Diagnostic guesses please

D

Disca

Senior member
 West London
Symptoms:
- Steering wheel vibration under breaking
- Occasional hard pull to one side under breaking
- Car doesn't always feel like it pulls straight when it hits the power band

BMW Suggestions:
- ARB brushes weren't installed properly when I fitted them
- Caliper is sticking

Step-dad's suggestions (mechanic):
- Caliper sticking
- 'Run out' on the discs

Things done:
- Tyre pressure is correct as of Saturday
- Pretty sure the ARB brushes are correctly done as step-dad oversaw the process

Which of the following seem the most likely based off those who have never ending wisdom in these areas?

I am going to check the brake discs for a blueing colour when leaving work as step dad advised this can be a sign of brake binding. Will have to wait until the weekend to jack the car up and check the wheels spin freely though.
 
If your caliper is sticking it'll be creating a lot of heat. Check the temperature of you wheel when you next feel the symptoms. Don't however wait to get home before doing this as the air will cool the wheel down once the caliper frees up and you wont feel the heat.

also, warped disk?
 
+1 On the stuck caliper, like Roundozo says, put your hand near the disk after a gentle drive to check the heat compared to the opposite side. A stuck caliper will also show excessive dust buildup and pad wear so also check those.

The heat generated could have also warped the disk which would explain the juddering under braking. Just make sure you fix the cause before changing the disks. Oh and top tip - don't ever ever buy budget disks/pads!
 
Will have to see if they show symptoms when I am next not on a motorway, don't fancy pulling over on that just to check the temperatures :p

We are pretty sure it will be the front discs whatever it is (if disc related) as had the dealer put new rear discs on it at time of purchase.

The car is currently under AUC warranty, if it does appear to be a sticking caliper is it something to get the dealer to sort?
 
I'm going to add front wishbone bushes as a possibility. Steering vibrations and pulling to one side (especially under acceleration and braking) are symptoms of these failing.
 
Stratts said:
I'm going to add front wishbone bushes as a possibility. Steering vibrations and pulling to one side (especially under acceleration and braking) are symptoms of these failing.
Click to expand...

The car recently underwent an Insp2, I would have thought that would have been picked up there?
 
Stratts said:
I'm going to add front wishbone bushes as a possibility. Steering vibrations and pulling to one side (especially under acceleration and braking) are symptoms of these failing.
Click to expand...
I agree - worn lollipop bushes caused my Z to vibrate a little under braking. I'd also check the calipers and disc runout.
 
TheHoff said:
Stratts said:
I'm going to add front wishbone bushes as a possibility. Steering vibrations and pulling to one side (especially under acceleration and braking) are symptoms of these failing.
Click to expand...
I agree - worn lollipop bushes caused my Z to vibrate a little under braking. I'd also check the calipers and disc runout.
Click to expand...


x2

changed mine and it fixed 95% of the vibrations, not sure if its my grooved disc now or if they could be warped.
 
Defo sticking calliper.

Exactly the same symptoms I had. Get it sorted before it seizes totally I nearly cooked the fluid , pads, discs and bearings as it seized on the M3 and only caught it by using a water hose playing it on the outside of the wheel. Steam for about twenty minutes before it was cool enough to limp home.
 
jan_tekin said:
TheHoff said:
Stratts said:
I'm going to add front wishbone bushes as a possibility. Steering vibrations and pulling to one side (especially under acceleration and braking) are symptoms of these failing.
Click to expand...
I agree - worn lollipop bushes caused my Z to vibrate a little under braking. I'd also check the calipers and disc runout.
Click to expand...


x2

changed mine and it fixed 95% of the vibrations, not sure if its my grooved disc now or if they could be warped.
Click to expand...


As above, surely I would have at least had warnings from my inspection two about a month ago if these were the cause? I know they warned me about the ARB brushes.
 
I would of thought the lollipop bushes would of failed along time before the ARB ones. I replaced mine at 80k and they looked to be in good nick.
 
Update: Service guy confirmed I *do* have a warning from the inspection 2 for wishbone brushes :D!

Car is booked in on the 16th for the issue mentioned in round two of this topic.

I am going to get them to check the calipers and the brushes while there.

How easy are wishbone brushes to replace if you do it yourself?
 
I won't say very easy, as that's dependent on experience and tools, but it's a straightforward job and in terms of garage labour. I have seen it done inside an hour so that can give you an idea of what it would cost you.
 
Update: Service guy confirmed I *do* have a warning from the inspection 2 for wishbone brushes :D!
Click to expand...

Thought so :D

Can really help as i paid a garage to replace my control arms with the complete HD kit, was going to do it myself but I asked a garage at work how much he would charge and he said £70 so I gave give him the parts. :D
 
jan_tekin said:
Update: Service guy confirmed I *do* have a warning from the inspection 2 for wishbone brushes :D!
Click to expand...

Thought so :D

Can really help as i paid a garage to replace my control arms with the complete HD kit, was going to do it myself but I asked a garage at work how much he would charge and he said £70 so I gave give him the parts. :D
Click to expand...

:D I was in my own little world when he told me what it was last time.

Will see what they say when it goes in for checks before I look to get it done elsewhere
 
Ok to close this thread out.

Today I had BMW change what they call "brake reaction bushes" under warranty and the car feels a lot better afterwards. They also re-balanced two of the wheels and the two things combined seem to have resolved it.

Anyone know what the brake reaction bushes actually are :D?
 
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