I purchased one of the hard to find aluminum master cylinders from a Moparts member awhile back and am now getting to the point in my build that I am mounting the new style unit into my Dart. Well looking at the back it seems that this unit is not machined for a brake pushrod retainer. Is there a fix for this, and or can I get away without using the retainer? Any suggestions would be greatly appreciated. Thanks for the post.

I'm not sure if there is a fix. How can you tell it is not machined? What do you have to look for?

I think some power brake mc's don't have a retainer slot. If you have manual brakes, I wouldn't run without a retainer.

I bought one from him, and my brake retainer operates just fine.

Now, why the caps seep brake fluid...thats another story.

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Now, why the caps seep brake fluid...thats another story.

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Mine does the same thing!

What size fittings do these master cylinders take?

On the car, I had purchased one from the local parts house, and it was a steel piece. A, it didn't work worth a damn, and B, it rusted all to hell in a matter of months. Spilled dot 3 on those eats the paint and they rust quick, but that's another topic. So when going to swap the MC's last night, I was trying to salvage the rubber retainer (Trying key word) and when checking the new aluminum one there was no resistance when I put the rod in. Of course this was all done on the bench, so taking a flashlight, and a scribe, I looked at the back of the piston, and it was smooth machined to the cup at the bottom, whereas, the steel one had been machined for the retainer. It is obvious when you compare the two. I think I'm going to disasseble the steel one, and see if the piston is swapable, and maybe that will solve my problem. The only other option I can see it to remove the piston and go and have it machined for the retainer, but what a pain in the butt, and cost, that would be. I guess I'm looking for the easy way out, but sometimes the easiest isn't always the cheapest, and vice versa. Oh, and yes mine is a manual brake car, and I was told that it would work with my setup. No mention of the retainer though, either by myself or the seller. I didn't think to ask at the time. Now that I am doing the swap, I learned another interenet parts buying lesson. You gotta ask the right questions before you buy from here, ebay, or anywhere on the net, because if you don't than it's going to bite you.

They take the same size fittings as the originals, which came on the car. Don't take my word as gospel on that, because for mockup way back when, I pulled a junker one and snagged the lines as well from the donor van at the jyard. So using the fittings I made all new lines. The forward one uses a 9/16 wrench, and the rear uses a 5/8 wrench to remove the fittings for the brake lines from the master cylinder.

Sometimes you have to file the parting lines off the plastic reservoir under the caps.

I just went back to the ads, and Rick is still selling these on here. He advertises that they are supposed to be machined, and a direct bolt on. I sent him an email with the problem that I have found. Maybe I just got a bum one that didn't get machined, who knows, but I'm going to see if he'll make things right. These are a really good price, and if needed he sells the adapter plates as well. The piece that I got from him is yellow anodized aluminum, and looks like a real nice piece minus the problem with the retainer on the piston.

This is a good post. I just bought one from him about a month ago and never thought to check the piston for the slot. I will check mine tonight too.

That's unfortunate that some out there are leaking too. That's the whole reason I am swapping!

i bought one from him too. it didn't have a recess in the piston either. i haven't got it together yet to tell if it will hold the rod. he said it would. i was surprized when it came with the gold finish because he shows a pic of the normal grey one. but it does say in the add that it comes with a gold finish. my fault i didn't read the add better. i just looked at the pic and thought thats what i would get.

I tried putting my pushrod in with the retaining rubber on it, and it just slides in and out. Without that machined groove in it, there is nothing to catch the retainer, so I don't know how he expects this to work without it??? If you re-read his ad, it's says that this are machined for the retainer, so if you have one like mine without it, than that is a problem that he needs to correct. I haven't gotten an email back yet, but I'll post what his reply is.

Yes let us know. i haven't got mine together yet to try it. i noticed it didn't have the grove but i didn't want to complane about it until i tried it.

Correct or educate me if i am wrong, but what would happen if it did not have the retainer?

The spring inside the reservoir pushes the piston back which in turn should return the pedal to the starting position. Even if the spring or piston fails then the pedal would stay put. right?

Curious indeed...

The point of the retainer is, say you go to hit the brakes. Take your foot off the gas, heads over to the brake pedal, coming up you catch the brake pedal. lifting it up some, pushrod can fall out = no brakes. I've caught it before with my foot, i have a retainer so no issue.

But its not to return the m/c, its a pushrod retainer.

The pushrod could pull out if you pull back on the brake pedal. Goody beat me to it.LOL

My instructions said to use a little Super Glue to hold the retainer in. If that don't work then use silicone to hold it in.

Tom

Right
the only thing holding the rod in the M/C is the retainer. well the brake light sw is behind the petal but it would bend out of the way easy.

Some, if not all, of the alum MC with the smallest bore, 15/16", does not have the retainer groove. All others should have the groove.

You do mean your missing the retainer groove and not the piston retainer (tab & screw) do you?