Vibration when braking at speed

[HokieZHP]

Hey guys so I was driving last night *in mexico* and I went to brake from a high speed and the brakes shuttered. Like a quickly paced vibration. Doesn't happen at lower speeds (less than 80) but if I am going faster and brake, there is this vibration from the brakes.

Any ideas?

[Hornung418]

Have you checked your rotors for flatness? It's very possible that they are warped, especially at 130k+ miles.

Changing my rotors stopped my shuddering at high speed braking.

[HokieZHP]

No I haven't. I measured the fronts the other day and they came to 25mm give or take 0.1. Are they getting close to being shot?

Here's a clip of a video I took of the vibration. Sorry but it's on a iphone... I am on the brakes (very lightly btw, not even stomping on them) whenever the video gets blurry or distorted.

http://i438.photobucket.com/albums/qq109/maxx919/2003%20ZHP/th_5d1b80c5.jpg (http://s438.photobucket.com/albums/qq109/maxx919/2003%20ZHP/?action=view&current=5d1b80c5.mp4)

[M3TA5IN]

Have you checked your rotors for flatness? It's very possible that they are warped, especially at 130k+ miles.

Changing my rotors stopped my shuddering at high speed braking.

X2. The reason you feel it really bad at high speed is because of the speed of rotation. At slower speeds warped rotors are very hard to notice or not noticeable at all depending on how severe they are warped.

[HokieZHP]

Well that's a bummer if they're warped. They're the BMW performance drilled rotors :(

This is relatively new though as I haven't felt it before... maybe it is time to get new brakes. Wonder if I can find any more BMW perf. ones, hmmmm.

[M3TA5IN]

Well that's a bummer if they're warped. They're the BMW performance drilled rotors :(

This is relatively new though as I haven't felt it before... maybe it is time to get new brakes. Wonder if I can find any more BMW perf. ones, hmmmm.

Take your wheels off and place a straight edge ruler on the rotors, if you see any gaps, even little ones they are warped.

[Hornung418]

How old are the rotors?

It's possible that you need new pads. Or you Powerflex FCABs may have backed out. Check into AKG Motorsports if that's the issue. They're line of products is far superior than that of Powerflex.

[HokieZHP]

I honestly have no idea how old the brakes are. Like I said I measured them at home at they came out to be 25mm +/- 0.1. I don't know what they were to begin with but that's what the fronts are down to now. They were on it when I bought it this past July. I know the rear pads are getting to the end of their life but the fronts are still pretty full.

I think I'm going to head over to my friend's garage here in town to get under my car and see what I can find.

[M3TA5IN]

I honestly have no idea how old the brakes are. Like I said I measured them at home at they came out to be 25mm +/- 0.1. I don't know what they were to begin with but that's what the fronts are down to now. They were on it when I bought it this past July. I know the rear pads are getting to the end of their life but the fronts are still pretty full.

I think I'm going to head over to my friend's garage here in town to get under my car and see what I can find.

Oh if you have a buddy with a shop just ask to use his dial indicator. Place on rotor, spin, watch for a fluctuation to the left or right.

[danewilson77]

Oh if you have a buddy with a shop just ask to use his dial indicator. Place on rotor, spin, watch for a fluctuation to the left or right.

$10 dial indicator is a pretty good purchase at Lowes.

Sent from SIGFest-2012, USA on HTC via TTv2

[Nivo]

Get new rotors, have them Cryo treated, That has worked for me for years now (I have a local Cryo place local to me http://www.nitrofreeze.com/)

[HokieZHP]

So I got carried away and ended up washing my car, again 2 days later haha and also checked out all my suspension and brakes and such.

The rotors are true it looks like. I used a straight edge and flashlight and such and didnt see any fluctuations. I'll go for a drive tonight (not as fast) and see how it goes and report back.

I did find out that the shocks are original and also have pics of the FCABs. Btw this light board I got from my dads scrap pile at work is awesome for working under the car!

Sorry for the iPhone pics..

http://img.tapatalk.com/62f90788-c6f0-b968.jpg

3749

Left bushing:
3747

Right bushing:
3748


I also saw this. Is my diff leaking??

http://img.tapatalk.com/62f90788-c804-c887.jpg
http://img.tapatalk.com/62f90788-c820-3e1c.jpg




Sent from my iPhone using Tapatalk

[Hornung418]

Diff probably has a small leak. Just make sure you don't end up with a huge puddle on the driveway...then you know it's bad, I should know :facepalm

Easiest fix is to get your wrench and make sure some of them aren't loose.

[danewilson77]

The gasket should be an easy fix....at next diff fluid change?

Oooh......good excuse to get finned diff cover.

[Hornung418]

To fix the leak, the differential has to be removed...which is very complicated unless you are dropping the whole rear end.

I just over torqued mine and have checked it every now and then to find no leaks. I just wipe it down when I do. That amount on the diff is not really that much because it spreads very thin and it picks up all the grime on the road.

[Oli77]

A brake caliper could be bad couldn't it? or does it have to be the rotor?

[derbo]

my performance rotors have a wobble recently too, but I believe its due to uneven pad deposits. I will use a race pad to agressively cut the rotor and then see if it improves.

[Mr Paul]

No I haven't. I measured the fronts the other day and they came to 25mm give or take 0.1. Are they getting close to being shot?

Here's a clip of a video I took of the vibration. Sorry but it's on a iphone... I am on the brakes (very lightly btw, not even stomping on them) whenever the video gets blurry or distorted.

http://i438.photobucket.com/albums/qq109/maxx919/2003%20ZHP/th_5d1b80c5.jpg (http://s438.photobucket.com/albums/qq109/maxx919/2003%20ZHP/?action=view&current=5d1b80c5.mp4)


Stock rotor thickness is 25mm. You could have uneven rotor deposits causing the brakes to pulse. You could try to do several 60-10 stops in succession to see if that cleans them off.

[LivesNearCostco]

I don't think they make gaskets any more for our diff covers. Supposed to use RTV instead.

[zhpnsnv]

my performance rotors have a wobble recently too, but I believe its due to uneven pad deposits. I will use a race pad to agressively cut the rotor and then see if it improves.


Stock rotor thickness is 25mm. You could have uneven rotor deposits causing the brakes to pulse. You could try to do several 60-10 stops in succession to see if that cleans them off.

That and that. Unless you were driving on a race track and then immediately sitting in the pits thus hot-spotting your rotors, you probably have uneven deposits. You feel it when you're lightly applying the brakes because you're not exerting enough pressure to get through it. Follow the advice above.