it's funny that my 5th gear doesnt engage anymore a day after i subsribed, so it's at the dealer and i hope i get the call to say i'm getting a new tranny...

nevertheless, great pics.....thanks.

 

thought I'd add this link for additional pictures
http://www.cutawaycreations.com/IMAG.../gallery5.html

 

Very cool...how the heck did you find that?

 

Thanks for the photos and explanation - especially for us non-technical dweeds.

Like myself, many of us are weekend racers without the resources to take transmissions apart much less fix them. With 3 racing seasons under my belt, I am pleasantly surprised that I have not broken anything (knock on wood).

 

I can't comment on the supra transmission in comparison with the 3000GT transmission because I've never been inside a supra trans, but the gears in the 3000GT transmission are very strong, there are plenty of 700-800 wheel torque cars running around with that trans. The transmission has its problems with regards to the case (it's flimsy and flexes alot) and there are lots of shifting issues with it as well because the synchro teeth and engagement teeth are freakishly small, but the gears themselves are quite strong when it comes to torque capacity.

To clarify something regarding the sychronizers according to the FSM:

Revisions 000 through 004:
1st: double synchro
2nd: double synchro
3rd: single synchro
4th: single synchro
5th: single synchro
6th: single synchro

Revision 005 through 008:
1st: double synchro
2nd: triple synchro
3rd: double synchro
4th: double synchro
5th: single synchro
6th: single synchro

Revision 009 (if there's a higher revision than this I haven't seen data on it):
1st: triple synchro
2nd: triple synchro
3rd: triple synchro
4th: double synchro
5th: single synchro
6th: single synchro

 

lol.. they are up to 010 now? because my 009 is popping out of gear again

 

I actually I think I misspoke. There are 10 revisions...but they are numbered 000 to 090.


Sounds like a personal problem.

 

Greats Pics ---Iv always wanted to tear into mine ( 03 with 57,000 ) but have had no reason to. At the very beginning I had some 6-5 grind but within 2 days, modified my shifting to eliminate it and it has not done it again in 40,000 plus miles. I am still,and especially after seeing pictures a believer in the 6 MT and still believe that 95% of 6MT "failures" are due to the man shifting NOT the transmission. Unfortunatly, no one wants to admit to errors and point fingers at them selves so the hysteria will continue.

 

very helpful info and pics.

 

I need help/advice. I have an 03 Z Coupe and an 05 ZR. I'm selling the ZR and turning the 03 into a circuit/track car and I am contemplating swapping the gearboxes.

The 03 gearbox shifts very smoothly and the 05 box sometimes grinds going into 2nd and sometimes has trouble getting into 1st from a standstill.

My question is would you take the 03 or 05 box keeping in mind the 05 had revisions like double and triple syncros?

Am I right in assuming that the newer gearbox which has all the upgraded revisions should be stronger.

Thanks.

 

+1 I have almost the exact same problem with mine, but with sub 500rwhp.

 

Try adjusting the clutch pedal point of engagement to engage at a higer pedal position and see if that helps a bit. We found it did help out, since it seemed as if our clutch was not fully releasing at times.

 

I have no special attachment to the Z's transmission. I'm all for going to something like a racing T56 or even a 5 speed of some sorts. Just something that's proven and works and shifts fine. As it is the Z's transmission on my car is a bit stiff to shift and I'm tired of grinding 3rd gear for no reason. It bothers me when I can shift in my celica or wife's jeep twice as fast with little effort compared to the Z using lots of effort to time it just right to try to avoid grinding.

I'm glad the Z's gearset seems to be up to the task of handling huge power though. It's just not up to the task of handling really fast shifting easily. I know it can be shifted fast, but it just doesn't feel good, and grinds all the time

 

I don't know whats up with your transmission or shifting, but mine handles very quick shifts like butter. Again..the reason I tackled this project had nothing to do with shifting as I've had zero shifting issues with my transmission. I just want to make sure I don't break it with all the abuse I have been and the heavier abuse I will be throwing at it. So far the thing has been a real champ. Maybe you should try some other gear oil. I use Redline MT-90 and have since the trans had about 1K miles on it.

 

Try shifting at 7500rpm from 4th to 5th, and see if it still feels like butter. Mine shifts very well at 7000rpm from 4th to 5th, but terrible at 7500rpm.

Thanks for keeping us posted, and keep us updated.

 

I use the exact same gear oil as you and have changed it every 8000 miles so far in hopes that things might get better.

I have revision 000 since my car is an aug 02 build. Don't know what else to say, I've used 3 different shifters, stock, rouge, and 350EVO. 3rd gear still grinds and I still don't feel like the gearbox is broken in with 23k miles on it. Going from 2nd to 3rd just doesn't feel very natural. It's like it doesn't want to go straight into 3rd. It wants you to move up, right, up into 3rd on a conscious level and same with 4th to 5th. All the other cars I've driven glide right into 3rd and 5th without even thinking about it.

On that note, I have driven 2 other stock Z's. An 04 and an 05 and they seemed to shift smoother than mine....I've thought about buying a newer transmission model, but I'd rather wait for a plug in play solution to come out that does make shifting unquestionably easier instead of the mixed bag that the newer ones seem to be

does anyone really think a 3.794 1st gear ratio is really necessary with a FI Z? Seems like a gear ratio that short/strong with a lot of power and slicks/drag radials is just asking for broken axles, not to mention having to shift to 2nd so soon

 

If my calculations are correct a 4-5 shift @ 7500rpm is over 130mph correct?? I don't know how often you need to quickly shift over 130mph..but I definitely don't.

I'll keep you updated...

 

sounds like you solved the 4-5 shift issue!!

 

Haha...good point. Well, when you build your engine, you will be shifting at 7500rpm. But make sure your guy addresses that gear, even though you havent experienced the issue. I was trapping 132-133mph, so I definately felt the issue.

 

Straight cut gears and dog engagement teeth (aka "dogboxes") are two separate and unrelated things. Straight cut gears have, of course, straight cut gear teeth. Dog engagement gears have dog engagement teeth (not talking about gear teeth here) as opposed to synchromesh engagement teeth. You can have a straight cut synchro gearset, a straight cut dog gear, a helical cut synchro gearset, or a helical cut dog gearset. Straight cut gears are what cause the gear whine (like in reverse in some street cars) but that has nothing to do with dog engagement teeth.

Here is a picture of a helical cut, dog engagement set for an SR20. Notice the 5 large dog teeth on the 3 gears at the bottom of the picture, and also notice that the gear teeth (the teeth that transmit torque) are helical to reduce noise.




If anyone wants to see what a straight cut, synchromesh gear looks like I can take a picture tomorrow at work.