outboost

So, I installed a QM 7.25 V-Drive twin in my 05 about a year ago. I had no complaints what so ever about the performance, but the damn thing only lasted 12k miles with less than 10 launches and almost all highway miles. I'm not really complaining about that because from all the other posts on this clutch on the fourm that seemd to be the average mileage regardless of use. Now to the real story:

Initialy when the QM started slipping it was only in the low and mid rpm band which I though was rather odd, but I didn't think much into it. After about two weeks of occasional slips during normal driving I decided it was time to start looking for replacment discs. I wanted to get them swapped out before I burnned up any for the friction surfaces. (pardon my lack of technical terms) I did a few searches to see if anyone had the QM discs listed and even looked on QMs main site, that listed every possible part excapt for the discs. After a little digging I saw that the PTT (Powertrain Technologies) looked almost identical and looked on thier sight. They listed quite a few diffrent 7.25 discs for the evo spline. Having no idea which thickness etc the QM stock ones were, I called PTT to ask them if they were compatable. PTT claims that the same people who made the QM used to work for them, anywho. . . they are all compatable. PTT's verson of the 2 disc is slightly shorted and uses .2in discs while QM uses .25in discs, however PTT does make their 7.25 discs in both sizes and you can also get either the metalic (same as the QM came with) or an organic material which isn't sutable for much over 450hp, but is a lot more drivable yet still has a good initial bite like the metalic. Sooooo. . . I ordered a set of the organic .25in discs. They arrive at my door and life is good.

I fianlly got around to getting the transmission off last night and expected to see 2 worn the hell out QM discs, but no. . what was there was 2 discs that were warn maybe 1mm on the engine side while the pressure plate side of both discs didn't even look visually worn. The pressure plate, center plate and Flywheel didn't show any excessive wear either. What ended the life of this clutch was the QM disc design. The center hubs of the discs, even when new had so little space between them, that once the discs wore down even a little bit, the hubs would contact eachother and keeping the discs from fully contacting the center plate. There are even hairline cracks in the top disc from where the pressure plate was bending it because it was bottomed out on the hub. Was it a calculated design feature to prevent you from wearing the friction material all the way down? Maybe, but if it is they left a lot of slack. I find it hard to believe that with all the other presicion machining and design of the QM unit that something like that would be over looked, or at least not mentioned on here before. (at least I don't think it has) It seems that the discs, could have been good for at least double the wear that was on them at the time I removed them provided the pressure plate would have the throw for another 2mm or so.

Enter the PTT discs:
I had only breifly opened the box and inspected the PTT discs before I set out removing the transmission just to make sure they were the proper ones. It had been a while sence I had installed the QM discs, so they just looked similar to what I remember the QM ones looking like, sans the organic material, when I slapped them on. Once I had the old QMs off and looking into all the stuff that I wrote about above, it was time to compare the two. right off the bat, the PTT's do not have any spacing on the disc at all. It is built around a circular disc with both the disc and friction material 360deg around with no gaps. So, it does not have the slots and holes where I noted the QMs developing cracks. Good thing? Maybe, I assume that everything on this is precision enough (as it looks to be) to not need any kind of slots for disc deflection added in. Next, and most importantly in my opinion, were the PTT hubs. They are well machined, and *gasp!* the bottom disc hub is concave so that the hub if the top disc has plenty of room to recess down into it. It has about 5mm more room to go than the QM discs. PTT didn't give up that 5mm of surface area on the imput shaft either. They added it to the transmission end of the hub, but not so long as to mess with the throwout bearing travel. I stacked both sets of discs together to have a look and it's a huge diffrence. You would have to completely eat away the center plate for both the discs to not make good contact. I'm very pleased with the design of the PTT discs this far, though I don't have them in the car yet so I can't speak of the performance. If they work half as good as they look to have been made, then I'm sure I have nothign to worry about. I'll be sure to update this once I have it all put back together.

If you bothered to read all of this rant, you probably want to post that little "This thread is worthless without pics" smiley. Don't worry, I took plenty and I will post them on here. I'm writhign this from work, so I can't upload my pictures from here.

bostonhatcher

iTrader: (18)

If the QM lasted even 50,000 miles and could take way more abuse it would be the ultimate clutch to run. I got a a taste of the QM driving my car around the block and the shifting was unreal. It didn't even feel like my shifter cables were hooked up to the tranny . I bought it used with 5000 miles on it and sadly it needs rebuilt. This was with .242" disc thickness left on each discs. I even did the hub mod to the flywheel disc.

For anyone who thinks this clutch is too loud or too harsh of an engagement, grow a pair of nuts. You guys had me worried the entire time I was looking at buying this clutch that it would be too loud/harsh and I just laughed the first time I drove it.

Wickedwhite8

iTrader: (9)

What's the verdict. Any update on driveability difference.

batty200

iTrader: (3)

There is a whole thread on here about the QM and the lack of space between the discs. I have a PTT and mine was worn unevenly as well when it slipped. I dont know why they do it but somehow they all wear unevenly even if the hubs arent hitting.

JmanMR

iTrader: (3)

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