Replacement Chevrolet master cylinder

[Hanno Spoelstra]

Great input guys!

This info should give the next one looking for a master brake cylinder replacement enough info to work with. This is the sort of subject where the combined knowledge of MLU members keeps these ageing vehicles running.

Thanks,
Hanno

[Tony Smith]

This M/C is of the correct configuration:

https://www.ebay.com/itm/NOS-1936-19...EAAOSwHMJYFAgk

However, the seller recommends that the correct kit to put through is the #3 kit, which is only a 1" bore. This may be a typo, as the kit for the 1 1/4" bore is a #33 (also known as TM3630). If this is actually a 1" bore, I wonder if it could be bored out to 1 1/4" when sleeving?

[Grant Bowker]

Visually, the ebay master cylinder is consistent with the commonly found 1" size. I believe there was also a 1-1/8" cylinder made.
The NAPA kits 3 and 33 kits look similar in style, so without measurement I wouldn't assume the seller is wrong. The Raybestos kit for the 1" bore is MK3, consistent with the NAPA information in the ebay listing. The Raybestos kit for the 1-1/4" cylinder is MK33 so possibly the NAPA 33 might also be 1-1/4" but this is not confirmed.
I believe the casting number on the 1-1/4" cylinder (ebay listing gives 5450256) ends 61. On checking the 1-1/4" cylinder I have at home awaiting sleeving has 5450261 cast into it.
Personally, I would not be comfortable taking 1/8" all round off the wall of the cylinder without a lot of careful measuring and thinking. Even more so if removing a bit extra to allow for the sleeve.

[Guy Verstrepen]

mss is a look at this site www.chevsofthe40s.com/

[Harry Moon]

Don't use the new master cylinder #5454576E as it has insufficient volume and requires excessive travel and while i'm hesitant to say defective the hole in the side for the sensor lines up with the seals which then tears the seals.....

IMG_0090.jpg

[Guy Verstrepen]

https://www.generaaltjes.nl/Content/...6642-15715.jpg

turning - milling - boring work.
his name is fred Send metalwork.
info@fred-verschragen.nl
the man lives in the Netherlands

[Grant Bowker]

To try to bring together another thread on CMP Chev master cylinders http://www.mapleleafup.net/forums/sh...aster+cylinder

This is rapidly becoming one of the "the more you study, the more you realize you don't know" things.

I recently pulled out a couple of master cylinders (all 1-1/4") thinking I would send them for sleeving to be "ready when needed". It turned out I had 4 master cylinders sitting. 1 side mount and 3 base mount. The side mount shows part number 5300918 (crosses to Wagner FD-4194). All base mount seem similar in sizing but were not measured with any precision tooling. One has number 0260 cast in the side and it looks as if there were other digits that were supposed to be there. Possibly the whole number 5450260 as in the C15A parts book? The other two have 5450261 cast in. The end caps for the base mount cylinders were all hexagonal to take a wrench but the one for the side mount was round and ribbed. Although they are all 1-1/4 bore, the end caps from the base mount exchange with each other but there's no way the one from the side mount can be threaded into a base mount cylinder (too large). I've no idea why Delco would have done that. The Chevrolet Master Parts Catalog 1929-1948 makes reference to several 1-1/4" master cylinders with different part numbers for the assemblies (not matching any of the numbers above) but all seem to use casting number 5450259 as a starting point. it is not clear if this is a side mount or base mount part.