Gear Flex?

Dick George · Posted: Mon Sep 23, 2002 2:05 pm Post subject: Gear Flex?

Has anyone experienced a problem with the 219 rear sprocket on the Rotax? I ask because I threw a chain in yesterday's race. I've covered all the typical chain problems, alignment, chain tensioner, motor mount, etc. The particular sprocket I had on really has a lot of metal removed in its design, more than my other gears.
Its possible my chain was astonsihed that the engine was actually running so well, and scared itself off the gear.

Nick Weil · Posted: Mon Sep 23, 2002 2:27 pm Post subject: Gear Flex?

quote
Quote:

The particular sprocket I had on really has a lot of metal removed in its design

What exactly do you mean by this? It sounds like you may mean the typical holes that some sprockets have to reduce rotating mass, or it also sounds like you have a wearing problem.

What did your chain 'sound' like while racing?

I can always 'hear' a loose chain, or a tight chain while I am driving.

99.9% of the people that have complained about the 219 chain problems, INCLUDING myself as Bill Wright can attest to, are overlooking something, not correctly checking alignment, tension, etc.

Last year I used to go through a chain every two races or so and thought that was typical. Now through experience, listening, watching and asking questions we replace chains on all four rental karts probably once every four to five events...

You may also want to take a look at the new Wipperman chain. It's design seems a lot more durable.

Nick Weil
SpeedQuest Rotax WebSite

[ September 23, 2002: Message edited by: Nick Weil ]

George Grenier · Joined: 23 Jul 2001 Posts: 105

I ran at Lime Rock this past weekend with the type of gear you describe. It is a very rough track and I knocked almost everything on the rear of the kart off (muffler bracket, number panel, battery cover) except the chain.
I also think alignment is key. I use a piece of milled ½” x ½”square aluminum about 14" long. I put it against the rear sprocket and get it to just touch the front sprocket. Eyeballing it never works.
I am on my second chain this year (10+ races) and only changed it as a precaution.

George

Jim Emerson · Posted: Mon Sep 23, 2002 3:32 pm Post subject: Gear Flex?

Nick-

"the new Wipperman chain"

Had any luck using a chain break on the links? I bent one pin trying to reduce the number of links. Love the chain when I can match the gears and motor adjustment to use it!

-Jim

PS-The gears worked on the big track...The rotax can haul the mail on a 1.8 mile road course with 16/75 gears!!! My neck is still sore from the straight away speed. Your gears finished 2, 3 and 4! We lost to a belt drive from Brian Kay (T2).

Nick Weil · Posted: Mon Sep 23, 2002 4:50 pm Post subject: Gear Flex?

As a public service announcement to anyone wishing to use the Wipperman chain. It appears that you also need to use the 'adjustable' 219 Chain Breaker in order to actually adjust the chain size.

You can get them from any worthy karting supplier (wink,wink).

Nick Weil
SpeedQuest Karting Webstore

Dai Feng · Posted: Mon Sep 23, 2002 9:51 pm Post subject: Gear Flex?

So how do you check the tension on the chain?

Dai

Jason Jones · Posted: Tue Sep 24, 2002 12:42 am Post subject: Gear Flex?

quote:
Originally posted by Dai Feng:
So how do you check the tension on the chain?

With the chain installed, measure the amount of up/down deflection at the mid-point of the upper section of chain between the sprockets. Rotate the axle to check this deflection at various points on the chain, this might indicate an out-of-round sprocket, or a chain that is stretched/tight at one point. If there's too much variation then bin the offending component. Use minimal finger pressure to test this deflection so that only the chain is moving. You should be looking for about half an inch of deflection, or one inch total (up plus down), for a 219 chain. Some chains (e.g. O-ring) are slightly "stiffer" and require a little more pressure to see the true deflection. Move the motor back/forward to adjust the tension, and be sure to lock it down tight when done. Chain tension is a bit of a personal preference, but the half inch figure is in the ballpark.
Hope this helps.
Jason

Glenn Holland · Posted: Tue Sep 24, 2002 10:24 am Post subject: Gear Flex?

I threw two chains last year. One was in practice at Streets of Willow, the other in the second heat race in the Nationals. That's not the place to throw them, but it made my miserable season complete. I lost it when I hit a bump exiting turn four of lap one, so I probably didn't have it set up right, like what Nick is saying.

Angel Figueras · Posted: Tue Sep 24, 2002 2:02 pm Post subject: Gear Flex?

Having been personally witness to Mr. George's predicament I can point to what I believe is the offending item: the engine mount.

Dick utilizes the often referred to "wimp” mounting brackets.... the kind that wedge between the two engine rails. My personal experience with this type of mount in Top Karts at least was that they slipped. Their propensity to slip was proportional to the amount of power delivery. In other words, Komer Jr 1.... rare slip. HPV, embarrassment level of slip. I can only imagine with a Rotax.

How about you folks.... which clamps do you use, the over the rail or the between the rails wedge? Experience?

I really would like to help my friend Dick with this predicament as it's becomming almost predictable. If the car runs well, the chain comes off. The alignment and tension was tits dead nuts on.

A.Figueras

Charles Pou · Posted: Tue Sep 24, 2002 2:59 pm Post subject: Gear Flex?

Dick, I too have excessive axle sprocket wear with my RMax. I think the problem with my kart is the chassis is flexing a little through turns/ bumps, etc. Throwing chains has not been a problem.

If you haven't checked it, check the axle bearing cassettes for excessive wear. If there is slop, the axle sprocket is moving side to side relative to the engine sprocket when you go through turns. :-)

Dick George · Posted: Wed Sep 25, 2002 11:39 am Post subject: Gear Flex?

Regardless of what Angle says, my mounting brackets are MANLY! Actually thats a good question, has anyone had a problem with these type of mounts?
The reason I thought it might be flexing the gear is because we've fixed just about everything else, including new bearings for this race. This particular sprocket has more material removed from the web area than any other I own. Maybe I should use all 6 bolts.

Jeff Cloud · Posted: Thu Sep 26, 2002 7:59 am Post subject: Gear Flex?

Definitely run all six bolts! On a lower power kart, you can get away with less than six, but I experienced fretting between the sprocket and hub when I only ran three bolts in my Rotax. Never had the same trouble with a Yamaha. BTW I use the AMC Racing mount. Very nice!

Jeff Cloud