Shimming the mainshaft/countershaft
07-07-2011, 09:16 AM
#1
Shimming the mainshaft/countershaft I noticed a discrepancy between the Tremec tech manual and a the Popular Hot Rodding rebuild article. The Tech manual says, .000 to .002 endplay on the main shaft and .000 to .002 PRELOAD on the countershaft. The article says 0-2 for both not pointing out PRELOAD.
So, preload means actual negative clearance or pressure right? Like if I measured .031 of play I use a .033 shim yes?
One last question, the exploded view shows a skip shift lever #175. Neither my buddy or I can remember removing it neither can we find it. The skip shift never operated on my car and someone else disconnected the solinoid and put a terminator plug into the connector. I figured that was what made it not operate. But now I'm wondewring was the tranny disassembled before? Their is no evidence of that.
Well, the real question is do I need that part?
What do you rebuilders lean towards in the specs, the looser side or the tighter side.
The guy I got my parts from said, on a tapered bearing transmission that he goes a little tighter to allow for the aluminum expansion over steel.
.001 preload on the main and .003 preload on the countershaft.
Ed
So, preload means actual negative clearance or pressure right? Like if I measured .031 of play I use a .033 shim yes?
One last question, the exploded view shows a skip shift lever #175. Neither my buddy or I can remember removing it neither can we find it. The skip shift never operated on my car and someone else disconnected the solinoid and put a terminator plug into the connector. I figured that was what made it not operate. But now I'm wondewring was the tranny disassembled before? Their is no evidence of that.
Well, the real question is do I need that part?
What do you rebuilders lean towards in the specs, the looser side or the tighter side.
The guy I got my parts from said, on a tapered bearing transmission that he goes a little tighter to allow for the aluminum expansion over steel.
.001 preload on the main and .003 preload on the countershaft.
Ed
07-07-2011, 11:45 AM
#2
Straight from the Tech manual
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.
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.
07-07-2011, 01:45 PM
#3
the exploded view shows a skip shift lever #175. Neither my buddy or I can remember removing it neither can we find it. The skip shift never operated on my car and someone else disconnected the solinoid and put a terminator plug into the connector. I figured that was what made it not operate.
In the early CAGS cars, that piece was originally 2-piece. They went to a 1-piece design 95 or 96 I'm guessing.
07-08-2011, 09:08 AM
#5
The problem like anything is the various opinions and what they are based on.
For example:
1) The transmission builder for Liberty transmissions (where I had the cryo, and polishing, bead blasting done said, set up the both the mainshaft and counter with preload like .001 -.002 on the main and .003-.004 for the countershaft on a tapered bearing tranny like the t-56. He said, that is for 2 reasons, 1 the cases when up to oerating temp expand more then the countershaft, and that tapered bearings usually settle in by wearing on the outside of the roller and open up just a little. He also said to make sure I tapping the shafts back and forth with a brass hammer just before measuring the bearings. I'm glad I did as I could see about .4 to .006 of clearance change and the measurement settled in between before and after giving it a little love tap.
2) Joey Huneycutt from T-56 rebuilds.com in a GM High-Tech Perf artical wrote,"I shoot for .003 PRELOAD on both the main and countershaft.
Read more: http://www.gmhightechperformance.com...#ixzz1RWQhKjod
3) Then on the flip side I called TREMEC directly and they said set it up to zero endplay.
So, what the shops said made sense and I went with .002 PRELOAD on the main and .003 PRELOAD on the countershaft.
ed
thanks for everyone who chimed in, this forums real benefit is an exchange of data and ideas, not a LSX yellow pages.
For example:
1) The transmission builder for Liberty transmissions (where I had the cryo, and polishing, bead blasting done said, set up the both the mainshaft and counter with preload like .001 -.002 on the main and .003-.004 for the countershaft on a tapered bearing tranny like the t-56. He said, that is for 2 reasons, 1 the cases when up to oerating temp expand more then the countershaft, and that tapered bearings usually settle in by wearing on the outside of the roller and open up just a little. He also said to make sure I tapping the shafts back and forth with a brass hammer just before measuring the bearings. I'm glad I did as I could see about .4 to .006 of clearance change and the measurement settled in between before and after giving it a little love tap.
2) Joey Huneycutt from T-56 rebuilds.com in a GM High-Tech Perf artical wrote,"I shoot for .003 PRELOAD on both the main and countershaft.
