I am looking at some Kind Sand cars which are small sandrails powered by a gen 1 engine. Some have the tooth skipping problem despite having the gears backcut. I know this a different application that what you guys build for with a higher load being placed on the transmission than what it is intended for. Has anyone has gears back cut possibly by someone that didn’t do the best job, continued having the tooth skipping problem, and then solved the problem by having the gears back cut by someone better? Or is all backcutting the same? I am trying to figure out why some of these sandcars have this tooth skipping problem (with backcut gears) and others don’t. Thanks.
Tooth skipping and back cutting
- Thread starter EastMT
- Start date
Depends who cut it and what cut they did. Different angles for different things, etc. Robinson is a good place.
Also those cars definitely need billet shift forks and heavy duty shafts, you can have a perfect gear set but if the shafts are bent, the forks are bent, you’ll still have issues.
Also those cars definitely need billet shift forks and heavy duty shafts, you can have a perfect gear set but if the shafts are bent, the forks are bent, you’ll still have issues.
So it’s possible that they did the wrong cut and having new gears cut by Robinson would make them last longer? Thanks for the tip about the shift forks and shafts.
Assuming they were cut incorrectly once, they may not be able to be repaired, but replaced and then cut.
They would have to be measured and inspected first.
From what I have read you might as well replace with a stronger one while you have it apart.
Fyi
Bent shift forks are not uncommon to find in most sportbike engines.
The main causes being abuse, and more so, the front sprocket nut being broken loose with the transmission in gear, especially using a breaker bar, as the torque is applied much slower than with an impact.
And, it's not just the forks themselves that can get bent, but also the pins on the opposite ends of the forks, that slide through the grooves in the shift drum.
The drum grooves can even get a lip or sharp edge along the sides of the groove/track, and they may need filed smooth.
The original problem with the gears themselves, specifically 2nd, and sometimes 5th, has no exact cause.
Some bikes have a slipping 2nd, some don't, with mileage, maintenance, or abuse not really seeming to be a factor one way or another.
What the probelm really seems to be is, is that some gears seem to be on the high end of tolerance, and other gears on the lower end.
Now, randomly assemble these parts, and with a little bad luck, you get 2 or more parts that eventually don't work as well together.
A new angle can be cut on the gears to help them mesh better, but as said, if that doesn't correct the slipping, then there is likely not enough material left on the gear(s) for them to be cut again.
Buying a new 2nd gear, or even all of the gears, forks, and transmission components garauntees you nothing, those too can slip.
This is almost completely a Gen1 problem as well, and it is rarely a Gen2 issue.
The Gen2's have a slipping 2nd about as much as any other sportbike, which in those cases, almost always comes from abuse.
Bent shift forks are not uncommon to find in most sportbike engines.
The main causes being abuse, and more so, the front sprocket nut being broken loose with the transmission in gear, especially using a breaker bar, as the torque is applied much slower than with an impact.
And, it's not just the forks themselves that can get bent, but also the pins on the opposite ends of the forks, that slide through the grooves in the shift drum.
The drum grooves can even get a lip or sharp edge along the sides of the groove/track, and they may need filed smooth.
The original problem with the gears themselves, specifically 2nd, and sometimes 5th, has no exact cause.
Some bikes have a slipping 2nd, some don't, with mileage, maintenance, or abuse not really seeming to be a factor one way or another.
What the probelm really seems to be is, is that some gears seem to be on the high end of tolerance, and other gears on the lower end.
Now, randomly assemble these parts, and with a little bad luck, you get 2 or more parts that eventually don't work as well together.
A new angle can be cut on the gears to help them mesh better, but as said, if that doesn't correct the slipping, then there is likely not enough material left on the gear(s) for them to be cut again.
Buying a new 2nd gear, or even all of the gears, forks, and transmission components garauntees you nothing, those too can slip.
This is almost completely a Gen1 problem as well, and it is rarely a Gen2 issue.
The Gen2's have a slipping 2nd about as much as any other sportbike, which in those cases, almost always comes from abuse.
michael parris heuberger
Registered
Hi. I had a GPZ 1100 that had the problem in 6th gear. It was a defect in the trams front new.
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