All depends on what you want a gearbox to do. It's true you can still
buy TR gearboxes, but they are not all that plentiful. It costs me a
lot more than $1000 to build one. the list of known flaws is pretty
long. I generally use straight cut gears though I have a Hardy
Prentice box that works even better that I'm hoarding. I consider TR
gearboxes to require a teardown every season. If you don't they can do
expensive things very quickly. Even with all the mods and care I have
a straight cut gearbox at Horizon Racing that just needed $2500 in
parts to fix it--it had the common problem of breaking the tab that
retains the layshaft and reverse shaft when the layshaft bearing
starts to go south.
My point is not that I'm looking to use a five speed (I'm not) but
that a rule that allows a reasonable substitution with a reasonable
penalty is a great way to go, and a lot more sensible than a ban.
You can convert a toyota five speed for about a thousand bucks, and
it's probably the last transmission you'll have to buy, and you'll
never learn anything about them because you'll never open the case.
On Feb 22, 2008, at 8:57 AM, Larry Young wrote:
> I didn't chime in last time this came up. Why not keep it vintage
> unless there is a compelling reason not to? Bill, my experience is
> completely the opposite, i.e. TR gear boxes are strong, plentiful
> and cheap. Most of us scrounge for out racecar spares. If you look
> around, you can find a good rebuildable 4 synchro box for $100 or
> less. If you rebuild it yourself with a close ratio gear set,
> you'll have a strong box with gearing like a 5 speed less 1st gear
> and the total cost will be under $1000. How much is a Toyota box
> conversion?
>
> I believe SCCA did not allow close ratio gears for many years, so
> they may not be legal with some vintage groups. Nevertheless, I
> consider them to be a more palatable alternative to a Toyota box.
>
> In Kas' days overdrives were used instead of close ratio gears. Not
> only for the additional higher gear, but for splitting gears,
> especially to reduce the jump from 2nd to 3rd. Overdrives
> (especially A-types) are very expensive, because everyone doing a
> restoration wants one. However, an overdrive is really not
> necessary with close ratio gears, because the overdrive gears tend
> to overlay the next higher normal gear. Of course you have to look
> at the rear axle ratio too. Close ratio gears with a 3.7 rear and
> close ratio OD with 4.55 will give almost identical ratios for the
> top three gears.
> Larry Young
>
> Bill Babcock wrote:
>> transmission replacement is a constant argument. I come down on
>> the side of "why break the few remaining good ones racing them".
>> The toyota trannys are as common as belly buttons, and don't break.
>>
Bill Babcock
Babcock & Jenkins
Billb@bnj.com
503.936.7660
www.bnj.com
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