Hi all,

 

I thought I’d throw this out here to knock some heads together as this problem is really frustrating me now!

 

It started off as a very mild vibration when braking at speeds at around 80mph and above but gradually got worse over a period of months. It was never “too” bad but I decided to try and rectify it before a trip to the Lake District and now it’s become “too” bad!

 

As it stands I get fairly severe vibration at all speeds down to around 20-30mph where it fizzles away. When I first take the car out, it’s nice and smooth with no feedback but after the 2nd or 3rd use of the brakes it begins to worsen and after that it’s at its worst. When I release the brake pedal, all vibration stops and it’s back to smooth sailing, no vibes are evident through the seat.

 

Here’s what has been done:

- Run out checks of both front wheel hubs

- DBA 4000 discs with around 10k miles on were turned down using an on car brake disc lathe

- Thermal paint marking on discs show no evidence of overheat

- New brake pads

- New front upper control arms after play evident in passenger arm, body side bush

- Calipers inspected for piston movement and pad movement

- Full fluid flush and bleed

- All bushes inspected (several times by servers people!) with no evidence of play

 

This little snag has me scratching my head, any ideas? I know spanking another £500 on discs is probably a good call but I just can’t see how these discs are at fault. I did another run out check on them today and they’re perfect!

 

Any advice appreciated.

What did the place who skimmed the discs have to say?

Hi Joel, have you checked the Steering rack and rod ends for play?

Wheel bearing/bearings???

What did the place who skimmed the discs have to say?

They recommended that I bed in the pads fully first and then take it back for them to assess. That’s on my radar.

 

Hi Joel, have you checked the Steering rack and rod ends for play?

There is no movement in the steering rack bushes, tie rods or ball joints.

 

Wheel bearing/bearings???

I can’t feel any play in the wheel bearings and the last MOT where they put it on the side-to-side jiggle machine showed no signs of movement.

My tension rod bushes have covered around 20k miles and I can’t feel any physical movement in them but I guess there could be some when under more load.

Try to rebalance your wheels. Do you have spigot rings ?

Sticking Piston in the calipers ?

My tension rod bushes have covered around 20k miles and I can’t feel any physical movement in them but I guess there could be some when under more load.

 

I had a beemer that exhibited the same brake judder issue even after changing discs and pads. Turned out to be the front tension rod bushes. I had already checked them and couldn't find any movement anywhere in the suspension. Checked it again with the car on shaker plates and the bushes showed up right away. The problem with jacking a car up to check for wear is that you can take some components out of their normal running position, which masks any play/wear. If you cant find a friendly garage with hydraulic shaker plates, get a mate to try rolling the front wheels back and forward with the handbrake on while you watch the bushes. Used to do that to check on old fords, problem is the Z is a bit lower so wont be easy to check unless you have a pit.

Try to rebalance your wheels. Do you have spigot rings ?

Although it doesn’t do it all the time, I also had the same thought to eliminate the possibility, nil fix.

 

Sticking Piston in the calipers ?

I had the pads out today and could move each piston in the caliper fairly easily, they’re smooth as silk! I rebuilt the calipers with a genuine Brembo rebuild kit about 10k miles ago so I didn’t expect to have issues but I had a good look to eliminate them.

 

I had a beemer that exhibited the same brake judder issue even after changing discs and pads. Turned out to be the front tension rod bushes. I had already checked them and couldn't find any movement anywhere in the suspension. Checked it again with the car on shaker plates and the bushes showed up right away. The problem with jacking a car up to check for wear is that you can take some components out of their normal running position, which masks any play/wear. If you cant find a friendly garage with hydraulic shaker plates, get a mate to try rolling the front wheels back and forward with the handbrake on while you watch the bushes. Used to do that to check on old fords, problem is the Z is a bit lower so wont be easy to check unless you have a pit.

This is what I’m leaning towards now. I can get access to the shaker plates so I’ll pop over them them tomorrow and see if the tension rods move.

 

There’s certainly no play in the lower ball joint, the steering ball joint, the king pin bearing, the upper arm bushes and the lower arm bush so if the tension rod isn’t the culprit, I’m torching the car! [emoji1] (after I’ve spanked another £500 on discs!)

