Sprocket "bounce", hub problem?

I bought all my gears back in the 80`s. They were stamped with the gear number on one half and a line stamped between the halves to match them up.
Don`t know if manufacturers stamp the number on both halves now, they should. I bought a set of number stamps to stamp the other half my self so that
I don`t get halves mixed up. Always be sure to mount your gears in the same direction. I always mounted mine with the numbers facing the sprocket hub.
Also, make sure your chain is always going in the same direction. Before removing my chain I would put a tie wrap thru a link facing the inside of the kart.
It`s little things like this that make a difference.
 
FXSquad said:
Sounds like a split sprocket issue to me.

If split sprocket:
1- Install both halves of the sprocket on the hub and tighten all 6 bolts to just before they start to grab
2- Install chain, adjust to the desired tension and tighten the motor mount.
3 - Tighten all 6 sprocket bolts starting with the center bolts in each halve. Spin axle so one of the center bolts is furthest away from the crank and tighten, do the same with the other center bolt and then tighten the remain 4
Click to expand...

I dont do this, so maybe this will help. Thanks for the input!
 
Ok guys, we found what I think might be the problem. After looking at a few things I noticed the hub definatly had a off center look. After a better look with the gear off, the mounting studs are also off center from the axle, around an 1/8 inch or so. I tried to take a video of the hub but my phone cant seem to capture what me and another guy see. So, I measured the bolts to the hub shoulder that the gear is supposed to center on and sure enough they are off. I think we are getting sub par parts and I dont know why or how. We are going to find a different supplier and see if their hubs are better. I know an 1/8 inch doesn't sound like much but I'd bet that when heat is introduced, with torque from the motor it really starts to accentuate the problem. Also I can can center the gear on the hub, but I'd bet during the race it moves into the bolt postions and throws everything off.

Anybody have a good supplier for hubs, and possibly gears?
 
I just got a nice one from MXK in Elma, NY from that auction site... But they'll sell direct if you call them. And there's always BMIkarts.com and PMI as well... And the usual big brick and mortar stores that have online storefronts...(CKI, Comet, Russell, Carlson, Rieken's, et. al.)
 
Lucky_7 said:
Ok guys, we found what I think might be the problem. After looking at a few things I noticed the hub definatly had a off center look. After a better look with the gear off, the mounting studs are also off center from the axle, around an 1/8 inch or so. I tried to take a video of the hub but my phone cant seem to capture what me and another guy see. So, I measured the bolts to the hub shoulder that the gear is supposed to center on and sure enough they are off. I think we are getting sub par parts and I dont know why or how. We are going to find a different supplier and see if their hubs are better. I know an 1/8 inch doesn't sound like much but I'd bet that when heat is introduced, with torque from the motor it really starts to accentuate the problem. Also I can can center the gear on the hub, but I'd bet during the race it moves into the bolt postions and throws everything off.

Anybody have a good supplier for hubs, and possibly gears?
Click to expand...

1/8th is .125 so quite a lot.
Phantom has good stuff.
I would try a hub your gears could be fine.
 
Good Job!:)
1/8" or .125" is huge.
I would throw it out if it was 1/2 of that.
Your video with the hub in a lathe tells me that you must have a dial indicator and a mounting base.
It would be interesting for you to turn the lathe by hand and show everyone the run out with the indicator.
As long as you have gone through all this work it might be wise to measure the axle at the same time.
 
Jimbo said:
Good Job!:)
1/8" or .125" is huge.
I would throw it out if it was 1/2 of that.
Your video with the hub in a lathe tells me that you must have a dial indicator and a mounting base.
It would be interesting for you to turn the lathe by hand and show everyone the run out with the indicator.
As long as you have gone through all this work it might be wise to measure the axle at the same time.
Click to expand...

We installed a solid billet ARC hub. For 21 dollars I think its a steal, and it was perfectly true when we checked the axle and hub in the lathe.
 
What I saw in the video is either some of your bolts are bent or the threads in the hub were not put in perpendicular. I don't see anything in the video to cause your gear to not be able to be installed and run true.

I think if your using a chain guard and it's being installed next to the inside of the hub it's causing the gear to be installed out a little on the stud. My suggestion is put one side of the gear guard on the outside of the hub washered to help hold it in place, then put the gears and the other gear guard on the inside of the hub.

Where the studs come out of the holes on the hub it rolls true. If the gear is put on butted up to the hub it will also roll true.

I guess I should ask if you use a gear guard? ... :)


edit: another idea. Since to me where the holes are the studs run true, why can you just put a nut on the end of a stud that's out of line and hit it with a hammer to knock it down a little. If the threaded holes are not put in perpendicular then the hub is probably junk. But because the holes seem to be in the right place measured out from the center, I still think you likely have some sort problem other then the hub.
 
Another dumb question from me.

If the new hub fixed the problem what was the brand/make of the bad hub?
That way others can stay away from the junk hub brand which has zero quality control.
 
Some of the sprocket hubs are way to fragine for my liking. Some of them are made like fishing lures. (Riddle for the day)
They make them so light in an effort to save weight they just aren't strong enough for the rigors of Kart racing.
 
Jimbo said:
Some of the sprocket hubs are way to fragine for my liking. Some of them are made like fishing lures. (Riddle for the day)
They make them so light in an effort to save weight they just aren't strong enough for the rigors of Kart racing.
Click to expand...

"Riddle for the day" ... hummmmmm... ????? got it ! yer a Muskie fisherman!


Humor of the day. What's the difference between bass and muskie fishin?


answer: Bass lures are $10 and muskie lures are $100. ... :)


... once caught a bass in the mouth of my muskie lure.
 
That definatly shows a problem.
Paul has some valid points ; though for 21 dollars I'd toss the old one in the use later pile , after salvaging the quick start bolts.
 
flattop1 said:
That definatly shows a problem.
Paul has some valid points ; though for 21 dollars I'd toss the old one in the use later pile , after salvaging the quick start bolts.
Click to expand...

I 100% agree with you about 21 bucks, forgetabout it it's fixed. Stuff just brings on questions and I ask them. No big deal weather their answered or not, it's just curiosity, not knockin anything. ... :)
 
paulkish said:
does that mean you fixed the problem?
Click to expand...

We shall see when we mount the sprocket. The studs in the video where are very straight, the hole location was the problem, I could take a video as suggested with indicator. But im not going to waste anymore time with those junk hubs. The difference in the arc and the bad hub was very noticeable. Oh, and the brand is from a local kart shop, we think that they are getting blem parts and selling them...No more for me.
 
Fishing lures are made to catch the fisherman first, catching fish is secondary.:)
Some parts (bling) are likewise.
 
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