My 70GS has non-power drums the problem that I have is the passenger side doesn't seem to be working, the driver side locks up. It doesn't matter how hard you push the pedal. The car has a new master, new wheel cylinders and have ran enough fluid though it for 10 cars. It has been pedal bled and power bled, and no luck. The shoes are clean and not contaminated. I have used the "one man bleeders" but still have had zero success. When bleeding it seems that the same volume comes from both sides. I don't want to put anymore money in it as I am going to convert all wheels to disc brakes. But its got to be something simple. So all you brake gurus..... whats up? TIA Rick
Maybe a kinked steel line? Or posssibly a funky flare that's restricting the flow? You may have a binding wheel cylinder. Try removing both front drums, and have a helper slowly apply the pedal and watch to see when the good side comes on, and look at the other side to see if it's expanding too. You can also do this test with the drums on and see if they apply evenly by trying to rotate the drums by hand with light pedal pressure. You said the other side locks up........does it do that too easily? I'm thinking maybe you have fluid on the shoes (or a missing spring) on that side and maybe the side that doesn't lock up is OK? o No:
Joe thanks for all the places to look. The car had good brakes when it was parked, three years ago the resto took place and the master was replaced at that time. Last summer when the car was finished the problem rared its ugly head. I checked the steel line last summer and didn't find any problems there. When you apply the brakes you have to be a little gentle or the driver side will start to work and pull the car to the left, a panic stop probably wouldn't be good. When I rebuilt the cylinders and replaced the hoses everything was dry inside no signs of leakage. This weekend I will check the crossover line again and maybe trade the shoes side to side. Thanks Rick
Could it be a defective wheel cylinder keeping the brakes from applying to that side, causing the working side to lock up. Maybe the new wheel cylinder is frozen in the position its in .
I havnt seen front drum brakes in a while... but do they have and adjustment like rears?? and also do they have the primary and secondary set of shoe set up....up front as well...??..any problems taking the drums off & on..??? ...and see if you can swap the wheel cyl (if do-able) ....just to see if one is binding or not...just to see if you get the same hard braking on passenger side once swapped..
Wow, this is a gimme!!!!!!!!!!!!!! Your distribution valve on the frame rail is bad! You have contamination and/or rust in it preventing proper fluid distribution to the wheel cylinders. That is another reason why you should avoid regular brake fluid! It is alcohol based and is hydroscopic (readily absorbs water). If I were you, I would stop wasting time, money and aggravation on your marginal drum brake system. I would get new lines from www.classictube.com or www.inlinetube.com, a disc brake set-up, correct disc brake combo valve and silicone fluid.
I still think it's most likely a brake hose.......try swapping them side to side......that's exactly how a restricted hose acts. I've had new ones right out of the box do that in the past. And silicone fluid is a great idea (although it's tricky to bleed).....but you should replace all the rubber parts with fresh new ones first before putting it in, as the rubber absorbs the old fluid and that can cause problems. :bglasses:
Joe both hoses are new and changing them made no difference. George where is the block that you are talking about, is it on the frame below the master cylinder? I am starting to gather stuff for the rear disc up grade, what master cylinder is needed? Thanks Rick
George a couple of more questions. When going to discs all around can I still use the non-power master cylinder (drum brakes)? If not what non-power unit can be used? Thanks Rick
I just did this on a 70 GS455 which has 4 whl disc brakes. The rear uses the 81-85 Eldorado/Seville/Toronado/Riv rear disc calipers. I used the stock front disc brake master cylinder. When you do the swap make sure you get the disc brake master since the front calipers require more fluid capacity and the master cylinder needs to have the large front reservoir.
With disc all around, I think you will need to convert to power brakes. This will include a different master cylinder.
