Our Formula SAE team is running a chain-driven straight rear axle race car. We want to have some roll compliance (i.e. not a simple swing arm) but I'm worried about the sprocket rotating relative to the pinion. Can the chain tolerate any misalignment without being thrown? I'm only talking about a few degrees of roll here.

Thanks!

 

In general a standard oringed street motorcycle drive chain isn't going to reliably tolerate a "few" degrees of tangent or offset. Consider a free standing suspended setup for the power transfer relative to the rear compliant section. Several rear suspension setups will allow. Or you could look at different drive methods or drop the rear compliance. Just curious, what kind of suspension setup are you guys running?

 

Unequal length A-arms up front. The rear is a little vague at this point but we want to run trailing arms. The axle is a simple chain driven shaft - no differential.

In the past we've run A-arms in the rear too. We are trying this to make the car simpler to make, and reduce weight (personally I like IRS better...)

Here's a pic of last year's car.

 

all the teams (3 ) that I know that are running formula SAE are all using custom rear differentials. I think you might have to bite the bullet.....

 

why not think of something where the chain is shortened and run directly to a sprocket that will not move which then turns a driveshaft? then again i know absolutely nothing about this sort of thing... but me and a friend were thinking about how cool it would be to put a motorcycle engine in a go-kart and this was our best idea.... i dunno just a thought...
sorry

 

hey shift....look in the archives of the motorcycle forum. Dustin is making a bike powered go-kart.

 

Actually I think shifter karts use small 2-stroke bike engines. The car in the photo is using a 600cc Yamaha R6 engine.

I don't think the dual pinion idea will solve the problem, since you still have one sprocket staying put while the other is twisting.

 

what kind of shocks are those and how much does that beast weigh? I understand the "simpler to make" concept, but how much performance do you think you stand to lose without a differential?

 

Pic doesn't work. By the way, if you can limit movement to the vertical plane you should be ok as the chain will hold its own tension within reasonable limits. Even better have a spring/tensioner in there somwehere and it'll allow you to easily add an oiling system. Then you can run a lighter/slicker ringless chain. Horizontal freeplay however will have the chain come loose in a blink. Btw, a relatively large free sprocket helps to hold the chain feed.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ED3-D15T &raquo;</TD></TR><TR><TD CLASS="quote">what kind of shocks are those and how much does that beast weigh? I understand the "simpler to make" concept, but how much performance do you think you stand to lose without a differential?</TD></TR></TABLE>

If it was my call we'd be running an indepedant rear and a limited slip. But with a car this light a spool is feasible. You have to understand that getting custom splined CV halfshafts is a massive undertaking in cost, outsourcing and in-house machining. And yesterday a busted rod end on the car in the picture caused the left rear suspension to collapse, splitting a CV joint. If it's ruined, I don't know how we are going to replace it

That car weighs 500 lbs w/o driver. The Penske shocks are heavy but very consistent and reliable. This year's car is targeted at 350 lbs

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ShiftStain &raquo;</TD></TR><TR><TD CLASS="quote">then again i know absolutely nothing about this sort of thing... but me and a friend were thinking about how cool it would be to put a motorcycle engine in a go-kart </TD></TR></TABLE>

exactly me too.... i know squat about that stuff.. but its awesome.

what is an approx. cost of a setup like that pic? a frame like that.. with a 600 cc motor? 5gs? 10g's?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Angry Joe &raquo;</TD></TR><TR><TD CLASS="quote">

That car weighs 500 lbs w/o driver. The Penske shocks are heavy but very consistent and reliable. This year's car is targeted at 350 lbs </TD></TR></TABLE>

thats a pretty ballsy target for a team that is bitching about money.....

 

car cost about $20,000 to put together. That's with most major components except the engine designed and fabricated by us. It really won't be much more expensive to build a lighter car, just harder...