'68 300
- Thread starter AlVal74
- Start date
rags
Senior Member
it may not be a good master, but it looks like your car has a disk brake master cyl. large rear chamber.
rags
Senior Member
personally, i wouldn't think twice about using the one in the vehicle so long as it's not contaminated internally, but i get away with this stuff all the time. converted my '65 300 drum car to dual master with a p.valve from a disc brake '86 f350. no prob.
65sporty
Old Man with a Hat
Quite the project you have there
bigmoparjeff
Senior Member
The block that's in your car now is strictly a distribution block with a pressure differential switch to trigger the warning light.
Your first option would be to keep your existing block and add an adjustable proportioning valve to the rear brake circuit.
forMopars A/B/E-body Disc Brake Swap Adjustable PROPORTIONING VALVE Cuda Charger | eBay
Your second choice would be to install a reproduction proportioning valve.
At some point in time Chrysler added a metering valve to their disc brake systems, which is the smaller, separate valve. The only purpose of the metering valve is to prevent early lock-up of the front wheels on ice, so it's usually not a must-have on a hobby/collector car. On the surface, this certainly looks like the best way to go, but the problem is that these China sourced valves have a tendency to leak, especially when used with silicone brake fluid. I recently installed one on a 1970 Challenger that I'm working on, and sure enough, both valves leaked like sieves with silicone fluid in the system.
Mopar Disc Brake Proportioning Valve & Metering Valve Disc Drum A, B, C, E body | eBay
Proportioning valve with metering valve
70-71 Mopar E-body 71 B Body Plymouth Cuda Dodge Challenger Disc Brake Valve | eBay
Proportioning valve only
Choice number three is to buy a used valve and hope for the best on leaks.
That's what I did with the Challenger. I bought a used proportioning valve and eliminated the metering valve. So far, so good as far as leaks go.
A, B, C, and E body valves are pretty much interchangeable. Front/rear bias was fine tuned with the size of the rear wheel cylinders, not different springs in the valve. The hard part with this choice is finding a decent used valve. This one on ebay is being offered for a reasonable price, but the seller has it listed wrong, as it is actually a drum brake valve.
USED Mopar 1970-74 E-body Disc Brake Proportioning Valve and Lines | eBay
Jeff
Thank you for the information. Since this will only be a spring/summer car, my best choice would probably be the last. Its good to know that some things are interchangeable between these cars. Now I just gotta find a good used one. Thanks again Jeff.
Yep, its coming along pretty nicely so far. My first total restoration. Im learning a lot and having a blast doing it
65sporty
Old Man with a Hat
Great that your having a blast, I enjoy following along with your progress
bigmoparjeff
Senior Member
You go to Napa and get one of these, then attach it to your grease gun.
https://www.napaonline.com/en/p/BK_7001193?partTypeName=Grease+Injector&keywordInput=grease+needle
Replace the inner axle seals, but don't worry about the outer seal that's trapped by the bearing. That seal only leaks when the grease has been contaminated with gear oil from a leaking inner seal. There are also gaskets on the axle flanges and backing plate. You can replace those if you like or just smear on a thin coat of silicone before putting it back together.
I just did some work on an 8 3/4, including replacing the inner seals. I bought some SKF/CR seals, and they weren't all that great. Ended up replacing them with seals from Yukon Axle, and those were much better quality. I got them from Rock Auto.
Jeff
https://www.napaonline.com/en/p/BK_7001193?partTypeName=Grease+Injector&keywordInput=grease+needle
Replace the inner axle seals, but don't worry about the outer seal that's trapped by the bearing. That seal only leaks when the grease has been contaminated with gear oil from a leaking inner seal. There are also gaskets on the axle flanges and backing plate. You can replace those if you like or just smear on a thin coat of silicone before putting it back together.
I just did some work on an 8 3/4, including replacing the inner seals. I bought some SKF/CR seals, and they weren't all that great. Ended up replacing them with seals from Yukon Axle, and those were much better quality. I got them from Rock Auto.
Jeff
Thanks again!! I got the ones from rock auto already on the way. When I took the axles out it didn't even look like the bearings had any grease on em. That's why I asked. Gonna take diff out and make sure the inside of the axle is totally clean. And change the oil obviously.
bigmoparjeff
Senior Member
It would be a good idea to put a couple drops of oil on the bearings and rotate them to make sure they are smooth before greasing them. The bearings are a pain in the *** to replace, but better to do it while it's apart.
bigmoparjeff
Senior Member
Ran across this Master Tech video tonight. It gives a nice overview of the 1967 to 1970 braking systems.
In '71 they went to the cast iron combination valve that combined the safety switch, proportioning valve, and metering valve into one housing, so that system isn't in the video.
Jeff
In '71 they went to the cast iron combination valve that combined the safety switch, proportioning valve, and metering valve into one housing, so that system isn't in the video.
Jeff
bigmoparjeff
Senior Member
I might be off on that. Some cars may not have gone to the new combination valve until 1972.
Jeff
Jeff
bigmoparjeff
Senior Member
No.
You need a proportioning valve and safety switch in the system and the metering valve is optional.
According to the video, Chrysler didn't use metering valves on full size cars at all up to the time the video was made. They did eventually, when they switched to the cast iron combination valve.
Here's a fourth choice: Simply add this proportioning valve to your rear brake line. Inline Tube is calling it a hold off valve, but it's what Chrysler calls a proportioning valve in the video.
70, 71 Mopar Cuda Challenger Disc Brake Hold Valve NOS | eBay
Jeff
I ordered the proportioning valve w/safety switch and a new rear distribution block from inline. Told em what I had and thats what they recommended. What should I clean my differential with without having to break it all down? I took it out of the axle but am kind of leary about taking it all apart to clean it.
bigmoparjeff
Senior Member
A solvent based parts cleaner would be best. You can get it in 5 gallon pails from Napa, and I think Tractor Supply may carry it too.
Jeff
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