ll be in and out quickly.

It is important to wait to lock down the control arm bushing brackets or the rear trailing arm bushing until the car is resting on the wheels. I use soap as a lube for the pin of the control arm and get the car on the ground and lock down the bushing bracket before the soap can dry.The rear suspension of an E30 isn't adjustable. Worn trailing arm bushings or bad subframe bushings will result in improper alignment of the rear wheels. In addition to degraded handling, problems there will accelerate wear of the rear tires.

With the car up in the air, grab each front wheel at 9 & 3 o'clock and try to wiggle the wheel. Motion along that line will be worn tie rods. Not the that there is an inner (under the dust cover) and outer tie rod ball joint. Either or both can be worn. Motion when wiggling the wheel at 6 & 12 o'clock will be bearings or control arm ball joints. Spin each wheel and listen for roughness in the bearings. If the brakes drag, remove the pads or caliper (and on the rear wheels the parking brake shoes) to eliminate sounds from dragging brakes. Any roughness when spinning the wheel is cause for bearing replacement.

Although only front toe is adjustable on an E30, a four wheel alignment will tell if there are camber or caster errors. Those errors can be the result of worn parts, bent parts, or frame damage. A single curb strike can result in damage.

thanks jim, great reply.

[JRKOUPE]

jim rocked that...

[long tall eta]

There are several things this could be, but check for bent or out of round/balance wheels, check front toe, and inspect the suspension:

To check control arm ball joints, squeeze the joint with a large (as in 24") pair of channel locks and pry on the joint. Any motion whatsoever in a ball joint is cause for replacement. Check rubber bushings by prying on them with a 24" pry bar. More motion than there should be (this is where experience comes in play) or any cracks are cause for replacement. On the front control arms I prefer the OE M3 offset bushings. That increases caster and yields better high speed stability.

Changing the control are bushings is really a press job. There are DIY ways to get the old bushing out and force in the new bushing. But for me that is an option of last resort. I prefer having a shop use their press. It is about a 15-20 minute job and if you make an appointment ahead of time you’ll be in and out quickly.

It is important to wait to lock down the control arm bushing brackets or the rear trailing arm bushing until the car is resting on the wheels. I use soap as a lube for the pin of the control arm and get the car on the ground and lock down the bushing bracket before the soap can dry.The rear suspension of an E30 isn't adjustable. Worn trailing arm bushings or bad subframe bushings will result in improper alignment of the rear wheels. In addition to degraded handling, problems there will accelerate wear of the rear tires.

With the car up in the air, grab each front wheel at 9 & 3 o'clock and try to wiggle the wheel. Motion along that line will be worn tie rods. Not the that there is an inner (under the dust cover) and outer tie rod ball joint. Either or both can be worn. Motion when wiggling the wheel at 6 & 12 o'clock will be bearings or control arm ball joints. Spin each wheel and listen for roughness in the bearings. If the brakes drag, remove the pads or caliper (and on the rear wheels the parking brake shoes) to eliminate sounds from dragging brakes. Any roughness when spinning the wheel is cause for bearing replacement.

Although only front toe is adjustable on an E30, a four wheel alignment will tell if there are camber or caster errors. Those errors can be the result of worn parts, bent parts, or frame damage. A single curb strike can result in damage.

Jim, what do you mean by wait till the car is on the ground before locking down the bushing brackets? just get them started then lower the car and then tighten them??? old arms are off now and waiting for new to arrive. i don't wana have to do this job twice.

[jlevie]

Jim, what do you mean by wait till the car is on the ground before locking down the bushing brackets? just get them started then lower the car and then tighten them???

I am going to change my article on the front control arm bushings.

This weekend I found out from a retired BMW Master tech that you should lock down the control arm bushing brackets and then immediately put the car back on the ground before the soap lube has a chance to dry.

[long tall eta]

I am going to change my article on the front control arm bushings.

This weekend I found out from a retired BMW Master tech that you should lock down the control arm bushing brackets and then immediately put the car back on the ground before the soap lube has a chance to dry.

good stuff, thanks jimmy