I noticed some brake fluid on my wheel last weekend. Checked it out today and the bleeder nipple on the caliper was loose. Checked it out further and a coil of threads came out.

My threads for the brake fluid bleeder on my front S4 caliper are gone.

What are my options for repair?

Will have to replace the whole brake caliper unit?

Thanks!

 

Rethread?

I'm probably going to call the shop tomorrow.

 

one of mine was so tight, it broke off, but when it breaks, its still closed. I now only bleed teh line with one of the two bleeders. This happened day one with the Holbert car. I was told to pull the caliper to have it fixed, but there is no guarantees that they will be able to get it out. So, one bleeder is enough.

in your situation, it sounds like you have no choice. you need to re-thread tape and get a new bleeder of the appropriate size. I wonder if a Time Cert would work for the same end result threads as a new or your undamaged bleeder valve.

mk

 

A Time-Cert or similar solid insert should work if they have the correct thread and depth. They probably do, but I haven't determined what the bleeder thread is before. If you have that, take a look at www.time-cert.com

 

IIRC the thread is M10x1mm
Timecerts are made in this thread.

I see no reason why Helicoils wouldn't work equally well , but I couldn't easily find a list of threads they produce on their website.

 

I was suspicious that coil-wire Heli-coils would leak more easily than a solid insert. Is that not the case?

 

Several options. Thanks for the leads guys!

 

OK. Doesn't look like it will be easy to find a shop willing to do the rethread work.

Anyone know what the S4 Brembo brake caliper is made out of? Cast iron or steel?

 

aluminum

 

While it may be possible to repair the threads, I'd be casually shopping for a replacement caliper.


The challenge is that you need to find a set of taps that includes a bottoming tap, and use it without getting into the seat at the bottom of the hole. The bottom is a tapered seat into which the tapered end of the bleeder screw fits. The threads limit leakage only when the bleeder screw is off the seat. You can sometimes get away with just a common tapered tap, progressively grinding the end off as you form new threads. It will be a chore getting it right without scratching the seat in the process. Inspect the existing seat, and you may find that it's already scratched and is the cause of the original leakage.


928 International sells the bleeder screws and rubber dust caps in a repair kit for the Brembo caliper. Mark, thsi is something you want to consider for the Holbert car. Use a ground-off square-end extractor to pull the stub of the bleeder screw from the AL caliper after you've heated the caliper. The replacement will restore your function. Note that the replacement bleeder screw has nice new plating on it, so it's a good replacement for bleeders that have any corrosion on them. You can't really use any anti-seize on the bleeders, so they need to be serviced/cleaned/replaced before they corrode and swell.

 

Bill,
The threads dont do the sealing, it is sealed by the taper on the bottom of the bleeder.
So a helicoil would work just fine, just make sure that you dont drill down all the way. As well hook compressed air up to the other bleed nipple, or inlet and have a constant stream of air blowing all the cuttings out.

 

Right, thanks for reminding me. Oh, and Time-Cert will provide bottom taps. At least they used to. At one time they would make custom kits when I called them.

 

As noted, caliper bleeders seal on the tapered bottom seat: if in the attempted repair, the new threads are slightly off line or the seat damaged, all is not lost ....

As a last ditch effort, tap the bore for the smallest pipe plug, say 1/8": SAE pipe plugs seal on the threads as the bore is tapered - so force a metal to metal contact. The caliper can still be conventionally bled after doing this if it is the outside bleeder. If the inside bleeder, leave it tight, and rotate the caliper upsidedown during bleeding to chase all fluid/air to the good outside screw.

 

The workshop manual lists the 4 piston caliper bleeder screw as M10. Is this the same as M10x1?

I am not well versed on these technical specifications.

I am looking to source a thread repair kit and want to make sure I'm getting the right size.

THANKS!!!!!!

 

In this case they are M10 x 1.0.