Brake cylinder hex bolt size

Pinkythelabrat

Pinkythelabrat

A2OC Donor
Hello there. Long time no post

Does anyone know what size of bit is needed to undo the onset hex bolt holding on the wheel cylinder?

It’s chewed. A torx 27 fits in, a hex 4 spins and a 5 won’t go in.

I don’t want to push in case I wreck it!

Help!


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Pinkythelabrat said:
Hello there. Long time no post

Does anyone know what size of bit is needed to undo the onset hex bolt holding on the wheel cylinder?

It’s chewed. A torx 27 fits in, a hex 4 spins and a 5 won’t go in.

I don’t want to push in case I wreck it!

Help!


Sent from my iPhone using Tapatalk
Click to expand...
Hi Pinky, I replaced mine a couple of weeks ago and from memory it was a T30
 
Yes. Item 7. I tried to post a pic but Tapatalk wouldn’t let me (and then my dinner arrived).

T30? Brilliant. I’ll hammer it in and try that.

Cheers folks

Sorry about my long silence. Work and study and work and no driving mean the car has been a bit neglected. Now the weather is a bit nicer I can get some stuff done. My replacement brake kit and service items will tidy up these new drums shortly.


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Pinkythelabrat said:
Yes. Item 7. I tried to post a pic but Tapatalk wouldn’t let me (and then my dinner arrived).

T30? Brilliant. I’ll hammer it in and try that.

Cheers folks

Sorry about my long silence. Work and study and work and no driving mean the car has been a bit neglected. Now the weather is a bit nicer I can get some stuff done. My replacement brake kit and service items will tidy up these new drums shortly.


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Click to expand...
Hi again Pinky ... just checked and the original bolts were T30, still attached to the old cylinders ... seem to remember struggling with an Allen key also before realising, 4mm too small and 5mm too big and ended up replacing with new M6 T30 stainless steel bolts.
 
Last edited:
Thank you. That’s helpful.

The cylinder was actually replaced about six months ago but the shoe hold down pin failed while I was driving and jumped the cylinder - which is now gushing fluid - so I need to replace it again.

I hope they didn’t just strip it while they were refitting it. I’ll get a mirror out for a good look then try the T30 tomorrow.

Thanks for checking.


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Or rather than try to remove the slave cylinder, take the pistons and seals out the new one and fit them into the existing slave housing. Either way the brakes will need a good bleeding. If the shoes were contaminated replace them also.

There should be a step on the face of the pistons where the shoes are pressed. This step needs to be on the outside so the shoe is retained between the step and the backing plate.
 
Thanks Audifan,

I had another go this morning but there’s just nothing to grab hold of and I couldn’t move it with mole-grips or a drift chisel. It’s stuck!

I gave up and took it to the place that fitted it this morning. The ABS alarm finally came on too.

The step on the fitted cylinder was on the inside though…


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Garage have managed to replace the cylinder but now can’t get a stiff brake pedal or braking force at rear left or front right brakes.

Why is it always when you have a trip planned?!?


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Pinkythelabrat said:
The step on the fitted cylinder was on the inside though…
Click to expand...
I wonder if that's why the shoe retaining pin failed in the first place. As Graham says, it should be on the outside so as to hold the shoe towards the backing plate. Since it's with the garage that got it wrong last time, it may be worth checking what they have done when you get it back, and also the other rear wheel before the same happens there.
 
There is air in the system. Bet the line went dry of fluid. VCDS ABS brake bleed is now the best option. Does not take all that long to do but remember AFTER the ABS is bled to do each wheel cylinder AND the clutch just to be sure.
 
This IS the new garage! Senior mechanic has a 2002 Polo (weirdly sporting the same TT alloys as my A2…) so is usually pretty good but I think he’s off at the moment.

Still no news.


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Back home and fixed.

New cylinders, shoes and hold down kit fitted.

Pedal doesn’t start to brake until a good third of the way down - is that the same for others? I think it’s always been like that but my wife’s car stops at the slightest brush of the pedal! Feels weird now.


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Perhaps the rear brakes self adjusters have not yet settled down. As long as the pedal is firm and not spongey not a problem more a retrain on how to drive (brake).
 
Pinkythelabrat said:
Back home and fixed.

New cylinders, shoes and hold down kit fitted.

Pedal doesn’t start to brake until a good third of the way down - is that the same for others? I think it’s always been like that but my wife’s car stops at the slightest brush of the pedal! Feels weird now.


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Sounds like somethings not right there, my pedal only needs a feather touch and it starts to apply the brakes
 
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