Slight shudder / vibration on braking

[Theog]

Evening all,

I have looked a little on-line and there seems to be mixed set of questions/ answers on this topic, so thought I would ask you guys to see your opinion.

So, I bought this car last Sunday (now wed). So far been great... I have been driving quite a lot today (4 hours or so) and so starting to pick up on small details of the car... I will say however that I have noticed this before, even before driving a lot in the day.

Main potential issue - sometimes when braking I get a slight shudder/ vibration. It's not extreem, but enough to notice once pointed out. Sometimes it happens on slight touches of the brakes, sometimes on more harder. But often if I add more brake it shudders/ vibrates less. Very odd.

Currently I get no swerving to one side in a straight line and currently the brakes are very strong. Much stronger than older 3L i models I have tried.

Currently car is 2007 SI Sport 3L, 118k miles.

Do you think its a brake issue? Or perhaps get my wheels need alignment? Issue with tires? Some people are saying about issues with bush's being worn out.... any ideas welcome and would love to hear if other people have had the same issue.

I may just be being fussy here, but would love to hear peoples thoughts.... also I may need to more tougher tests to see if I can identify exactly when its doing it e.g. turning slightly left at x mph and breaking at x% and so on.

 

[mr.tourette]

most likely cause of vibration under braking is a warped disc

 

[skelters]

Could be tyres, could be alignment or it could be a brakes issue.

Get the wheels balanced and see if it cures the problem before going to any further expense.

I had similar and it was a dodgy Goodyear Eagle F1 AS2.

Others will no doubt have their own experiences and things to check.

 

[bemo]

I am experiencing the exact same symptoms as you, mines a 3.0si on 80k. I've not had it long, similar to yourself.

Is what you are getting like a shimmy through the steering wheel? It tends to vary in severity on mine, and never happens under really hard braking, just moderate and light. When at it's worse it can be felt through the whole car.

Anyway, after I got the car home and gave it a once over on the lifts I discovered there was some play in the rearmost front wishbone bushes on both sides, and I figured that this could be the cause. (It's worth noting that I'm not a mechanic and cars are just a hobby so I may be wrong. ) I've ordered Meyle HD (recommended on here) replacements for the whole front bottom end including the drop links and I intend to fit them this weekend if I get time, so I'll report back and let you know if this solves the issue.
I couldn't see an issue with the brakes, I know a warped disc would be difficult to see by looking but I thought I maybe had a sticking caliper, took both of them to bits and they were fine.

Would have thought if it was a balancing issue then it would not happen exclusively under braking, mine is quite fidgety round the straight ahead also, finding ruts and cambers that aren't visible which could be down to worn bushes. Although I know the Z4 has a reputation for tram lining.

 

[Maxsam]

Was the car standing for a while proir to you buying it.... Rust on the Discs...??

 

[Swiftly]

When I experienced vibration/shudder on my 3.0Si it was traced back to warped front discs

 

[Mike6]

Warping of the discs takes place generally as the metal wears down. Its fairly easy to spot if you look through the gaps in the alloy wheel at the edge of the disc. If there is a fairly substantial lip around the edge your discs almost certainly need replacing but some home mechanics file this down when replacing the pads.

 

[Theog]

Was the car standing for a while proir to you buying it.... Rust on the Discs...??

Hey... just contacted previous owner... he said it was standing for a month... I spoke to a local indy BMW guy and he said it could be rust. I'm going for a weeks holiday to Cornwall (ragging it around everywhere) so if its still bad I'l go see him.

 

[Theog]

So as mentioned in my post above, I'm going on a trip to cornwall.... Before the car was standing for a month so could be rust on disks. However I have run it for around 400 miles now, so I though that would have gone away.

I spoke briefly on the phone to a mechanic I know and he said with high mileage, all things should be considered... suspension, tires, disks, and most of front half. He said that it prob not balance/ alignment as it would still shudder on acceleration etc... however I'm not really sure about this.

Turns out there is a BMW indy specialist down the road form me... cant believe it, such a small place I live in its crazy... I spoke to him and he said give it a go in Cornwall then come back if still back in a week.... however, worn brake disks sounds like a culprit... either way I will let yo know how it goes for me.

@bemo - I have read online and it's a tricky situation.... I have read many threads where people have pretty much replaced most of the front of the car and still had the issue, so I really hope it's not going to be like that for us I will note however that my car is up for a service soon, and it could probably do with two front tires. Seems a bit odd that a car would do that when the wheels are old though. Doesn't seem safe!

Just to clarify, the vibration starts when I slightly brake over 50mph. Below it doesn't do it.

Just out of interest everyone... I have the SI Sport 3L... when driving slow, there are slight squeaks from the suspension at low speed. Is this normal or do you think this could be the culprit e.g. loose / worn part of suspension or something linked?

 

[ChrisN53]

Front wishbone rear bushes worn perhaps?

 

[Theog]

Front wishbone rear bushes worn perhaps?

Yeah could be... but to be honest I have no idea about these things... I wouldn't be able to tell the difference between a spanner and bush to be honest ( car bush that is haha).

I just hope this guy down the road diagnoses it pretty quickly... that's if its still around after Cornwall.

 

[Wildfire]

I had this quite soon after I got my Coupe.

The root cause was warped/worn discs on the front, that combined with shot wishbone bushes was causing a vibration, that was the exacerbated by the worn bushes. I suspect the brakes went first and then hastened the deterioration of the bushes.

