dinanm3atl

See thread here - https://classicoldsmobile.com/forums...ront-disc.html

MC and Booster were replaced new. Bled. Drove the car 500-600 miles without an issue. It then sat for a couple months due to cold and rainy weather. Took it out on a nice 70 degree day and while the pedal isn't mushy it didn't instantly bite at the top of the pedal travel like it did before. Stopping distance is extend as well. Took it home and found the front reservoir to be low on fluid. Topped it off and basically same issue.

MC/Booster were from Fusick.

I need to pull wheels but I don't see obvious quantities of fluid going anywhere at first glance. So my questions are as follows.

1 - Where should I start? I plan on looking at the front calipers since the rear isn't leaking anything.
1b - It seems replacements don't exist? Is a good option if they are leaking is one of the bolt-on Wilwood kits that aren't too expensive but still fit under a 15in wheel?
2 - Is there some common failure I didn't know about or missed item? Leaking fluid from MC/Booster seems odd after 500ish miles.

Thanks!

Vintage Chief

If I had just performed your R&R MC/Booster and had the symptoms you describe (especially no obvious fluid), my absolute first item to address is to do a complete and thorough bleed of your brake system - again. You can perform it whatever way you want (I have a bleeder vacuum pump like Joe described in the link you provided), but I would strongly suggest you bleed your brakes the old-school (IMO) never fail manner. Please ensure you begin the bleeding process at the brake furthest from the MC/Booster which is going to be the rear passenger brake. Bleed the brakes twice. I suspect you have air in your system. This is the fastest and certainly least expensive item to address firstly. If this fails, then move on to troubleshooting further.

steinec

Check the vacuum hose.
Front calipers are available from many sources, OEM, OEM upgraded, and aftermarket, you can even get the OEM ones in red if that floats your boat !

dinanm3atl

Issue is it didn't 'just' happen. It drove ~500 miles with zero issues and a nice firm pedal. Then it was suddenly... not. My first guess if this happened immediately would be to re-bleed of course but it seems something else is amiss. Likely not that much air was in there and kept a hard pedal for that mileage and then suddenly didn't. I also know how to bleed I have two road race cars that my friends and I do endurance races in. We always have great feeling brakes.

Hopefully this week I can get the wheels off and see if it is easy to spot where some fluid went.


And as to OEM suppliers I tried to use Fusick site(which is terrible) but they don't seem to list any OEM calipers. And at a few hundred for direct fit Wilwoods it seems if front calipers are needed no reason to go OEM.

Vintage Chief

Sounds like you have it all figured out. Best of luck.

Fun71

1 - It is possible that the master cylinder is leaking into the booster. I had that happen back in the 90s. Was losing fluid from the reservoir but didn's find any external leaks.

1b - You're looking in the wrong places. Check with your local auto parts store - these calipers were used on just about all GM vehicles from 1968-ish up to 1990-ish, so there were millions of them manufactured, and as such remanufactured calipers are readily available from your local parts store.

2 - New doesn't always mean good. You would be surprised how many auto parts are bad out of the box, or fail within a short time of use. It is not uncommon at all.

Remember that Fusick is merely a reseller of parts. They do not manufacture, they just resell. And many items they sell are also available from your local parts store. Just because your car is old doesn't mean you have to buy common items from a restoration house.

dinanm3atl

Is that a common item to happen? I come from the BMW world and having a MC fail when new is far from common. Like never happens. To have one fresh out of the box fail in ~500 miles is quite frustrating. If I can't find any fluid I'll have to assume this happened again(which is what happened before and why it was all replaced new).

Gotcha. My assumption was they wouldn't stock something like that even though it was used a lot and if it was stocked it would have been sitting for a LONG time. I know in some areas parts like that likely turn over more but where I am I doubt many are buying re-man calipers from NAPA or similar around here. Assumed Fusick would have good turnover and thus newer stuff.

Appreciate your help.

Fun71

Are referring to an OEM BMW master cylinder? Or an aftermarket one made by one of BMW's European suppliers? If so, I am not surprised that they didn't fail. Who made the master cylinder for your Olds? Or perhaps I should ask where it was made? Likely China. Need I say more?

dinanm3atl

Any OE Replacement. A very rare failure. We run on OE replacements, IE an OE Suppliers or 'aftermarket' master cylinders on our 1980s BMWs that we endurance race. We have run 14-24 hour races on them. No problems. We would never go to the BMW dealers to buy a master cylinder.

It came from Fusick as they seem to be one of the respected places. " New reproduction dual reservoir cylinder with original appearance and bleeders." is all it says. I just searched common auto parts stores and they seem to only have reman units done in house. IE Napa has Napa ones. So not sure exactly where one would go. A GM Dealer and purchase a 'new' one that could have been sitting for who knows how long? Open for recommendations.

Fun71

Auto parts stores do not rebuild the master cylinders (and other parts) in house - they get them from commercial rebuilders. NAPA is one place that packages most everything in a NAPA box, while other parts stores leave them in the manufacturer's box or maybe a plain white box.

In the past I have always bought master cylinders from the local auto parts store. The one on my car now came from the local store, as did the calipers. 20 years and no issues.

Rock Auto has several brands of master cylinders to select from:
https://www.rockauto.com/en/catalog/oldsmobile,1970,442,7.5l+455cid+v8,1213489,brake+& +wheel+hub,master+cylinder,1836