Dragon

I've broken 3 transmissions in my car in the last 3 months...

all of them went shifting to 3rd gear under power...

The first one 1 took apart and fixed... the reverse syncro had exploded and the 5th gear syncro was mangled.

The second 2 were diffrent and I haven't had time to pull the missions apart yet.. there was a pop followed by a lot of grinding for a few seconds... the shifter stayed in 3rd gear, but it wasn't there. on the way back to the staging area I pulled it out of gear and put it back in 3rd and it worked fine, however 5th gear is completly gone. Reverse is also fine.. If I go into 3rd under power it still isn't there, but it is ok for normal driving...

I'm assuming that the shift linkage is trying to grab the 3rd and 5th gear shift rods at the same time and that the 5th gear syncro is completly gone and the synco like teath must be striped off the gear and that 3rd gear one's must be nearly gone too, it however shifts in to 3rd great.
(that's a nice run on sentance)

just for refrence I'm running a ORC triple plate clutch good for 1,000hp and pushing probably mid to high 400 hp range.

Anyway Just wondering if anyone has had simular problems and it there are any fixes/mods to the stock mission that will cure this problem short of forking over 1,000's of $'s for a dogg or race mission...

Thanks...

atihun

Is it possible you are mis-shifting second to third gear? I would suggest you try a short shifter first, if you don't already have one.

Dragon

I'm using a B&M short shifter...

atihun

Damn man, are you depressing the clutch?

Seems odd, as there are many people using the stock tranny on the strip that are pushing 400+, and not breaking things that easily.

Since you are in Japan, can you get a low mileage tranny that hasn't been opened?

cewrx7r1

iTrader: (2)

Maybe you are having too much rotational movement of the engine-drivetrain. When going from such high torque in second to none when shifting, this movement causes the top of the trans to move sideways and makes it harder to do a clean shift with a stock trans.

I have one of Kyle Krutilek's FD torque arm braces
and it works great even with stock motor mounts and stock diff bushings. It prevents all sideways movement. You can contact him at: kkrutilek@houston.rr.com.

Dragon

I have a aluminum tork brace mounted to the right side of the engine, the left motor mount is solid, I made it out of steel, I also made a tranny brace out of steel and I made a solid steel diff mount and I have a Mazda Speed power plant frame. There is absolutly no movment in the drivetrain unless the whole car is moving with it. I also have a 5 pt roll bar I welded in to the rear of the car with a couple of added on bars, so the body is pretty stiff.. I also droped the whole rear crossmember and rewelded the whole thing since it is only spot welded from the factory, it is also out of a 95' RX-7 so it has the 2 extra lower arms that mount to the body that the earlier RX-7's didn't have. The last tranny to explode was out of a 99' RX-7 with about 15,000kms on it...

atihun

Are you sure you're only at 450 hp at the rear? That would mean about 500 at the flywheel, no? Which would mean you have some considerable torque, 350, 400 lbs?

I think that possibly coulpled with the way you shift and the power you're putting down, the stock tranny can't handle it; especially if you've put in such a new tranny.

Could it be possible that the clutch may be engaging/catching too quickly?

Dragon

the clutch is a 1 metric ton clamping force triple plate it has 2 settings off and on.. I'm pretty sure the tork shock is probably helping with killing the mission, but the fact that it is killing 3rd and 5th (and Reverse) at the same time says its somthing with linkage... I'm running a To4R turbo with A/R 1.0 exaust, 3 1/4 inch exaust, large side/exaust port and dumping 80-85 injector % with 2 x 1600cc and 2 x 850cc injectors & boosting 1.15kgcm... The port seems to have really good low end tork compared to stock so I'm assuming it's probably got pretty good top end tork as well, I also shift at about 8,500 rpm...

There has to be some mod/mods to keep the stock tranny together. If there keeping them together with slicks and over 500+hp in the states... I just need to know the secreat. I've been wondering if maybe they are taking out the 3rd-5th gear syncros?

GsrSol

I'm not a tranny guru so I don't really know how they work but I have always heard that a short shifter will end up messing up the synchros. I would also think that you would need just a little bit of movment in the drivetrain or else it will be to hard on the tranny and with the clutch you have its just like Wham Bam...Boom.