O.K. guys, I have done a search and I still don't feel like I have the answer I am looking for. I keep hearing that the five speed is "stronger" than the six speed transmission. Is this true? If so what makes it stronger and how can the six speed be fixed in a way that makes it as strong as the five speed if this is true?
What I can't understand is why would put a weaker six speed transmission in a car named "MR" for racing? You would think that this would be the best transmission for a "racing" version. I have ordered a 2006 Tarmac Black IX MR and, of course, it comes with the six speed. The car is slated to arrive at my dealer on the 15th of this month. But some of my friends that have Evo's tell me I should get the GSR Special Edition instead because it has a five speed and would last longer and be more durable. I had a 2003 that had the five speed and then traded for a 2005 MR with the six speed. I felt the six speed shifted better but I am asking which is stronger and can take more abuse for drag racing, auto crossing etc.

Any thoughts or comments would be welcome.

Thanks in advance,
Maximum Boost

 

I would have to say 5-speed. Look at all the high-hp evos out there. They are all 5-speeds. Even when you get a transmission rebuild, they are 5-speed. IMO, 6-speed is for daily drivers you know like having an extra gear when you are on the highway so instead of being at 3.5-4k rpms in 5th on the highway, you can be at like 2.5-3k with the 6-speed. In drag racing would it be quicker to shift through 5 gears or 6? I usually see more MRs in autocrossing rather than the GSRs and I think this is because of the Bilstein suspension components.

 

I find this a little hard to believe . Regardless, your tranny of choice for drag racing or auto x is indeed the 5-speed.

 

the 5 speed is better at taking abuse. there is more room in the gearbox to make the gears thicker due to the lack of a 6th gear. the IXs gear ratios are practically identical to the 6 speeds with the exception of the top 2. if you drag then you wont need the 5th gear or 6th. the purpose of the 6th gear is for highway cruising...sure its a cool feature, but thats more for a daily driver. and the 6th gear can be useful in autocross...due to the ability of the car to run on a lower rpm at top speeds (most tracks wont allow you to go that fast. lol).

the bilsteins are softer but offer better handling because they adjust to the groove of the ground to find traction and stick to the ground...while the GSR is stuck with a stiffer suspension (which many believe is stiffer=better....they are WRONG) that doesnt adjust to the ground and can result in the car bouncing along and not sticking to the road.

 

Then why would they put a weaker tansmission in the top of the line model?

 

O.K. so you think I should cancel my order and get the GSR with the five speed in stead, uh? I am guessing you have the five speed in your car?

 

Well since I believe that the MR is more of daily driver, I would assume Mitsu. didn't really mind putting in a weaker tranny. If you think about it, you would drag a 5-speed evo more than a 6-speed. They might have actually been saving money since the MR had some extra features like the zero-lift kit, BBS rims, Biltein shocks etc. Mitsu. I believe was down in the dump anyways and why would it matter if putting a slightly weaker trans. in a daily driven car matter?

 

Based on my read of the posts to this thread, your question has still not been answered with any fact-based information (and such information may be difficult to find). Personally, I would not worry about the relative strength of the 6-speed vs 5-speed. I doubt there is much of a difference. Unless you are abusing the tranny with powershifting, etc., either tranny will give you a lot of miles. Abuse them and they won't. Have you ever blown a tranny? Most people have not.

 

Thanks for the kind words, this is what I am trying to find out. I think that Mr. "LetIt Breath" seems to think that I have never done a search here before and that EVERYTHING I need to know about Evo transmissions can be found on this web site.

 

Wow. What track do you go to? There are people who have broken the 6 speed on road courses (4th gear in particular). Warrtalon did this recently. FWIW, he's also given his evo the run-through and the 6 speed held up over many passes and events. There's no definitive whp that causes the 6 speed to break. So, if you're looking for that data good luck. TRE says it's not as stout. That's all the data you need. Smaller gears to fit in the same space = weaker tranny. Is the five speed stronger? Sure. Is the six speed made of glass and kandycakes? No.

 

I was just stating my opinion. It wasn't based on facts.

 

So, it was fine for drag racing, but he broke it road racing? I think I remember Jon@TRE said that 1st and 2nd gears in the 6 speed were wider than the five speed, but after that the five speed had wider gears. I think he said something like 19mm wide for 1st and 2nd in the six speed and 17 or 18mm wide for the five speed in 1st and 2nd can't remember exactly though. I will see if I can find that thread and post it. He also said that made the five speed and the company that buids transmissions for toyota built the six speed.

 

Here is the best info I can find, I would love to know if the gears are made from the same material though.....


WRXtoEVO, you clearly are looking for answers and just about everyone on this forum can appreciate that. However, you may want to try being a little more diplomatic and lighten your words up by using some humor.

First off, some brief history for those who care to know.

I grew up with a dad who always brought back more junk from the city dump then he took there in the first place. He was always bringing home something that didn't work and would fix it. I was 8 years old when I rebuilt my first lawn mower engine. I vividly remember carrying a Briggs & Stratton engine in for Monday show & tell and having my mom come pick the thing up from the principal’s office. I rebuilt my first transmission when I was 10. My dad brought home a 74 Rupp motorcycle that had a bad shift drum. Anyway I have been rebuilding transmissions for many years, ranging from garden tractors to dirtbikes. In 85 when I got my driver's license I broke teeth off of 2nd gear in my old man's 79 Plymouth Champ and that's when I got hooked on Mitsubishi. How do you break teeth off of 2nd gear? The same way you snap axles and destroy clutches, lots of abusive driving. This kept the garage full and my dad raising hell from the time I was 10 until I left for college. Are you bored yet? Me too.

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

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I've seen your posts before and by no means was I under the impression that you dont know how to search. But I do know that the answers to your questions can certainly be found on this web site, with the exception of "why would they put a weaker tranny in the racing model?" In answer to that question, Mr. Maximum Boost, 6 speed's are indeed more useful for long road course racing where you may encounter long straights. Its the principal of having more gears being more suited for racing(road racing). knew this and basically said "make the 6 speed happen". So their engineers made 6 gears fit in a case about the same size resulting in some weaker gears and less beefy syncros.

 

since when did the MR come in black?