A Friend of mine on Facebook was looking for the oring that holds the stock brake rod into the master cylinder and it brought up a safety issues I remember hearing about. Didn’t a few guys have issues with the brake rod popping out and guys losing their brakes. Seems I remember some guys were putting a mechanical stop on the pedal to prevent this from happening. Does anyone have more info on this subject. Thanks

Yeah, there's a limiter on the pedal of my old SS/IA car, been there since its Hamburger days as far as I can tell. Amusing thing is, it still has its tiny (lightweight at the time, right?) drum brakes, so braking has never been its strength, haha...

John I recall reading about here it a couple times over the years. A stop was added to the pedal to keep it from moving enough to allow the rod to come out.

I put a stop on both of my cars.. I ended up
using a 3/8 push rod cut to length.. I have to
take the pedal off to get the rod out.. never
had any issues

In stock configuration, the brake light switch is the up stop, once it's removed a mechanical stop is needed.

Thanks guys. I thought my old brain remembered reading about an issue with this. I will check our cars out over the Winter

I was at the Mopar Nats when a Dart had the pushrod drop out and the poor driver had zero brakes. He hit the gravel trap at high speed. It looked like the car was severely damaged, maybe totaled.
From that moment on, I have considered a positive stop to limit the upward travel of the pedal 100% essential.

It sounds like a good winter project for all of us
to take a peek at. A diaper may be another wise investment to help keep the shinny paint shinny and the driver safe too. I know I won’t race without one now.

Had that happen at Quaker back in the late 80's- My cousin who was driving had a bad habit of picking up the brake peddle with his foot - the rod fell out on the floor - he got it stopped as we still had the parking brake in the car - he downshifted the trans and held on! - put a stop in after that!

Seen a fresh built Mustang get totaled at my home track. Very fast car, G force pulled the peddle back and he ended up hitting a tree past the sand trap. He hurt his back and has not raced since, has a hired driver now 💩

I did the same thing a few years ago with my car. My foot hit the brake pedal coming off of the gas and the rod popped right out. Talk about a tight butt moment. I was just driving around the block so I got it stopped but it sure scared the heck out of me. Made me a believer in a stop..

This very thing happened to me 2 seasons ago. I hadn’t looked under my dash in years, I did my burnout and pre staged the truck, put it in neutral and cleaned the motor out. I was having an issue with my throttle springs not quite letting the carb back down to idle. I pulled the gas pedal up a touch with my foot and I believe I hooked the brake pedal moving my foot out from behind the gas pedal. I had no idea that the brake rod popped out until I went to the lights at 150, I was in no hurry to jump on the brakes because I shut the motor down to check the plugs. Bristol has an extremely long shut down. I hopped on the brake pedal and it went to the floor, I dumped the chute and got slowed to around 60mph
Before I hit the safety net, terrible learning experience. My truck now has a Wilwood dual master cylinder set up on it. It was a very expensive lesson learned. The only thing that keeps the brake pedal coming up too far is a plastic bracket that held the light switch.

I compared the tailor made snip of black rubber or neoprene that came with a MC at the parts house & it was identical to a piece of common black rubber vacuum hose off of their hose reel except for a shallow groove along the length of it I'm assuming for air to excape so it can go all the way down into the bottom of the piston recess & lock in solid. I've went that route several times & it has always stayed locked in their super tight. It does require that the rear piston tapered "thimble" recess has the circular shallow groove about halfway down the barrel for this piece to lock into. Power brakes can use a MC with a recess or no recess (of the right bore of course) but manual brakes require it if useing the snip of rubber or use some other method of retaining the pushrod as mentioned. Ehrenberg even used some RTV to lock the pushrod down in there on a piston without the circular groove. I have yet to try that!

All the stock Mopar M.C. from the early 1960s came with the rubber retainer on the tip of the rod so it will not come out of the piston without a lot of effort, they don't just fall out
That being said I replace the original master cylinder in my old 1070 Bracket Duster and didn't replace the rubber retainer on the rod with a new one, I had tore the old one up pretty badly prying the rod out of the piston so I discarded it through ignorance
That car still had the stock brake light switch and bracket on the pedal assembly, I had worked on the cars sixty foot times enough to finally make the swinging pedal weight bend the brake light bracket back far enough for it to slide the rod out and hang straight down off of the stock bolt resulting in no brakes
Luckily I was at LACR which has a big uphill long shut down area so by down shifting and swerving the car around to scrub speed (it would run right at 130 MPH in the 1/4 mile back then) off I made the last turn off safely
Be safe, make sure you can stop safely all the time
Happy New Year to All

I have seen so many cars wrecked and torn up because of this, I've lost count. Nice cars, not hacked together junk. Seems like at least one every year and I've been doing this since the 70s. Not just Mopars. All kinds and flavors of race cars into the net or the wall.

I always use multiple redundant methods to prevent this on anything I'm involved with. The OE O-ring is OK, but is often lost, ruined or just not used or there is an aftermarket pushrod used that is not cut for the ring. Brake light switches are often plastic, flimsy or missing.

At a minimum, I use a positive mechanical stop on the pedal to limit movement coming back up to a point where there is just some freeplay at the MC. In addition to that, I use a mechanical retainer on the pushrod itself or a kit made just for this. This one is sold by various chassis supply places.



I've also done something as simple as fabing up a cup or strap, which is captured between the MC and firewall or mount, to cover the MC bore with a small hole in it for the pushrod. Then weld a washer on the pushrod or cut a groove and use an e-clip to capture the pushrod under the retainer. There just has to be something on there to keep the brake pedal/MC linkage from falling apart.

I have used a piece of vacuum line as well, works fine. I'm here to tell you the stop lamp switch isn't good enough. Seen it first hand, not good. Mine also has a positive stop. And while we're on the subject a screw style hose clamp below the steering column U mount (it only has a small sheet metal tab). This will stop the column from sliding up out of the fire wall grommet. Yank on the wheel hard enough and you can pull the stock steering coupler apart. I watched it happen on a friends car, not good.
Doug

I tried a return spring and it eventually popped out when I hit third gear.It was hooked between the firewall and the brake switch. I was able to pop it back and braked. No more spring. The brake switch will eventually twist and you'll have the same problem. If you somehow pull the brake pedal up higher than it usually travels, you will be primed for a rod slip out. I'm looking at fabricating a bracket with a tube long enough to keep the rod aligned with the MC.

If you need the little rubber bushing, Doctor Diff has them.

That's how this started off today. A friend on Facebook was needing one and I recommended Mancini Racing or possibly even Ace Hardware but then I told him about this safety issues. It sounds like a good time for all of us to take a peek at our set-ups.

Yes, it is a good time to check those brake pedals out. I’ve learned a valuable lesson on this subject, if it can fall out, it will fall out. Don’t assume, since it’s never been an issue, that it’s ok, like I did