Pulling left under high speed braking. Solved

Z4 Gaz · Post by **Z4 Gaz** » Mon Aug 06, 2018 8:45 am

Only does it at higher speeds, around 60 and above, even when only braking gently.

The car has new Meyle wishbones and Lollipops.
All caliper sliders are free and greased.
Checked the front right caliper piston and that is free from rust and moving fine.
Discs and pads are good all round.
All new suspension.
Track rod ends have no play that i can see from beneith or feel when moving the wheels or pulling on them.

What am i missing here that could be causing this?

I re used the top mounts when doing the suspension as the bearings were tight with no play, so i just re greased them.

markplant · Post by **markplant** » Mon Aug 06, 2018 12:13 pm

Air in the braking lines , just a guess ,

Z4 Gaz · Post by **Z4 Gaz** » Mon Aug 06, 2018 12:22 pm

Pedal feels firm, but will try bleeding the drivers side to see if that makes any difference.

coupedan · Post by **coupedan** » Mon Aug 06, 2018 12:43 pm

May be a silly question but are these tests on the same road or different roads?

I had a road near me that I had to fight to keep straight under breaking.. only done it on that stretch of road though...

jamie_z4 · Post by **jamie_z4** » Mon Aug 06, 2018 1:02 pm

You only checked the right caliper?

Z4 Gaz · Post by **Z4 Gaz** » Mon Aug 06, 2018 1:48 pm

coupedan wrote: ↑Mon Aug 06, 2018 12:43 pm May be a silly question but are these tests on the same road or different roads?

I had a road near me that I had to fight to keep straight under breaking.. only done it on that stretch of road though...

It's everywhere.

jamie_z4 wrote: ↑Mon Aug 06, 2018 1:02 pm You only checked the right caliper?

Yeah, pulling left would suggest the front left caliper is working harder than the right, hence the car trying to rotate to the left, assuming it is even brake related, meaning it would have to be the front right caliper that was sub optimal. Non of the calipers are sticking though.

Jembo · Post by **Jembo** » Mon Aug 06, 2018 1:56 pm

Wheel alignment?

If you have had new wishbones/lollypops next to check is the steering tie rod ends which would have been undone... then done up again which could have thrown out the tracking/camber

Z4 Gaz · Post by **Z4 Gaz** » Mon Aug 06, 2018 2:17 pm

Was doing it before the wishbones were changed, I also didn't remove the TRE's when I changed them.

Doubt it is alignment related as it is perfect apart from high speed braking when there is a pronounced pull to the left. Full set up was done recently too.

Jembo · Post by **Jembo** » Mon Aug 06, 2018 2:46 pm

Round 2 for other thoughts
- tyre pressures
- dodgy shock absorber / cracked spring
- worn ARB drop links
- broken main ARB clip
- fractured ARB
- worn tie rod ends

Z4 Gaz · Post by **Z4 Gaz** » Mon Aug 06, 2018 2:57 pm

Jembo wrote: ↑Mon Aug 06, 2018 2:46 pm Round 2 for other thoughts
- tyre pressures
- dodgy shock absorber / cracked spring
- worn ARB drop links
- broken main ARB clip
- fractured ARB
- worn tie rod ends

Pressures fine, ARB fine, tie rods seemingly have zero play, shocks, springs, arb links and bushes are new

This is why it is so strange.

Once I have bled the brakes I will report back, but may just change the TRE's anyway to make sure.

Jembo · Post by **Jembo** » Mon Aug 06, 2018 4:44 pm

Blimey... looks like you took the journey I made with my old 3.0SE, though at each change it improved as I did 1 by 1

Good hunting

Z4 Gaz · Post by **Z4 Gaz** » Tue Aug 07, 2018 2:49 pm

Bled the brakes on the drivers side front and back, no air came out.

Took the car for a quick drive into town, when I got back I put the infra thermometer on the back of the pads. The near side pad was 20c hotter than the off side, so for some reason the OSF caliper isn't working as hard as the NSF. Hopefully this is the cause of the issue and not a result of.
Rather than rebuild the calipers I am going to go for a 325mm upgrade. Now I just need to source some cheap SI or e46 330 front calipers.

Z4 Gaz · Post by **Z4 Gaz** » Sun Aug 12, 2018 4:00 pm

After changing the front calipers for used ones from an E46 330 along with new discs and pads the problem is solved.

Why I don't know, as the discs and pads were in good, barely worn condition, the pistons are rust free and the slide pins greased and moving freely.

Mr Tidy · Post by **Mr Tidy** » Sun Aug 12, 2018 10:14 pm

Sounds a bit strange, but at least the problem is solved!

Havard · Post by **Havard** » Mon Aug 13, 2018 12:34 am

I have exactly the same issue with the M. Started about a year ago but up to about 60 mph, you wouldn't notice.

I will drop it off at my local specilaist and see if he can sort it.

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