Hi Tony
Unfortunately once the shaft has been finished it is too late to improve the
hardness as the hardening process creates scale and can cause the component
to change shape / straightness, there may be scale free methods but it seems
to me they would need to be very specialised (oxygen free) and therefore
possibly a lot more expensive. When they make these things they are
machined, drilled, hardened then ground to final size. The only way to
improve would be to have one made from scratch, not difficult if you can
find the material specs and the dimensions / tolerances for the component.
To my knowledge there are two things one can do to make this last longer,
1 Have the laygear cluster machined deeper to take another needle bearing on
the high load end, so you have twice the contact area, which will halve the
load on each needle. (Recommended by Chris Witor 2000 2500 Guru)
2 Use the bearings with smaller needles, as from a logical perspective you
get more needles transmitting the load to the shaft and although they are
smaller in diameter the contact area of two cylinders varies very little
relative to diameter. (I think) My solution and working so far!!
Hopefully Helpful,
Graham.
----- Original Message -----
From: Tony Rhodes <ARhodes@compuserve.com>
To: Triumph List <triumphs@autox.team.net>
Sent: Wednesday, March 15, 2000 12:52 AM
Subject: Machine shop work
>
> I am in the process of a transmission rebuild. I have 2 transmissions
apart and
> they BOTH have had layshaft failure by delamination of the hardened
surface
> at the rear bearing near the 1st laygear.
>
> It would appear that the hardness of the surface or the depth of the
hardening
> is not adequate for the force the needle rollers apply.
>
> I want to get my new layshaft hardened better (more?) (deeper?). Before
> I make a lot of phone calls, is this something most machine shops can do?
> If not, then whom?
>
> Also, for those of you with tranny experience, is my impression correct
that this
> area is a high failure rate area? This and the top hat bushing?
>
> -Tony
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