N2O + Clutch

[dantheman68]

Ok... SO originally, i bought a Spec stage II clutch for my SHO with intentions of running Nitrous through it, figureing that the stage 2 would still have a long life, and still be able to hold up to an ocasional shot of 55-75HP of N2O (probably like once a month in the summer the nitrous would be used)


well i had problems with that clutch and was forced to replace it with a HP series ZOOM clutch. it is also a kevlar design, but it is not windowed, like the SPEC stage II is...

here are two stock photos:

ZOOM:



SPEC:


so obviously the ZOOM unit is not stock, and it is not organic clutch material, so it is a bit stronger, but if im looking at a 15000 mile life out of the clutch because i will ocasionally use N20, i dont see it being worth it, so... i know not many people use ZOOM clutches, but what have been experiences with N20 and stock clutches... or just any expereince with a clutch for that matter... i know that using N@O will decrease the life of the clutch...but basically how drastically will that be affected with ocasional use?

 

[AREA 91]

As long as the clutch isn't slipping, it will hold the N20. If the clutch starts to slip RELEASE THE THROTTLE! It only takes a few seconds of slipping to glaze the clutch. They never seem to be the same after that. By looking at the pic's, I would say that the zoom is a stocker. Cast pressure plate, and full faced disc. A "segmented" clutch will have more holding power, due to less surface area. The negative, is it wears out faster.

FWIW, I have ran many bottles at the 75-100 HP jetting, and have had ZERO problems. I am running a CM1 Pressure Plate, SHO NUT 9 Puck disc, Ceramic TOB, and 9LB Fidanza flywheel.

This is all my opnion, so enjoy.

 

[dantheman68]

As long as the clutch isn't slipping, it will hold the N20. If the clutch starts to slip RELEASE THE THROTTLE! It only takes a few seconds of slipping to glaze the clutch. They never seem to be the same after that. By looking at the pic's, I would say that the zoom is a stocker. Cast pressure plate, and full faced disc. A "segmented" clutch will have more holding power, due to less surface area. The negative, is it wears out faster.

FWIW, I have ran many bottles at the 75-100 HP jetting, and have had ZERO problems. I am running a CM1 Pressure Plate, SHO NUT 9 Puck disc, Ceramic TOB, and 9LB Fidanza flywheel.

This is all my opnion, so enjoy.

i am not looking to replace my clutch again though with a 9-puck or whatever... the information is great, but i mainly want to know how much of the life of a clutch is decreased by spraying... i know that the CM1 has an orgainc disk, and they say that that is THE clutch to run if youre using N20.. and thats a full face on top of it... so is the major concern clamp load on the clutch... because mine is supposedly holding 70% more than stock....

also i sure as **** hope that the clutch im using isnt stock... i paid over 500 not including labor (yeah i know a ripoff)

 

[AREA 91]

You should be fine with the stocker jetted at 75.

 

[Geek SHO]

I think it's going to have a lot to do with how you shift too. If for instance, you're powershifting on your clutch on the spray, your clutch is not going to be happy. When I was using nitrous, I noticed that quick shifting would result in a little slippage too, however I was using a damaged Spec Stg III (it had oil on it for a while, then I took it out, degreased the pants off it, and put it back in). You'll be fine if you make sure the clutch is engaged before mashing in each gear.

 

[SHO Dude]

Here's the thing about Kevlar clutches.

Kevlar has a high static coefficient of friction, but a low dynamic coefficient of friction. That means that once you get the clutch hooked up, it won't slip. The issues comes when trying to apply the clutch. When you shift hard or try and shift on the bottle, the Kevlar slips before it can grab and hold. That being said, once it does hook and hold, it won't slip.

I don't care that much for Kevlar for clutch facings. They are very durable for stock style applications, but it's not the disc that wears out on these cars anyway. For hi hp cars or gassed or blown applications, I recommend a double diaphragm pressure plate. This type of clutch gives you plenty of clamp to apply and hold just about anything you can put thru it.

 

[JustinSane]

As long as the clutch isn't slipping, it will hold the N20. If the clutch starts to slip RELEASE THE THROTTLE! It only takes a few seconds of slipping to glaze the clutch. They never seem to be the same after that. By looking at the pic's, I would say that the zoom is a stocker. Cast pressure plate, and full faced disc. A "segmented" clutch will have more holding power, due to less surface area. The negative, is it wears out faster.

FWIW, I have ran many bottles at the 75-100 HP jetting, and have had ZERO problems. I am running a CM1 Pressure Plate, SHO NUT 9 Puck disc, Ceramic TOB, and 9LB Fidanza flywheel.

