Between 60mph and 80mph. The steering wheel vibrates really badly. Also during braking between 40mph+. Typically I would assume it is the rotors but thinking it can be something else. I have two sets of wheels and happens on both sets.


I noticed the top strut mounts are making noise when it was cold lately so probably are worn out. Should I begin with replacing top mounts (will to trusts at the same time too) or should I start with rotors and pads? Would worn top mounts give me those symptoms described above? Anything else I should be looking into?


Thanks

**** Update ****

Please see post #7 for additional information. Thanks for all the help/suggestions so far!

 

if the car is shaking when not on brakes, it probably is not pads or rotors, could be seized caliper. My first guess is tires, do you know if they are not flat spotted, cords damaged or out of balance? I would probably put the wheels on a tire balancing machine.

 

Worn balljoints in either the track rod ends or lower control arms will cause this. Both are very serious issues and if either balljoint breaks, the results can be catastrophic. I'd recommend you stop driving your TT until you get to the bottom of this.

Keep us informed with your diagnosis and progress.

 

If the behavior occurs with two different sets of wheels/tires this points to a common problem and that has to be with the car.

With the car raised have you check the tire, wheel and even rotor runout at all 4 corners? Be sure you check lateral and radial run outs.

If a wheel/tire combo is not mounted to its hub correctly or if the hub is not mounted to the spindle correctly this can account for the behavior.

If you replace the strut hardware the car probably will require alignment. However, if there is a problem with a badly fitting hub or wheel to a hub the alignment may not be any good and could complicate things.

There could also be two problems. One is a hub or wheel/hub problem and another is brake discs that have developed a pulsing during usage. This can arise if new pads are not bedded in properly and an emergency stop is made from speed and the hot pads left in contact with the hot rotors.

Another way is if the rotors are rusted -- such as can be the case if the car is washed then not driven after to dry the brakes -- and again an emergency stop is done and the hot pads are left in contact with the hot rotors. (This happened to my VW Golf TDi. Afterwards the brakes had a pulsing to them when used lightly at slow speeds.

If either of the above is the case only a resurface of the rotors will correct it --- well that or replacement of the rotors. In either case the brakes need to be bedded in again.

 

Sounds like a thorough check of your entire suspension is due based on your comment about the struts being worn. Lots of variables here.

 

It is something in the suspension. Not the brakes or tire balance.

 

So was pretty set on agreeing with the suspension diagnostic. Yesterday I decided to check the tire pressure... well overdue... The front were WAY too low. I went up to proper tire pressure and went for a very quick drive.

So on the highways (up to 80mph) steering wheel no longer shakes. There might be VERY slight shaking but these wheels and tires were recently bought used so might need to re-balance them. Anyways braking (very light or firm) the steering wheel shakes badly. Like 1/2" each direction. So am I back to think it is brakes? Brake pedal does not pulse.

I don't think it is suspension related because there is zero suspension noise. Typically worn bearings, ball joints give off noise. The only noise I get are from upper mounts under hard braking but nothing over pot holes or tracks.

The car has only 40k miles and I highly doubt the previous owner ever tracked it. Hard to believe brakes are already bad?

Would something like this cause the shaking:


I didn't do research yet on stock pad thickness, but this is how much of the pad is left:

 

check rotor thickness to see if in specs next

 

Based on the rotor the pad is worn in that one spot

 

So would that cause the steering wheel shaking? I would imagine bedding would not solve my issue. New rotors and pads are in order?

 

Check in following order:

1. tire pressures
2. wheel/tire balance (could be tire AND/OR wheel roundness problem)
3. alignment

i predict most of the problem will be solved

if not, then

4. brake rotors/pads
5. suspension links/bushings/mounts

 

Generally when there is some shaking/vibration when braking the cause is uneven pad material deposition on the rotors. "Warped" rotors often get the blame but truly warped rotors are rare.

I actually caused uneven pad material deposition with one of my cars, a VW Golf TDi. I washed the car and left it sit overnight. The brake rotors rusted up something fierce. The next day I took the car out and drove through town not using the brakes much if at all. Got out on a county road and had to make an emergency stop to avoid a collision. Another car pulled out in front of mine. I brought the VW to a safe stop and avoided contact, but I left the brake pedal applied. I was just glad I avoided an accident and wasn't thinking of the consequences of leaving the pedal applied, wasn't aware at the time it could be a problem. But with the rust and heat and brake pedal remaining applied pad material ended up on the rotors and from then on with the brakes having a mild pulsing when lightly using the brakes. I tried bedding in the brakes again but this had no effect.

The only cure for this if this is what is wrong of course is resurfacing the rotors or replacing the rotors. If the pads have plenty of material left and are in otherwise good shape they can be reused.

Otherwise, the pads should be replaced too.

However, based on what you posted this diagnosis can't be made with any confidence.

Loose/worn/damaged suspension/steering hardware could account for the behavior. Obviously when braking a lot of force is transmitted through the suspension and any loose bushing or bearing can cause something to deflect and move out of position.

Unless the cause of the problem is obvious most of us will require expert help in diagnosing what's wrong.

I'm sure you are aware of this, but throwing parts at this kind of behavior is an expensive way to sort out the problem.

 

Thanks ^

I wanted to do brakes anyways on the car, the pads seen getting thin. I'm a big fan of EBC RedStuff pads for brake dust control and extra bite. I managed to buy new front rotors with new pads front/back, sensors for under $400 shipped. I'll install then on monday.

Agree I don't want to just start throwing parts at the car hoping to find a fix. But the first thing I wanted to do is new brakes on a 15 year old car and new suspension (monoball top mounts, bilstein struts, springs).

Those upgrades were on top of my to-do list anyways so might as well do them. If shaking STILL occurs, I have no issue getting proper diagnostic done.

Thanks all for the help. But seems proper tire pressure eliminated half of my problem.

 

A suspension refresh isn't complete without tie-rod ends. They are definitively a consumable. There are a lot of bushings that can wear as well, so don't forget to check them out.

Cheers,
TomF

 

As long as the brakes have been bled on schedule age is not really a concern. For instance the original front brakes on my 2003 Turbo lasted to 120K miles and 8 or 9 years after the car first touched pavement. The rears are still in service and the car is 13 years old and now has covered over 140K miles.

But in the case of your car in the pics the rotors do look like they could possibly stand to be replaced.

And if you want to do a suspension refresh that's entirely up to you of course. My thinking is even if the hardware replaced/renewed during the refresh aren't responsible for the behavior while the tech is there removing parts/hardware he might spot the cause of the problem and bring it to your attention for permission to address it.

Last but not least and I don't always post this and perhaps I should whenever wheel or tire balance, vibration, or other abnormal suspension or steering behavior happens tire pressures should be the first thing checked and corrected if not correct. At the same time all tires and wheels and brake hardware should be checked for any obvious signs of problems. This includes making sure the tires are the right size, right specification, and if uni-directional they are all mounted the correct direction.

With wheel/tire steering or suspension problems it is my opinion the easiest/simplest things to check for is the best way for the non-professional to approach resolving the issue if the cause of the problem is not obvious.