I don't trust the T-45 or TR3650 for even stock power driven aggressively. Feb 28, 2008 #19. 01greycobra Built and Blown! Established Member. Messages: 2,440. Tr-3650 '05+ 5-speed manual transmission: vss output speed sensor. Fits tr3650 equipped: ford mustang '05+ 4.6l; tr-3650 identifiers: aluminum case, cast 'ccca1271ag', remote shift, with bolt-on rear output.

I know there are differant problems with this trans. Most common seem to be 1-2 and 2-3 shift clunk. The other is grinding into gear.

Well here is my fix for a 1-2 clunk. When my Mach 1 was cold this was VERY noticible. Had to shift very slowly and ease it in gear. Would take 10-15 minutes of driving before it started to go away, even then I would hear it every once in a while.

Called Tremec. They told me two things about the Tremec TR3650:

- Dump the factory fill (was told by Tremec For used Mobil 1 syn). Replace it with Texaco (Havoline) Dexron III.

I replaced it with Royal Purple Synchromax. It is synthetic and I did a lot of research and a thiner cold tempature fulid seemed to be the best choice.

Tr3650 Bellhousing

- Drop the fill amount from Ford's recommendation of 3.8 for the Tremec TR3650 to 3.2 quarts.

They said this would fix the 1-2 shift clunk problem of the Tremec TR3650. I wasn't as sure as they were. What do you know, it worked. No clunk with the Tremec TR3650 and the new fluid change and level, even when I try to get it (pop the clutch a little too early). Dont' even get it on a fast downshift like a Iused to. Feels great. If anyone has a shifting clunk I would highly recommend the change.

Shouldn't take you more that 20 minutes to do:

- Warm up the and get it up on ramps or jacks. The higher the better as the fill hole is a little tough to reach.

- Use 3/8 inch ratchet to remove drain plug (bottom rear of trans).
- Clean / replace plug and remove the fill plug. Same type plug, higher up on passenger side of trans rear.
- Don't use a 2 hose hand siphon pump on the Tremec TR3650. They are garbage for this job, trust me. Go to Meijer and buy a pump that screws directly to the top of the trans bottle. Make sure the 'fluid out' least 1 foot long to reach the fill plug. The 'fliud in' line to the pump drops right down in the bottle. Makes it easy to pump out 99% from the bottle.
- fill with the Tremec TR3650 with 3.2 quarts (3027 ML to be exact). Bottles are marked in ML's.
- Replace fill plug and your done.

I am extremely happy with how the Tremec TR3650 is shifting now. I ran it through is paces hard, even cold and it is great. If anyone is going to try it and has a question, PM or e-mail me.

Thanks to GoLions for this info.....