Slight play in the wheel bearings ?

Slight play in the wheel bearings ?

 

I certainly can’t feel any but if I manage to get the car on a shaker plate tomorrow, I’ll be sure to pay attention to those too. At least 4 different people have had a good rock to assess the wheel bearings so I don’t hold out much hope! I have a new wheel bearing in a Nissan bag in my arsenal too so it’ll never make it that easy for me! [emoji1]

The only thing “steering” me away from the tension rods is that the vibration is pretty much non existent for the first braking episode. The fact that it’s heat related screams a disc defect to me. Then again, I’ve never known or heard of discs that are perfectly true when cold and then assume a new, warped lifestyle in the heat of action!

 

Another point to note, there is no feedback through the pedal when this happens, it is all through the steering wheel.

Can a mod please correct the spelling of Virbration in the title please! [emoji1]

Done

How about. ABS fault. Try deactivating it and seeing if it goes away.

Gotta think logically. What happens when you brake, I mean suspension wise. One of the things is the lower arms try to drag backwards and exert toe out, that flutter is probably what you can feel. This is most likely the tension rod bush in most cases but could also be the lower arm bush to the subframe. That’s my gut something in that part of the equation is struggling.

Discs not balanced. I don't even know if it's a thing. I was going to say you could have a wheel not ballanced or buckled, but that would be there independent of braking. However if your discs aren't balanced they could do that but pass a runout test. A manufacturing flaw perhaps.

 

It's a bit of a whacky suggestion but you're into wierd and wonderful territory.

 

Consider trying some odd stuff like swapping wheels about.

If you access to a ramp or can drive the car with the front wheels of the ground and not under load you can determine whether its suspension/brakes and if it persists try removing wheels and try again

If you access to a ramp or can drive the car with the front wheels of the ground and not under load you can determine whether its suspension/brakes and if it persists try removing wheels and try again

 

Drive the car with the front wheels off the ground? I’m getting visions of these videos you see from India with trucks cruising down the motorway using a trolley jack as a replacement wheel! [emoji1]

 

How do you mean, Jack?

How about. ABS fault. Try deactivating it and seeing if it goes away.

Gotta think logically. What happens when you brake, I mean suspension wise. One of the things is the lower arms try to drag backwards and exert toe out, that flutter is probably what you can feel. This is most likely the tension rod bush in most cases but could also be the lower arm bush to the subframe. That’s my gut something in that part of the equation is struggling.

 

I’ll give it a shot with the ABS fuse pulled and see if it changes anything. [emoji106]

Discs not balanced. I don't even know if it's a thing. I was going to say you could have a wheel not ballanced or buckled, but that would be there independent of braking. However if your discs aren't balanced they could do that but pass a runout test. A manufacturing flaw perhaps.

 

It's a bit of a whacky suggestion but you're into wierd and wonderful territory.

 

Consider trying some odd stuff like swapping wheels about.

 

I’ve swapped wheels to no avail. The defect still has a feel of a disc defect about it so eventually I’ll end up changing them if I don’t find a cure.

Do you think they might have a minor hairline crack somewhere that doesn't show when the disk is cool but become prevalent under heat/load?

Joel...If you think it is disc related...instead of splashing £500 on a new set...could you not try a cheap front pair first to try to prove the theory?

 

I'm not sure if you can get 'cheap' rotors for your setup..but if you can...while being a pain...swapping them over to test isn't too big a job....

I mean lift the front of the vehicle up so the wheels remain off the ground axle stands/ a vehicle ramp haha then stick it in gear until your up to speed so the car will be stationary but you will be driving with load off the suspension if the problem persists its brake related if not its suspension. If your near milton keynes i have access to a workshop and a load of ramps 24/7

I mean lift the front of the vehicle up so the wheels remain off the ground axle stands/ a vehicle ramp haha then stick it in gear until your up to speed so the car will be stationary but you will be driving with load off the suspension if the problem persists its brake related if not its suspension. If your near milton keynes i have access to a workshop and a load of ramps 24/7

 

Hi Jack, this would work if it wasn't a rear wheel drive..... :innocent:

I meant rear haha sorry