Brake Woes

Mine did that. Check your pushrod is not catching on the washer under the snapring inside the boot.
20230529_073458 by Joe with a jeep, on Flickr

 

So, this Crown master cylinder is crap. I can't get the pushrod to operate properly and it's leaking from every orifice.
Has anyone ever found a rebuild kit for the stock master cylinder? All the websites I'm finding list a single bowl master cylinder, which went away several years before my Jeep was built.

 

I don't think rebuild kits are available anymore. I haven't been able to find them either. I have one rebuild kit here I'm *not* getting rid of that I got from oldtime. You might PM him to see if he has any more of them. If not, you may be able to use the seals from the Crown unit in your old mster cylinder.

 

I thought of that, pretty expensive rebuild kit.

 

Doug, will either of these master cylinders work? A bit pricey. I would ask who the manufacture is since it could be Crown.

Master Cylinder With Dual Reservoir 1966-1971 CJ5, CJ6 All V6 And Some 4 Cylinder Models - vintagejeepparts.com

CJP 945556 Brake Master Cylinder, V6-225 engines, 1966-71 Willys Jeep CJ-5, CJ-6 | Bernie's CJ Jeep Parts

 

This NOS kit on E-bay is the correct one: https://www.ebay.com/itm/112022795149?

Get one while you can.

 

I tried finding a rebuild kit, local Napa owner measured everything looked it up in his book. I had to pre-pay and still had a straight bore Kit arrive.

I might be able to dig around the garage and send what I have (entire master torn apart and scattered) but it sounds like you have a mechanical issue for it to hard stop without any pressure.

 

Well I had to use the 53 year old fittings and copper gaskets from the old master cylinder to get it to stop leaking. Re bled it and put it back in and it seems to be working now and not leaking. I'm not sure why removing and reinstalling it seems to have fixed the brake pedal issue but I'm gonna go with it, at least for now.

 

Just makes me wonder what shape the cups are in.....Just Sayin.....

 

I'll find out when it arrives.

 

Probably better than brand new Crown ones.

 

That said, you shouldn't need a stepped master cylinder to make it all work. As long as you have the needed residual valves and properly sized wheels cylinders (and possibly an adjustable proportioning valve in the rear brakes) a non-stepped master cylinder will work fine.

The math works out to needing a 1.39 front wheel cylinder to keep the same front to rear proportioning with a non-stepped 1" master cylinder, so a 1 1/8" would get you pretty close. All that's assuming the factory proportioning is what you want.[/QUOTE]

Wouldnt it be a 1" for the front brake and 7/8 for the rear brake ?

 

No. A smaller piston on the pedal side makes more pressure. The pressure is lbs (force from your foot) divided by square inches (the size of the piston). If the piston is smaller, the pressure is higher for the same amount of force. It does move less fluid per amount pedal travel though.

 

There is a lot more going on in the stepped master cylinder than one thinks...

That's all I have to say about that.