Ernie W

iTrader: (1)

I have a LT1 T56 transmission I converted over to a LS1 style for my Trans Am WS6. Ever since it was converted, it had trouble going into 4th gear, most of the time it would not. I thought for sure I had a shift fork, fork pad, or syncro key issue.

Here was my last thead....

https://ls1tech.com/forums/manual-tr...d-get-out.html

This past Monday since I was off work I decided to remove the transmission from my car and swap the midplate and input shaft into another LT1 T56 I had. Still the same issue. With the midplate off I would hold the input shaft and shift from 3-4, it would not slide onto the LS1 Tremec input shaft. Both transmissions would work fine with both of the LT1 input shafts I had. That's when I started looking closer at the engagement teeth on the input shaft. If I'm not using the correct names for the parts, please excuse me. This is my first time being inside a T56 or any manual transmission for that matter.

I noticed the 3-4 syncro slider would not slide over the engagement teeth on the Tremec LS1 input shaft. I would slide fine and fully engage over the LT1 input shafts.

<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_113928690_zpsq4c4dc2j.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_113928690_zpsq4c4dc2j.jpg" border="0" alt=" photo IMG_20160530_113928690_zpsq4c4dc2j.jpg"/></a>

After measuring the LT1 input shaft I got this...
<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_114927640_HDR_zpsbmb0lks1.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_114927640_HDR_zpsbmb0lks1.jpg" border="0" alt=" photo IMG_20160530_114927640_HDR_zpsbmb0lks1.jpg"/></a>

After measuring the Tremec LS1 input shaft I got this...
<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_114844766_HDR_zpseb8ny2tw.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_114844766_HDR_zpseb8ny2tw.jpg" border="0" alt=" photo IMG_20160530_114844766_HDR_zpseb8ny2tw.jpg"/></a>

I also tried to get a decent measurement on the syncro slide and it was barely smaller than the measurement I got on the LS1 input shaft so there was no way it would ever fit completely over it. I ask a guy I know and he said he has had to sand some aftermarket input shafts down on the engagement teeth but never a Tremec input shaft.

I wrapped my bearing up and taped the gear up also. Painted the engagement teeth so I could see where I was at and took a small 1/2" belt sander to the teeth while rolling the input shaft slowly. Stopping a couple times to clean and measure.

<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_121854452_zpsc8fhcwje.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_121854452_zpsc8fhcwje.jpg" border="0" alt=" photo IMG_20160530_121854452_zpsc8fhcwje.jpg"/></a>

Eventually got to the same measurement of the LT1 input shafts.

<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_123433220_HDR_zpspqthmlsf.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_123433220_HDR_zpspqthmlsf.jpg" border="0" alt=" photo IMG_20160530_123433220_HDR_zpspqthmlsf.jpg"/></a>

After a good cleaning I put the input shaft in both transmissions and it would fully engage 4th gear in both.

<a href="http://s254.photobucket.com/user/1992redvr-4/media/IMG_20160530_124253242_HDR_zpsmk7pxcdn.jpg.html" target="_blank"><img src="http://i254.photobucket.com/albums/hh95/1992redvr-4/IMG_20160530_124253242_HDR_zpsmk7pxcdn.jpg" border="0" alt=" photo IMG_20160530_124253242_HDR_zpsmk7pxcdn.jpg"/></a>

So after all that, I finally have 4th gear working in my WS6. I would have never thought it would be an input shaft issue as it was a genuine Tremec input shaft which I paid dearly for..... $275.