Beast From The East

My transmission is beginning to make a lovely growling noise (two different high pitched bearing noises, actually). This will be the fourth time I've had to crack the case open in 6 years - once for input shaft bearing, once for 5th gear synchro replacement, once for replacing the silly gear that drives the speedo, and now this. <sigh>. It just looks like the tranny can't handle the increased power, at least the internal bearings can't handle it.

One things I've noticed is that there seems to be little talk of transmission upgrades short of the Guru dog box or Quaiffe. Is there any other options out there that can improve things? For example, Kennedy makes an adapter to fit the T-5 (Tremic) 5 speed, which is what is used by the Mustang Cobra. I'd need to get a custom driveline and clutch disc to do this. A new Tremic cost ~$1400 from Jegs, then the adaptor is $300, then the drive shaft would run ~ $250, plus labor to install. However, my neighbor with the supercharged custom built Mustang (which ran an 11 sec quarter mile at 133 mph while smoking his street tires all the way through to the finish line, and then shredded his Tremic on the next run) says that the Tremic is clunky and not really built well. Instead he recommended the T-56, which is what comes stock on the Viper, or Aston Martin Vanquish, believe it or not. That one costs more in the realm of 2~2.5K, plus I don't know if the same Kennedy adapter would work. With any swap, I have to deal with speedo hook-up and calibration (which there is a company here in Sac that will custom make speedo gears to match up the calibration for your speedo), and will also need to change out the disk on the clutch to match the ACT pressure plate and splines on the output shaft.

They way I see it, I have three options:

1 - rebuild this one and stop griping about having too much power. Two modifiers to this are I can buy a second used transmission and rebuild this one, and always have a hot spare, and or harden this transmission. Are there upgrades to the internals I can also do (besides adding the modified 5th gear to give it more power).

2 - swap out and custom build something with the t-5 or t-56 tranny (I know, gasp, not a Mazda part - screw it, I need to harness the power and not break).

3 - other choices? Please remember that the other choices need to meet with the requirements of the car - daily driver, that sees both drag and autocross/road courses.

Any ideas? Anybody got a used stock tranny in decent shape I could purchase? I think someone also has the part number handy for the 5th gear changeout - wasn't that a 323 5th gear?

Ideas are welcome. What are guys like Xcessive and others with monster power doing? You can't be using the stock tranny with any longevity....

Beast

radkins

I am interested as well!

mark57

Me, too. I've been trying to determine what's out there that will fit in both manual and hi-perf auto applications.

A nice road-race Richmond 5-sp. manual would do it for me.

Rhode_Dog

There was a thread a while back with talk that HKS makes a synchromesh and dog box 6 speed, but at a high cost.

here is the thread...

https://www.rx7club.com/showthread.p...hreadid=216669

Beast From The East

Thanks for the reminder on that thread. At this point I think my best bet is to just rebuild my stock unit (actually, I'm thinking of buying a used spare and installing it, then rebuild the old one and keep it as a hot backup with the shorter 5th gear). However, we are going to see if the Kennedy adapter will match up with the t-56, and if so, then that seems like the best way to go for when I have more disposable money. These other trannys are nice but don't seem to be streetable, while the t-56 might be able to do both for much less.

Now, if I could just find a reasonably priced extra tranny....no luck in the For Sale section yet.

Beast

rex u.k

I have the guru racing box, the way to go IMO.

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iTrader: (2)

The best way to upgrade the Stock trans is to Use TII Syncros. They are a direct replacement. The 3rd Gen Syncros are lighter. They are made lighter as its a racing trick to allow the trans to shift quicker between gears. The downside is it makes them weaker.
There is a shop in North Carolina that Rebuilds all thier FD transmissions with TII synchros with more success then the stock part. Its still mazda if that matters. What matters to me is that it works. I even think they are less money which is fun. Check out www.rotorsportsracing.com Give them a call they can give you part #'s and details on thier success doing this. Also Cryo some other parts and you should be set. Run some Amsoil also. best stuff Ive used. Ive used Redline and Regular Factory Lube and the Amsoil is the best.

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iTrader: (2)

Also Buy the mazdaspeed upgraded Shifter Bushing that replaces the Plastic one that breaks with an aluminum one. Here is what it says on the mzdacomp website about it. I cut and pasted from thier website. The part is 9 bucks
Notes:
Replaces the stock plastic bushing which can wear quickly under racing conditions. A worn shifter bushing causes increased wear to synchro rings which can result in serious damage to other trans components. Aluminum bushings are not available for 1981-86 RX-7's. Fits 3rd gen RX-7 and all Miatas.