Doing my disk brake conversion on my 66, i picked up a MC for a 70 442 because i had read that the W30 cars had manual (non power) disk brakes due to low vacume.

Got the master- however it has a shallow piston bore- unlike all the deep bore manual masters i've had before.

Is there a pushrod retainer clip or something specific to this car that holds the pushrod in place?

If you step on the brakes a few times, eventually the brake pedal returns faster than the piston and the pusrod falls out of center- very dangerous.

Does anyone have any experience with a 70 W30 car with manual disk brakes that could tell me what this peice is? If i could see a pic of one maybe i could figure out how to fab it

 

seems like the mystery of the 1970 W30 master cylinder is a tough one here....nobody jumping to the answer.....I have the same question. I have seen that The Parts Place sells a brake rod for manual brakes, butI have never seen a consistant picture of the master cylinder

 

The brake rod on manual disc brakes cars is different. The rod is actually 4 parts. The rod which has a short type nipple that goes into the shallow piston, then there is a retainer cup that is snapped on the back of the master that keeps it from comming out, then there is a small rubber boot that covers the back of the master, and lastly the clavis. I know I have one somewhere, I would just need to find it to take a picture.

 

didn't realize this thread was still alive.

After doing some research last summer, i just figured out that i had the wrong MC period. The one they gave me for a 70 olds 442 w/ manual disks, while it had the right bore size, it was the wrong body. it had the same size resoviurs on both sides and the shallow piston groove.

After some research- The 1969 camaro also had manual disks available- same 1 1/8 bore size, but a deep piston hole.

With the deep piston hole, there is no way for the pushrod to fall out, even if the piston sticks in the bore, so no need for a retainer.

So that is what i bought, made myself a new pushrod from a long grade 8 bolt, put on teh rubber boot & threaded into the clevis.

Bada bing- works great. I've got a couple thousand miles on it since completing the brake swap last summer.

Interesting side note- there is another thread here going on about the "correct" 70 w-30 manual disk MC... and with the exception of not having the bleeder valves, the 69 camaro mc i got from napa (new not rebuilt) is identical. shape, cap, size, and of course bore.

So thats what i'd recommend. Get yourself the 69 camaro manual disk mc w/ 1 1/8" bore and you'll be good to go. :thumbsup:

 

Ben,
I have the same issue with the push rod falling out of the m/c. It angers me that the seller of the car knew he had the pedal rigged with a piece of bailing wire. I could have been killed. I've been looking everywhere for a retaining clip. I guess I just need to buy a 69 Camaro m/c. Will the stock push rod work or will I need to make a new one like you did?

 

I stumbled on these parts tonight. Hope this helps someone else with the problem I have. I ordered the complete kit. I'll report back as to how it works out.

INL12439 1964-79 GM Master Cylinder Cup 1pc $16.75
INL12440 1964-74 Gm Master Cylinder Push Rod Manual Brakes 1PC $16.75
INL12441 1964-72 A-Body, 67-69 F-Body, 68-74 X-Body Manual Brakes Master Cylinder Push $51.50
Assembly

Rick

 

http://www.classicparts.com/1967-72-...tinfo/BR-0014/ Don't know if it'll fit, but it's only 3-4 bucks. Might be worth a try?

 

I installed the kit mentioned above and it worked very well. No more rod falling out of the master cylinder!
Rick