Slight shudder / vibration on braking

bemo said:
Theog said:
Theog said:
Just out of interest, when you say shudder, is it making the steering wheel go slightly left/ right or is it more of a general vibration?
Click to expand...

Also, to top this, could you brake around a left/ right corner to see if it worsens?
Click to expand...

The steering wheel wobbles from left to right from the straight ahead but doesn't pull in either direction, the wobbling is almost rhythmic.

I've not driven the car for a couple of weeks as I work away and take a different car to work with me, the Z4 is tucked up in the garage. I'll be changing the wishbones and bushes on Saturday hopefully so won't really get chance to drive it between then and now but I can have a look for you. (Although braking mid bend is generally not advised :P)
Click to expand...

Ok cool, please let us know how it goes once you do get around to it :)

Your lucky that you can mess around with these things... I have never even changed a tire! I look under the bonet and go 'yep its an engine'. About as far as I go... wish I knew more about it all... then again, I used a drill for the first time last year, and now I have renovated a fair bit of my house, so happy with that :thumbsup:
 
This happened on my last roadie. It was diagnosed as a front control arm bush being completely shot and a warped disk as a result. New control arm bush and new discs and pads sorted it. From experience of reading lists on here, the general consensus is that when these cars get to around 100k miles or more you really need to think about replacing suspension parts up front if it's not been done.
 
Bing said:
This happened on my last roadie. It was diagnosed as a front control arm bush being completely shot and a warped disk as a result. New control arm bush and new discs and pads sorted it. From experience of reading lists on here, the general consensus is that when these cars get to around 100k miles or more you really need to think about replacing suspension parts up front if it's not been done.
Click to expand...

hmm that's interesting. I kinda had a hunch that maybe the case. But I suppose if your going to have the car for a long time, its going to be done at some point anyways. May as well have the nice stuff sooner haha (me trying to justify things).
 
What Steve said. The Indy told me it was warped discs on the front. Without a doubt. Balls! The shudder/rumble only happened after a certain braking input. As cars are front biased the harder you brake the greater effect the rear will have, hence increased shudder. But no/little effect on steering. I say little because if your bushes are shot the car will be unsettled, which may cause undulation at the front.

Do check the condition of your discs and pads on both ends.
 
I just tried something out.. i pushed down on each corner of the car above the wheel.. there seems to be a squeak from the back left (if looking towards the bonet) suspension. A bit like an old sofa or the likes.... is this a different issue or could it be connected with the back shuddering?

Perhapps once back brakes engage over 50 mph it bends slightly?

Or do you think its just squeaky and the disks are worn? Perhaps combo of both

Update - this could be something similar - https://www.google.co.uk/url?sa=t&s...d5Y9HHGXq6XCXPiQg&sig2=L6ATJzYfkQlVfou5-T1MTA
 
Rust causing shuddering - cobblers. The rust will go after a few brakings. Still bet its the disc. Have you had a look at the edges to see if there is a big old lip. Discs are designed to wear particularly now harder material is used on the pads (asbestos was softer) and if car has done high mileage and some hard braking. Enormous amounts of heat are transfered onto discs so as it wears and material gets thinner they warp slightly.
 
Mike6 said:
Rust causing shuddering - cobblers. The rust will go after a few brakings. Still bet its the disc. Have you had a look at the edges to see if there is a big old lip.
Click to expand...

just about to head off to Cornwall, but once there, could I take a few pics of the brakes and you let me know what you think?
 
That doesn't explain why they warp. My judder was so bad you could hear the steering wheel vibrating as it shook (rotating).
This could only be explained by warped discs by every professional I asked. Heat cycling the discs cured the issue and I am still using them 18 months and 2 track days later with >50% life on the pads.
It's a method worth trying first before throwing away good money.
 
Re bed them , 60 down to 20 a dozen or so times on a quiet road then drive home normally but the long way , you need to get them stinking hot so brake as hard as you possibly dare . It's free so it's the first thing you should try .
if it doesn't work you could get them skimmed on the car to true them up properly , then start looking into suspension bushes .
 
I wasnt aware anyone had discs skimmed these days. The surface I believe is hardened so you may already be down to the sotfter metal which with skimming may in turn accelerate wear. They arent that expensive a component and are often qouted as service items.
 
Pro cut I think it's called , discs skimmed on the hub to take out any run out and ensure they are true , I've had a couple done and it works . There was a video kicking around where they bolted a new disc onto a car and checked it for run out and it was miles out !
New discs are buttons to buy and 20 mins to fit . I've only had it done on 2 piece discs
 
Hey peeps

Quick update... i've tried doing the whole 60 to 20 a few times and no luck so far. Im pretty sure its the pads/ disks as when i brake softly at slow speeds to a stop i can feel and hear that it rhythmically connects on one part of the wheel turn. This makes me think there is one part of the brakes that is connecting before other parts. Maybe inconsistan wear? Or maybe disks have 'done a wobbly' haha.

Interesting about getting the disks ground back. I think i would prefer new ones though just for peace of mind. Im guessing it means more time in the garage too?
 
Invest in some tools and swap the discs yourself, will save you in the long run, no markup on parts and no labour to pay.
 
Scooba_Steve said:
Invest in some tools and swap the discs yourself, will save you in the long run, no markup on parts and no labour to pay.
Click to expand...

Dont feel quite confident with that yet. I have service booked now for next monday. Think inspection 2. So can ask then.
 
If they have the wheels off during inspection it's really easy to diagnose if the discs are warped.
You just need a micrometer (dial/clock) and a magnetic stand. Every mechanic has one (or should have one :o ) as it's only £30 or so for that tool setup. (but sometimes I come across mechanics who dont understand that setup....)


No need to buy new discs if the problem lies somewhere else. (or a garage has a nice excuse to sell new discs).
 
GuidoK said:
If they have the wheels off during inspection it's really easy to diagnose if the discs are warped.
You just need a micrometer (dial/clock) and a magnetic stand. Every mechanic has one (or should have one :o ) as it's only £30 or so for that tool setup. (but sometimes I come across mechanics who dont understand that setup....)


No need to buy new discs if the problem lies somewhere else. (or a garage has a nice excuse to sell new discs).
Click to expand...

Nice will ask them once i drop it off!
 
Here some vid on how things basically work (youtube probably has more..)

https://www.youtube.com/watch?v=t_IZzyQcBPA

I dont know how much the measurement gets influenced when the caliper is still on the wheel.
Removing the calipers is a lot of work. Maybe pushing back the pads a bit is sufficient.
 
that sound you hear from the rear left maybe worth checking, it could be a broken coil spring as this is a known failure on Z4's, but as I understand it, the sport model has uprated springs so maybe okay. Worth getting it checked at the service.
 
You must log in or register to reply here.
Back
Top Bottom