Changing a shifter seal and o ring on FMX trans

Mac · May 3, 2020

OK Guys,

Being an engineer with a lot of time on my hands, I decided to change my leaky shifter seal on my FMX trans. Using info I found on this site as well as bits and pieces from other sources, I created a manual using lots of my own pictures and discriptions. Just in case I am ever stupid enough to do this again.

See attached, hope it can be of use to others.

Mac

Replacing the shifter seal.pdf

vintageman · May 3, 2020

Good job, thanks for posting this.

Tom

Bentworker · May 3, 2020

Excellent, I could have used that about a year ago! Thanks for posting it.

Don C · May 3, 2020

Well done. Not an easy or clean job, I've replaced them on C6s in the car, and I know what you mean about ever doing it again.

machattack · May 4, 2020

OK Guys,

Being an engineer with a lot of time on my hands, I decided to change my leaky shifter seal on my FMX trans. Using info I found on this site as well as bits and pieces from other sources, I created a manual using lots of my own pictures and discriptions. Just in case I am ever stupid enough to do this again.

See attached, hope it can be of use to others.

Mac

Very Good tutorial on a common problem. Thanks for all the good work!!!!!! You will help many.

Gregaust · May 4, 2020

Nice write up . FMX can be fiddly but are a good trans

92GTS-R · May 4, 2020

Great job on that PDF Thanks for taking the time to write things up.

Mac · May 4, 2020

....Forgot to mention, use Type F transmission fluid.

Mac · May 5, 2020

OK Guys,

Being an engineer with a lot of time on my hands, I decided to change my leaky shifter seal on my FMX trans. Using info I found on this site as well as bits and pieces from other sources, I created a manual using lots of my own pictures and discriptions. Just in case I am ever stupid enough to do this again.

See attached, hope it can be of use to others.

Mac

Something that I discovered after posting this repair write up. After trying to reinsert the detent sping and plunger into the trans housing many times plus using all the words that the Army taught me (along with a few new ones I made up) I stumbled onto a good solution.

Coat the detent spring with a light coating of grease, just enough to get it to stay in place once you reinsert it into the housing, the take a short (say 4" long) piece of fuel line, split the end about 1/4" back two places (180 deg apart) then position the detent plunger round nose side down into it. Put a dab of grease on the flat end sticking out of the fuel line. Now hold the torsion lever to one side and reinsert the plunger. Move the fuel line to one side as you reposition the torsion lever under the plunger to keep it in place. After reinstalling the manual shaft nut, I used the end of a 1/4"drive socket extension to get the plunger into the detent slots in the torsion lever.

Mac

Mac · May 9, 2020

OK, since I was changing the seal and oring, I decided to cover all the bases and replace the oring on the dip stick tube just to play it safe. For two day I soaked the junction where the tube went into the trans case, remove the one bolt on back of the head that held it in place. Tugged, pulled, swore and repeated that process with no luck, so since the trans pans was still off, I took a block off wood and ball peen and tried to "persuade" the tube to come out. Nothing!! Finally after looking at the dog gone thing from below, I discoved this tube will never come out. See attached pictures, when my trans was built, this tube was "staked" in place! So it you decide to pull yours beware.

Mac

Gregaust · May 10, 2020

Oh dear someone made a mess there , no wonder it was stuck

Mac · May 16, 2020

Replacing the shifter seal.pdf

Added more detail to reassembly process of these instructions.

Mac

user 9724 · Apr 5, 2024

Mac said:
OK Guys,

Being an engineer with a lot of time on my hands, I decided to change my leaky shifter seal on my FMX trans. Using info I found on this site as well as bits and pieces from other sources, I created a manual using lots of my own pictures and discriptions. Just in case I am ever stupid enough to do this again.

See attached, hope it can be of use to others.

Mac

Replacing the shifter seal.pdf

Mac,
Thank you very much for taking the time to document the shift seal fix on the FMX tranny and for sharing it with us. I wouldnt have attempted it otherwise. You are the man!!

Richard

Brocks · Sunday at 5:53 PM

Mac said:
OK Guys,

Being an engineer with a lot of time on my hands, I decided to change my leaky shifter seal on my FMX trans. Using info I found on this site as well as bits and pieces from other sources, I created a manual using lots of my own pictures and discriptions. Just in case I am ever stupid enough to do this again.

See attached, hope it can be of use to others.

Mac

Replacing the shifter seal.pdf

Hello Mac,
Nice work with this document. It gave me the confidence boost I needed to take this job on. Much appreciated.

Changing a shifter seal and o ring on FMX trans

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