willysmjeeps.com

Hi Guys,

I've been digging thru old posts on here trying to find out if the aluminum master cylinders were originally installed on late production A1's.......but haven't found an answer. I'm assuming all jeeps left the factory with steel MCs.....and the aluminum ones came later as service replacements........but that's just a guess. Anybody know the deal regarding aluminum MC's?

Oh.........one other question. In the ORD for the master cylinder it lists the Manufacturer's part number as LO-FExxxxx. I can't find the abbreviation "LO" listed in the manufacturer's name abbreviations in the beginning of the ORD. The WO is listed, but nothing for LO. Is it Lockheed something? All the steel MC's I've found in posts on here were made by Wagner.......so I don't get the LO abbreviation. Any help would be appreciated.

thanks,
bob

Wagner used to be Wagner-Lockheed.

The only aluminum master cylinder cylinder used on the M38/M38A1/M170 was the early M38/M38A1 WO# 648069, LO# FE3441, ORD # 7697478. It was only used 1950/52 or so then was directed to be used until exhausted then switch to the cast iron units. It had an entire top lid that bolted on the housing.

The M38A1 ORD 7 shows it being discontinued 1952 and the FSN for it, 2530-00-769-7478, was cancelled January 1962.

30 years ago when I got my 1950 M38 I was going to replace the aluminum master cylinder with another.My father told me to go with cast iron because back in the day the Air Force had problem with the aluminum getting very hot from the exhaust pipe and brake fluid doesn't work well when it is hot.

In addition the heat is a problem with the aluminum's higher expansion/contraction rates.