Are all axle clutches considered non-vintage? I've seen a few that would seem to fit into the new time line. Most, I admit, I've seen in enduros but a few were available as sprint clutches as well.
What about the rubber band drive systems, (Gilmer belts)?
I remember something about axle clutches in the rule book I got when I joined VKA, ( I can no longer find the book), but the time lines have changed since then. Does this mean that that you can use an axle clutch on your 1985 chassis and engine in the promoters option classes?
Thanks,
Lance Mearing
VKA #264

A number of Vintage Enduro Clubs allow the Horstman axle clutch on foreign engine karts.
Pre-1985 also.
The obvious reason is they are more bullet proof than the early dry clutchs and they out last the early axle clutchs.
As for Sprint, it seems to me that the Promoter Option would be up to the Promoters.
Hope you get soem kind of answer.
I am interested in this out come.
Rick Chapman

I thought axle clutches were not illegal in VKA sprint races. I'm pulling my hair out trying to get a Burco clutch dialed in on my Panther X, missed the second and third heats at New Castle because of clutch isssues. I run a Hegar Mystery clutch with a belt drive on my Concept Enduro and it's bullet proof, no clutch isssues at all. I'd love to put a Hegar axle clutch on my sprinter and throw that Burco in the botttom of a river!

Lance,

All of the early (pre 1985) axle clutches have to be spun around 2,000 rpm to engage which equates to roughly 65mph so they will never hook up on a typical sprint track. The gear ratios used on most sprint tracks are just to low to make them work. It might be possible to modify one or more of them to increase the weight of the shoes, reduce spring tension or create more leverage but that will take some advanced engineering and machining skills.
Also, the belt drives are pretty much enduro track only as well. To get the gear ratio needed for a sprint track the front pulley must be too small and the belts fail when they have to wrap around a tight radius and take all the load on fewer teeth.
Stick with the engine clutches for the sprinter.
Steve O'Hara

Thanks for the information, guys.
As I said the only axle clutches I've seen were on enduro karts and they worked very well.
Steve,
it seems to me that I once saw an advertisement for a Hegar axle clutch that could be had as either an enduro version or a sprint version. I don't know how that was done and apparently there are no parts for them from Hegar any longer.
As for the Gilmer Belt drive I guess a jack-shaft could be used, I saw that on a Yamaha powered dirt kart. Don't know about the power loss, though.
Lance

Lance,
I tried to use a Hartman axle clutch a few years back and it worked well, up against a Reed Valve engine.
BUT, it took a lot of work and many days at the local track on practice days, to figure it out.
That is about the only dry axle clutch that I know of that you might make work.
Horstman makes a Sprint oil axle clutch.
I had one of those and it worked great up against an Open K-78.
Easy to adjust and consistant.
But Vintage??
I doubt that dog won't hunt...
Good Luck.
Rick

Lance...I know those Burcos are tuff to deal with...but, if yer gonna throw it in the river, let me know.....

but again...I'm sure there are guys out there that can make it work for .....

VKA378
Gary W

Don't forget the Tripp axle clutch from the mid 70's. It was specifically designed for sprint racing and is an absolute marvel of engineering. I've got one that I picked up a couple of years ago, but alas no instructions on how to set it up. I know Ted Johnson used to run one, but said it was a real pain to it to work right.

Lance, when the Burco clutches first came out, a friend of mine, who I crewed for, Mike Hill, was a very successful enduro racer that used that clutch with great success. When he decided to do some street races, we worked long and hard at getting the Bucro to work as a sprint clutch. As Steve O'hara suggested, we made special heavy weights and had lighter springs made. The clutch did work good, but it preferred the early asbestos style shoes (light brown in color). When we tried the later generation shoes, they would not last very long. As I remember, we piled weights on top of the weight pockets (which were full of the round discs). Doing that, it is a must that they be safety wired. The clutch will work--if you have a buddy who can wind springs for you or are willing to pay the set up charge to have springs made. Also, it was critical that you carefully measure the spring setting, to keep both sides the same. We kept records on spring height settings, and found that very helpful. All of that said we were running a Haddock tt-25, and the clutch setting was above 10,000 rpm. Best of luck.

Dan's right. I got two Tripps from Pete Michel back in the late seventies. It was a really neat piece of engineering, but it didn't work well on the Florida Street Race sprint series; you couldn't twist it tightly enough to get consistent slip, even though the long street straights and relatively gentle corners kept the RPM up high. Tripp even sold a steering wheel mounted remote adjuster. I also had a Hegar with the sprint weights and some internal mods that we ran on the streets. The linings were experimental ceramic ones that I got from Terry Hegar. I ran that in B Limited and 100cc Open, and it did quite well on my radical 101, and my Atlas open and LMR open. My buddy Charlie still has it (he still has the Atlas and the LMR, too). There was a young guy named Chris from Jacksonville who ran reed light in the street series back in the late seventies/early eighties. His dad modified Bystrom axle clutches for him, and he was a rocket ship: he won tons of races with his '91/Bystrom. I always thought that the Bystrom was suitable for sprint modification. Ted Johnson

In the mid 70's I ran a Tripp Axle Clutch in Stock Lite at the Barnesville Winternationals and won the 1st heat. The drum however cracked at the axle and it was inconsistent from then on. Wicked engineering! In '73 we actually drove to Tripp's place in Texas and met him. He told us that he was the inventor of the original Weedeater! The pivoting shoe engagement was controlled by a small cam and wheel which rode up a ramp. So it was legal then and should be legal now! Also saw the Horstman oil bath Axle Clutches in Vegas a couple of years later at the 'World Championships' but the direct drives slayed all of the N. Americans. I think Ron Emmick ran the best that weekend.

As for Burcos Bill Adkins was one of the first to use hard chromed drums. His secret was to use very worn out shoes with an 'X' machined across each face. The thinnest shoes you could find! Then load them up with 3, 4, even 5 plates on each shoe. New shoes would not work as after a couple of laps they retained too much heat and cooked the oil. I used half and half X-15 and X-30 Burco oil and serviced the shoes with a triangle file every heat. Fresh oil natch. Burco came out with the dreaded rings (attempting to keep the shoes away from the drum on trailing throttle) which went square immediately...threw them all away! Burcos still rule.

Just a little history and my first recollection of chrome drums was by Dan Lumello from APPCO. He used to build really peaky engines (the old Stk Appearing and Open days) and had a hell of a time getting clutches to work and the chrome plating helped the clutch slip at the lower RPM's. (Bill Adkins built similar engines as well) IMO, they were more of a benefit on B Ltd's and Duals that had power to burn. My experiance was the chrome drums slipped in mid range and I got better results running the stock drum and building mid range engines with milder porting and pipes. (Carbs worked better too!) I remember Kyle Adkins putting a chrome drum on his Mac at Barnesville and getting murdered on the starts as well and going slower. He put the old drum back on and kicked some more azz! lol

Mike