Just wanted to see if anyone could help me out. I'm looking to rebuild my manual transmission and/or upgrade it at the same time. Does anyone know my options to upgrading it? Also, I can do it all myself, just haven't really seen the options and I think it would be great if we could all pool our minds together and come up with a great source on the forum to learn about all of the different options. I definitely want to rebuild my tranny and have heard about dog cut gears and hardened gears, but not really sure what those mean either. If you could help at all I would really appreciate it. Prices, where I can get it from, and descriptions would be great.
Thanks again,

Craig

 

Run a search both in this forum and in the race forum. It's even mentioned in the FAQ under 6-speed.

I'll get you started: dog boxes have no synchros, which means you as the driver must rev-match each gear, and double-clutch on downshifts. They can handle more torque than synchromesh transmissions since the the engaging teeth (dog teeth) are much larger and simpler than synchro and clutch sleeves. You can get dog gear sets for the FDs tranny case for a few thousand.

Apparently there are a couple of synchromesh gearsets for the FD that cost several thousand $.

Another option is to replace the entire tranny. In all 3 cases, you won't get anywhere without $5k to spend.

For the stock transmission, changing 5th gear for a shorter ratio and upgrading the driveshaft and PPF are sensible upgrades. All stock gears are hardened steel. You can also put a T2 transmission in, which is an equally durable but simpler system.

Dave

 

sorry for the thread jack, but would a t2 tranny be cheaper to buy used than to rebuild my fd tranny. All i need is 5th/ reverse fixed but this T2 sounds tempting.

 

5th / Rev is an easy fix. I know the T2 tranny requires something to handle the PPF. You should be able to get a price (tranny included) from KD Rotary - I know they do this.

Are you installing the tranny yourself? If so, do the 5/R yourself too. IMO.

Dave

 

First off, you have to think what you're going to upgrade. The stock tranny actually can handle a LOT of power - it's pretty beefy. People have made upwards of 400 horsepower on it.

Fix the 5th gear synchro with the updated part and change the select spindle (I think that's the term for it) to the updated part and enjoy.

I don't see a reason for running a T2 tranny - it's basically the same guts-wise as the FD tranny.

Used Japanese transmissions go for pretty fair prices - that's another option.

Dale

 

Well, I'm thinking about buying an extra tranny b/c i think some of my synchros/gears are bad. I'm running a T78 so I am definitely past 400whp. I wasn't looking to get a six-speed yet and I did do a search, but couldn't come up with anything, I searched under transmission rebuild and upgrade, but got nothing about what I was looking for. Any more help would be great, I appreciate the explanation of the dog-cut gears. Is it very hard to shift when using one?

Craig
Anybody else? Please post links if you do know of the other threads where I can find info. I have definitely thought about upgrading to a six-speed though.

 

https://www.rx7club.com/showthread.p...=speed+tran%2A
https://www.rx7club.com/showthread.p...=speed+tran%2A
https://www.rx7club.com/showthread.p...hlight=dog+box
https://www.rx7club.com/showthread.p...hlight=dog+box
https://www.rx7club.com/showthread.p...hlight=dog+box
https://www.rx7club.com/showthread.p...hlight=dog+box

 

I've got a new set of OS Giken close ratio gears that's getting ready to go in my transmission when I get it rebuilt. Its gears 1-5 with 1-3 being taller, 4 the same, and 5 being a litle shorter. I'm hoping this will make the car much nicer to drive in the lower gears since its all ported out and singled now.

 

My jerico 4-speed dogmission should be here within the month.

Straight cut gears should sound nice.

anyways this is by no means a bolt in installation, I am going to have to cut the trans tunnel to mount the shifter. (it has external linkage that makes the shifter sit to the side) and then it will be covered up with some tinning.

I have an adapter kit that allows me to run the stock FC bellhousing/clutch hydrolics. I also have a steel driveshaft made already. Just waiting on the trans.

Why does everybody think that a 6speed is an upgrade? More gears does not mean it's better by any means.