* Update 11/26/10 *

It does not appear that any of the gears failed. The case simply split in two. See page 5 for pictures of the gears themselves.

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I was always under the impression that the MR 6-speed was rather stout in the lower gears but simply suffered from heat issues in 3-4-5 gear. Obviously I did not expect it to hold 1000 whp like built 5-speeds do, but I never expected a single launch at my power levels would kill it.

Some background about the car. Currently at 54,000 miles. Daily driven, never road raced, occasionally autocrossed and very occasionally drag raced. First 48,000 miles were at around 290 whp (Dynojet). I then went to a BBK/cams/supporting mods and eventually made 375 whp on CBRD's Mustang Dyno, still on stock clutch. At 53,000 miles I tried launching it with the stock clutch and it slipped like crazy so I had a Fidanza 4.3 installed. Broke it in (over 1000 miles) and went back to the strip yesterday.

Oh, trans fluid was also changed at 15,000 miles, 37,000 miles, and 53,000 miles. Last two changes were with Castrol SynTorq, the MR-specific stuff Mil.Spec sell.

Cold track (40ish degrees), street tires, recommended tire pressure (32ish front, 29ish rear), 6000 rpm two-step. I slipped the clutch until just before it grabs, hit the two-step, and slipped the rest of the way quickly. Read: I DID NOT just sidestep the clutch. About a half second and much wheelhop later, I heard a thud and felt the shifter go dead in my hand. It felt like the trans was suddenly full of clay. Didn't want to move at all. I didn't even have a chance to slam it into second gear, let alone the "weak" 3rd or 4th. The launch killed it.

I should add that this was maybe my 5th launch EVER with the car. 3 launches at 290ish whp, 1 launch at current power levels with stock clutch, and the 1 launch yesterday. I will readily acknowledge that I am not the best at launching it because I don't really care about drag racing, but I refuse to believe that I did anything so wrong that it doomed the transmission. Standard launch with a 2-step recommended by my tuner. That's it.

No pictures of the carnage yet. Should be taken apart tomorrow. But I am fairly certain it is the trans as there was lots of fluid leaking out of it and large chunks of metal were found on the track.

Options now are a 5-speed swap or maybe Shep's new 6-speed gearset. Either way I'm not happy, obviously. I always defended the 6-speed when people bashed it, convinced that 1-2-3 gear are actually stronger than the stock 5-speed's and so drag racing at 400 whp should be no problem. I was wrong. If anyone has some insight as to what might have happened, I'm all ears.

So let this be a warning to the other MR owners. I never thought mine would fail, so be careful out there guys. The important parts:
- Car was never road raced
- Car was making "only" 375 whp (MD) and for only 5,000 miles or so
- Car was launched a total of 5 times in 50,000 miles

On to the video.

http://www.youtube.com/watch?v=C82GciOb1wQ

Just got back from the shop. I couldn't believe my eyes. The trans SPLIT IN TWO. There's no other way to put it. There is actually one place where you can see the gears INSIDE the trans with the trans still on the car. I'll let the pictures do the rest of the talking. Un-****ing-believable.













Okay guys, here is the weird part. There appears to be a crack in one of the engine mounts right above the transmission (see following pic). I am hoping this can be repaired and will not necessitate a new block or something. My question is how could all this damage possibly come from one launch with 400 whp? I know there was a lot of wheelhop but Jesus Christ. The trans split in two and damaged a motor mount! My builder said he has never heard of anything like this. Asked a few other places and they agreed. Transmissions fail, yeah, but to split in two like this? I'm starting to think there may have been something wrong already. This is ridiculous.

 

No way!!

 

Hello Blitz. I don't post too much at all on here. Usually just pop in and out. I did notice your post and wanted to share my $.02.

Having been in the industry for a while here is my theory. I'm not 100% on the Evo but most 6speed boxes typically share narrower(therefore weaker) physical gears. The other thing that caught my eye about your post was wheel hop. This is probably more harsh on drivetrain components than dead hooking. Everytime the wheels hop and freespin it's like revving the car and launching on a dead hook again. Very harsh! So you have two things working against you. If you can a. get the car to spin a bit more so the car does not wheel hop or b. leave softer so you do not wheel hop(also easier on the drive train) I think you will find the tranny and it's accompanying parts lasting much longer. Launching a car is very harsh, especially on an awd car. Suspension settings and tires can have a large inpact as well.

Take my info for what you will. I'm not necessarily the drivetrain expert here, but my theory seems to work in my head. lol

 

Damn...sucks the trans went out on you with so little abuse...Between the street and strip my 6 spd has over 100 hard launches on it with the 2 step setup to no lower then 6k...my power level was from 320-420whp on a mustang dyno...my 4th gear has been grinding on high rpm up and downshifts for probably 15k miles but normal driving all the gears are fine...Either late this winter or early next spring I plan on doing a built 5 spd...very much looking forward to it...pretty much the main weak point on my car now...

 

were you redlining it then launching? it honestly sounded like you just dropped the clutch. I, too heard some wheel hop. feel for you man, my tranny is shot as well. post some pics!

 

****ty deal...not really surprised though

 

Doesn't sound good at all. Hope you get her fixed up soon man.

 

that was an expensive launch!

 

Sucks for the situation, sorry to hear you pain bros. It is however informative to other MR owners as myself. There has always been the threads on how much HP the 6speed can take and what not. More information the better.

 

Nope. 6000 rpm 2-step, like I said. Made a conscious effort not to sidestep the clutch. If I had to guess it was the wheelhop that did it. I honestly don't think I had enough time to react differently. Instant failure.

 

I have to agree that the wheel hop is what did it. If you hear or feel it you have to let off imediatly. When the wheel hops and starts rotating super fast then is virtually stopped when it comes in contact with the track. This will send the force back up the drive train to the weakest link....

My budy did not make it 60ft his first time at the track with his cobra. He got wheel hop off the line and tried to power through it and boom. Destroyed his entire rear end all the way out the lug nuts lol.

I am sorry to hear about the loss. I believe that shep is working his magic on the 6 spds. now so they can go crazy fast. Anyway good luck with it.

 

I'm in the process of swapping to the 5spd now. IMO, if I were you, I'd just do the 5spd swap. It's proven unlike the 6spd upgrade.

 

that sucks

 

Like others have said, I can almost guarantee the wheel hop is what did you in. If you ever feel wheel hop like that again, just push in the clutch.

 

Sucky deal. Time for a 5 speed.