Jackshaft considerations for reeds

What clutch are you hoping to use that can withstand the rpm and power of a reed when direct mount to crank.
 
I know of someone running Ital Red clutches on their twin F100, so that's an option, though when I had an ARC, it had the same type of clutch and that broke and I was only seeing 14000rpm. I'm in two minds, though the idea of being able to play with the clutch slip over a useable rev range does appeal.
 
b0son said:
I know of someone running Ital Red clutches on their twin F100, so that's an option, though when I had an ARC, it had the same type of clutch and that broke and I was only seeing 14000rpm. I'm in two minds, though the idea of being able to play with the clutch slip over a useable rev range does appeal.
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Lol, been there done that, all my low stall yami type clutches stopped becoming clutches once I ran up to 18,000rpm. The steel stretches and they become semi locked sort of thing. The Ital red and all other low stall clutches we have in Aus inculding the Tag stuff is pure junk. and will just keep causing you headaches.

Actually thats a lie, Horstman have a pretty good clutch for the PRD fireball. But then it never gets turned like an F100 on a sprint track.
 
Go with the ignition mounted belt driver and back to a J/S with either a Birky clutch or a gear with a dry 3 or 4 disk clutch and use one our clutch pipes and not the VeVey style pipe.jmo
 
I took one of my drivers and used a 12m. x 1.0 tap so it can replace the nut on the ign. side, might need to trim it some , but you can get a real tight fit close to the ign. rotor. That way you'll never need a shaft extention.
 
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arc100 said:
You have to run the #35 chain which you cant get in a competition chain in Australia either. Well at least I've never seen it. I get all my stuff from USA. You will need all the consumables as spares because you wont be able to use anyone elses stuff because it just doesnt excist here. It cost a few bucks to set it all up and you WILL have to mess around a lot to get it to fit but once you're up and running you will NEVER EVER go back to a DD (direct drive) set-up.
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Just run a Panther HTK #219 chain Problem Solved. 1 chain 1 whole season 50hp (No Joke/No kidding) & run the Tomar TD-43 and/or the SMC and/or the Big Horstman Sprint Axel clutch
 
b0son said:
arc100, thanks for the offer, I will probably get in touch after the new year when I've had a chance to have a good look at all my options. I suppose my most immediate question right now is... how do you start it? I have an external starter for my old KT100s with strike clutch, and thought of putting the starter nut on the jackshaft, somehow ... is this appropriate? my engine has a splined crank so no way to attach anything direct to engine.
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You can tig weld/fill the valley s of each spline then machine them smooth on a lathe after . Just go real slow
 
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ttownwideglider said:
For the kts we use the jackshaft as an overdrive setup. We set the ratio at about 2.7-3.0 to 1. So the engine is turning about 10500rpm and the jackshaft i and clutch are turning about 3,874 rpms. We lock the clutches around 10,000-11,000 rpms where ever the powerband hits for the engine. Once the clutch is locked in it doesnt matter how many rpms you turn on the top end becuse the discs are no longer slipping. The overdrive helps greatly with the amount of wear the discs are subjected too becuse the clutch is turning so much slower than the engine when it locks up. A lot less expence in clutch rebuilds. The belt drive for the jackshaft will require a crankshaft pully on the kts it keyways on a tapered shaft.Dont know how your engine crank is set up but some guys make special drivers for their engines. The rear pully on the jackshaft is where the large overdrive pully is located. This also eleminates the weight of the clutch on the crank so the engine seems to accelaretes faster.Plus this make gear ratios extremly flexable, you can change the # of teeth on the clutch driver, the# of teeth on pullys for the overdvie ratio. You can go to a very low ratio 13 to 1 with a much smaller axel sprocket for short tracks. Hope this helps you. Some of the other guys on here my be able to help you better with your type of engine. Jack Burroghs and Jon Brogden or John Hilton can probably help. See ya Mitchell
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" we use the jackshaft as an overdrive setup" or do u mean as a gear reduction setup ?
 
I kinda solved the whole issue by using a left hand drive kart with a Kt100. The clutch and drivers are all inboard, and the kt is set up for LH drive.. This allows a belt drive off the crank, and 219 chain off the clutch. Clutch is set for ~ 4300, which works out to 10,300 at engagement. I am using a 2 disk clutch. Real nice off the line.

Going to a modified tt75 this year. Just wish it was an electric start.
 
IMHO, your best bet is to use, "Regina", #35 chain and a belt primary, in the previously stated 3.0 or 2.71 ratios. Mitch, that combo is under drive. If it were O.D. as you stated the clutch would be going much faster than the engine.
 
Yeah Jack mybad your right. The main point is that clutch sees much less wear and were capable of running a very high gear ratio without the gaint axel sprockets.
 
