T-56 Shimming Specs
01-05-2009, 06:55 PM
#1
Teching In
Thread Starter
Join Date: Feb 2007
Posts: 15
Likes: 0
Received 0 Likes
on
0 Posts
T-56 Shimming Specs I am getting ready to rebuild the T-56 in my 2001 Corvette and am having trouble figuring out the proper endplay/preload specs for shimming. I am getting conflicting settings between the GM DVD Service Manual and the TTC T-56 Manual.
GM says the main shaft gets .000-.002 PRELOAD, the TTC manual shows .000-.002 ENDPLAY.
For the counter shaft extension GM shows .002-.005 AXIAL play (Huh?) and TTC shows .002-.005 ENDPLAY.
Both manuals show .000-.002 PRELOAD for the counter shaft.
After searching the IntarWeb I have found many different ideas of the way it should be shimmed with no real consensus.
Does anyone know the real answer?
Car is stock but is driven hard with several trips to the dragstrip each year.
GM says the main shaft gets .000-.002 PRELOAD, the TTC manual shows .000-.002 ENDPLAY.
For the counter shaft extension GM shows .002-.005 AXIAL play (Huh?) and TTC shows .002-.005 ENDPLAY.
Both manuals show .000-.002 PRELOAD for the counter shaft.
After searching the IntarWeb I have found many different ideas of the way it should be shimmed with no real consensus.
Does anyone know the real answer?
Car is stock but is driven hard with several trips to the dragstrip each year.
01-06-2009, 07:17 AM
#3
TECH Fanatic
iTrader: (6)
Join Date: Oct 2002
Location: Charlotte metro area
Posts: 1,959
Likes: 0
Received 3 Likes
on
3 Posts
The descriptions are not really too far off. The reason the TTC manusla calls for end play over preload is because you can measure endplay. Preload has no play. You can calcualate preload but field builders don't generally do that because it requires assembling the case twice( at least). The reason they call out a n axial description is because most people grab the input gear and "wag" the end and think they are measuring endplay. Endplay is a part for that wag but it is a poor measure technique and you certainly cannot trust any numbers you measure that way.
The perfect build is one that has zero endplay when the trans is up to temp. That can only be achieved by the most experienced builder with lots of time with these units. The specs allow a range that is more generally achievable.
As you build in end play, the trans loosens and is easier to shift. Its also quieter. Too much end play and the tapered bearings don't like in and the gears are not fully meshed= yielding loss of gear strength. It a balance. Follow the specs of the manufacturer(TTC)
The perfect build is one that has zero endplay when the trans is up to temp. That can only be achieved by the most experienced builder with lots of time with these units. The specs allow a range that is more generally achievable.
As you build in end play, the trans loosens and is easier to shift. Its also quieter. Too much end play and the tapered bearings don't like in and the gears are not fully meshed= yielding loss of gear strength. It a balance. Follow the specs of the manufacturer(TTC)
