Personally, I'd keep the 6 speed and let TRE build it.

 

I am now leaning back towards the 6 spd because I cannot really afford the whole 5spd conversion currently. Time will tell.

 

I'm still rooting for the 6spd to see if there are anyways possible to improve upon it. I've been following this thread closely hoping something can be done.

 

does anyone know the number of teeth and gear width on the 4th gear in both the 5 spd and 6 spd? Maybe ask TRE if they've got your trans? I'm curious if it's gear strength, heat, or a combination of both. I assume a combination but it would still be interesting to know the size difference.

 

Do a search for GEARS on here (jon@TRE) he has the gear MM listed out for both boxes. Off the top of my head, the 1st gear is larger in the 6 spd but 3rd and 4th are MUCH smaller.

 

Fedex picked mine up yesterday morning, so it's en route to Shep...

 

I'm sure yours will be done before mine. Jon@TRE got in a Mtn Bike accident this weekend. He is ok but suffered a seperated shoulder and a couple other things. Who knows when I will get my transmission back now.

Car has been down for 6 weeks so far now.

My neighbors Yaris is looking kinda good for $11,000. Maybe I will buy one this weekend.

 

This is Eric and I work for Jon. If you can decide whether you want the 5 speed conversion or to have your 6 speed gone through either one could ship within a few days. I did see Jon today and he's pretty smashed up but we'll have it done once you decide on what you want to do.

Eric

 

Thanks Eric,

Jon emailed me and I replied. Thanks again for getting those quotes to me!

 

Now let's talk about the 5 & 6 speed transmissions found in the EVO.

The 5 speed designed & built by Mitsubishi while 6 speed is designed & built by Aisin. You probably already knew that because you own an MR and I'm sure you know the gear ratios so I won't bother you with stuff you already know.

Looking at underside photos of both transmissions one would immediately assume the 6 speed was built like a brick **** house but don’t judge the book by the cover.

Like I said earlier in this thread the shaft center spacing the 5 speed input shaft & output shaft are roughly 10mm further apart than the 6 speed. This may not sound like much but anytime you increase the shaft spacing you greatly reduce the amount of force on the teeth. However the final drive on the 6 speed is a 4.85 whereas the 5 speed is a 4.53 so there is a little more torque multiplication going on there which probably makes up for the shaft center spacing.

Here are the gear width measurements for the 5 speed.

1st = 14mm
2nd = 17mm
3rd = 19mm
4th = 18mm
5th = 18mm

Summary: Be CAREFUL when launching the car. I rarely see any breakage problems with the 5 speed other than 1st gear, it is possible to crack the teeth on the input shaft or lay the teeth over on 1st gear. For some unknown reason people tend to think that manual transmissions are immune to gear breakage from dumping the clutch yet it is common knowledge that you don't rev up an automatic in neutral and put it into Drive. The fact is you will, over time, fatigue a wheelbarrow's worth of drivetrain parts if you launch any car abusively.

Now here are the gear width measurements from the 6 speed.

1st = 19mm
2nd = 19mm
3rd = 16mm
4th = 14mm
5th = 14mm
6th = 14mm

Summary: 1st-3rd are very stout and shouldn't give you much of a problem but I'd be careful in 4th-6th. The tooth profiles on 4th-6th is dainty making for a quiet transmission. For the record the DSM 4th gear is 15mm and it's known to eventually give up the ghost, especially if you are making over 700whp so I'm skeptical about the 6 speed. In this business it's good to be skeptical. It doesn't mean that you don't agree with somone's findings, it only means that you've been doing it long enough to know that most of what you've read on the internet has a signal to noise ratio of an old short wave radio on a hot summer day. In time I will have more data on both of these transmissions and I'll happily share my findings.

As for the final drive gears the 6 speed is incredibly stout yet I rarely see the teeth on the 5 speed have any problems. The fuel economy of the 6 speed can be attributed to the 4% taller 6th gear and the narrow gear teeth yet with the CEL tune of my MR I can barely manage 24mpg on the highway.

The synchronizers on either transmission are pretty good and with a properly adjusted clutch one shouldn't have too much of a problem with them but if you are shifting it fast as you can there will come a day when it may not shift as good as it used to. Contact me if you need help.

As for Teflon cables, thinner transmission oil and the other improvements they will help make for a nicer shifting transmission but this won’t improve the strength of the transmission. If this MR wasn't my first new car I'd have the 6 speed out and the 5 speed with drag gearing and never look back.


Jon@TRE

 

I had a 03 and now have a 06 MR. The MR tranny KILLS the 03 one in feel as well as 5th gear is not a dog.

 

the difference in feel is mainly due to the teflon coated shifter cables on the MR (I think), not so much the tranny itself.

 

The 05+ 5spds have that as well.

 

05+ meaning 06s only? I didn't think the 05 5spds had it - it was a feature on the MRs for 05.

 

I think the 6 speeds also have triple cone synchros and more moving parts in the tranny which contributes alot more to the shifter's smoother feel ... the teflon coating also contributes a little to the shifting.