ALUMINUM MASTER CYLINDER QUESTION???

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?

What perfect timing..

https://board.moparts.org/ubbthreads/show...;gonew=1#UNREAD

I still haven't received a reply from Rick, but just to do a little investigating of parts interchageability, I removed the pistons from both master cylinders, and what a difference. The pistons on the right are out of the New aluminum piece which did not have the retaining boss, and the ones on the left are out of my Autozone steel unit. You can see the difference of the two master cylinders in the one photo. I took diameter dimensions and they both check out right at 1.122" inches. What surprises me is that the piston lands are larger on the left one, which is the steel autozone piece, than the nice aluminum one on the right. Not only that, the big difference is the connecting rod between the pistons is dramatically larger on the Autozone piece. To me this all goes to durability. With all the piston lands lining up, it looks as if it would be a good swap to interchange the parts. Remember the ugly mc in the back ground was a new piece from autozone, and has only sat on my car for a couple of months, while still doing the build on the car. I even painted it to prevent rust, but I guess not good enough, huh? So the internals are all still brand new. I'm going to swap them and see how well it works. For those of you who bought the same piece from Rick, this is one solution, I guess. Just go to Autozone swap out the guts and take it back for a refund. I know, I know, pretty cheesy, but it's money saved right?
Anyway the retainer is a safety feature to keep the rod from falling out of the master cylinder. Your right spring pressure is what resets the piston after depressing the brake, but if your pedal was to come out too far, for whatever reason, than you better hope your emeergency brake is working good. I'll let you know if I ever hear back from Rick. He was pretty quick to respond when I wanted to order the master cylinder, but I'll let you know when and if he responds about my issues with the piece.

Another pic

master cylinder pic

my 80 volare has manual brakes from the factory. Its m/c is the newer style aluminum one. maybe use that app when you order your m/c from the parts house? I got lucky and found an NOS one, for a little less than parts store reman prices, on Ebay

Well I got my response from Rick, and I'm posting that email here for you guys to read.

This is what Rick wrote in his email:

Do it the modern way: RTV.

Install m/cyl. Fill recess w/RTV. Slip pushrod, attached to pedal, into
the
goo, bottomed. Use bungee cord or weight, to maintian light / moderate
pressure. Don't touch for 24 hours.

Done.

Rick
----- Original Message -----
From: "Bob McKinney" <moparrush@yahoo.com>
To: <rick@richardehrenberg.com>
Sent: Thursday, February 28, 2008 12:40 PM
Subject: aluminum master cylinder question


> Hi Rick,
> A few months back, I purchased one of your
> master cylinders for my project. Well I have gotten
> to the point of my build to install it, and looking at
> the back of the piston last night, my MC that you
> shipped me does not have the machined area for the
> retainer. Can you help with this?
> Bob McKinney

First of all his ad clearly states that these are machined for my pushrod and a direct bolt in deal. Well gooing up my master cylinder with RTV isn't exactly a bolt in deal, and secondly what a half [Edited by Moparts - Keep it clean] solution to the problem. I'd have to say be weary of this seller. I sent a response stating I wanted one with the machined recess, so in all fairness I'm giving him another shot to do the right thing. Well see....

i used one off an 85 b350 on my cuda change over. thats what i was going to do until i saw Rick's add on here with the adapter plate. seemed like a good deal.

Okay Rick has emailed me back again, and after refusing the idea of RTV, the only thing he would offer is to just refund the whole thing, which is admirable, but again a word to the warning of the Moparts consumer. I had thought maybe, just maybe, I had a bummed out one that missed this critical machining. I guess they are all that way. I recommended to Rick to change his ad, because as you read earlier this is not a plug and play piece. Whatever you do, if you think that putting your life into RTV is the way to go, than my prayers go out to you. Just don't be misled and end up where I have had to go with this. I'm going to keep the Master Cylinder since I have allready swapped the pistons for the machined one, and fix my problem. Thanks again for the post.

