Hey Everyone,

First post here on the forums, have trolled for a lot of useful information for a few years thus far. I am working on a LS1/T56 conversion into an '89 BMW E30 and am sure will have many more questions through the process.

I'm finishing assembly of the engine and waiting for new head gaskets and in the meantime have started working on the transmission. I have a '94 LT1 T56 which I am converting over to use behind the LS1. I've got the new LS1 midplate, bellhousing, input shaft, input shaft seal and shim kit to do the conversion.

As I dig in, I've got a clarification question regarding the shimming procedure for the input and countershafts when doing the conversion. This is my first time into the T56 so I appreciate the help.

I've seen several different opinions regarding the enplay/preload settings for these but have decided to go with the Tremec recommended numbers.

My biq question is regarding the steps needed to get the correct measurements. Here is the procedure outlined in the Tremec T-56 Service Manual:


SECTION 5
SHIMMIN PROCEDURES
5-1. INPUT SHAFT, MAINSHAFT AND
COUNTERSHAFT

5-1-1. TOOLS REQUIRED
a. Dial Indicator Set
b. Countershaft End Play Measuring Tool (Fig. 6-1)

5-1-2. INSTALL OR CONNECT
a. Position transmission in vertical position.
b. Input shaft (10) to adapter (1).
c. Mainshaft (23) to input shaft (10).
d. Countershaft (105).
1. Lift up mainshaft (23) enough to install
countershaft (105).
2. Install countershaft (105).
a. Transmission case (44).
b. Adapter to transmission case bolts (178).
c. Tighten
¨ Bolts (178) to 26 lb. Ft. (35 N.m.)
d. Place tip of dial indicator on end of mainshaft (23).
e. Measure
1. Input shaft/mainshaft end play by moving
input shaft (10) up and down.
2. Select shim (6) to achieve 0.000 to 0.002 in.
(0.00 to 0.05 mm) end play.
a. Place tip of dial indicator on end of countershaft (105).
b. Place end play measuring tool through adapter plate
plug hole to engage threads in countershaft extension
and tighten to eliminate any free play in counter shaft
joint.
c. Measure
1. Countershaft end play moving countershaft
(105) up and down.
2. Select shim (102) to achieve 0.000 to 0.002
in. (0.00 to 0.05 mm) preload.


The big question is that this obviously is the procedure for a full rebuild in which only the main shaft, input shaft and counter shaft are installed in the case and the tailhousing is not yet installed. If I am only opening it up from the midplate and the rest of the trans is fully assembled, how does it affect the procedure outlined in the manual?

My hope is that I can swap the midplate and input shaft and take the two measurements from the front of the trans (tip of input shaft and tip of endplay measuring tool).

If that will work then what I'm unsure of is:
- Will the same enplay/prelead tolerances apply if done this way?
- Do you set up the input shaft endplay INSTALL REQUIRED SHIMS, THEN check countershaft? Per the above instructions, it appears not, rather that you check both before installing any shims. Or do you get the input shaft settled then move to the countershaft?

I've reread the procedure in the Tremec manual several times, watched youtube videos and read through many of the threads here. I think I've learned a lot but also raised more questions in the process. Maybe I'm over thinking this but I'd rather do that than just slap it together with the old shims.

Appreciate any help!

 

With a used unit, I would much rather re-set all 3 shim sets, to include the countershaft extension-shaft last. It is dependent on the countershaft being set to 0 or pre-loaded to be able to be set correctly.

 

Thank you for the info on the countershaft extension, makes sense to verify all three.

In order to set the three of them, it seems that this may be a rough progression?:
- Install LS1 input shaft and midplate with no shims on input or counter shaft races
- Remove the tailhousing and measure input shaft (do you shim input shaft before proceeding to countershaft or after you measure both?)
- Measure counter shaft & shim as required
- Reinstall tailhousing and measure countershaft extension through midplate then shim as required

Is it necessary to disassemble the trans any further than this to get accurate measurements?

This is my first go round at this so apologies if some of this seems obvious.

 

Hi all, any additional help or feedback would be appreciated before I start to put the tranny back together. Thanks!