Liam's Z4C race car project

[Beedub]

what a thread!!!

[Liam22]

The Z4C is still going well. Last weekend was its 21st race, and my 200th. Time flies when you're having fun...

My son stitched together my onboard camera with the live stream footage. Check out the last 10 minutes for some interesting BMW-on-BMW action

https://youtu.be/5CmqrZ6Itto

[enuff_zed]

Snetterton! Wish you'd told me!

[enuff_zed]

Just watched the video. Damn, I missed a good'un!
Does it not frustrate you that on a circuit like Snetterton the more powerful cars can get past you without any ability to go round corners?
I loved the way you just nipped back past on every bend.

[beanie]

Great race, such a shame you didn’t quite get 2nd as you definitely deserved it imo

[Liam22]

Snetterton! Wish you'd told me!

Oh jeez, I feel quite bad about this. Thought it was on the schedule I'd posted but looks like I forgot about it. Promise I'll let you know next time!!!

Was back out at Donington on Sunday.

Screenshot 2023-06-19 at 18.10.50.png (747.8 KiB) Viewed 465 times

A lucky win in many ways as I only qualified 6th after suffering with an ABS fault in qualifying and flat-spotting a tyre. Everyone ahead of me either crashed (red flag), retired with mechanical issues, or had a bad pit stop. I had none of those things, and took the chequered flag after a shortened restarted race.

No in-car footage (my dashcam is a piece of crap) but there was a live stream at https://www.youtube.com/live/Oi7qjqw227 ... re&t=12057


The ABS fault is a new one and not yet diagnosed. The general brake warning light would flicker red, as if there brake fluid level was too low (it isn't). But then the ABS warning light (usually yellow because of disconnected steering angle sensor) would also flicker red. Sometimes I would hit the brakes and they would lock, sometimes they were fine.

Lots of error codes, one of which being brake light switch. This was a problem once (brake lights not illuminating) but I could not reproduce it. Cleared all the codes and drove around the paddock without any warning lights. But as soon as I was back on track it came back.

For the race restart I forgot to press the sport mode button which I find useful for rev-matching downshifts. And there wasn't a single problem throughout that race.

Any clues on how to dig into this one would be much appreciated. I might just have to wait for the problem to be less sporadic before it's clear what's wrong.

[enuff_zed]

Gresat result then, all things considered.

Not to worry, I'll see you next time.

Sorry, not sure what your ABS problem could be. Worth swapping the sensors as they're an easy hit?

Edit: Meaning the ones in the engine bay.

[TheDan]

Sometimes I would hit the brakes and they would lock, sometimes they were fine.

Any clues on how to dig into this one would be much appreciated. I might just have to wait for the problem to be less sporadic before it's clear what's wrong.

Do you know which wheels were locking up or was it all four?

By the way, great result despite having to nurse some issues in qualifying!

[Liam22]

Worth swapping the sensors as they're an easy hit?

Wheel speed sensors? They're all showing accurate speeds but I was planning to give the rings and sensors a clean just in case. However, in my experience, a dodgy wheels speed sensor gives only the trifecta of warning lights, not a flashing red ABS warning.

Do you know which wheels were locking up or was it all four?

Whichever was most loaded. There was no pedal pulsating, so the ABS was totally absent. The front left got the worst of it as I got caught out overtaking a slower car at the fastest part of the circuit.

[enuff_zed]

Worth swapping the sensors as they're an easy hit?

Wheel speed sensors? They're all showing accurate speeds but I was planning to give the rings and sensors a clean just in case. However, in my experience, a dodgy wheels speed sensor gives only the trifecta of warning lights, not a flashing red ABS warning.

No sorry, I edited my post. I meant the two on the brake cylinder in the engine bay.

[Liam22]

I meant the two on the brake cylinder in the engine bay.

I only have one of those (later MK60 model in 2007+ cars). I have a spare master cylinder, so an easy swap and worth doing as a preventative measure if nothing else. Thanks.

[enuff_zed]

I meant the two on the brake cylinder in the engine bay.

I only have one of those (later MK60 model in 2007+ cars). I have a spare master cylinder, so an easy swap and worth doing as a preventative measure if nothing else. Thanks.

Well I just learned something new.

[TheDan]

Whichever was most loaded. There was no pedal pulsating, so the ABS was totally absent. The front left got the worst of it as I got caught out overtaking a slower car at the fastest part of the circuit.

I only have one of those (later MK60 model in 2007+ cars). I have a spare master cylinder, so an easy swap and worth doing as a preventative measure if nothing else. Thanks.

With total failure of ABS I'd expect it to be pump or module failure which is not uncommon on our cars and a bunch of places do repair/rebuilds. I believe to test the pump you can try to cycle it using INPA (some good code readers also have the option) and then listen to check if the pump is working. As the issue seems very sporadic, you may have to do this a number of times to see if it fails to cycle at any point.

I wonder if anyone who has had the ABS pump/module failure can tell us if it gives the trifecta or just the red ABS light you are seeing.

[1536Z4]

I wonder if anyone who has had the ABS pump/module failure can tell us if it gives the trifecta or just the red ABS light you are seeing.

Trifecta for me . Well done Liam

[Liam22]

Yup, I've already had the typical ABS unit failure.

It's on page 35
viewtopic.php?t=112593&start=510