PMB 914-6/GT - Rear Calipers

[glovebox]

A magnet is best. If it wont fit down the hole, just stick it to a screwdriver and poke that down the hole to collect any swarf, then without the nipple fitted, slowly let some fluid through to finally wash it out from the inside.
Good luck.

That won't work with an alloy caliper!

JW

Ah, I wasn’t aware it was an alloy caliper body, and different to the stock cast iron one.
In that case, from the description/symptoms I’d be fearful that the thread is stripped and a tap will not cure it. Then you’re in a whole load of hurt as the supplier may say you over-tightened the bleed, as it was ok when it left them after the pressure test.

La la La not listening

I know you right Darren, Wont know until I take them off again.
Cant help thinking the Bleed Valves were supplied fitted ?!

[camperco]

Had to fit them offset so the inner Pistons worked with the handbrake??
They have to be fitted with shims (large washers) behind the mounting bolts to centralise them on vented rear discs. I fitted longer bolts to compensate. As the Pistons would not stretch far enough to push the pad to the rotor even with the pads adjusted ??

I did the same. Fitted longer bolts and shimmed them so they were equal to the disc. But then I had no handbrake ?? Even with adjusting the inner piston and tightening the handbrake cable. How far should the piston press out ?? I took the pads out and with the cable pulled they hardly move at all even with the handbrake lever on the caliper pushed fully back??

And now I cannot get the bleed nipples to stop weeping !! I dont think I can tighten then any further with fear of braking something. They are not leaking as in dripping but just wet around the bottom of the threads !??
Any ideas guys or tricks ??
Can or should I use a thread sealer ?? No!
Or can you get a bleed nipple with a O-ring?? No! Try to get replacement calipers.



Best regards

Mark.

The annoying thing is that they are basically superb calipers. Our car already had S calipers on the front, and these balanced and improved the braking immensely. I just keep getting excuses from Eric. [/quote]

[/I have e mailed him this morning. I wont hold my breath !color][/quote]

I'm sorry to butt in with a non-constructive comment but you seem to know so little about something so vital are you sure you should be fitting them yourself? I'm not trying to be a smart arse but your questions about bleeds nipples for example gave me the shivers.

[glovebox]

Good question? But I've been in the industry for over thirty years and had several project cars of my own. I'm not a master mechanic but I have a hands on logic. I rebuilt my original calipers on this car that I don't think had ever been apart since they left the factory ! And they didn't leak before or after I was finished with them.
I'm not in the firing line of what's new in world of mechanics that for sure, that's why I asked these questions. For example before this problem I never knew speed bleed did a "speed bleed thread sealant "??
That's why I bought these calipers from the experts and that's why when there is a problem I'm also asking the experts.
When I first bought these calipers there was a manufacturer problem ! Which the supplier admitted. He said he fixed the problem and sent them back all working
He now is saying if you have the batch he thinks I have ? There was a machining problem with the bleed valve base. So he is suggesting either I send them back again !!! Or do it myself or new calipers!?
I also think it's a great question:) and not non - constructive at all.

[Bruce M]

Speed bleeders have a sealant on the threads to stop air being sucked back in (you open them a little and the internal check valve allows bleeding without other tools).
If you can tighten the bleed valves without it skipping a thread, I'd guess either the thread isn't cut deep enough (so it binds up before the valve seats) or the seat is not cut properly.

Hopefully the thread is short and the bottom tap fixes it. Correcting the valve seat will be tricky (if that's the problem, I'd be tempted to try a small thin copper washer as a seal under the valve but that's a bit of a botch).

[glovebox]

Thanks Bruce, I think that's what the supplier is suggesting. As he said in the first batch they produced there was a problem with the machining of the valve seats or bottoming.

[Darren C]

Something a little fishy is going on here with the supplier? (if your account of events is correct....which we have to accept is)

First they send out calipers with a manufacturing fault.

Then take them back to rectify it, and tell you that they've been pressure tested.

Send them back out and the bleed nipples leak.

Then acknowledge there's another fault with machining of the bleed nipple hole and send you the tool to fix it yourself!

Doesn't quite inspire confidence in a very important product.....brakes

I hope you get it sorted without too much heart ache, but if I were you, as much as a pain it is, I'd send them back again to sort it out or ask for a refund.

The minute you intervene with a tap you'll void any warranty and free them of all responsibility.

[glovebox]

Thanks Darren, to make matters worse every time they come through or back through the German border I get hit with a custom bill !! Even if it's my fault or theirs

[Darren C]

Then I think maybe they need to compensate you for the customs charges under the circumstances

[Darren C]

Just had a thought....

Not sure about German Customs (but we're all in the EU so must be the same for you), but certainly here in UK there is an option/declaration that you or a sender can fill in listing the item as "Returned Goods". This can exempt you of repeatedly paying customs charges on goods from outside the EU in your example.
You might want to look into it.

Regards
Darren

[glovebox]

Yes I did . But even if the supplier admits fault , which too be fair he did . I guess coming from the US of A that's a big thing for them! [FACE WITH TEARS OF JOY] you still pay the tax again because you are bringing in the value of those goods into the country! I can and have tried to get the money back . But so far I'm still waiting! I guess lesson learnt !! In future buy German!!! [FACE SCREAMING IN FEAR][FACE WITH TEARS OF JOY]

[gridgway]

I don't think I'd be going anywhere near new calipers with a tap. I'd cut and run in your circumstances. Ship them back and get a refund.

Out of interest, i presume it's to cut more thread not a tool to reface the sealing face at the bottom?

[glovebox]

Oooh my understanding was the the other way, they said they had a problem with the ....and I quote "the first batch needed to have the 7x1 threads chased out with a bottoming Tap as there was an issue with the computer code for the bleeders" although to be fair they think mine were the second batch but they are saying regardless we can try to chase those threads with a 7x 1 bottoming tap !

[glovebox]

Sooo yesterday before taking the calipers completely off the car. I re spaced the calipers to the rotor just for future reference when or if I ever refit them. So with Davep info regarding 0.10 mm pad clearance and the handbrake worked much better! Two washers roughly 4mm plus the rotor dust shield bracket and they are centred to the rotor. Thanks Dave:)


I had not touched or Checked the leaking issue for a day or so , and there is a definite leak ! Or obvious drip built up now below the bleeder. Although one caliper seems wet around the bolt above the bleed nipple ! This is where they leaked the first time I fitted them about 8-10 months ago !!



So onto the scary part now of removing the calipers and checking the bleed nipples to see if I had cross threaded or stripped the threads !!
To be honest, too me they look fine ! I even swapped them around and they all screw in easy with no resistance. The calipers threads look good with no burs, the only thing I noticed was the seating base of the valves looked black and dirty on one of them!




Wasn't sure if it was dirt or just a staining of the alloy? But to me the valves are not bottoming out the bottom of the seats.
Not until I drained the fluid from the caliper did I get a surprise!!' Small plastic container is from the caliper and the metal pan is fluid drained out from the car from the hoses.
And the fluid from the caliper is not just dirty looking but full of bits as well!



Apart from sticking them in the bin !
Any ideas guys ?

Best regards Mark.

[Bewildebeest]

to me the valves are not bottoming out the bottom of the seats.

If you've got a vernier it would be interesting to check the thread length and the total length of the nipple compared with the depth of the hole in the caliper.

[Bruce M]

From your photo it looks more the like the nut (wet bottom edge?). Flush the area clean and dry. Wrap a little toilet tissue round the bleeder & separately, the nut (secure with a tiny piece of masking tape) then see for certain after few hours. If you lean on the brake pedal, maybe a lot quicker.