Bergfelt Racing Enterprises, LLC
4412 W. 6th Avenue
West Mayfield Boro
Beaver Falls, PA   15010-1915
U.S.A.

(724) 462-7440

info@bergfeltracing.com

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Dually Hub

Dually Kart Rear View

 

The Bergfelt Racing Enterprises, LLC Dually Hub is intended for use primarily on unlimited/outlaw high horsepower oval track karts that have so much power and travel so fast it is difficult to find enough grip into, through and off of the corners.

The hub was first inspired when it was noticed that tires that were too soft for the right rear cornor of a kart would show indications of excessive wear or overheating on the inside edge of that tire first. Most often the remainder of the tire appeared to be ok but the tire definately lost grip during the race. That raised the question, wouldn't it be nice if tires could be made with a dual compound tread, hard on one side and a little softer on the other? Knowing that would not be practical, the next idea was to make a hub that allowed mounting two different compound tires; one soft, to work best at the beginning of the race, and a harder one to be warmed up to optimum temperature for the end of the race. Both would be working at the middle of the event. Of course it is sometimes advantageous to use the same compound for both tires. This is usually the preferred set-up on damp tracks.

The prototype hub was first tested in Unlimited All-Stars action in 2003. It produced the most noticable difference on low grip flat tracks. It's advantages were less pronounced on high banked tracks with a tacky surface. Generally, the dual right rear tire set-up allowed the driver to drive about 5 to 10 feet deeper into the corner before lifting off of the throttle with a Parilla Sudam powered kart. Drivers of twin engine karts that tend to "burn-off" the right rear tire found that the dually eliminated that problem.

Obviously when dual right rear tires are utilized the second tire would prodrude from the body excessively. This can create a potential hazard. When dual right Dually Front View rear wheels are utlilized. To eliminate the hazard, the user must provide extended nerf bars or body work to shield the wheels to eliminate wheel hopping potential. Allowing the wheel to protrude excessively is irresponsible.

Racers who have experimented with the dual right rear tire concept have generally agreed that chassis set-up is not that much different than with a conventional arrangement. It is recommended that corner weights be set with only the inner wheel installed. After scaling is complete, install the second tire. Most dually users set up the outer tire with 1/4 in more circumference than the inner tire. Some users have found that lower tire pressure can be used with the dual tire because there is twice as much tire supporting the same weight as one. One user has experimented with making the outer tire a bit smaller so that it is onlyh making solid contact with the track when cornering hard. His theory is that drag is minimized when traveling down the straights when less traction is needed any way. The idea does have merit and is an option that Dually Hub users have.

Some racers have installed dual right rear tires by installing a longer than normal rear axle and simply install a second hub and wheel. Although this method works, it is very difficult to change the inner wheel and tire when that is necessary.

With the Bergfelt Racing Enterprises, LLC Dually Hub, it does not take much longer to change two tires than it is with one. The Dually Hub allows swtching back to a single wheel set-up easy too since it does not requres a longer axle since it acts as an axle extension.

The Bergfelt Racing Enterprises, LLC Dually Hub is designed to fit 1 1/4" axles. It is also intended to be used with rims with a maximum of 3" backspacing. When using the Dually Hub, the inner wheel should be installed so that the valve stem faces inboard toward the chassis rails. This allows tire pressure to be adjusted with out removing the tire. The outer tire is installed in the normal manner.

Dually Hub

The Dually Hub is manufactured from high quality billet aluminum and aircraft quality aluminum tubing. The 5/16" diameter steel studs were made specifically for the Dually Hub. A back-up aluminum locking collar is supplied and is necessary to keep the hub from being pushed inward toward the chassis due to the additional grip.

Parts

$185.00 plus shipping.

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