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Discussion Starter #1
Should i use the 1982 rebuilt turbo trany, or a 1992 rebuilt turbo trany. I've heard 82 are the coolest but 92 has the larger pinion gear etc etc..i've checked the #'s on 900aero about both tranys and i'm leaning towards the 92. Was wondering if anyone has any comment on either trany performance wise, speed wise, and how it felt with a t3 supr 60/.63 turbo :) thanks
 

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The '91-'93 5-speeds are far superior to the early ones. No contest there.
'89-onwards had a much stronger pinion bearing assembly amongst other things, and the '91-on versions improved on that with wider gears (again, amongst other things).

The only old 99/90/900 gearboxes that are actually worth something are some 4-speeds that have stronger casings.

As for gearing, like for like (i.e. same primary drive ratio) the '89-onwards transmissions are shorter geared, but the later ones are more likely to have #7 primaries instead of #6. In any case, you can swap primary drive sprockets around (pairwise, of course :D ) between the two.


Greyspg said:
Should i use the 1982 rebuilt turbo trany, or a 1992 rebuilt turbo trany. I've heard 82 are the coolest but 92 has the larger pinion gear etc etc..i've checked the #'s on 900aero about both tranys and i'm leaning towards the 92. Was wondering if anyone has any comment on either trany performance wise, speed wise, and how it felt with a t3 supr 60/.63 turbo :) thanks
 

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Eric van Spelde said:
The '91-'93 5-speeds are far superior to the early ones. No contest there.
'89-onwards had a much stronger pinion bearing assembly amongst other things, and the '91-on versions improved on that with wider gears (again, amongst other things).
interesting, do you know what "amongst other things" means in each case?
another question is, the '91-on transmission got wider gears but as a result not so strong shift forks IIRC.

so, how much more Nm (or abuse for that matter ;-)) can an '91-on box take in comparison to an '89?
would be nice to know whether an upgrade makes sense, because my 900 is an '89 t16.

best regards,

stephan
 

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Iäm not sure if I have the '91-on gearbox right now, since my car was built in late 1990. It could have that, and at least the box has been very durable.

It does have upgraded pinion bearings, but other than that, it's all stock.
I have #8 primary, and with 260+ hp and 414+ Nm the gearbox hasn't
become loose or anything; in fact, after 100k km on it after the performance
mods, the bbox still feels very fresh.

A big turbo and a sympathetic way of driving the car are the most important factors. If you have a small turbo ( like the Mitsu Te05-12b ) The low-down torque kills gearboxes.
With my T3/T4E hybrid, gearbox durability is much better, as torque comes on more progressively and at higher rpm. So, even though I have much more power and torque than the stock Mitsu turbo could safely produce, the gearbox still holds on better than with those small Mitsu turbos.
 

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Greyspg said:
what boxes to the #8 primary gears come in, incase i wanted to swap them out?
At least the one that's on my car, had to be specially ordered from ETT.
The #8 primary was an official factory option for Turbo models at least, though. However, they weren't stock with any model, so there isn't a gearbox type that comes with a #8 primary automatically. Also they are very rare.
 

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Discussion Starter #8
Great thanks for the tips everyone. I was talking to a friend and he said something like i should put a 88+ shift rod in or something in the console, i forget exactly what he said. I do have a 87, so are the 88+ rod better or connect to the trany rod stonger or something?
 

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Gear linkage

Do a search on the Workshop forum for Gear linkage, i took a picture of the 2 side by side, very basically the older boxes align gears using the selector/linkage whilst on the newer ones it's done internally from within the gearbox.
 

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The later 'boxes do work very well with the older shifters that have the centering spring (up to MY '86 1/2 IIRC), though - I like the feel of mine, it just seems more er, positive than any other 900 with OE shifter assembly. That, and the later shifters apparently had a cost cutting measure of two applied to them which causes them to fall apart with age - I can't remember the details but it was discussed on the (US-based) Turbo! mailing list a few weeks ago.
 

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yes the turbo! list! Nigel here... :D
 

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Eric van Spelde said:
The later 'boxes do work very well with the older shifters that have the centering spring (up to MY '86 1/2 IIRC), though - I like the feel of mine, it just seems more er, positive than any other 900 with OE shifter assembly. That, and the later shifters apparently had a cost cutting measure of two applied to them which causes them to fall apart with age - I can't remember the details but it was discussed on the (US-based) Turbo! mailing list a few weeks ago.
yep, later cars received a shift shaft with an integrated metal pivot ball welded to the shaft. the earlier cars had the better known white plastic assembly that slid onto the shaft and was held in place with a clip. the later ones routinely broke at the weld point- all that heat created a weak spot in the shift shaft.

IIRC the split was in 91 or 92.

91-93 boxes had slightly different synchro design which allowed them to last longer. AFAIK that is the only difference between them and the 89-90 boxes. in 89, along with the larger pinion (which can be retrofitted to earlier boxes) the gearsets were change, tooth angle was lessened and the gears themselves were widened. for high h.p. that is the important part; stronger gearsets, bigger pinion.

if you're building from scratch i could recommend some things to help with longevity. mpi test all the gears, shotpeen gears, cryotreat bearings. alternately cryotreat the entire box. and spring for new shafts in the box as well as new synchros.

James
Team Saabworks
http://www.saabworks.com
 
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