Brembo caliper bleeder thread goosed!!

[nick3814]

Arrgghhh[][][]!!! Thought I would bleed the brakes today having rebuilt the front calipers, have 8 new bleed nipples/valves to fit purchased from my local OPC, got seven of them fitted no problem but number 8 just wouldn't seal! No matter what I did the brake fluid kept seeping out, and thats without any pressure in the system.

I'm afraid I think I fitted it cross threaded [] and now the thread is goosed. I don't want to have to buy another caliper if I can help it now I have rebuilt this one.

Is it possible to cut another thread and fit a larger nipple/valve or weld it up and drill and tap it or is the caliper now wrecked[][]

Its the front drivers side, inboard valve!!

Your help would be greatly recieved []

 

[944 man]

Its possible yes, but not always successful...

 

[snarf]

The best solution may be to use a Helicoil type thread insert. See: http://www.emhart.com/products/helicoil/repkit.asp

 

[Big Dave]

If it was me.
Ide be looking out for a good used caliper + then use all the bits from the "rebuilt" one + rebuild the "used" one....
Sorry you probably didnt want to hear that.. But brakes are there to stop you,, Saving your life...dont skimp on them...

 

[snarf]

ORIGINAL: Big Dave UK

If it was me.
Ide be looking out for a good used caliper + then use all the bits from the "rebuilt" one + rebuild the "used" one....
Sorry you probably didnt want to hear that.. But brakes are there to stop you,, Saving your life...dont skimp on them...

Dave, sorry to disagree but Helicoil inserts are frequently used in the aerospace industry either as original equipment in light alloy structures or as a repair solution, there are probably no aircraft flying that don't have a Helicoil insert somewhere on-board. The physics of the spring-like insert is such that the clamping load is evenly distributed over the entire length of thread engagement and as such it is often superior in performance to a more standard arrangement. Although fitting is relatively straight forward the use of some (low-cost) special tools is needed so it might be more economical to find a local outfit who could carry out the work.

 

[nick3814]

I've done nothing all afternoon but read up on helicoils, recoils, thread inserts etc etc etc [8|] I'm adamant after making such a good job ([]) of the rebuild on this caliper that I'm going to save it, having worked out the size of the thread I'm going to puchase a kit and have a go myself (I'm a sucker for a new tool []) still half the price of a second hand caliper anyway so it seems to be worth a shot.

I will keep you all posted

Cheers

 

[ExAudiSi]

Good luck with this one Nick!

I went through all of this with my Brother-in-Law when he stripped the bleed nipples on his 911 Turbo callipers.
I had a local engineering company weld inserts in and then re-drill and tap the holes. Unfortunately, I don't think that they picked up the centres quite right and he still couldn't get them to seal properly. In the end he put standard 3.2 callipers back on and sold off all the Turbo bits.

I hope you have more success.

 

[Big Dave]

ORIGINAL: snarf

ORIGINAL: Big Dave UK

If it was me.
Ide be looking out for a good used caliper + then use all the bits from the "rebuilt" one + rebuild the "used" one....
Sorry you probably didnt want to hear that.. But brakes are there to stop you,, Saving your life...dont skimp on them...

Dave, sorry to disagree but Helicoil inserts are frequently used in the aerospace industry either as original equipment in light alloy structures or as a repair solution, there are probably no aircraft flying that don't have a Helicoil insert somewhere on-board. The physics of the spring-like insert is such that the clamping load is evenly distributed over the entire length of thread engagement and as such it is often superior in performance to a more standard arrangement. Although fitting is relatively straight forward the use of some (low-cost) special tools is needed so it might be more economical to find a local outfit who could carry out the work.

Fair enough...
I have used helicoils before, just never on braking components....

 

[Lancerlot]

You may be able to clean up the existing thread if there's not too much swarf about. Or else, as Alan has said, a Helicoil will be fine, but take care not to damage the valve seat when fitting. []

Otherwise, drill and re-tap the tread using a slightly larger diameter bleed valve.