Read more: http://www.gmhightechperformance.com...#ixzz1RWQhKjod
3) Then on the flip side I called TREMEC directly and they said set it up to zero endplay.
So, what the shops said made sense and I went with .002 PRELOAD on the main and .003 PRELOAD on the countershaft.
ed
thanks for everyone who chimed in, this forums real benefit is an exchange of data and ideas, not a LSX yellow pages.
07-08-2011, 11:06 AM
#6
Setting up a transmission that has tapered roller bearings with end-play/no-preload only accomplishes one thing, and that is bearing wear/noise a few years down the road when the clearences open up and there is too much play...
Great for rebuild shops and dealerships as they get more work. Sucks for the consumer...
All, and I mean ALL, new tapered roller bearings will open up slightly compared to used bearings. For used bearings you *STILL* want slight preload (like .001"-.002"), but for new bearings you want more (like .003-.005") depending on the size of the bearings.
Look at any spec in regards to tapered roller bearings in any application, such as rear-ends, wheel hubs, etc, and you will find the pre-load for a new bearing is different than the pre-load for a used bearing.
Actually, for race applications you can have an excessive amount of preload required in certain instances to deal with the extreme shock-loads, as in those apps with lots of heat and material expansion you need to make sure there is NEVER any end-play as it WILL result in a failure combined with excessive shock-loads.
Great for rebuild shops and dealerships as they get more work. Sucks for the consumer...
All, and I mean ALL, new tapered roller bearings will open up slightly compared to used bearings. For used bearings you *STILL* want slight preload (like .001"-.002"), but for new bearings you want more (like .003-.005") depending on the size of the bearings.
Look at any spec in regards to tapered roller bearings in any application, such as rear-ends, wheel hubs, etc, and you will find the pre-load for a new bearing is different than the pre-load for a used bearing.
Actually, for race applications you can have an excessive amount of preload required in certain instances to deal with the extreme shock-loads, as in those apps with lots of heat and material expansion you need to make sure there is NEVER any end-play as it WILL result in a failure combined with excessive shock-loads.
07-08-2011, 11:10 AM
#7
I may add, tapered roller bearings can take a TON of pre-load depending on the size. Hell, in certain differential configurations that have screw-adjusters for the carrier bearings in some cases it is believed that you can never preload them enough.
Most tapered roller bearings fail because of too little preload (ie, endplay), or inadequate lubrication (which results in excessive heat).
Most tapered roller bearings fail because of too little preload (ie, endplay), or inadequate lubrication (which results in excessive heat).
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07-08-2011, 12:48 PM
#8
Setting up a transmission that has tapered roller bearings with end-play/no-preload only accomplishes one thing, and that is bearing wear/noise a few years down the road when the clearences open up and there is too much play...
Great for rebuild shops and dealerships as they get more work. Sucks for the consumer...
All, and I mean ALL, new tapered roller bearings will open up slightly compared to used bearings. For used bearings you *STILL* want slight preload (like .001"-.002"), but for new bearings you want more (like .003-.005") depending on the size of the bearings.
Look at any spec in regards to tapered roller bearings in any application, such as rear-ends, wheel hubs, etc, and you will find the pre-load for a new bearing is different than the pre-load for a used bearing.
Actually, for race applications you can have an excessive amount of preload required in certain instances to deal with the extreme shock-loads, as in those apps with lots of heat and material expansion you need to make sure there is NEVER any end-play as it WILL result in a failure combined with excessive shock-loads.
Great for rebuild shops and dealerships as they get more work. Sucks for the consumer...
All, and I mean ALL, new tapered roller bearings will open up slightly compared to used bearings. For used bearings you *STILL* want slight preload (like .001"-.002"), but for new bearings you want more (like .003-.005") depending on the size of the bearings.
Look at any spec in regards to tapered roller bearings in any application, such as rear-ends, wheel hubs, etc, and you will find the pre-load for a new bearing is different than the pre-load for a used bearing.
Actually, for race applications you can have an excessive amount of preload required in certain instances to deal with the extreme shock-loads, as in those apps with lots of heat and material expansion you need to make sure there is NEVER any end-play as it WILL result in a failure combined with excessive shock-loads.
^^^^^ This, = words of wisdom!
I set a preload on every T56 mainshaft and countershafts I've built, as well as heavy preloads on all the 9" rears I've setup.
Mike
