T45 Issue

[bhuff30]

Last year, I had the T45 transmission in my GT rebuilt, at ~185k miles. It recieved all new bearings, seals and upgraded syncros (kevlar?, from Hanlon Motorsports). It also has improved 1-2 and 3-4 shift forks and I buttoned everything together with a fresh clutch and turned flywheel. Everything felt great and worked perfectly.

Now, one year later with ~15k miles on the setup, I am seeing some signs of problems. Sometimes, the transmission will stick in reverse. So far, I have always been able to shake it out of R and continue on my way. The issue is pretty random, but seems to only happen on cold starts.

I have also noticed noise while cruising in 5th. It is somewhat load dependend, and only exists in 5th gear. There is no noise in 4th, so it is not road or rear end related. The noise sounds like a rotating type of grinding sound. It is fairly faint, but certainly there. The noise is similar to what you might hear if you spin a brake disk while the wheels are in the air. Just a faint smooth metal type grinding sound.

What are the possible causes of the issue? Can I expect to tear out the transmission soon, or could I keep driving it for years like this?

 

[bhuff30]

I am still looking for answers. The noise appears to be present in gears 1, 2, 3 and 5 (most noticeable in 5th). I didn't notice reverse since I never move very far in that gear. The most noticeable thing is that the noise is NOT present in 4th gear. Any ideas? The noise is not there when the transmission is in neutral, 4th gear, or the clutch is depressed (but transmission still in gear).

 

[Maxpowers]

...clutch is depressed (but transmission still in gear).

I would start there. Easiest thing to fix. Make sure it is engaging and disengaging completely.

What brand TOB did you use? Some are known to go bad quickly.

 

[bhuff30]

The TOB is the bearing which was included in the box with the Ram HDX clutch. Like I said though... no noise in 4th, so it doesn't seem a likely culprit. Also, the noise varies with load. At no load, the noise is faint or non-existant. as I increase the load, it gets louder (until I can't hear it because the exhaust is louder).

The clutch is definitely completely disengaging. The clutch engagement is in the middle to the top of the clutch pedal travel. It shifts nicely (except R) and doesn't give me the feeling that it is hanging up.

 

[Maxpowers]

What type of oil did you put in?

 

[bhuff30]

I used mobil 1 full synthetic ATF, which meets mercon V requirements.

 

[trinity_gt]

I'm going to guess you've got a clustershaft bearing issue, possibly in thrust.

In 4th, the input shaft and output shaft are directly coupled and, since the clustershaft is freewheeling, there's no load and thus no/little noise.

Similarly, in neutral, no load and likely little or no noise.

 

[bhuff30]

Thanks, My best guess was a bearing of some sort, but I couldn't imagine which one or what other problems there could be. I am trying to find out so I have some idea what kind of parts I need to order.