What does the "gear drive" mean in the twin disk clutch name

[turboglenn]

Just as the title says, what does the name mean by gear drive? is there something else IN the clutch that's being driven by gears, is the Throw out driven by gear or what? i just am confused since it looks normal like any other twin disk, i just want to know where the term "gear drive" comes in adn what it's reffering too

thanks

 

[twicks69]

Glenn, the term was coined by Quarter Master for the clutch hub design on the disks I had them specially make for our platform. It uses a fixed-hub attached to the rear disk with external splines, while the front friction disk has internal splines on a substantially larger diameter hub that "slides" on the rear disk assembly. Essentially, it is very similar to a transmission hub and slider assembly. It substantially increases engagement area, torque capacity of the hub and uses a single hub to engage the input shaft splines instead of two seperate floating hubs that can prematurely damage the input shaft or fail from vibrations and 4th order harmonics.

The benefits to the gear drive hub vs. a standard multi-disk floating hub design is that there is only one thick splined hub engaging the input shaft splines instead of multiple thin splined hubs engaging the input shaft splines. As well, in the case of the QM Gear-Drive disk pack vs. a standard disk pack, the single hub increases surface area by ~83% (~8.52 square inches of surface engagement of gear drive hub vs. 4.67 square inches of surface engagement of standard drive hub; not taking into account spline surface area for either calculation) that physically engages the input shaft splines. The common failure point on the race friction standard hub disks was not the friction material exceeding its torque capacity, but rather the disk hub splines either shearing at torque limit, or by simply wearing themselves down by elongating the splines until failure. As well, the original QM disk design was notorious for offset rear disk hub splines so only 60% of it was used; leaving you with only 0.680" of actual material engaging the input shaft including at the tip of the shaft. So, now you are taking a disk pack that originally had 0.850" of engagement and chopping it down to 0.680"; that alone is a net surface area of engagement of 3.73 square inches. This results in the gear drive hub disks having an increase of effective engagement area of 128% when compared to the original design standard hub disks that were incorrectly offset in the past.

No longer is the hub the fail point on a multi-disk, rather it can finally be the friction surface friction coefficient and temperature range.

Another added benefit to the gear drive hub is that there is better clutch modulation, and lowered decelleration harmonics when compared to a standard multi-hub multi-disk clutch design.


Check out this link for images of what happens to the standard disk hubs over time. One pic shows a disk hub that is completely worn away, and the second pic shows a disk hub that is almost at a fail point; the splines are no longer square-tooth they are now saw-tooth. Page #2 - Post #46 - http://www.dsmtuners.com/forums/dri...-sneek-peek-prototype-design-twin-disk-2.html

Otherwise, here are detailed images of the gear drive disk hubs for reference: http://www.tmzperformance.com/Mitsubishi QM Clutch Parts.html

Here is the original QM Gear Drive thread on this forum I made in 2009 after receiving the prototype disks for testing: http://www.dsmtuners.com/forums/dri...ch-sneek-peek-prototype-design-twin-disk.html .

I am still running these original disks in my race car with excellent results!

 

[BrokenTsi]

I have some real world experience using both style of discs. Last season, I used the QM clutch with the standard discs. After 4k miles of street use and only a few launches on normal street tires, I twisted the splines on my evo 3 input shaft.

I switched to the gear-drive discs and a replaced the input shaft. After several hard launches on slicks and about 1500 miles of street use, I found no wear at all on my input shaft. The clutch is noisey, but not as noisey as the standard discs from last year. So far, I am very happy with the QM clutch and the revised gear-drive HD discs.

 

[turboglenn]

Awesome explanation and great info Tim, thank you! Seems as though it's a little bit similar to how a motorcycle clutch setup works with the way the spliing engages it's contact points (a little vague but after as many motorcycles as i've rebuilt/repaired i tend to be able to relate a lot of things to the )

Thanks again for the thorough break down and links, i'm off to go look at them now.. Sounds like the clutch to have honestly. These days i can't decide on keeping the big turbo and going auto FWD and putting my quaife in that or if i should stay 5spd FWD and get the HX/HY-35 turbo i truely want.

The big turbo is fun, but i miss having a powerand of any sorts below 5k RPM, add the lag between shifts when i don't want to beat on the car too hard since i'm daily driving, and it's more aggrivating than fun to pass some one and that's no good

thanks

 

[twicks69]

I am not sure if anyone is currently making a FWD flywheel for the PTT or QM clutch assembly, but it is worth contacting QM, PTT and MAPerformance regarding the flywheel.

Yeah, it is like a bike clutch, or like the Tilton Carbon/Carbon design that has an entirely floating hub instead of being attached to the rear disk hub and all disks float on that hub.

 

[Chrispy0530]

I can speak for the Excedy Twin Clutch when I was running FWD. With a few occasional track launches, I had my splines destroyed on both my discs. Was a really great clutch at first, love the almost stock feel, and perfect grab when it was warm, but after a few thousand miles, it just toasted itself.

I pretty much have the same carnage pics as listed in the links above.

 

[turboglenn]

ha! go figure that would be my luck even if i had the money for it and nothing else taking priority there's not one currently produced

Anyway, I have a lot of things to sort out and buy before i even think about buying that type of a clutch for my car. I tend to sit here and think too much about engineering, DSM's and going fast and with no one to bounce ideas and such around with, i post up on here, but at least i'm always learning

I am really honestly stuck between keeping the large turbo and eventually trying to extract the 750+ it's capable of. Which is what has me looking into a clutch like this to start with, but then again with my personal limitations an auto would probably do me just as good (or a dog box where i only need a clutch to launch and to be nice when i downshift.

But if i go to the HX-35 that i've planned for over the last couple years i could still possible exceed my overal goal of 500whp by a good amount and then may possibly need the clutch for that as well, but i could focus on other areas in the mean time instead of working to match the rest of the car to the big 67mm turbo.

I would LOVE some real coil-overs (or hell just new shocks )

I plan to keep the GS-T no matter what unless things go horribly wrong in life and make it into a track car but for now daily driving it is really messin with my decision of which way to go in the build, because i have to think of normal daily comfort and practicality.

The twin disk clutch seems great but they seem as if they can completely go out really fast (faster thana normal ACT) if you wre to slip them too much in one session.. Am i right on that or what? My friend who i got the pt6776 from when he first got that turbo on his car he also put in the Tilton Carbon/Carbon you mentioned and he tried adjusting engagement point and the car didn't make it out to the main road from his driveway and it was ruined! (had to buy new disks and some other part, but they did machine him this nice adapter that uses what looks like a GM TOB that i was able to spec out and keep the info to build one for future use of my own)

I just don't know if they can handle DD or not, i figure maybe 2 years more of daily use on this car and i can hopefully get a pick-up so that i can either tow the car to the track or take my bike to the mountains for some back road corner carving

well let me stop rambling, i need to sleep so i can build a wiring harnes for the karmin ghia tomorrow and hook up all the heater parts as well.. night all!

 

[twicks69]

If you are going to go for huge numbers, I would recommend switching to an AWD transmission that is FWD converted anyways, then you can run the twin disk and handle the power levels better with a good LSD differential installed and the stronger AWD gearset.