This is all my opnion, so enjoy.

hehe scratch that clutch is now toast.
by the way is the center force a dual diaphram design? im looking to upgrade soon to a street freindly clutch that can handle a beating and up to 100 more hp over stock.

 

[drivinhard]

hehe scratch that clutch is now toast.
by the way is the center force a dual diaphram design?

No. They change the fulcrum points on the stock plate for (slightly) more clamp load and change the friction material on the disc. They claim no room for centrif. weights but I've seen at least one clutch builder in NJ who's done it.

Really, if you want good driveability, you need more clamp load, and a friendly friction surface (preferably full face, with marcel spring). Otherwise, the only other way to increase holding power is to use a very aggressive material on the disc (which makes for not so smooth engagements, at eats up the FW and PP quickly).

The downside to that is the twin spring clutches are heavy (pedal effort) with the SHO's cable system (no hydraulic assist) and you put more force (since you are fighting 2 springs) against on the crank (thrust bearings) and TOB shaft bushings and fork tongs.

The best clutch (for racing) I ever used was a stock load plate (no increase in clamp force) with beefed up straps and rivets (also a weak point on the stock clutch for high rpm upshifts/downshifts). It used a small 9.25" dia disc w/ 8 pucks of velvatouch (sintered metallic lining) on what was basically a stock 9.25" valeo disc (plastic hub, etc). Thing was a toggle switch but it would chirp the tires 2-3 (powershift) NA on drag radials, and worked awesome with slicks and nitrous (never had the cajones to powershift on the bottle).

Basically, you can't have your cake (awesome holding power at the track) and eat it to (light and smooth like stock, on the street).

 

[JustinSane]

it dont have to be as light as stock i just dont want to have to work out at the gym to use it, so the center force is a pretty good clutch for a 100 hp over stock? i mean the high revs jr in it now dont slip as long as you let it clamp before applying power, but we all know that isnt how we drive at the track nor is it how i want to have to drive. so i want a clutch that is not a on and off switch as you said it , yet will clamp down even when speed shifted.

 

[shobote]

The only guy I have talked with that runs a Centerforce in a SHO is Doug Mellum up in Madison; been a few years but he said the holding power was great, but it chattered quite a lot upon engagement.

I had a Centerforce II in my 300 HP Datsun 240 race car and loved it; it had the centrifugal weights on the cover though and the model they make for the SHO does not.

 

[drivinhard]

it dont have to be as light as stock i just dont want to have to work out at the gym to use it, so the center force is a pretty good clutch for a 100 hp over stock? i mean the high revs jr in it now dont slip as long as you let it clamp before applying power, but we all know that isnt how we drive at the track nor is it how i want to have to drive. so i want a clutch that is not a on and off switch as you said it , yet will clamp down even when speed shifted.

The CF real world has no real increase in pedal effort. I've driven a few SHO's with it.

I haven't put a clutch in a SHO (other than my 92, which got an old IRT plate I had and a stock disc) in about 4 yrs, so I don't even know what SHO NUT, etc are selling these days. His 9 puck fibertuff ones were pretty popular for awhile, dunno if these are still used a lot.

The 35,000 ft view reality, is the SHO clutch is a poor/weak spot for the car. There's not much room to put a properly size clutch, the plates (and cars) are made in low numbers, so nobody makes their own plates. They are all based on Valeo, cast iron (very heavy) units. There are few cars that used a big cast plate like that, most are stamped steel, etc.

John Hrinsin runs a CF on his 3.4L stroker motor which makes pretty good torque, and I think it's held up pretty well. The stock disc will hold for a decent amount of torque (250 ft/lbs) but just don't get it hot.

IMHO if you are doing a clutch in a SHO, an alum flywheel is an all benefit/no downside deal. The SHO's PP is so heavy that there is still PLENTY of rotating mass even with an 8/9 lb FW (the little 9.75" SHO PP/disc/FW is almost the same weight as the 11" FW/clutch/disc in my Z06). About the only downside (I ran into) is if you like to drag a lot, and doing a lot of drag hot lapping (run after run after run) the alum doesn't have the thermal capacity that the big stocker has. But for occasional drag racing (especially if you don't slip the clutch much), road racing and street driving, it's the way to go.

 

[JustinSane]

yeah i get into alot of hot lapping as the rounds get down to the end cool off time gets short, area 91 is putting a new clutch in soon i will see how that feels, i do plan on running NOS and or eventually boost, so i i know a real light pedal clutch is out of the question, but a on and off switch type of clutch is annoying on the street.

 

[AREA 91]

SHO's are NOT drag cars. Of all the things a SHO can do well, Drag Racing isn't really where it shines. Besides, you can't afford clutches and labor rates.

 

[JustinSane]

yeah i guess we are blessed that we dont have to pay those crazy labor rates leaves more money for clutches lol.