303M HydraMatic rebuild

[rustystud]

Using the special clamp tool again I compress the seal rings and install the rear drum assembly.


Now after installing the front and rear bands the drum assemblies are ready to go into the case. You need to "stab" the front shaft first angling the assembly into the case. The TM shows this. I don't have a helper to take pictures so I cannot show you how I do this .

Once the assembly is in place and the main support is bolted down, you can pressure test the whole assembly.
This hole applies the front clutch.
This hole applies the rear clutch.

After tearing down everything due to the high leakage, I checked the iron seals for clearance. Since I only have four seal rings at this time, I never checked this as it is a moot point. You need a .002" and .007" feeler gauge to check this gap. The gap must be over .002" and under .007" .
Everything checked out as I figured it would. Since most likely the military rebuilt it last.


Now everything is almost back to where I started this morning !

 

[rustystud]

This Monday I'll be taking all the pistons I have down to the machine shop to be modified to except rubber seals. Hopefully this will not take too long.
In the meantime I have seven HydraMatics to tear down. Lets see what parts I can salvage from them.

 

[rustystud]

I got the pistons back from the machine shop and reinstalled everything. Pressure tested it and all is fine.
But in the meantime, I tore down one of the five 303M transmissions I got in Canada two weeks ago and after cleaning it up found out it needs a new return wave spring in the reduction unit. This is becoming a problem. In the last four 303M transmissions I tore down; all needed a new return wave spring.
I am being forced to find a supplier of these wave springs if I want to complete this rebuild. There are several manufactures of wave springs, I just need to find one that makes one as big as the 303M needs.
Either that or a manufacture that is willing to make up some springs.
Since it has been fifty to sixty years since these transmissions have been built, these springs are shot. Putting one of these old springs back in service is just asking for trouble. Just like the one I tore down two months ago which had the wave spring shatter causing the apply piston to break.
So I'll continue rebuilding this transmission until I get to the reduction unit.
I need to cleanup a few more parts from the last 303M I tore down, then I'll get back to work.