Upon replacing the bushes, discs and pads all was normal, until around 5-6000 miles later, when I got shudder but no shaking of the wheel. I had a chat with an Indy who told me my discs were stuffed and I needed new pads and discs, or I had a stuck caliper. I popped the calipers apart and all looked good.

On inspection of the rear, the dealer had put new pads on, but not discs and the pads were rubbing on the rust inner area of the rear discs upon harder braking. I switched out the rear discs and pads and all is now good.

 

[Theog]

I had this quite soon after I got my Coupe.

The root cause was warped/worn discs on the front, that combined with shot wishbone bushes was causing a vibration, that was the exacerbated by the worn bushes. I suspect the brakes went first and then hastened the deterioration of the bushes.

Upon replacing the bushes, discs and pads all was normal, until around 5-6000 miles later, when I got shudder but no shaking of the wheel. I had a chat with an Indy who told me my discs were stuffed and I needed new pads and discs, or I had a stuck caliper. I popped the calipers apart and all looked good.

On inspection of the rear, the dealer had put new pads on, but not discs and the pads were rubbing on the rust inner area of the rear discs upon harder braking. I switched out the rear discs and pads and all is now good.

Hmm interesting. I know nothing about how cars are made, but I get the impression when something is shuddering it normally causes issues else where e.g. bush's getting destroyed or eventually other components wearing off due to the shuddering else where. If not carefull you whole car could be 'shuddered' to pieces.

Just watched this video - https://www.youtube.com/watch?v=AAbET9aKq_g

Long and short of it, he tries find the cause of the shudder. To check if its from the front or the back. He says if you apply the handbrake whilst driving, it will apply braking just to the back tires. Therefore if it shudders then, its most probs back.... however... that only works if you have xzy type of handbrake as mentioned in the video... anybody have any idea if this would work on the z4?

The reason I say this is because he says that often shudder that effects the steering is most often warped disks at the front, and general shudder is from the ones at the back. Or as he refers to it, shudder from the ass. lols.

Given that I think the shudder is more general (from the ass) than in the steering, perhaps it's an issue with mine in the back.

 

[bemo]

Wildfire's post above makes sense, as mine seems to be getting worse, so initially a brake issue is now having an effect on the bushes. I may do the discs and pads for piece of mind even if the bushes do cure the vibration as I don't want premature wear on brand new bushes!

Theog, yes it can be frustrating, however once you've replaced everything you know your front end will be good for many more miles and the car should feel as tight as BMW intended. Mine is also only above 50mph so it sounds like the same issue.

 

[Scooba_Steve]

I don't believe that discs are so easy to warp and subscribe to the theory that what is describes as warping is most often pad deposits. I had some juddering and a brisk cleaning routine resolved it - that would certainly have been put down to warping. When the discs are replaced the solution is vindicated

As for locating the handbrake method won't work as you have discs all round, if the steering wheel wobbles it's the front, if you feel it in the seat it's the rear.

My method of fault finding would be this:
Take the car out when it is quiet to a safe, national speed limit location. Get up to at least 70 and brake heavily without activating ABS to about 20. Repeat at least 3 times then allow to cool by driving without braking for a good few miles.
If you find that reduces or eliminates your judder then it's deposits. If you sit on the footbrake often this can contribute to deposits.

If not then start thinking about sticking callipers - a DIY service of them isn't hard - or brake reaction/lower control arm rear/lollipop bushes for front judder.

 

[bemo]

Given that I think the shudder is more general (from the ass) than in the steering, perhaps it's an issue with mine in the back.

Ahh, mine is most definitely through the steering wheel, only when particularly severe do you feel it through the car.

 

[Theog]

I don't believe that discs are so easy to warp and subscribe to the theory that what is describes as warping is most often pad deposits. I had some juddering and a brisk cleaning routine resolved it - that would certainly have been put down to warping. When the discs are replaced the solution is vindicated

As for locating the handbrake method won't work as you have discs all round, if the steering wheel wobbles it's the front, if you feel it in the seat it's the rear.

My method of fault finding would be this:
Take the car out when it is quiet to a safe, national speed limit location. Get up to at least 70 and brake heavily without activating ABS to about 20. Repeat at least 3 times then allow to cool by driving without braking for a good few miles.
If you find that reduces or eliminates your judder then it's deposits. If you sit on the footbrake often this can contribute to deposits.

If not then start thinking about sticking callipers - a DIY service of them isn't hard - or brake reaction/lower control arm rear/lollipop bushes for front judder.

Interesting. I suppose if my car was sitting for 1 month, then it could be build-up. I will try tomorrow/ over weekend. To be honest I haven't slammed the brakes at all as they are so sensitive, just a small application seems to do the trick.

 

[Theog]

Given that I think the shudder is more general (from the ass) than in the steering, perhaps it's an issue with mine in the back.

Ahh, mine is most definitely through the steering wheel, only when particularly severe do you feel it through the car.

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?

 

[Theog]

Given that I think the shudder is more general (from the ass) than in the steering, perhaps it's an issue with mine in the back.

Ahh, mine is most definitely through the steering wheel, only when particularly severe do you feel it through the car.

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?

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

 

[bemo]

Ahh, mine is most definitely through the steering wheel, only when particularly severe do you feel it through the car.

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?

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

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 )