cisurfer

Recently my 3rd gear has been grinding every time i shift faster than normal. I cant race without it grinding or even shift fast, im not even power shifting. Is it my synchro or could it be fluid related. I changed from royal purple to penzoil and thats when it all started. Should i switch back?

Fobra

Well its probably you as a driver but, it could be a synchro, could be a lot of things, check her out a bit, check the obvious stuff and let us know

WhiteFoxGT

Say goodbye to your synchro... Theres a TSB out on grinding 3rd from Ford... Its a known problem for 3650s.

Time for a rebuild

cisurfer

how bad is the rebuild? keep in mind i did my own 373s...

WhiteFoxGT

I've been a Ford tech for 3 years and I had some trouble when I attempted to rebuild my old T45... Basically had the master trans tech hovering over my shoulder telling me what to do. The 3650 is an even harder trans to rebuild. Its not something a novice should even attempt. Unless you have done a handfull of manual transmissions before I wouldnt even think of attempting it.

cliffyk

Here is the TSB, along with the replacement parts it also specifies using only 3.0L (3.2 qts) of fluid in the tranny--this reduces the tendency for the shift rods and detents to "hydrolock" when in motion.

I would also go back to using the RP Synchromax, or Mobil 1 ATF (which is Tremec's recommended fluid--see below). The Pennzoil Synchromesh fluid is spec'd only for GM and Chrysler per their web page...

From the TR3650 shop manual: