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-   -   Differential rear on go cart (http://www.diygokarts.com/vb/showthread.php?t=41174)

Ltcjc 04-28-2019 04:51 PM

Differential rear on go cart
 
I have a Ken - Bar cart w/22" rear, 8" front tires, Predator 212 engine, 30 series TC/the rear is a differential axle. Issue: when the rear end is on jack stands, the TC/Engine spin both wheels with no apparent issue, however, when I get in the cart and try to drive I may get 15' before it stops. Engine still wants to go, but cart won't move. Any suggestions? I can't seem to find a "thread" on issues with differential rear ends. Thanks.

Tpdingo 04-28-2019 04:54 PM

Sounds like a gear ratio issue over a differential issue. If it was a diff. issue, it would just not go anywhere, period.

itsid 04-28-2019 05:17 PM

^^ THAT!

'sid

Joe-405 04-28-2019 08:28 PM

I’m gonna have to agree with above statement also.

What is the current gearing sizes ? Those big rear tires is why were suggesting that FYI.

landuse 04-29-2019 12:08 AM

I agree. Tell us what the tooth counts are all round for the sprockets. Better yet...post some pics as well

Ltcjc 04-30-2019 12:54 PM

2 Attachment(s)
Was out of town, thanks for the replies. The axle has a 60 tooth sprocket, the T/C has a 10 tooth. Still new to this site, trying to figure out how to insert pics. Thanks for your patience.

Ltcjc 04-30-2019 01:04 PM

In the pics: 1st pic, 6" TC pulley, 10 tooth sprocket, 60 tooth axle sprocket. All help's appreciated. Thanks

Tpdingo 04-30-2019 02:03 PM

Quote:

Originally Posted by Ltcjc (Post 521536)
In the pics: 1st pic, 6" TC pulley, 10 tooth sprocket, 60 tooth axle sprocket. All help's appreciated. Thanks

Well thats your problem. 6:1 on 22" tires is never going anywhere. You need to go somewhere near the 7.5-8:1 range. I bet your belt is also slipping up a storm as well.

Also:
Are your tires fully inflated?
Are your brakes loose when not engaged?
Is your engine allowing full RPM(throttle screw backed out)?
Is your road/driving area inclined in any way?
Who is riding this kart and how heavy are they?

Ltcjc 04-30-2019 02:12 PM

Tires are fully inflated; disc brakes not dragging (spin freely on jack stands);Haven't checked the full rpm on new 212 engine; mostly flat field area, no hills, etc.; 185lbs (mature grandfather...). The other issue is I'm not able to replace/remove the axle or axle sprocket. Suggestions? Thanks.

Ltcjc 04-30-2019 04:20 PM

Regarding the rear axle: it's 1" (micro'd out at 1-1/128th?) - I'm assuming it's 1". It's attached to the frame by 4 - Axle bearings (triangle shape w/3 bolts & nuts each). The support is triangle shaped and welded to the cart frame. The bottom of the support is open (triangle with cut-out on bottom) I thought all I had to do was to unbolt all four bearing flanges and drop the axle out. For some reason it didn't work out that way. I'm not sure if I'm supposed to: pull the hubs off; and pull the axle shaft out? If so, I've got a problem as the hubs are rusted to the axle. Any hints or suggestions? (I've already thought of just cutting the axle into pieces and replacing it with a live axle kit.....or not? Thanks for all the comments for the rookie here.

Functional Artist 04-30-2019 06:10 PM

Quote:

Originally Posted by Ltcjc (Post 521357)
I have a Ken - Bar cart w/22" rear, 8" front tires, Predator 212 engine, 30 series TC/the rear is a differential axle. Issue: when the rear end is on jack stands, the TC/Engine spin both wheels with no apparent issue, however, when I get in the cart and try to drive I may get 15' before it stops. Engine still wants to go, but cart won't move. Any suggestions? I can't seem to find a "thread" on issues with differential rear ends. Thanks.

It goes ~15 ft. before it stops? :idea2:

If the gear ratio was too high, it seems like the kart wouldn't (want to) move at all
...just sit there smokin' the belt :ack2:

Sounds like somethings binding.

Have you driven this kart before?
...with the same set up (as current) motor, TC, tires etc.?

