GIGAPUNK

iTrader: (2)

Will a triple disc clutch require more frequent shimming than a dual disc clutch? I've read that this is the case, but this seems contrary to logic. At a given torque rating: a triple will usually have a lighter clamp load, and a greater surface area. Shouldn't this make it last longer not shorter?

When comparing the difference between the stock/fresh build stack height:to the minimum stack height (time to rebuild/shim) between triple and double disc clutches, I've noticed that the diference is the same (say ~.060"). Of course this means that the individual wear discs on a triple can only wear ~.020" while a dual disc can each wear ~.030". The TOTAL wear height though is still the same.

I'd like to go from a double to a triple just to get some extra thermal mass (I don't need the extra torque capacity). But I don't think I'm willing to have to rebuild/shim more often, if that's the case with the triple.

SPEC-01

iTrader: (2)

I think its best to start with everyone on the same page. There are different types of "shim" that can be added to or removed from a clutch assembly. Some companies use shims to reduce clamp-load and allow for some initial slip as the clutch begins to engage. Other companies use shims to equalize height differences (by moving the TOB closer to the fingers) as we have with our single-disc and Super-Twin set-ups. I am assuming that you are referencing a shim behind the bearing/slave on your specific set-up. Is this correct?

GIGAPUNK

iTrader: (2)

Correct.

I'm thankful to have Spec in here! Your mini-twin gets me all hot and bothered.

Project GatTagO

iTrader: (7)

Racing multi disk clutches like those made by Quarter Master are not shimmed. These clutches are designed to be rebuilt when the individual components, such as disks and floater plates are worn below a certain thickness. At that point a new disk pack and maybe even floaters are installed to regain the original stack up height.

Once exception are the carbon/carbon clutches. As they wear small shims are installed to regain the original stack up height.

Andrew

GIGAPUNK

iTrader: (2)

Thanx Andrew! Using something like the a 7.25" Ceramettalic or Hybrid Tilton as an example, will a triple need rebuilding sooner than a double? If so, why?

SNLPerformance

iTrader: (15)

Anytime you compound wear vertically like you are saying a little wear will make more of a difference.

What exactly are you trying to accomplish with your new setup?

GIGAPUNK

iTrader: (2)

I'm trying to get a silly low MOI clutch (something <9" and <20-30 pounds total)that can be used on for street/autocross/road course and handle 500 ft lbs. I'm seriously looking at Tilton's hybrid (one organic, one ceramettalic) 7.25 twin, PTTs 7.25 organic twin/triple, the Aussie Mantic street dual sprung clutch, and spec mini twin. In an ideal cash filled world I'd just buy a carbon/carbon clutch and be done with it, but $4000 isn't in the cards for a clutch right now.

SNLPerformance

iTrader: (15)

I can build you a 7.25" or 8.5" that would give you one of the lowest MOI's possible. PTT, Tilton, and QM can do it as well. It's old technology that's easily made. Budget and timeline is important... I can get it much lighter than 20-30lbs as well.

Shoot me an email and let me know, steve@monsterclutches.com.

GIGAPUNK

iTrader: (2)

Thank you Steve. I've never seen a button style monster clutch advertised, but it's good to know that another company with such a great reputation is available. From my limited research it seems that 19 pounds wouldn't be too difficult, I just worry about loosing too much thermal mass, and or the car actually stalling on decel. I'm sure there's a fine line there somewhere.

SNLPerformance

iTrader: (15)

Here's an example of a super light twin we built, you will definitely have to retune for it...
http://www.youtube.com/user/vegaman7.../6/VXcMR-ejxsU

Nowhereman

Your talking the clutch assembly only, right?
Not the flywheel also.

Project GatTagO

iTrader: (7)

In my FC RX7 I used to run a Quarter Master single disk 8.5" clutch with a one piece flywheel and a sintered iron disk on a solid hub. The flywheel and clutch together were under 20 pounds. It was a drag car but it worked well.

You can accomplish something similar by using a Quarter Master dual disk 7.25" Rally on a button flywheel and a automatic transmission flexplate. The 7.25" Rally uses a 3 disk cover in conjunction with thicker disks. Don't be afraid of the solid hubs especially in a light car.

Also keep in mind that these little clutches don't like to be slipped. A quick blip of the throttle and a rapid release will make for a clean start without too much drama or overheating the clutch. Don't forget that these clutches use a flat diaphragm spring and thus require a radius face bearing for release. Quarter Master makes an adapter to use on a T56 in conjunction with their Tri-Lite bearing.

Andrew

GIGAPUNK

iTrader: (2)

Steve, that's what I'm talking about. Last time I heard a car free rev that fast was when I heard a Porsche Carrera GT (factory with a triple disc carbon/carbon clutch and way small flywheel)., check out this video:

http://youtu.be/bUFt1_EJSD8

Nowhereman, I'm talking about "button" clutches. The button is like the flywheel's friction surface alone, but then it's usually just bolted to an automatic transmission like flexplate to give the starter something to engage.

Andrew, I kept hearing the miata guys say not to sweat the solid (non mercel) friction hubs. They do it to get a lighter clutch for small cost. Why does it works better in small cars?

HioSSilver

iTrader: (8)

My tilton triple requires no shimming threw out it's life of disc wear.

Project GatTagO

iTrader: (7)

I am not even talking about the absence of the mercel spring. I am talking about the lack of springs in the center of the hub. Small diameter, multi-disk clutches don't have the room for sprung hubs.

To get a small car moving is much easier than a big car, especially with a big V8 engine. The 8.5" single disk that I used just worked. Blip the throttle and quickly release the clutch pedal and I was on my way. No drama. Heat is the enemy of all clutches, especially small ones. They don't have the mass to absorb and dissipate the heat, so various components start to warp if overheated. If a floater plate warps, it is over. The clutch will not release cleanly because the edges of the floater will start to dig into the legs of the cover.

Andrew

SPEC-01

iTrader: (2)

A button option is certainly light...but as you seem to recognize, too little weight is not always ideal. We offer these as well but they are not always the best option. Our 7.25" unit with our aluminum flywheel will have a weight of just under 20-lbs. It sound like this (SC09MT2) would be a great option for you! Let me know if you have any further questions. Thanks,

Project GatTagO

iTrader: (7)

Would you happen to have a picture of that setup?

Andrew

GIGAPUNK

iTrader: (2)

That clutch looks perfect. I've admired it for a long time.

http://speed-eng.com/store/spec-mini...ag-p-8512.html

It's already engineered, and well supported. But it's also about $500 (or 50%)more than comparable clutches from Tilton or PTT.

Project GatTagO

iTrader: (7)

The extra cost is in the flywheel. A button clutch is OK, but a flywheel, like the Spec, is a more elegant solution.

That actually looks like a 8.5" and not a 7.25".

Andrew

GIGAPUNK

iTrader: (2)

Other than added elegance, does the flywheel have any advantage mechanically or thermally over a button and flexplate?