Planning the tractor powertrain

I have spend some good time to fiddle with the parts I have in my garage and decided that I will use 4×4 Sierra front wheel mounts and CV joints even my original plan was to use Ka’s parts for those.

It turns out that 4×4 Sierra front outer CV joint is almost perfect fit to Sierra’s small plug-able rear drive shaft:



This is very good news since now I don’t need to cut Ka drive shafts and weld it to those Sierra’s drive shafts to be ably to use Sierra’s diffs. Instead I can use standard parts already available, only a slight reconfiguration is needed.

My intention was to avoid using 4×4 Sierra front parts since they are becoming rare and replacing them may not be so easy at future. But since this is so nice fit and I have the parts I will use those. This means Sierra’s 240mm brake discs + calibers and all the wheel mount parts except the suspension parts. Those discs are the same size as Ka’s, but with that difference that they have some additional cooling (which is totally unnecessary for this project).

Now since I will have complete Ka drive shafts I stated to think that maybe I can minimize the need for custom parts with those… And then I figured out that I will only need two flanges that need to be lathed. This is the plan for front diff:

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That cardan shaft flange represents the mount at diff itself at these pictures. It means that with this CV joint + wheel hub I only need one flange to be machined to be able to bolt it to the front diff.

As a side note I want to mention that the wheel hub and CV joint were quite tight together and needed proper puller + some heat to take them apart:


For rear diff I will use the Ka drive shaft and wheel hub with it’s bearings to mount it to the center of the frame where it will act as a cardan shaft output mount point (+center bearing bracket). For cardan shaft I will modify one from two Sierra’s cardan shafts. I take the longer part of Sierra’s rear cardan shaft and disconnect the shorter part from the joint.  That shorter part will be replaced with similar flange from other Sierra’s rear cardan shaft like used to connect it to the diff. Only new part needed for this is the universal joint since Ford has decided that you need to break the universal joint if you want to take Sierra’s cardan shaft to pieces. Similar way like to the front diff I will need one flange to be lathed which will connect Ka wheel hub to Sierra’s diff flange.

I also have been thinking and planning how to do the front axle wheel mounts and replace the suspension parts with some fixed stuctures. I come to a conclusion that I will most probably use Lada Niva ball joints for upper and lower joints. They are rather cheap to obtain and they have designed so that both upper and lower ball joint will carry the weight of the car (or tractor at this case). Usually the lower ball joint is not carrying the weight of the car, at least not as heavily than the upper one.