Nearly ready to build my own compact tractor but need help??!!!

[nikb]

im going for the front wheel drive car option, but once i put axles front and back and then up the size of the wheels im pretty much close to being where i started with gear ratio's.

i cannot find an old tractor here in the UK, as they are like £2000+ and are crap chinese imports, what better way but to use old car parts, so far i have nearly everything i need for £100, and then my time is free, any odd evening i get will be spent building it, i do like a challenge and what better way everytime i start it up and drive around my property i get that sense of acheivement, that i couldnt get from me using a chinese/or other manufaturers vehicle,

i have to import spares due to the build quality, its easier to make or chuck another gearbox in it from the local junkyard

 

[jas67]

It would be cool to find a diesel drivetrain, like a VW TDI for this project.

Also, keep in mind, that most FWD cars use an open diff, which may make you 4WD useless if a wheel loses grip.

You may want to weld-lock the differential.

 

[David Devuono]

I am with jas67, you will basically have a 1 wheel drive tractor using a FWD transaxle and I am not sure how it will hold up with welding the spider gears. Not sure what is avail in europe, but a Suzuki Samurai is a good platform. Since it uses a divorced transfercase, you can connect the transmission to the transfercase via a double chain homemade aux underdrive. Using 4:1 you would get 133:1 reduction in 1st hear (approx)

 

[nikb]

yes i have the choice of a ford turbo diesel, and a vw diesel, both about 1.8 litre, with matching gearboxes, i can weld up the spider gears or i have a lathe and can turn something out

ive heard about suzuki axles being used, i see what you mean about the transfer box, would it really have that kind of gear reduction ???

 

[pat32rf]

In a perfect world you would find a FWD engine/tranny with a limited slip diff.
I have always found that it is better to maintain traction on all four wheels than to try and regain traction after loosing it. Which HAS to happen anytime that you make a sharp turn with the old style transfer cases. This is why most tractors, ATVs etc are hard to turn when in 4wd on hard surfaces, (and why they tear up lawns in 4wd)
You can control wheel spin in the rear axle by using the emergency brake cables, the way they used to in VW dune buggies.

 

[korydz]

Admittedly I don't have a bunch of experience building such a project from the ground up, but I remember a rock crawler that was built using a Saturn front wheel drivetrain. This was a short run production vehicle from a specialist located in California (I think). The genius part was that they turned the drive train sideways so that would would have been the left wheel drive drove the front wheels and the right drive drove the rear using locking differentials at each end.

Looking to what the serious off road guys are doing might be worth while. Good candidates could be Honda or a Subaru gas engine. There's lots of performance products for those platforms.

 

[pycoed]

yes i have the choice of a ford turbo diesel, and a vw diesel, both about 1.8 litre, with matching gearboxes, i can weld up the spider gears or i have a lathe and can turn something out

ive heard about suzuki axles being used, i see what you mean about the transfer box, would it really have that kind of gear reduction ???

Another good stand alone transfer box is the Lada Niva- I've got two Nivas (one for shooting & one for spares) & you can pick up a transfer box for ｣20. It has a diff lock as well as hi/lo & nice flanges you could drive a pto from (sandwich a sprocket between the input prop & input flange) or mount a disc for a transmission brake too.

 

[David Devuono]

100:1 overall gear reduction will give you the torque you need to idle your tractor through tight quarters. At the extreme is a Unimog 406 with 20 speed tranny. LowLow 1st gear is 4,066:1. Otherwise you will just have a small buggy and mise well chop up a Landrover.

 

[nikb]

so if i have the car gearbox in first, and the tranfer box connected to one output shaft, that would be 100:1, and then if it went into a 3:1 front/rear axle, would that be 300:1 , and what sort of incline would that climb ???, obviously the size of the rear wheels would then be a 3:1ish ration cancelling the axle reduction, does this sound about right???

 

[Marcle]

Is this project still running?

I've been down this road several times with great success.

The last vehicle I built from scratch was a 4 x 4 x 4! I used two front axles from a Suzuki 1300 4x4, then used a front wheel drive automatic (very important) gearbox and engine from a Honda Accord. I should have researched the engine more as it was very heavy, hey ho. I removed the Honda gearbox diff and machined up a new shaft with the crown wheel bolted to it, thus giving permanent drive both sides the diff. The engine/gearbox was rotated 90 degrees so that the drive shafts faced the front and back axles. This set up gave a top speed of around 30mph with the engine screaming, but loads of low down torque. The front axle diff was welded closed and I used Daihatsu front drive shafts with a collars around the barfield joints to give extra strength. The rear axle used the standard shafts with collars the same as the front, however with a lot of machining I modified the diff so that it was manually lockable. Suspension was via coil springs. The end result was very manoeuvrable, especially with fiddle brakes on the rear axle. In recent years I have used it with a blade on the front for landscaping (far more nimble than a JCB). The blade lowers and raises by using the hydraulic system of the power steering.

I have seen others on a similar theme. Some have retained the centre diff so they could use different size wheels on different axles, but as soon as one wheel spins, you loose all traction, even if the axle diffs are locked! Manual gearboxes are a dead loss as the ratios are all wrong, hence the use of the auto transmission.