Brake bleeder thread size?

[Gary S.]

On my 72, to the best of my ability, I think I have determined that the threads on the brake bleeder screws are 5/16" X 24. I have searched here and the internet and it seems that all I can find is that size. So, it should be the correct one, right?

Thanks as always.

Gary
ps, slowly but surely conquering each little issue.

[Mark E.]

Re: Brake bleeder thread size?

You can always check it with a thread gauge.

What are you trying to get done? Chase the threads in the caliper?

[Gary S.]

Re: Brake bleeder thread size?

Yes, Mark - chase threads on an assumed original caliper. Three years ago I sheared a bleeder on this one and recently got the old bleeder stubb out (most of it?) and wanted to clean up the original threads. I don't have a thread gauge but found a tap & die that seems to be perfect. Just confirming but the seat my be boggered up so it is questionable to begin with. I'll see how it goes.

It pays to bleed brakes every other year or so just to keep the threads good. At the time, I was living in Pittsburgh but working in NYC and just didn't drive it much for 10 years.

[Mark E.]

Re: Brake bleeder thread size?

Confirm the thread size using a die on one of your remaining good bleeder valves. Then use that size tap on the caliper.

[Gary S.]

Re: Brake bleeder thread size?

That's what I did but my inexperience with tap & die sets causes me to question and verify before I do anything that is permanent.

thanks for the suggestions

[Gary S.]

Re: Brake bleeder thread size?

Yep, 5/16 x24. That's the good news and the seat is good. The bad news is that I don't know if I have enough threads to secure the bleeder. I'll see tomorrow with some new, non-stainless leaders.

[Joe L.]

Re: Brake bleeder thread size?

Yep, 5/16 x24. That's the good news and the seat is good. The bad news is that I don't know if I have enough threads to secure the bleeder. I'll see tomorrow with some new, non-stainless leaders.

Gary------


Yes, all 1965-82 Corvette caliper bleeder valves were 5/16-24 thread EXCEPT some L1980-81 (which could end up on other years via caliper exchange) which were M8X 1.25. GM did the latter just to keep things interesting.

[Joe L.]

Re: Brake bleeder thread size?

Gary------


By the way, the original GM bleeder valves and the last available GM bleeder valves for Corvette calipers are discontinued. However, excellent replacements are available as manufactured by Dorman under their numbers 484-146 or Dorman/Help! #12704.

[Donald S.]

Re: Brake bleeder thread size?

Gary------


By the way, the original GM bleeder valves and the last available GM bleeder valves for Corvette calipers are discontinued. However, excellent replacements are available as manufactured by Dorman under their numbers 484-146 or Dorman/Help! #12704.

Joe,

I found a box of bleeder valves that I've had for quite a while, but I had picked up ones from Lone Star a year ago and noticed the hex was smaller than the GM 5469230. Would this have anything to do with your comment on 1980-1981? Don

[Joe L.]

Re: Brake bleeder thread size?

Don------

It's possible but I kind of doubt it. I expect that this is just a variation of a 5/16-24 bleeder valve. You could check, though, by simply running a 5/16-24 nut down the threads.

The metric bleeder valve was GM #18003151 and, later, GM #18060081 and GM #19244561