Amici,
Although I am still reeling from trying to absorb all the great information
from the bearing/brake thread, I have a gap in my gearbox knowledge I need
help resolving.
I am going to be building a full syncro A-type OD gearbox for my TR3. I
have a dependable A-type OD in the car right now, but it is connected to a
TR3 non-syncro gearbox. I've located two TR6 gearboxes which I believe are
suitable candidates for parts or transplant. They are gearbox numbers are
CD22490 and CD34961, which according to the TRF catalog are the third latest
of the four versions of the TR6 gearbox and have the following components:
1. 17 tooth first gear and closer ratio's in general
2. all 30 symmetrical dog teeth on the syncro's, versus the earlier only 8
of 30.
3. bronze top hats
4. The newer tooth profile (with greater engagement) on gears 1,2 and 4.
The big difference that I see with these gearboxes, as opposed to the very
late TR6 gearbox (which have no serial numbers) is that these have bronze
bushes instead of the steel top hat bushes, a desirable but not required
feature.
My questions are as follows:
1. With regards to gearbox cases, I was initially planning on installing
the
TR6 gears in a TR4 case, but have heard that the TR6 case is stronger. Is
this true? I believe the TR6 gearbox will drop right into my TR3, but is
everything the same, ie., shifter location and can I keep my TR3 cover, with
the dipstick?
2. Will the later steel bushed TR6 gearbox boltup to the A-type OD? I have
access to a TR4 OD mainshaft at a reasonable cost. Is the steel tophat's OD
mainshaft available?
3. Aside from the steel versus bronze bush issue, are there any advantages
to the very latest TR6 gearboxes (those without serial numbers) versus the
post CD21769 boxes?
4. Also, the guy with the two TR6 gearboxes I anticipate buying has a
third,
with gearbox number CC83555, which he claims to be a TR6 box, but TRF
doesn't list "CC" numbers. Any idea what this is from?
Thanks,
Jack Brooks
1960 TR3A
1974 Norton 850 Commando
Hillsdale, NJ
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