Ltcjc 04-30-2019 07:35 PM

The cart originally had (I think) a B/S 8hp "snow thrower" engine bolted to the engine mount (the engine was "toast"). I replaced all the tires with exact replacements. The Predator 212 is a new engine. I started with a cc and took two laps around the yard and the cc was smoking hot. I replaced the cc with a 30 series TC and was able to take one lap around the yard before the belt just spun, however, with the rear end up on jack stands, the TC spun the tires with no problem. Put the rear end on the ground and the TC just smokes the belt. I shut it down and .........

Tpdingo 04-30-2019 07:38 PM

Quote:

Originally Posted by Ltcjc (Post 521574)
The cart originally had (I think) a B/S 8hp "snow thrower" engine bolted to the engine mount (the engine was "toast"). I replaced all the tires with exact replacements. The Predator 212 is a new engine. I started with a cc and took two laps around the yard and the cc was smoking hot. I replaced the cc with a 30 series TC and was able to take one lap around the yard before the belt just spun, however, with the rear end up on jack stands, the TC spun the tires with no problem. Put the rear end on the ground and the TC just smokes the belt. I shut it down and .........

Well no kidding. Thats the reason, the engine is TOO SMALL!! I mean that was a 8hp briggs. That thing was a cast iron torque monster which would have made sense with 22" tires. The little 6.5hp motor doesn't have that kind of hp, none the less TORQUE! You really need atleast the 301, and if it fit a 8hp briggs, it can probably fit a 420 with an issue. Also with 22" tires, I bet it came with a 30 or 40 series stock.

landuse 05-02-2019 12:08 AM

Basically you have a few problems. As it sits at the moment, the gearing is too high and you need to lower it. If you cannot do that for some reason, then you will have to get smaller tyres...like 16-18" tyres. Or....you are going to have to get a larger engine.

Unfortunately, all of these options are going to require a little work.

You said that the rear sprocket cannot be removed. Is it welded on?

Ltcjc 05-02-2019 10:06 AM

The "hubs" are rusted on and I can't remove them to replace the axle (thinking I could just cut the axle into 4 parts and remove it completely, replacing the axle and sprocket. A lot of work...

J.S.@SMS 05-03-2019 07:48 AM

With a 9t tc sprocket, a 7" driven, and a 203591 belt, it'll work with a 212. Mine does, and it has the torque to spin the tires a bit on take off. It also does good off road, with the exception of always wanting to go straight when turning under power. But that's because the front tires are junk.

PS: My kart has the exact same rear frame setup.

Tpdingo 05-03-2019 10:11 AM

Quote:

Originally Posted by Ltcjc (Post 521685)
The "hubs" are rusted on and I can't remove them to replace the axle (thinking I could just cut the axle into 4 parts and remove it completely, replacing the axle and sprocket. A lot of work...

PB Blaster and a sledgehammer and you'll get it off no problem.

Denny 05-03-2019 08:20 PM

Ltcjc, I fear you have been lead astray by the unknowing due to lack of age and experience. In 1988 I bought a Dingo it had a 8hp flat head Briggs, 40 series cvt, and 10 tooth primary drive and 60 tooth secondary axle sprocket. 22"x11"x8' rear tires. It ran 42mph with my skinny little 220 pound but on it. It would climb anything I tried. If you follow this formula you can not go wrong. Manco sold a lot of carts like that. :thumbsup: I almost forgot open up that diff you may find broken spidergears in there.


Denny

itsid 05-04-2019 04:56 AM

288 Dingos had torque monster 8horse flatheads mounted,
not 6horse OHV clones.
(~30% less torque)

that must be compensated for if the engine should stay on.

So no, he's not been led astray (except by you a bit at this point ;))

'sid

Ltcjc 05-04-2019 11:23 AM

Ok, the saga continues......I replaced the 22" tires in the rear with 18" golf cart tires (for testing purposes), put the rear end up on jack stands - tires spun with throttle idle thru wide open. Shut it down, took it off the jack stands and fired it up. I watched the TC through out the throttle range and it seemed to perform as advertised. Sat in the cart and throttled away, went about 8' and watched the TC spin the belt. So, as not to burn the TC or belt up I shut it down. I guess the 6:1 ratio just won't cut it? Suggestions? Thanks in advance


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