This GT6 has a T50 5 speed so can't say much about the others (besides the
others are much larger and heavier than the T50). However, they did modify
the front of the T50 case to accept a larger input shaft ball bearing
assembly in the later gearboxes which was supposed to help. When buying
spare parts (which are readily available if you know where to look) you need
to know which box you have.
I have looked inside 100K gearboxes and 50K gearboxes. Bearings show little
or no wear in either. Even the syncro's are still good and Granny drove the
car for 20 years.
Used gearboxes are everywhere for $150-$200. Really good ones from Japan are
$500-$1000. A variety of close ratio gear sets are available if you look
hard
.
I know I will get hammered for saying this.....but most of us are just
wannabe drivers anyway (me included) and how much advantage will the gearbox
really give you. It will sure keep you on the track longer and seeing the
cars on the track is really the fun for alot of us.
----- Original Message -----
From: "Michael Porter" <mdporter@dfn.com>
To: "Bill Babcock" <billb@bnj.com>
Cc: <fot@autox.team.net>; "Young Randall" <RYoung@navcomtech.com>
Sent: Friday, September 21, 2007 6:05 PM
Subject: Re: [Fot] gearbox legality
> Bill Babcock wrote:
>> Toyota gearboxes are as common as belly buttons, and most have
>> minimal wear on them. The Japanese have interesting licensing and
>> inspection laws that ensure the domestic cars turn over frequently.
>> The drivetrains are frequently exported to the US. It would be
>> unusual to rebuild one--you can get a replacement for next to
>> nothing. I paid a hundred bucks for two from 2TG toyotas--of course
>> that was four years ago. I pulled them apart to check the typical
>> wear areas and they were indistinguishable from new.
>>
>>
>
> What Bill says is probably true of the transmissions today. However,
> this is not precisely true of the Celica/Supra/4WD 5-speeds of
> yesteryear, so be careful from whence the transmission comes. From the
> late `70s until around the mid-`80s, the 5-speeds had a tendency to fail
> mainshaft bearings. Toyota was aware of the problem and decided it was
> cheaper to just informally extend the warranty on the transmission than
> to do a mold and machining change to modify the case for a wider roller
> bearing at the front, and continued to use a ball bearing, which wasn't
> up to the loads. Oh, and if someone tells you their transmission came
> out of the diesel truck and is therefore stronger, that's not
> true--those transmissions were the same as the above.
>
> All that probably does not apply for anything made beyond the mid- to
> late-`80s, but there are still lots of the older transmissions in
> junkyards, so it's worth remembering.
>
> To a lesser degree, the same was true of the Corolla 5-speeds of the
> time, but they didn't suffer the same rate of failure because they just
> couldn't be pushed as hard. Even so, in the sixteen months I was at a
> Toyota shop in the early `80s, I did do a bearing replacement on a
> Corolla 5-speed with about 30,000 miles on it.
>
> All that said, though, they're a much better starting point than the GT6
> gearbox....
>
>
> Cheers.
>
> --
>
>
> Michael Porter
> Roswell, NM
>
>
> Never let anyone drive you crazy when you know it's within walking
> distance....
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>
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