ok, well we have this tubing bender, and only one thing is stopping us from building a NA carbed 13b front engine kart. The third member.



Using the 50$ auto tranny, we will have a custom length driveshaft connected to a solid third member mounted to a truck arm type suspension, with the differential housing behind the seat where the engine would normally be, with drag racing kevlar engine blankets shielding the driver from drivetrain



we plan for a rear mounted fueling, cooling, and electric system and maybe an alternator to supply the needs of the electric fans and fuel pump.



At first, we thought junior dragster, but none of us knew how they were set up so that was a bust,



now we think we need to find a very compact car's rear end, and have it narrowed and re geared to like a 2.0X:1 gear. We also would like input as to whether or not we should weld the diff, hope for a limited slip, or if a open diff will do us.



Also, arent there like qtr. midget tires that are bigger than kart tires, but would keep us close to the ground?



I know this has been done to death in theory, but i am self employed, in the automotive industry, and have a lot of time and resources to do eccentric projects like this. I also did a search and many of the links in the kart postings were dead

 

i calculate that with a 11 inch diameter 7.25" hoosier midget tire and wheel combo with a 2.78 gear ratio a top speed of about 95 mph limited by gear, with a 3700 rpm 60 mph cruise in OD.



do they make lower (numerically) gears than 2.7x? I'd love to have a 2.50 or lower gear.



check this out:



2.78 gear 6500 shift point

in MPH

1st 22.13

2nd 52.50

3rd 76.54

OD 95.68



2.50 gear 6500 shift point



1st 24.61

2nd 58.38

3rd 85.11

OD 106.39



2.20 gear 6500 shift point



1st 27.97

2nd 66.34

3rd 96.72

OD 120.90



I think the ride would be better with the 2.2 or 2.5 ratio, as it gives usable lower gears.



BUT



With the 2.78 gears, anywhere between like 45 mph (3000 rpm) and 95 would all be one gear...



lets hear it guys. anyone know about gears?



Oh and brakes.

 

I was under the impression that go-karts didn't have differentials. You could just spin the engine around 90 degrees and run a sprocket off the gearbox output shaft and use a chain to drive the axle. You could pick whatever ratio you wanted then with the 2 sprocket sizes?



Sounds like you're building more of a buggy than a kart though so that may not help.

 

the idea is to have something SLIGHTLY larger than a kart, i dunno how having a sprocket chained to the end of the tranny would work, as it'd be wider than the kart.



Does anyone make really low numerical gears for the stock rx7 diff?

 

i think he means don't use a tranny.



kevinn

 

Nah, he got me right I just overlooked his point. That's a tough one mate, good luck with it.