Hi Tony,
My own research on gearbox strengthening agrees with yours. Bushings won't
do.
Triumph themselves upgraded the gearbox when they put it in the Stag (to
accommodate approx. 50% increase in horsepower and a heavier car) by putting a
total of 3 roller bearings in the layshaft, up from the two used in TRs. I
understand that Moss Europe sells a kit that is basically an adaptation of the
Stag
shaft.
One of the British vendors has taken it a step further with a total of four
roller bearings on the layshaft. I forget which, though, probably Revington,
Cambridge or Racestorations.
You're also correct, there have been reports of insufficient hardening of the
shaft the rollers ride upon, too, among replacement parts. Buy from a
reputable source that will exchange it if it tests poorly and check it before
installing.
Other TR gearbox improvements I've heard mentioned are roller thrust bearings
and an improved 2nd gear bushing.
I'd be interested to hear others' comments and experiences with improving
gearboxes in any other areas.
Cheers!
Alan Myers
San Jose, Calif.
AMfoto1@aol.com
http://hometown.aol.com/amfoto1/amfoto1.htm
I did a little research on the layshaft and its failures. I thought about
replacing bearings with bushings, but I found that the load is too great for
any bushings I could find. The layshaft fails when the hardened surface
delaminates from the softer metal underneath. I would want to get a better
layshaft. Thicker hardened surface would be the ticket, I think.
That layshaft area around the first gear takes some mighty loads!
- -Tony
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