Re: Attention Stock/Superstock competitors..
 

When these cars were new, they were not equipped with lightweight, aluminum, Mopar or aftermarket master cylinders, that lack the factory pushrod retention clip, to secure the brake pedal pushrod into the master cylinder piston.

Re: Attention Stock/Superstock competitors..
 

It happens when you use an aftermarket or mopar style master cylinder. A positive retention device such as I mentioned above is a must have Item. There should be no compromise on safety.

Re: Attention Stock/Superstock competitors..
 

That happens on GM cars when using a power brake master on a manual brake setup because the recess on the master cylinder piston is shallow on power brake setup and deep on the manual brake setup.
Some aftermarket masters come with a piston spacer to be used only with a power brake booster.

Re: Attention Stock/Superstock competitors..
 

The rubber retainers did a reasonable job of keeping the pushrod in the MC piston. It is a one time use item. Once it's jerked out of the piston, it won't work. And they can be hard to find new.

Aftermarket pushrods are not usually made with the groove for the ring either.

Most of the time, the brake light switch, and brackets, are removed on race cars. That acted as a stop for the pedal in OE systems.

A hard leaving car can cause a pedal missing a stop to swing back far enough to pull an unretained pushrod out and let it fall down.

A new to you car, a car you borrow, a car in your shop, need to be looked at.

Re: Attention Stock/Superstock competitors..
 

Here is the page of Billy’s thread with the pics. I will be swapping from the stock ‘70 Nova brakes to aftermarket with Mopar master this season, and was having trouble envisioning some of what was being described. This helps a lot.

https://classracer.com/classforum/sh...t=44903&page=3

Re: Attention Stock/Superstock competitors..
 

On most gm cars i found that of course the mopar master cylinder worked the best, I put an adjustable bolt thru the stop light switch bracket with a pad welded to the end that lined up up the brake pedal arm making adjusting the clearance on the rod to m/c a snap.

Re: Attention Stock/Superstock competitors..
 

This is what I'm getting at. Thanks, CMc.

I'm looking for a source for the retaining ring that you mention. I'll post my results.

I looked under the dash of my '74 Dart Sport, and I saw what you mention about the brake light switch bracket. It keeps the pedal from being pulled out of the MC.

I have an aluminum MC from Dr. Diff. It came with a new retainer ring.

When I installed the alum MC in my car (several years ago), I guess I saw that the pushrod is retained by the clip, and the brake light switch bracket. I didn't realize that when a Mopar style MC is installed in something other than a Mopar (or a Mopar without the brake light switch and bracket), it could be installed in a manner that would allow the pushrod to fall out. (Or the driver's foot could inadvertently lift the pedal out of the retaining ring if the brake light switch and bracket were removed on a Mopar.)

I hope I'm being clear. I'm not a technical writer, for sure, lol. I was in a street car years ago that lost it's single MC. The driver made a valiant effort using the E-brake and avoiding obstacles until a telephone pole ended our ride. One passenger lost an eye, one had a collapsed lung, I had a back injury that piled on to other back problems my physical working career created.

EDIT: Here's a link to Dr. Diff. They have it, and also Detroit Muscle Technologies has it. https://www.doctordiff.com/manual-br...r-grommet.html

Re: Attention Stock/Superstock competitors..
 

This might be for Mopars only, but here's a picture. The retaing ring is simply refered to as a "ring".<img src="https://www.forabodiesonly.com/mopar/attachments/1712516049494-png.1716232911/" alt="1712516049494.png"/>

Re: Attention Stock/Superstock competitors..
 

Factory Ford manual brake vehicles used a similar retaining ring to lock the pushrod from the brake pedal, into the master cylinder piston, but every power brake master cylinder that I have seen, do not have a groove for the retaining ring to lock into.

Re: Attention Stock/Superstock competitors..
 

The cup style retainer in the link works well. On my 3rd gen F body I removed the pedal quadrant and mocked it all up on the bench. I welded in a flat piece of steel with a hole drilled in it which guides the rod and prevents it from dropping out of the Mopar MC. Also a stop to prevent the pedal from being yanked back. At one time I used a cast iron MC from a GM pickup with manual brakes and it had a pushrod that locked into the master cylinder piston.