T-5 Nightmare

[Shelby_r_b]

So, about a month ago, I decided to swap out the original T-10 transmission on my Carryover over to a brand new World-Class T-5 Tremec.  The belief was that having the extra gear would allow for easier highway driving.  I made the swap and even posted about how pleased I was with the ability to run 70 MPH at 2,200 RPM - I was in heaven!

However, I started to realize that the transmission would grind each time I went into 5th gear, and 5th gear only.  I could down shift from 5th to 4th with no issues, and there was no grinding if I double clutched going into 5th (which I later learned eliminated the 5th gear synchro).

I called TREMEC, and after running several tests at my home, they decided I needed to send the original transmission back for warranty repair.  I pleaded with them to replace the transmission, but they refused.  In the end, I had the transmission removed and shipped back to TREMEC.  TREMEC then did the warranty repair and sent the transmission back for installation. 

The reinstallation was just completed, and for the first 5-8 shifts from 4th to 5th, there was no grinding.  However, now the transmission, once again, grinds every time I shift from 4th to 5th.  Ugh!

I'll call TREMEC this morning, as I'm guessing they changed the 5th gear synchro (and maybe 5th gear).  However, it seems that the 5th gear synchro is the symptom, not the problem.  Something is causing the 5th gear syncro to go bad.

Thoughts?

[2112]

Shifter malfunctioning?

Clutch fully disengaging?

[Shelby_r_b]

Shifter malfunctioning?

Clutch fully disengaging?

Good questions.  We checked the clutch several times, and it is fully disengaging (this was one of the first tests TREMEC had me preform the first time).  I hadn't thought about the shifter, though.

[gjz30075]

Ruben, was it MDL suggesting calling Tremec?    Could be a bad batch of sychros.     My friend who rebuilds the  2000e gearboxes used in English Fords deals with this
all the time.    It's really hit or miss.

[Shelby_r_b]

Ruben, was it MDL suggesting calling Tremec?    Could be a bad batch of sychros.     My friend who rebuilds the  2000e gearboxes used in English Fords deals with this
all the time.    It's really hit or miss.

Hey Greg - thanks for the info!  Yes, it was MDL that suggested calling Tremec.  And, I fear you may be correct, regarding the synchros, as that seems to be the weak link...pun intended. 

[pbf777]

We checked the clutch several times, and it is fully disengaging (this was one of the first tests TREMEC had me preform the first time).

     Out of curiosity, and in an attempt to assist, please expound on the procedure executed?   

     Also, perhaps your typical technique of engaging 5th leading to the difficulty?     

     Realize that attempting to discover the solution on a forum from afar is not really likely, but perhaps, some food for thought may be conjured.  And , you asked.     

     Scott.

[pmustang]

Please don't read my post about T10 issues recently, I almost teared up reading your post. I had nightmares, rebuilt trans was a mess. Best of luck with your issue. Peter

[KR Convertible]

Did they provide trans fluid with the transmission? Or recommendations?  I have a fairly new T5z in one of my cars, and I get an occasional grind going into third.  I have been experimenting with different fluids.  I have a semi-synthetic in now.  I was thinking about trying the GM Syncromesh people seem to rave about.

I'm not sure if it should have a non synthetic in it at first as a break in oil.  The car wasn't assembled when I bought it, but I don't think the trans had been used at all.

[pbf777]

Yes, it was MDL that suggested calling Tremec.

     And, thank you for your order!.............N E X T  !!!!       

     Scott.

[deathsled]

Engine too strong for the transmission? I've read that it isn't necessarily the best to put a T5 with a hipo 289 or Boss 302 combination. But if that's the case I would think you'd have a lot more than that problem.

[2112]

Engine too strong for the transmission? I've read that it isn't necessarily the best to put a T5 with a hipo 289 or Boss 302 combination. But if that's the case I would think you'd have a lot more than that problem.

+1   

[pmustang]

My 66 GT350 loves the T5, No issues at all.

[KR Convertible]

T5z is rated for 330 ft-lbs

[NC TRACKRAT]

Ruben, what fluid is in it?  Synchros are very sensitive to the type fluid used.  Sometimes, too slippery is not the way to go. Here's a thread that may be of interest discussing the preferred fill of 50W vs. ATF vs. 75W/90 gear oil.
https://www.allfordmustangs.com/forums/5-0l-tech/320994-what-best-fluid-t5-transmission.html

[Shelby_r_b]

Thanks to all!  A couple of quick answer before proceeding:

- The clutch does completely disengage, as this has been verified through 2 different tests.  Plus, if the issue were the clutch (according to Tremec) the grinding would happening in other gears or coming out of 5th to 4th
- I don't recall off hand which oil was used.  The first time the tranny was installed (prior to issues), I used the fluid provided by MDL.  The second time the tranny was installed, I used fluid sent straight from Tremec with the rebuilt tranny - they were both different brands, but I couldn't tell you what type
- MDL wanted to help; however, Tremec's policy is to have their warranty work completed by their technicians (or, at least that's what Tremec said)
- The T-5 is (from what I understand) not a bad transmission for a HiPo 289; however, it all depends on how the car is driven and if the engine has many power modifications.  Tracking with this tranny is no bueno - it's better to step up to the TKO 5-speed from what I understand.

I just got off the phone with Tremec, and they are going to do a 1 for 1 swap.  I asked what they thought was causing the problem, and they said it could be two items that, if out of tolerance, would take out the 5th gear synchro.  Also, they confirmed that they changed the 5th gear synchro and 5th gear originally before sending the transmission back.  Also, another person had the same issue with their T-5 (although the serial numbers were very far apart), and their components are being sent to Mexico for testing as well.

So, I'll drive it for now, double clutch it into 5th, and wait for the new tranny to come.  The saga continues!