Hub Gear Reducers

[Little Bandit]

Has anyone used hub gear reducers, or something similar to reduce the gear ratio of a FWD drivetrain? I am thinking of using a Pontiac Firefly for an off-road buggy, but since I want to run 27" tires, I think the gearing will be a little tall. I would like to put in another 1.5-2 gear reduction in-line somewhere.

I know that VW had Hub Gear Reducers, but apparently they were not very good. If required, would be interested in something that I could mount to the inner CV's as well.

Thanks

[LiveWire]

Maybe you could put a small chain drive off the back. That would also allow you to compensate for the offset output of the trans. The driven sprocket could be mounted on a hat so that the CV is closer the the center of the buggy. You would need a heavy duty chain since post gear reduction.

On a Dodge Shadow trans I once looked at, there were two gears under a cover on the nose of the trans. It would have been possible to have custom gears made to gear down prior to the differential. The downside is more stress on the diff which is already going to be subject to shock loads it would not see in a road car.

[nutz4sand]

The BIG 5 ton and 2.5 ton axles monster trucks use use planetary gears out at the hubs. SOmething similair might be found but would be heavy if strong. Plus as Livewire mentioned the offset output means travel issues on one side.This might be a better option AND be light weight and strong while giving you wheel travel. Chain Drive Rails, when your serious about hill climbing.
These guys run propane powered turbo V-6s and such thru VW bus trannies driving 44 inch tires (Yah 44 inch). The tranny cannot do it directly of course and survive but they use at least a three to one gear reduction from the chain to the wheel. The chains front sprocket mounts on the end of the CV shaft nearthe front of the trailing arm and the chains run back the swingarm to give massive wheel travel capabilites.

[bdkw1]

VW bus gear reduction box, up to 1967.



These were on the swing axles only and had terrible torque reaction. The car pictured has a Johny Johnson kit on it which makes the gear box floating and has a torque arm eliminating the dreaded "hop". Gear reduction in them varied from 1.36 to 1.65?

[millbilly]

John johnson + bus reduction + 33 = a hard time for 4X4 to follow in the mud. Had a lot of fun in the early 80's

[Little Bandit]

Thanks for the reply guys

I want to stay away from using a chain on this buggy. I actually have a 600cc motorbike engine that I was thinking of using along with a Honda tranny, but this will stretch out the car at least another 12"-16" over using a Firefly motor. I want to keep this thing as small as possible.

As for the offset CV mounts, my plan was to centre the diff in the car, and have the motor offset to one side. Then use the shorter axle on both sides to keep the track to a minimum. I am not overly concerned about offsetting the weight, the driver, battery, etc will be able to balance everything out.

I am very interested in those VW hubs gear reducers or ones of similar size. Too bad that I they reverse the rotation. How do you think they would hold up to 70hp and 27" tires?

Do you know if there are any chain driven ones of similar size that keep the rotation the same?

I am probably going to use trailing arms on the rear, so that should take care of any wheel hop issues that it would see.

[Little Bandit]

Originally Posted by Little Bandit

I am very interested in those VW hubs gear reducers or ones of similar size. Too bad that I they reverse the rotation. How do you think they would hold up to 70hp and 27" tires?

Do you think there would be any issues if I turned the motor around so it faced backwards and used the VW Hub Gear Reducers? This would give me the proper rotation at the wheel.

The only think I can think of is that now the engine will be offset to the drivers side and it would be more difficult to get the proper weight balance.

[bdkw1]

The hubs will stand up to quite a bit of abuse. I'm running about 100HP through them with 33" tires on a 1300# car. Thats probably about max I would feel comfortable running them at.