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Clutch Master Cylinder?

Printed From: Unofficial Allis
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Forum Name: Shops, Barns, Varmints, and Trucks
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=170963
Printed Date: 24 Aug 2025 at 8:58am
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Topic: Clutch Master Cylinder?
Posted By: modirt
Subject: Clutch Master Cylinder?
Date Posted: 09 May 2020 at 10:19am
Getting ready to install this new replacement for the clutch master cylinder on the hay monster.  We put on a new brake master last summer, and it seems to be leaking around the brass insert. If memory serves, there is supposed to be a copper crush washer in there that is used to seal this joint up, but neither the brake master or this new clutch master came with one.

Do you use teflon tape instead? If not, what?





Replies:
Posted By: jaybmiller
Date Posted: 09 May 2020 at 10:57am
I'd use a copper crush washer. Just take the brass fitting  into an auto parts store.HF has 'kits' of them, sad thing is I've got  3 boxes of them on the shelf here..aslo got SNOW courtesy of 'you know who'....

Telflon might not seal 100%...

Now you could ,maybe, use a 'gap filling, medium strength ' locktite.....

Jay


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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water


Posted By: modirt
Date Posted: 09 May 2020 at 11:52am
If those needed the copper washer, curious why they would not have already installed it? Or at least included it with the brass insert.

If it was just to save some money, the guy who made that call ought to be smacked around some.....as in beaten to within an inch of his life.

Also, no instructions. All that was in the box is what you see. NAPA if it matters.


Posted By: PaulB
Date Posted: 09 May 2020 at 1:38pm
From what I can see; you're trying to mix 2 different thread types. The brass fitting is NPT (National Pipe Taper) pipe thread are designed to seal when the two tapers come together. The master cylinder is SAE (straight). Until you get the proper matching threads, it will never not leak. The SAE threads can seal with a O-Ring or the copper crush washer.

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If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY


Posted By: DMiller
Date Posted: 09 May 2020 at 1:44pm
Was also going to note that Paul, you are quite correct. Would not be surprised to see a taper seat down inside that bore for a Double Flare, that or be set for a Bajo style fitting and a double flare line.


Posted By: modirt
Date Posted: 09 May 2020 at 2:10pm
The brass fitting came with the cylinder. Threads are about 1/2" deep, and at 3/8", starts to firm up and stop. So I"m thinking both are tapered threads. The threaded cavity in the MC is over 3/4" deep, so that pretty much rules out the copper washer.

Tapered threads on the line that threads into the brass fitting insert has a flared fitting on it.

So plan is to try some teflon tape on brass fitting as it screws into MC body, and tighten the line fitting until it stops.

Adjacent brake master is leaking at same place. No washer or tape on it......if the tape works on this, will try it on that too. A leaking brake master gets a bit dicey when the pedal goes to the floor and nothing happens. Done that once and once of that is enough for anybody.


Posted By: DMiller
Date Posted: 09 May 2020 at 2:18pm
Flared fitting will not be tapered. As to that threaded bore, if can thread a 3/8" bolt into it is NOT tapered if larger is 1/2-20. Teflon will not seal Brake Fluid.


Posted By: DMiller
Date Posted: 09 May 2020 at 2:20pm
What is the MC part Number, may be able to bring up tech drawing.


Posted By: modirt
Date Posted: 09 May 2020 at 2:29pm
NAPA part# 72513




Posted By: DMiller
Date Posted: 09 May 2020 at 2:51pm
Has two outlet holes? One will be 1/2" 20 thread will need a 1/2" 20 drain plug for the other if does.

Designed for Banjo Bolt and Fitting. Will not ever get a pipe thread to seal in that.


Posted By: modirt
Date Posted: 09 May 2020 at 3:14pm
As it came out of the box, it had a brass plug in the straight through hole and plastic drain plug in the hole/opening that points down. It also came with that brass insert in a small plastic bag. That is pretty much the exact setup as the master it replaced......no banjo fitting...... except that one wasn't working when I came upon the scene.  Not sure what it's problem was, but it does look like the original equipment. Both slave and master were all rusted up and line was blocked.....no not operable.  It had been replaced with a cobbled up, high friction, cable system.....that works.....but not very well.

I'm trying to put the "band" back together......a hydraulic clutch system.




Posted By: DMiller
Date Posted: 09 May 2020 at 3:27pm
These are assembled and boxed by Neanderthals, they are told put Piece A in box, install Parts B in box.

By application it is for mid 60s, Dodge Truck, those used a 1/2 20 Banjo fitting. TRUST Me. Owned or Worked on SEVERAL.


Posted By: modirt
Date Posted: 09 May 2020 at 3:36pm
That was going to be my next comment......whatever was used on Dodge trucks from that era. That would be the model to follow.

That being the case, I assume it has to go back to NAPA for the banjo bolt and new fittings? And the line with flare fitting has to be converted as well?


Posted By: DMiller
Date Posted: 09 May 2020 at 3:51pm
Depends, if has the standard Male Double Flare, no. To double check try a 1/2" 20 bolt in it. If they sent a Pipe Plug for the bottom hole, SOME had a NPT thread there, try the bolt in it too.


Posted By: modirt
Date Posted: 09 May 2020 at 5:38pm
Checked and a 1/2"  20 bolt and it didn't get past the first couple threads and stopped dead. Brass plug that came with MC goes into both ports, but snugs down and stops as it gets deep in. So I'm assuming NPT threads?

BTW, on a lark, I retrieved old MC out of the rust remover bath it was in and it has a different brass fitting. That one was put in with teflon tape and mates to both ports and also mates up with flare fitting on the line. Gonna try all that with new MC and see where it takes me. Stay tuned!


Posted By: DMiller
Date Posted: 09 May 2020 at 6:27pm
Well I have been wrong before!!



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