Help me diagnose a trans' problem

tpiini · #1 (**permalink**) 08-10-2004, 09:47 PM

Hey All,

Once again I show up here asking for help. My problem is with a Tremec 3550. I'm running a very high-strung small block with 4.57 rear gears. The engine makes almost no power below 3,000 RPM, but just screams on the top end. Needless to say, downshifting is a regular event. But I absolutely cannot downshift into either fourth or third gear without RPM matching. My initial assumption is that the synchro's are bad in these two gears, but no matter what, they NEVER grind. Upshifting is a breeze, but once I'm in either 4th or 5th, getting back down is a delicate throttle exercise. Going down into 2nd or 1st is no problem. Wouldn't I occasionally (always?) get gear-grinding with bad synchro's?

I've only had this car for six weeks, so I'm not sure how badly it has been abused. I've rebuilt auto's before, but have never been inside a manual. I'm assuming that I can just buy a "rebuild kit" somewhere & start swapping parts?

Thanks in advance for any help/advice, (again)

Tom

Clois Harlan · #2 (**permalink**) 08-11-2004, 07:05 AM

Tom,

I had a similar problem with my former transmission a T-5. Mine turned out to be my syncro's and blocker rings. I replaced all my syncros and blocker rings. Cost was insignificant but it took me two full days to pull and dissamble trans, replace parts and re-assemble. Lots of little roller bearings. Had to wear my glasses the whole time working on trans.

Clois

tpiini · #3 (**permalink**) 08-11-2004, 07:33 AM

Thanks for the reply, Clois.

Once you got inside the transmission, was the disassemble/reassembly pretty intuitive? I've rebuilt engines, automatic transmissions, built houses, repaired appliances, etc. But I've NEVER been inside a manual transmission.

Also, did you find a rebuild manual somewhere, or is it just so simple that having a manual is totally unnecessary? And did you find parts online or have to source them locally? I'd sure like to find a web site where I could just order up a rebuild kit and have everything I could need.

Thanks some more, Tom

coyled · #4 (**permalink**) 08-11-2004, 09:28 AM

Tom, the inside is pretty simple on a tremec. I have had this problem before. Each syncro assembly has 3 rectangular detents that engage the gears. These detents break off at the corners from down shifting. It will still upshift ok but will not downshift. I have had this happen on 2 tremecs. When you pull it apart, you will see what I mean. If the syncros were bad it would grind like crazy. Scott

tpiini · #5 (**permalink**) 08-11-2004, 04:02 PM

Quote:

Originally posted by coyled

Tom, the inside is pretty simple on a tremec. I have had this problem before. Each syncro assembly has 3 rectangular detents that engage the gears. These detents break off at the corners from down shifting. It will still upshift ok but will not downshift. I have had this happen on 2 tremecs. When you pull it apart, you will see what I mean. If the syncros were bad it would grind like crazy. Scott

Thanks Scott,

I figured that if the synchro's were "bad" the gears would grind like crazy. That's what has had me confused. Now for the REALLY stupid question: Is there an "upgraded" set of synchro's I can put into it? I don't mind pulling it out & replacing parts, but I really don't want to make it an annual event.