Regards,

Clive
PS. Don't worry too much about the repair. I once did 4 days of the Lombard RAC Rally in an Opel Manta 400 with only a self tapper to replace a front brake bleed nipple that was damaged on the first day.
I still have that screw in my trophy cabinet!! []

 

[fhauser]

Hi Nick,I own an engineering company unfortunately a long way from you.
You could use a helicoil but be sure you have the correct insert drill and be vey careful not to damage the valve seating,Itwould be better not to go to deep and if it does not seal ,remove a couple of threads from the bleed nipple to allow it to seat down.
Another way is to completely retap bigger.make an exact copy of nipple thread and seating,Screwcut the same thread as you have just retapped bigger and screw the whole assembly in with a loctite sealer.Then put the bleed nipple into it.I would not weld at all,Hope this helps you a little
Fred

 

[elvis]

Silly question: are you absolutely sure that the thread is wrecked? I'd be surprised if you could cross thread a bleed nipple all the way down into the caliper, even though it is going into alloy. Have you tried using swapping bleed nipples and seeing if the problem is still there?

If you have stuffed up the thread then a helicoil would work, but it's a very critical application for your first attempt at helicoiling. Also, as others have said, DON'T DRILL OUT THE THREAD TOO DEEP. If you damage the valve sealing face at the bottom of the hole then for all practical purposes the caliper is scrap (with respect to Fred I'm not sure there's too many people who could fabricate the nipple thread and seating face at home and I can't see it being much cheaper than a second hand caliper if you get the professionals in).

Good luck, if it was me I think I'd be souring ebay/breakers by now...

 

[nick3814]

This helicoil lark is just not working, finding it impossible to get the bleeder valve/nipple to seat correctly!

I have seen these on ebay, it appears to be a possible answer,

http://cgi.ebay.co.uk/BMW-STAINLESS-STEEL-BRAKE-CALIPER-INSERT-BLEED-NIPPLE_W0QQitemZ250353062748QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item250353062748&_trksid=p3286.c0.m14&_trkparms=72%3A1689%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

the main boss fits in the original hole (tapped to M12) and then there is a bleeder valve fits in that, am I right in thinking this should work?

I look forward to your comments []

 

[Lancerlot]

Nick,
M12 is quite a hike in hole size. If you're considering this you need to verify you have enough surrounding metal to support it.

Personally, I'd be be inclined just to retap the thread and fit a larger diameter bleed valve. If you are not confident enough to do it yourself, then take it to a good auto or precision engineer. It's not that big a job. The heilcoil system should have worked just fine.
Good luck.
Clive

 

[nick3814]

M12 is the size hole thats in it now, loads of material left! The original bleed nipple on these are M10, quite chunky valves. Even to get it re tapped again its getting it dead straight so the valve will seat correctly which is why I thought this item on ebay might sort it as I assume the seat is within the main boss.

 

[Lancerlot]

OK.
A machine shop will easily be able to cut a suitable concentric thread, but source the valve first!
Regards,
Clive

 

[snarf]

ORIGINAL: nick3814

This helicoil lark is just not working, finding it impossible to get the bleeder valve/nipple to seat correctly!

I look forward to your comments []

Nick, sorry the Helicoil didn't fix the problem - I feel sort of responsible. It sounds as though the problem is down to the quality of the surface finish of the sealing interfaces rather than the thread. You could try fitting a new bleed nipple (if correctly engineered this should be made from softer material than the caliper) but failing that the kit on ebay (subject to the concerns raised by Clive) looks as though it would work.

 

[nick3814]

Well I seem to have fixed it! M12 boss with built in bleeder valve, drilled and tapped the original hole to M12 having filed the top flat first to smooth the surface as there was some corrosion on the top which probably caused the original valve to go cross thread in the first place! Fitted the boss with some thread lock and a copper seal washer, might try and get it pressure tested first before I fit it []

 

[snarf]

Nick, pleased to hear that you have sorted this out.

 

[ashley]

well done mate, time served meccano engineer[]

seriously looks a top job and hopefully done the trick