Fred Thomas wrote:
> Listers, T/R 3-A tranny with O/D, should the input shaft have any play in
> it??? Mine has a little up & down motion, not much, but, yes some, is this a
> sign of trouble to come. When driving through the gears as well as cruising,
> no gear noise, drag, or anything, just a pleasant standard trans. sound,
> nothing unusual. Thanks for your help "FT"
Fred,
Not sure how you define "a little up and down motion", but yes, there will be a
few thousands play here. If it were a straight shaft riding in two bearings -
one on each end, then play should be absolutely minimal and almost undetectable,
but that's not the way a transmission works. The input shaft is supported by
the front bearing. Clearance in the bearing allows for a small amount of
off-axis deflection. Inside the trans case the input shaft meets up with the
mainshaft, and in between the two is another roller bearing. Again some play is
inherent from the clearance. Essentially what you end up with is a shaft with a
somewhat flexible joint in the middle supported by a bearing on either end.
input shaft bearing joint bearing mainshaft
----------||-------<<-------||-----------
^
|
wobble occurs because of clearance in joint
In the non-OD trans, the situation is a little better because the mainshaft runs
clear through to the tail housing where there is a third bearing. This way, the
mainshaft is securely supported by two bearings and is more stable - thus the
only play is from the front bearing and the input bearing - play from the rear
bearing in the main case is eliminated due to the additional support from the
tail housing bearing.
input shaft bearing joint bearing mainshaft bearing
----------||-------<<-------||--------------------||----------
^
|
no joint here makes better support between two
bearings
In the OD unit, the mainshaft ends just after the main case and is joined to the
planetary carrier by a spline - again necessitating some clearance.
input shaft bearing joint bearing mainshaft OD planet carrier
bearing
----------||-------<<-------||--------------------- = =
------------||----
^ ^
| |
two clearance joints allow wobble from one end to the other
Fortunately, when the trans is installed, the pilot bush in the end of the crank
supports the front of the input shaft so as long as the play isn't excessive,
say no more than .020", you should be fine. If you do find a great deal of
slop, then you're likely due for new bearings in the gearbox.
Sorry to hog up bandwidth, hope that explains it good enough.
Regards,
Brian Schlorff '61 TR-4 '64 TR-4 '72 TR-6 '79 Spit
---------------------------------------------------------------------
Power British Check out Power British
1242 E. Ridge Pike on the 'net!
Plymouth Meeting, PA 19462
(610) 270-0505 http://www.powerbritish.com/~britcars
---------------------------------------------------------------------
|