50-60 mph wobble

[30csl]

Hi Guys,

I have a front wheel wobble when braking down through 40-60 roughly speaking.

Accelerating through this range doesnt produce wobbles.

The car has just had new control arms, has recent front subframe mount bushes. It is on 16" alpinas which I believe to be properly balanced.

At 100mph there is no wobbles etc.

When I put the 14" wheels on the car there is no wobble even when she had the old worn control arms.

Im guessing that I need to have the alignment checked and might have to replace the tyres just as they are low mileage but old.

Any thoughts? I was sure the new control arms would cure it.

 

[nashvillecat]

I have a front wheel wobble when braking down through 40-60 roughly speaking. The car has just had new control arms, has recent front subframe mount bushes. It is on 16" alpinas which I believe to be properly balanced. Any thoughts? I was sure the new control arms would cure it.

Several things come to mind. There can be a great difference between fact and your belief. Since you do/did not have the problem with 14" wheels/tires, I would start there. The "new "16" problem wheel/tire combination could be out of balance, out of round, have a minor belt separation or an irregularity that only shows up when the tire is under a load. Years ago, I can recall some shops shaving or "truing" tires. If the tires are not directional, have you tried swapping the two fronts? Wheel bearings snug? Changing taller skinnier tires to presumably wider and possibly heavier ones creates new issues - most of which can be satisfactorily redressed.

The fact that you mentioned braking makes me wonder about the front tension strut bushes. Coupe alignment is typically rudimentary - toe adjustment. Caster and Camber are not ordinarily adjusted, except that new bushings and mounts should maintain the original specifications. If the bushings are sloppy, and this is especially true of the upper strut mounts and the tension strut bushes, setting the toe may make the problem livable.

Good luck.

 

[Malc]

Wobble under braking can be caused by warped brake discs. It may only be very slight but with a new combination of wheels and tyres it may have been "unmasked" as it were. Have you checked the disc run out with a dial gauge?
Check the hub run out too, as the bearings may have a tiny bit of play.

Oh, and of course there all this combined with everything nashvillecat has mentioned :roll:

 

[dang]

My guess is tires (assuming the wheels are true).

 

[30csl]

Well guys I had the chance to swop over to a different pair of front alpina 16s with new tyres and lo and behold the wobble at 50mph is gone. The wobble was there slightly under normal driving but when braking it became very noticeable.

I had the old wheels balanced and they said they were out before but having put them on the car it is no better. The wheels were new and I dont think they are buckled.

Anyone had tyres cause this? They are nine years old but have done about 6k miles.

Rohan

 

[dang]

I still think its bad tires. If it were mine I'd have the tires removed and have the wheels checked for true (spin on a hub or balance machine slowly by hand and see if its out of round). After you've eliminated that as a possible cause, buy new tires.

Dan

 

[30csl]

Hey Dan, I think you are dead right.

Fair play for calling it, I just couldn't believe tyres would do this. I hope so and will do like you say.

 

[30csl]

Well new tyres and no improvement - pretty damn annoying!

Still the tyres were old. Im hoping now that changing out the steering box and linkages will cure it.

 

[abe3.0CSi]

Might be cheaper to change the wheel bearings first before doing really expensive stuff.
abe

 

[jhjacobs]

I have a front wheel wobble when braking down through 40-60 roughly speaking.

This sounds like improperly seated brake pads to me (irregular pad to rotor material transfer). Warped rotor will typically wobble at all speeds but pad seating can cause strange results. I've heard that you can go back through the brake pad seating process with old pads/rotors and sometimes get them back to normal; I've never tried it though. Is the wobble only under braking?

Are you sure that the old wheels and tires didn't produce this effect? Do you still have them? It might be worth a quick test with the old wheels.

I've also noticed that wider rubber than the original 178/185 stock tires can bring out suspension problems not seen with the stock wheels/tires.

My money is on the pads / rotors.

 

[dang]

I'm confused now. It wobbled with the old rims and tires under braking. New tie rods didn't help. Different rims and tires made it go away, but new tires on the old rims did not make it go away. So, doesn't this point to the old rims? You did say that with different rims and tires it went away, right? If you've changed the tires, what's left? Rims? I'd be tempted to change the rims and tires out again to double check before replacing any other parts.

Maybe I'm easily confused, wait, don't answer that , but if you really did get rid of the problem with different rims and tires, I'd concentrate there.

 

[30csl]

Dan you are correct- going to try those wheels again to make sure I didnt imagine it. The tyre shop checked the wheels and said they were ok. I am getting sick of taking wheels on and off the car!!

Rohan

 

[Bill Riblett]

One more obscure possibility is worn strut bearings, although I would expect these to show problems at slow speeds too. If the bearings look dry you may be able to force some grease into them without disassembly. If they are rusty, I would just replace them.

 

[30csl]

Thanks for the replies guys.

Abe - the bearings are 6k miles old and she rolls nicely and they feel very tight when i tried them.

JJ - I did as you say and tried the other 16" wheels and it did indeed wobble - not sure how I thought it didnt before!

It definitely didnt with the 14s and 195 rubber so now Im looking at steering joints ans the control arms and subframe bushings are fairly new. There is definitely a good bit of wear in the joints and box but amazed it does this.

I'm pretty confident it isn't pads or rotors but it does feel like them due to it being mainly noticeable under breaking. Had this on an m635 and it was control arms but i just changed them on this car.

Very annoying.

Thanks,

Rohan