What BORE for a new dual MC?

[Deleted User]

Researching the possibility of changing from single to dual Master Cylinder and wondering what bore to get. 

I see the front wheel cylinders have a 1 1/8 bore and the rear wheel cylinders have a 15/16 bore.

I'm hoping someone like Frank (hint hint) will chime in and give me a good part number for a master cylinder conversion.

Frankvintagefullflowcom

Oops, I went right up to the shop to retrieve the M/C # for you and got distracted by something.......probably a never ending sea of projects.

Frankvintagefullflowcom

Damn this thing! I just wrote a book and when I clicked send, it only sent the part you see above. I'll try again................

I used NAPA NMC 2534, @ 24mm bore. As you could see in the photos I sent a while back, it's not a straightforward install, requiring substantial modification to the cyl itself and fabrication of some custom mounting hardware. I chose this unit because; It's cheap, common, has a nearly correct bore dia. (better slightly undersize than over) has 2) 3/8-24 outlet ports aimed away from the frame, has no downward protruding features, and has mounting ears oriented in the horizontal. It comes with the reservoir attached which must be carefully pried off as it is intended for firewall mount (on the booster, of course). If you break it, there is a replacement available for almost as much as the whole thing. No, I didn't.
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Frank

Lee ODell

Same thing happened to me yesterday Frank. Had to rewrite the rest of the message to finish post.

Maybe we are both too long winded. ha ha.

Thanks for info on master cyl.

Lee O'Dell

[Deleted User]

Great info guys, thanks as always!  I'll look for a 1" bore and look further into Frank's set up.  I need to figure out how to get the reservoir on the firewall and how to get the fluid down to the MC.

Sounds like I have a weekend (or more) full of work.  Love it!

[Deleted User]

Frank, I'm assuming you chose the 3/8" line because it will work with the original wheel cylinders. Are they 3/8" line?

Frankvintagefullflowcom

Nope.
The 3/8 dimension is in reference to the fitting size, i.e., 3/8-24, which is the ordinary tube nut for a 3/16 brake line tubing in the Jet.....and all "Stepdowns" for that matter. It's simply the diameter and thread pitch. thread
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Frankvintagefullflowcom

I should also mention that the 24mm bore (.946") makes no detectable difference in pedal travel. In order to use that cyl. there is a lot to do. The original lines won't be useable with this set-up but I would recommend re-plumbing all of that system anyway. Note the 10 PIS residual valves in the photo. The original Wagner cyl. has a 10 PSI valve built-in but this new one was meant for a system with that feature built in to the proportioning valve or somewhere, so you should install them in each of the frt and Rr lines.

Where did that extra word "thread" come from in the last post? This thing is a mystery sometimes.
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BillUSN1

Where's the photo showing the MC and residual valves?
I also couldn't cross the MC part number on napaonline or AZ. Any other reference for it?
Thanks

Frankvintagefullflowcom

Funny, it comes up on Napaonline here. The reference to photos was a bit of a goof 'cause I had sent them privately to Mike and thought that's who was asking.

Frankvintagefullflowcom

Damn this thing! The rest of what I wrote didn't make it! Re-writing.....
The NAPA # is NMC M2534 and is for '95 Chrysler Town and Country, amongst many other Chrysler apps.

Here are a few photos that I fully descried in the first attempt and I'm too lazy to do it all again. I can't find the "installed" photo to which I referred in the earlier post. Let's see if this goes.
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Frankvintagefullflowcom

OK.here's the installed pic that I mentioned.That thrust bracket has a 3/4 inch spud on the backside that fits into an existing hole in the Jet frame so that thrust is taken on it, not through the fasteners.

BillUSN1

Very nice job. Thanks for posting. Pics are worth a thousand words!
I now have lathe envy. Time to hit craigs list and the DRMO!

HUDSONBROTHER1

Looks good. What a nice sanitary install.

Frankvintagefullflowcom

Thank you. In addition to being able to stop, that makes it all worth it.
Some place I have photos of the reservoir.....found it.