I've been kart racing since 1980, and when the J/S concept came along, I fought it, then some yrs. back I bought a K-35 that included a J/S, and now It's all I run, think I have 4 or 5 of them, all Buller, because they are proven and easy to adjust. Only 1 belt problem since 2005, buy a new one every yr. and write date on it with a silver marking pen. Loan my old ones , or give them away.
 
ttownwideglider said:
Yeah Jack mybad your right. The main point is that clutch sees much less wear and were capable of running a very high gear ratio without the gaint axel sprockets.
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wideglider my correction of your overdrive vs underdrive wasn't a personal nit pick which perhaps spurred your "big boy pants" chastening in the what's a kart part worth thread. It was an general info correction for all newbies who might have erroneously gleaned a j/s was an overdrive or quasi taller gear rather than more accurate quasi underdrive or gear reduction device. It seems it was taken personal, and caused a retort but that was not the intent. Sorry if you took it like that. JMHO
 
arc100 said:
What clutch are you hoping to use that can withstand the rpm and power of a reed when direct mount to crank.
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When I started karting, (1966) the 100 CC Komet and the 135 CC B bomb all had clutch's mounted on extension shafts on the ignition side.
Running a clutch is a whole lot different than direct drive. I raced a K88 with direct drive for a couple of years so I speak with some experience. First off, you're not going to see 20,000 RPM. I think you'll find yourself running a lot less gear with the clutch. You'll also find, coming off the corners, you'll have the clutch set so that the engine is turning an RPM right at peak torque. (10,300, +/- some). Of course that could change some depending on your engine rules.
So more RPM off the corner, and less RPM on the top.
We raced a KT 100, with a Horstman 3 disk clutch for years, and would regularly see 15,000 -15,500 RPM. That's in the stock class. Others, running DD, would see 17,000 plus with the same stock class engine.
When I first started racing DD, I was really surprised at how much faster than the DD was vs. the clutch. But that was before the disc clutch. I don't know if the same would be true today.
Comments compliments criticisms and questions always welcome.
 
You are exactly right, (arc100) and hence the advantage in jackshaft mounted clutchs on the secondary side. By removing the clutch from the engine you do several things. First and foremost you remove a lot of weight, heat and a lot of inertia resulting from clutch diameter. The pto mounted clutch induces heat into the engine which robs power. It also is not the most balanced since it most often is running out of balance because of the changing shape and loose components that constantly change. Also the engine mounted clutch has to be large enough to dissipate heat yet small enough to reduce inertia. Coupled with these power robbing factors are the limited number of teeth on the drive gear and chain that continually have to "facet" around also inducing heat and harmonics directly into the PTO. NOW ENTER THE MODERN DAY JACKSHAFT: The design of modern day jackshafts are far more in significance than to simply allow for gear reduction. The std BULLER primary side with an aluminum pulley of 21 tooth drive to 57tooth driven allow a perfect 2.714 reduction to the clutch on the secondary. This allows for a dry disc clutch to operate at lower rpms and less heat while the engine sees very little comparative weight. Consequently the engine sees virtually no heat induction and pto vibrations are greatly reduced and the inertia of the lightweight aluminum driver is very low. Often the low speed secondary side allows for a larger chain driven clutch of 20-24 teeth with an smooth rotating assembly. Our Controlled engines back in the day were easily operating in a 12-17,000 rpm range with this drive and simply the only way to go on dirt ovals. There are other factors that are enhanced by the jackshaft in engine placement and clutch operation that allow an oval kart to corner better. The forward placement of the engine balances the chassis better, and the disengagement of the drivetrain allow the kart to make a quicker pivot through the center.
 
What ever jackshaft configuration you use with a boxstock 4cycle type clutch, your first consideration is clutch engagement rpm.

What ever clutch you use, decide what rpm will be best for clutch engagement and then work pulley and gear sizes from there. IMHO, it's better to engage at a lower rpm, with fewer heavier weight and springs; then at higher rpm with more, lighter springs and weights or lower rpm with more, lighter springs and weights . Higher engagement rpm with fewer heavier weights is not an option to consider and should be avoided. What I consider a low 4cycle type clutch engagement speed to setup your clutch for is 3200 rpm.

If you have a choice between taller or smaller input to operate the clutch, IMHO go with smaller because IMHO it will stress weaker engine and clutch parts less and stronger axle parts more. Your choice between smaller or taller clutch input, will also make you choose between normal gearing on the axle in the 60's+ tooth range and mine axle gear sizes. I chose mini axle gear size and had no problems. In fact using mini gears will solve clearance issues if you want to put output to the axle after the jack shaft, inside the right rear bearing hanger.

Edit: I think the best configuration is engine output pulley on the inside driver side of the engine. Then back to jackshaft input with a belt. The other outside end of the jackshaft mounts the 4cycle type clutch and then back to mini gears on the axle. The mini gears will allow you to run your chain from the clutch to the axle above chassis rails.
 
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