'44 Chevy CMP C15 Master Cylinder

[Harry Moon]

I bought the one that was new manufacture, Argentina, and it was off by a couple mm's as it was obviously manufactured to metric specs, took some work to install on the C60. I would buy the rebuild that requires a core.

[Grant Bowker]

Originally Posted by Harry Moon

I bought the one that was new manufacture, Argentina, and it was off by a couple mm's as it was obviously manufactured to metric specs, took some work to install on the C60. I would buy the rebuild that requires a core.

My C60 manual says the master cylinder assembly is part # 5450260 (same as the C15A). The only master cylinder I see today at Chevs of the 40s that looks to be the same general shape as CMP master is part # 5450257, listed as fitting cars. I thought most cars and pickups had 7/8" or 1" master cylinders rather than the 1-1/4 usually found on CMPs.

Is more information available about you got and how close it was to the CMP master cylinder?

Chevs of the 40s do sell kits, but todays catalog seemed to be for 7/8 or 1" master cylinders.

[Craig McKelvie]

thanks everyone, going with Grant's suggestion and sending to John Stuart in Stoney Creek. Try a fresh start.

Always wonderful help from the forum!!!

[Harry Moon]

Originally Posted by Harry Moon

I bought the one that was new manufacture, Argentina, and it was off by a couple mm's as it was obviously manufactured to metric specs, took some work to install on the C60. I would buy the rebuild that requires a core.

A follow up on this master cylinder. It failed before I got on the road. There is a outlet at the end for the brake sensor and when you rotate the push rod to install or adjust the seal cuts itself on that opening. no way to avoid rotating the push rod. in addition it is a one inch bore which required a longer stroke or travel to the pedal. seemed to work fine but after adjusting it it started to fail. I recall the same damage to a similar later master cylinder adapted to another truck, same 1 1/4 master with the mounting holes on the side and I think back then the culprit was the same outlet on the side ripping the seal when it was being adjusted. So I have taken Grants suggestion and sent an original one off to Stoney Plain for sleeving and a Rebuild.

[Phil Waterman]

Hi Guys

Some photos of the master cylinder unit preferably with a original in the picture would help others understand the issue.

Would also be interested in the dimension of the bore casting, just wondering if the casting between the larger and smaller bore are the same? Wonder if there is enough metal in the walls to bore for the larger size?

My solution has been to have the original cylinders sleeved this has been a once and done solutions with sleeved master and wheel cylinders lasting 30+ years. With just replacement of the rubber parts every 5-7 years.

Cheers Phil

[Andrew H.]

Originally Posted by Phil Waterman

Hi Guys,Some photos of the master cylinder unit preferably with a original in the picture would help others understand the issue. Cheers Phil

Here is an original master cylinder from a 1942-45 civilian Chev truck.

[cletrac (RIP)]

I bought a NOS military master cylinder off ebay several years ago. The guy didn't know the difference between it and the civilian ones. The civvy ones have the bolts going in from the side and the CMP ones go up from the bottom.

[Hanno Spoelstra]

Barry Churcher made a bracket to fit the more common master cylinder to a CMP. May be a solution for others as well.

HTH,
Hanno

[Jonathan Moore]

I had the same problem with my HUP, I did think about having the master cylinder it lined but in the end I bought a new one fro Rockauto in the US. Its slightly different in that it has two bolt holes that go through the chassis and you need to make a couple of spacers but mine already had the holes. The part number is MCA4555.

Jon