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Originally Posted by Rotarydave
Got another thought for your too. What about have a tranny built for your application. I think that if you had spent the money to have one tranny rebuilt with new bearings etc then you may not have had as many problems.
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I think I will do exactly that, with the best bearings that I can afford.
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Originally Posted by Rotarydave
You also don't talk about other things which are just as important, what driveshaft are you using, how old is it? when you went to the turbo tranny in a NA chassis did you also replace the rear end if not who built your driveshaft and what RPM and balance spec did they use? Another thing you didn't mention, you talk of engine vibration but what motor mounts are you using, what tranny mount and what about the rear end mount as well. Used/worn out rubber ones will then put something in the drivetrain in a bind usually the tranny or driveshaft.
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I have full Turbo Drivetrain, the NA Diff was not a fan of my 245/40/R17s and I was not a fan of the noise that it was making under throttle. The driveshaft is not new, but it is in good repair, I ran over 165 MPH on the dyno without vibration.
I have 1 year old Mazda Engine mounts and the transmission mount was replaced with the US spec transmission (about 10,000 miles/1 year ago).
The Front Diff mount broke again about 2 years ago, it was replaced with a new Mazda one.
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Originally Posted by Rotarydave
I have plenty of "good used take out trannys" that I know absolutely nothing about car looked good, looked like it was taken care of but the motor was blown..... hmmm its really easy to say it ran fine when it was put away. Another problem we have seen is that trannys stored on their noses for a long time with little or no oil tend to corrode the gear sets and internals due to natural condensation and water getting in the tranny. I have esp seen this problem with JDM engines/trannys. It isn't a great crisis but enough to shorten the life esp when used heavy. You mention drag racing so I am going to say it, how many times have you missed a shift or speed shifted or power shifted, don't bother to deny it I race to and have a passel of trannys to prove it. Using a used stock tranny for racing application I expect to lose one about every 6 months just a fact of life If I don't want to do that I need to upgrade and then something else will break that is how the system works.
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The transmission that died at the drag strip was not in great shape when I went. The synchros in second gear died completely (there was barely anything left). I did miss a shift, but it was going for 3rd. I only went the one time, as I am worried about getting thrown out for not having a roll cage. I was running high 13s with the 6-port at 155WHP. I am now well above 200WHp and have removed about 100 pounds of unnecessary spare parts, which I think will put me in the low 12 second region. 12 is the cutoff for a roll cage around here. (G-tech gave a 12.05@123, my data log which indicates more like 12.4 seconds to 123.)
Okay, so I occasionally beat the car pretty hard, but for the most part, I drive like a Grandpa. My total Average fuel economy with the 9.2:1 4-port is 27.3 MPG, that includes tuning and breakin.
I never speed shifted second while drag racing, as this just causes tirespin. I did speed shift 3rd (kinda cool, the tack barely nudges below the redline). Either way, I have only done that a couple times ever on this transmission and that was only right after installing the Defined Autoworks Headers - almost 6,000 miles ago. Would it take this long to show up?
If this is par for the course, I will accept it. I think that the failures are a little bit too frequent. I posted this to see if any others had similar experiences. If completely rebuilding a transmission doesn't make it last any longer than 10,000 miles, I might try the RX8 6-speed or the T5 next (I would prefer a WC T5 as I would love to have 0.625:1 overdrive - the 45 kPa of vacuum I pull while cruising does not sit well with me).