On another part of this forum z24bb and I had been discussing drive-train parasitic drag and its impact on performance. Bombardier has always made reference to this in their Racing Manuals. I for one believe strongly that there is HP / torque to be found in drive-line binding, miss-alignment and suspension setup. Just to give an example: Two engines are built and dynoed to within 1% of each other. They are both installed into the same type of machine. One is 10 mph faster and doesn't drop rpms in the top end. Reason ?? The faster machine has had some time invested into "blueprinting" the chassis. The effort of rechecking alignment of the motor & jackshaft. The parallelism of the suspension swing-arms, skid-frame and driveshaft. The condition of the idler wheel bearings. It takes enormous amounts of engine power to overcome friction and such a little investment of time to reduce parasitic factors as mentioned above. z24bb has asked if indexing the chassis with points of reference (as done in drag racing) would be a good idea in sledding. I think anything that is successfully in one medium can work in another. Putting marks on the underside of the tunnel front and rear, center points in the front steering / suspension is a great way to routinely check the health of any machine operated in a "Hostile environment". ;)

This is a post from the Ski-Doo section. It was posted by "usedtoskidoo"


I want to reduce all friction when I get my 7c rev. I figure I will re-do and put in the best bearings i can get as well as balnce the whole chassis. I figure that I can get better mileage and overall performance this way.
Any other suggestions on how anyone has lessened the friction on their sled.



Thumbdoctor (or anybody else) can you give us some more specifics on how, and what to do, to reduce chassis friction?

Thanks,
Brian




SWRules

Here's a link.Chassis (http://www.geocities.com/Yosemite/campground/5379/genchass.html)

that artical was great ...should help a lot

good article: one question: What do you use on the axle to see if it is square? Just a framming square or something more hi-tech?

The last time i changed a track, it was on a s-2000 chassis. I remember the drive axle was held by the gear case on the right side. If the shaft is not square, doesn't the adjustment come from the re-mounting of the gear case?

thanks
Jon

Yes, With the chain case installed on the RH side (with chain & gears installed) unbolt the flanged bearing on the LH side. Look at where the shaft sits hanging off the chain case. The shaft should be centered in the chassis through hole. If it's sitting high you need to shim the bottom chain case mounting bolts, if it's low, shim the uppers. The shims are available from most dealers or auto body supply stores. While the LH bearing is accessable check it for run out and re-lube it. :)

All of this asumes that tyour chassis is square . In my case the sled is new so I am assuming that it is. If its not their is no baseline to start with.

Hey Thumb, How do you like your grizzly.....any mods.

I can add two additional items that work very good for chassis set up.

1. The chassis article says to make sure that the rear suspension is square to the drive axle. This is very important. It is also beneficial to make sure that it is centered from side to side. Make sure the hyfax is running down the middle of the clip so that there is no chance of it contacting the drive lugs.

2. Balancing of all the idler wheel makes a huge difference. I use a gadget that is made for balancing props for model airplanes. I machined up a small adapter that fits the ID of the bearing. You can add weight by threading very small machine screws into the wheels at the outer most diameter. Obviously, stay out of the rubber portion at all costs. Trick oil in the wheel bearings instead of grease works great also but requires more maintainance.

You won't believe how well your sled rolls.