Rear suspension thoughts wanted

[spongerich]

I'm working through some ideas for an off-road kart.
I've got a 12hp vertical shaft mower engine along with its Peerless 5 speed transaxle. I'm planning to use a friction clutch setup similar to what's on the mower now.

Since I'm old and don't really want to have my brains bounced around inside my head, I definitely want some sort of rear suspension. (I have the front covered.. I've got a frame and almost all of the suspension parts from a Honda TRX250x quad.

To keep things simple, I'm thinking of leaving the solid axles on the transaxle and mounting the engine and/or tranny on a subframe and springing it with either some coil over shocks from a quad or using some front forks from a motorcycle.

Would it be a bad idea to mount the engine to the main frame and put the transmission on a sprung sub-frame? I'm worried that the belt is going to jump off the pulleys if I allow more than couple of inches of travel.

I'm also giving some consideration to putting some universal joints on the ends of the rear axles and making a fully independent rear suspension, but I suspect that's going to be a lot more complicated and perhaps left for a future mod.

 

[souperman000]

What you are thinking of is a swingarm...search the forum. lots of posts on swingarms.

 

[klicky96]

I'm working through some ideas for an off-road kart.
I've got a 12hp vertical shaft mower engine along with its Peerless 5 speed transaxle. I'm planning to use a friction clutch setup similar to what's on the mower now.

Since I'm old and don't really want to have my brains bounced around inside my head, I definitely want some sort of rear suspension. (I have the front covered.. I've got a frame and almost all of the suspension parts from a Honda TRX250x quad.

To keep things simple, I'm thinking of leaving the solid axles on the transaxle and mounting the engine and/or tranny on a subframe and springing it with either some coil over shocks from a quad or using some front forks from a motorcycle.

Would it be a bad idea to mount the engine to the main frame and put the transmission on a sprung sub-frame? I'm worried that the belt is going to jump off the pulleys if I allow more than couple of inches of travel.

I'm also giving some consideration to putting some universal joints on the ends of the rear axles and making a fully independent rear suspension, but I suspect that's going to be a lot more complicated and perhaps left for a future mod.

A swing arm would be the way to go for you. It is easy and cheap. The only problem you will have is switching gears, but after a while, you will figure that out. It will cost you maybe $20 in steel tubing and, if you can't get it free like me, then maybe $20 for a plate of steel.

 

[spongerich]

Thanks... My original thought was to mount the motor on the fixed section of the frame and just the tranny on the swing arm to reduce the unsprung weight, but I don't think I'll be able to keep the belt on the pulleys.

The more I think about it, the more I like the idea of cutting down the axles and putting on some extended half shafts with universal joints and some coil over shocks... I don't have the transaxle here with me, but I recall it being a bit narrow anyway, so I think a few extra inches of width would improve the stability quite a bit. I have some extra front hubs from a quad that I can use.

 

[klicky96]

I do like the idea of coil-over shocks mounted with the u-joints. I've seen it done, but unless you use a good u-joint, then you won't get a lot of clearance. And, with some planning and designing with the swing mount, you can make sure the belt stays on the pulleys. You could have the swing mount swing on an orbital point so that the belt never even loosens or tightens as you ride it.