brake caliper bleed value stripped

[mitchelltjohn]

I think I have overtightened a front brake caliper bleed value on my std TR7. As a result the bleed value spins and will not tighten. On extraction the bleed value threads look crushed/crossed. I inserted a new bleed value but it does not does not seal and fluid leaks when break pedal is pressed. On extraction the new bleed value also has crushed/crossed threads. I now worry I have damaged the threads in the caliper inself.

Any suggestions what I do next...?

standard 1981 DHC

[PeterTR7V8]

1stly, get a new bleed valve. Get a thread tapping set (make sure it has the right thread of course) & carefully clean out the thread in the brake caliper & see if the new valve tightens up in the caliper. If it doesn't then you may be able to repair the caliper thread with a helicoil if they come in such a small size otherwise take it to an engineer to fix.

I've never used a helicoil but as far as I understand you open out the hole & cut a bigger thread into it to fit the helicoil then screw in the helicoil & the helicoil becomes the thread that you will screw the valve into.

Here's how to do it with a Tennessee accent. http://www.youtube.com/watch?v=RFYa6sjhh_E

Good luck.


Never say die. At least not while you're still breathing.

[Marko]

the calipers are cast iron , thats tough , you probably twisted the first coil of the thread and then it destroyes the thread on the bleed valves. bleed valves are made of much softer material than cast iron.


ordinary thread tap should fix it.

[jclay (RIP 2018)]

Use a bottoming tap so you don't damage the seat at the bottom of the hole. The top tap is a bottoming tap, the second one is an intermediate tap and the last one is a taper tap. You usually use a bottoming tap on a hole that has already been started with a taper tap.




Next, Replace all your bleeder nuts with speed bleeders.

http://www.speedbleeder.com/


jclay

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