Question: Clutches for alcohol motor

Ok silly question time, I am being pretty generalised here but whats the deal with clutches on alcohol fueled engine (any setup fueled with alcohol). It seems alot run pedal clutch, what are the whys and why nots of that setup?

I have heard some running crowerglide style setups but it has me confused how does the setup and performance differ from a pedal clutch, most of the info I find on this is focused on nitro cars.

The main thing that people seems to comment on is you have to launch from idle with a glide is that true? if yes then why?

I have also heard of people running lockup clutches on alcohol now how does that differ from a pedal and a glide style clutch?

Sorry for any confusion I am just trying to get my head around this.

 

Most run pedal clutches because of the RPM range of the typical blown alky, or at least the screw blown stuff.. You could run a glide, but it would be a little more difficult to get the flare in low gear RPM you're looking for and maintain the plate load you need to move the car. A/Fuel cars flare around 4,500-5,000 when they step on the gas and the clutch kicks in with their glide clutch. Top Fuel hits 8,000, BUT they have a bearing held in place to let them flare, a luxury most Alcohol cars don't have.

Main difference between a glide clutch and a pedal clutch: You control movement of the pressure plate with the pedal, as the levers are actually attached to the pressure plate by a yoke or clevis system and do the lifting when you press the pedal. The springs involved in this clutch also PUSH the pressure plate, adding to the total pressure.

The levers in a glide clutch actually just rub the pressure plate. They are held in place by pivot pins, just like the pedal clutch, but there is no clevis system attaching them to the pressure plate. When you push the clutch pedal in a glide equipped car, you are merely pushing the levers back to their flat/zero point and that allows the stall springs to lift the pressure plate. Think of a glide clutch like a centrifugal clutch on a go cart, weed eater, chain saw, etc... When it idles, it doesn't move, give it some RPM and the forces overcome the springs and the clutch applies. Same thing here, just bigger. The springs involved on this style actually PULL on the pressure plate, trying to keep it from engaging the clutch pack. So instead of dumping the clutch at a pre determined RPM, you find the balance of counterweight and stall spring pressure to achieve the RPM and clutch engagement you're looking for. The levers typically apply a lot more plate load and are heavier than a pedal clutch, so as for revving it up with your foot on the pedal, it may prove to be difficult, but I don't know. Never tried.

I think that's where the problem comes in for running a glide in blown alky drag cars without having clutch management like a top fuel car. Finding the right combination to let the motor get up, yet still have enough plate load to keep the clutch with the motor fighting all the stall spring you need to let it get up. Not to say it couldn't be done, just my opinion on why you don't see more glide clutches in Blown Alky drag cars. You see them in Nostalgia, in similar RPM ranges, but the nitro they use appreciates the load and helps suck them out of weak areas that straight Alky just gets the wind knocked out of it.

If you watch those big 5 engine tractor pullers, they run the motors around 8,000-8,500, their glide clutches actually start tugging the vehicle about half that RPM. A typical Top Alky car is just hitting it's power band around 8,000.

As for Lockup clutches, I wouldn't get too concerned about them. Unless you run an outlaw series, they are typically illegal... And even at that, I haven't seen too many instances where a lockup clutch is any faster than someone who knows what they'e doing with a regular clutch. At least with Alky.

 

I think you will find all TopDoorslammers in Australia use lockup clutches.

 

Clutch my disk

has anybody tried a top fuel cannon style controller on a alky car yet? i know its usually illegal, but wonder if anybody has tried one with or without a trans?

 

I know the doorslammers in australia are or have run lockup clutches.

 

I don't know to be honest. I know a lot of the ADRL blower cars used the AFT style cannon that mounts on the side of the can and controls the cross shaft.

And as for lockup clutches.. Every clutch is a lockup clutch. If you're not allowed to run a cannon type system on a standard clutch, then what you have is a "staged" clutch. These are typically what people refer to as lockup clutches. Two different types of levers working together. There are some that run mechanical interference with springs, which are supposed to be illegal in most applications where the rules say there can be no mechanical resistance on the levers. Most, to stay within the window of rules will have primary levers and secondary levers like an A/Fuel or Top Fuel clutch that all release off the bearing at the same time. Secondary levers are generally lighter, and have to spin faster to apply significant force. Door slammers love them because they are heavy.. have to be softer down low to get the car moving, but need the extra force to keep the car accelerating. I know these have been tried in Top Alcohol before, were they any faster? Maybe, but I think what it really did is let you screw up in the first 60-300 feet on your clutch/gear/car tune and still salvage a decent run. Most of us can't figure out how to optimize what we have so it always sounds like a good option. lol.