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GM metric calipers leaking.

6K views 11 replies 8 participants last post by  Don Datsun 
#1 ·
Both the calipers are leaking where the banjo fittings connect.
I removed the fitting and the calipers look a bit rough where the aluminum spacer is supposed to seal.
These calipers came with the front brake kit for a mustang II that I purchased from Speedway Motors about 5 years ago and I am finally putting it together.
Just wondering if any of you have had a similar problem.

Ed
 
#6 ·
GM Metric Caliper leak at Banjo Bolts

Yes, I feel your pain. I'm build a 27 Chevy Sedan Hotrod and have the GM Metric Caliper leak you have all decribed oh so well. I've had the right side caliper Banjo off now 6 times and the left side off about 5. I've tried about every washer out there you can buy and although I'm still leaking I think I've gotten to the bottom of the problem. What is took me to where I'm at right now with this issue is a Micrometer and a trip to the wrecking yard to dissassemble a virgin banjo fitting from an 82 S10 Chevy that uses this GM Metric caliper. This is what I found: The copper washers needed are 10 MM but when you buy at most parts stores they range from .050 to .060 in thickness and they are much too hard and will not conform to the footprint to seal on the side of the caliper. The thinest copper washer I found was .030 but even at 30 lbs of torque all you see are lines around the washers when they are removed and the washers are just not soft enough to imprint into the caliper circular recesses to seal......now I'm sure I have all you guys having this problems full attention ! So lets go forward....what I found at the wrecking yard are copper washers that measure .030 thick but the material has to be much softer than what I found at my local part store. I'll tell you now these OEM copper washers were squished and had the same exact impression as the caliper sealing area and the banjo brake line which also has this same circular saw tooth pattern radiating out from the Banjo bolt hole and that's why they didn't leak! So I came to the conclusion GM when building these vehicles used a soft .030 washer (That I cannot find) that at 30 lbs of torque conformed and imprinted exactly into the surface of the caliper and the brake line Banjo. Problem is GM no longer sells these copper washers as they have all gone OOP (Out of Production). So what do we do.....I'm still working on it but think I have the answer which involves a 10MM copper crush washer that ACE Hardware sells and for me I'm going to modify the stock brake line banjo (Use it instead of my Speedway banjo because it has twice the sealing surface) and modify to accept a 3AN fitting for my stainless steel lines. The Right side is done this way with no leak at all and the left side still leaks but not from the washer area but where I brazed the 3AN fitting to the OEM Banjo. Bottom line here is you need a soft sealing washer. I tried the aluminum 10MM ones from Speedway and no luck.....too hard and will not conform to the caliper surface. So this is just a pain but I'm going to fix it for sure !! Hope I was of some help to you all !
 
#10 ·
I also had leak issues with the banjo bolts and crush washer connections. Mine too are GM calipers on a Fatmans mustang II. I had the same hardness and size problems on the aftermarket crush washers. I finally went to a brand name brake shop and they let me go through their box of take off washers. I got 6 of the thick ones for nothing. On one side I had to heat the washer with a propane torch to get its softness back. This fixed my leaks.
Good luck,
Tom
 
#11 ·
About the 3rd or 4th try at fixing this leak I also thought about the bolts being too long and bottoming out. Not the case and both sides are completely fixed and dry now. The issue is the washers. But I don't think we've done the casting ridges on the calipers any favors either putting in rock hard washers and cranking them down to 30-35lbs(35 is max so watch out). I'm sure the once sharper pointed edges on the sealing surface on the calipers are now a little flatter since we've all been squeezing the crap out of these banjo bolts in an effort to stop the leaks. What is needed is a nice soft washer (aluminium or copper) that will conform perfectly to the caliper when torqued to 30 lbs.......good luck with all those copper washers out there (and aluminum ones from Speedway). The compression washers are the answer for me at this point. I said Ace hardware carries them but now finding out there is only one Ace hardware store in my area that has them and this Ace was a conversion from a good ole Mom and Pop Hardware store. Get on the internet and google crush washers and buy some 10MM ones, install and torque to 30 lbs.
 
#12 ·
GM Metric Caliper leak at Banjo Bolts

Well after many many attempts to repair I'm very happy to report I no longer have a leak on either side of my Hot Rod project. What a pain in the butt but after all my research the problem was totally obvious. You just need a washer that will conform to the imprint that's cast into the GM Caliper so that means a real soft copper or aluminum washer (that I could never find) or what I did was to use a 10MM copper compression washer. I also used the OEM Brake line Banjo ends with the 3AN's brazed onto them to increase the surface sealing area of the banjo. I think the 10MM banjo fittings you can buy from Speedway would also work with-out going to extent I did (OE banjo with 3AN brazed) but in a effort to repair this leak I destroyed my banjo fittings for their 3AN fittings. The problem is the sealing surface at the GM Metric caliper.
 
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