I just emailed him too. i ask if it was true that none of the MC had the recess? if he was going to refund the ones that people like me bought. this is what his ad says. page 2 a-body parts for sale.

"It has the machined recess in the primary piston so a manual-brake pushrod will work
(the stock pushrod is fine, no mods required. I will supply the rubber pushrod retainer
for $1 if requested when you send payment). This m/cyl also works fine with a power
booster – again, no mods, 100% bolt-on."

I just got one last month as well.

The ad shouldve been written right.

I have just examined about 40 of them, all have a deep pushrod recess. There is no way the pushrod can fall out. Some of the early/mid 60s stock pistons on masters designed for PB only had just a small dimple for the booster pushrod centering which would be very dangerous with manual brakes, but that is NOT the case with these.

Rick

Hi again All. I'm glad that Rick has jumped in on this. I'm posting a couple of pictures to clear up what I'm talking about. These are pics of the piston where the brake pedal pushrod goes into the piston. The piston that is mounted into the Gold anodized master cylinder is the one that came out of my autozone steel piece. I swapped them last night, and the other pic, which isn't mounted into the master cylinder, is the one that I pulled from Rick's piece. You can clearly see the machined recess which is to be used with the rubber retaining bushing. I'm not sure on power brake cars about the need of having this but I do know that manual brake cars required this. It's not just an early 60's thing either. This went into the 80's, and probably beyond, but I have no experience there, so I'd be assuming. If you were to put a rubber retainer on your rod, and pushed it into the non-machined piece than, as you can see, there is nothing there to hold it in place, and the machined piece goes down appoximately .250", or a 1/4 of an inch, and is machined back about a 1/16" of an inch to the bottom of the piston area where it rounds out for the end of the rod. That machined area is what is designed for the retainer is what I'm speaking of. I'll be emailing this to Rick as well, for his thoughts. I hope this helps clear up things.

This is the non-machined piston that had came with Rick's aluminum piece.

power brakes don't have the retainer rubber, and don't need it. That is not to say you won't see a power master with that groove, as people get sloppy with the kits.
The reason manual brakes need it, is because you can pull the pedal up and pull the push rod out of the master cylinder.
That part does not pull back on a power car because the booster doesn't let you.

I believe he is right about the power brake issue. Sounds like someone with more experience than I with power brakes. My autozone piece for for a B200 Van from 1985 is what I ordered. My donor piece from the junkyard was from the same vehicle, and since it came factory aluminum, I thought that is what I would get in exchange. When they handed me that steel cast one (and all of them on the shelf were like that) I was bummed, but the one out of the salvage yard didn't work well so that is why I bought that one. The aluminum ones are kinda hard to find and when I saw Rick's ad on here selling these at a pretty reasonable price, I jumped on it.

Some more food for thought; When measuring from the end of the piston to the bottom of the bore of the pushrod cylinder it is only approximately 1/2" deep. That goes for both pieces that I took the pictures of. That isn't much room for a rod to fall out, or drop out and wedge up against the firewall. I see what Rick is talking about with the early power brake cylinders not having as deep a bore as the one's he sells, but I don't have a multitude of old master cylinders here to check. I still have my original one, before the upgrade, and it has the same bore dimensions (with the machined groove) as the one piece I got from autozone.
My thinking is that if the Chrysler Engineers put it there for a few decades, and on different models of Master Cylinders, than it stands to reason that the retainer, for non-power brake cars, needs to be there! I've read most all of the mopar mags, and have them dating back into the 80's when they first starting publishing them, as well as service manuals, guides, etc... Whatever mopar I read it, but I have never read anywhere that a fix for not having the retainer is to put RTV in it. I might have missed something somewhere along the line, and maybe this is an idea that this is a trick fix that Rick has become aware of, I just have never heard of it myself. As for myself, I have just spent years working to get my car back on the road, and I sure would hate to see all that time, money, and divorces wrapped around a tree because of a $1.00 piece of rubber.

I have three of Rick's masters and they all have the machined recess for the plastic/rubber retainer.