I just finished flushing my brake system. (Girling calipers, front and rear). Had purchased a pressure bleeder but the cap for the reservoir was not a good fit and fluid sprayed out. So I fashioned a new cap using the cap from a replaced master cylinder I'd kept around. Worked great when pressure was kept under 10 psi. Now, here's my question:

Exactly what size are the hexes on those bleeders. 8mm and 5/15" are too big and 7mm and 1/4" are too small. I managed, using an 8mm deep socket for cracking and final tightening, and an open ended 8mm to control the actual bleeding. But it sure would be nice to have a proper-sized tool, and one that would fit better in those confined spaces on the calipers.

Wonder what Planetman uses?

if you snap one there is a kit where you can drill a larger hole and then it has it's own bleeder, of course best not to snap them off but it happens.

what I;d do is use a small 6 point socket, put some pressure on the wrench and at the same time use a small hammer to tap the wrench , the shock and torque ombined can help to not snap them.

I made up a bleeder using a pressure cooker as my reservoir and a vacuum generator. I connect the vacuum generator to the pot and it creates suction and runs off my air compressor. the pressure cooker collects the used fluid that way.

you can look up "vacuum generator" if unfamiliar with them, very simple venturi device, no moving parts. they make an air rushing sound and use a fair amount of air

I prefer to do that than to try to pressurize the system. Just a different approach.

3/8th UNF I think.

Definitely not 3/8ths. I never paid any attention to whether they're metric or otherwise. I find either 8mm or 5/16ths will work. When a 12 point wrench slips I use a 6 point wrench or socket. A 12 point is more convenient because the wrench can be positioned with more options than with a 12 point. Sometimes the bleeders have been re[placed with non-original type. I worked on a 240 recently that required 3 different wrenches to cover all 8 bleeders. -- Dave

Maybe next time I do this I'll pull one out first and see if I can find replacements that accommodate some standard sized wrench. As you said, 8mm and 5/16" work, but I've never come across a 7.5mm or a 9/32" wrench, which would seem to be what is needed.

At least all my bleeders were the same size and, for the first time ever, having taken the trouble to cobble together a proper cap to go with the pressure bleeder, I didn't end up with brake fluid all over everything. Guess now that I have the rest of this sorted I just wanted to have the perfect wrench, too.

Dave;

...a little late to the party, but I have a picture which shows ALL the brake plumbing threads, from flarenuts to bleeders are 3/8" 24TPI:

https://www.sw-em.com/brake_notes.htm#brake_plumbing_and_fittings

Cheers

Wow, Ron. Your usual compendium. I've made a PDF of that link and will file it away against the day I have to dig out the complete set of new brake lines I have in my spares. It will be invaluable.

However, we were talking about the hex on the external part of the bleeder, the one used to loosen/tighten it, not the threaded part that screws into the caliper. I quick look through your material doesn't seem to offer an answer to that question. However, the fact that the threads are SAE and not metric should hint that the hex part is also SAE. So I guess there really must be some sort of 9/32" tool floating around somewhere.

Speaking of not ending up with brake fluid all over everything, a dozen years ago I bought a brake bleeding catch can with a magnet mount. It remains one of the best $14.99 I've spent on a tool. Brake bleeding is frustrating enough without dealing with leaking hoses and random bottles tipping over at the slightest touch.

https://smile.amazon.com/dp/B000W7F2GI/ref=cm_sw_em_r_mt_dp_WBYJKDB5Q3YYDD58QDQ8

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XC60 / Odyssey

3/8th UNF I think.

According to Ron at SWEM I got the thread right. Just need the correct wrench size. I will check my brake tools next time I go to the garage. I also have a calliper with bleeder to check them with.

Dave B has an 1800E and it should have 4 piston Girling front and 2 piston Girling rear calipers and they have smaller brake bleeders.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

According to Ron at SWEM I got the thread right. Just need the correct wrench size. I will check my brake tools next time I go to the garage. I also have a calliper with bleeder to check them with.

Hello,

5/16" is the proper sized wrench and IIRC, the threads are 1/4-28 UNF.

We've had to deal with corrosion that reduced the size of the hex.

You should consider getting new bleeders.

You can get speed bleeders if want to spend the extra money.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

In the old days it was a bi-yearly maintenance chore. But I've let it slid a bit lately as I've only put about 1000 miles on the car in each recent year. I know that time as well as mileage is a factor, but when I flushed the brakes this time, the fluid was remarkably clear. Not that dark, water-sotted color it used to be. Maybe the fluid is better today. I've installed speed bleeders on my motorcycles in the past, and like the convenience (kind of a built-in check valve). So maybe, in two or three years when I get around to this again–I should live so long–I might give you a buzz and pick up the eight required for my front and rear Girlings.