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.

Pluggable Sierra driveshaft

Some people say that you cannot dismantle Sierra’s  plug-gable drive shafts, or actually they say that you cannot but it back together. I think they are wrong, even though I have no intention to put those drive shafts back to their original configuration.

But it is rather easy to take off the metallic cover by carefully bending it open piece by piece from the outer edge of the joint:


I might have bend it even a big too much open than needed, but still that would be rather easy to put back together. If I needed to put it back together I would use some good glue instead of trying to press it in a form like it were mounted. I would just clean the grease off from the outer edge surfaces and apply some glue like Sikaflex 521 UV or similar. While the glue dries I would tighten it up with pipe band. But like I said I will not do this since I need to reconfigure this drive shaft for other configuration than it has meant to be.

Like the picture shows I recommend using some tape to keep the bearings in their place. If those go off you quite likely need to spend some not so enjoyable time to find all the needles from the floor that will drop off…

After you have taken the wheel mount off the rest will look like this:


Tractor project recovered from a short hiatus

I got the BMW good enough shape even it took more time than I anticipated. Let’s see does it continue somehow at next summer or not…

But I started to collect tractor pieces about to their end locations:

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Unfortunately I got a flu and not feeling that energetic at the moment. Usually that won’t last long, but let’s see. I try to get some work done no matter of that, but probably I cannot do that long days I otherwise would like to do.

BMW Roof Window Handle Fix

For some reason the sun roof handle had been broken:

20140720_113549I decided to try to make a working handle by my self and this is the end result:

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I took 12mm stainless steel rod and drilled about 2cm deep and 7mm wide hole in the middle of that. Next step was to the part with hole out from that rod and make the hole oval shape 7,5mm x 9,0mm. It took some time with the tools I had available (I used mainly electrical handheld drill) to make the hole oval shaped, but the end result was really nice. Then I just welded two small pieces of metal and did some finishing to it, like adding mechanism to lock the lever in its place.

Here is the final installation, not as nice as the original, but looks good enough at least to me and hopefully it is stronger:

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BMW Handbrake

Once I took the drivers side rear brake disc off these dropped out:


Root cause for this is rust:

20140718_130517That hole should not look like + sign, instead it should look like minus sign… So even I purchased a new mount/spring set for the hand brake system I needed to figure out how to make the spring to stay at it’s position. I come up with this solution:

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Note the two nuts inside the spring. They were needed to center the spring so that it sits nicely. I used nylock nuts to make sure they will stay there.

Only one spring needed this fix, others were still good enough shape, however I expect them needing this same fix after a couple of years since they had started to rust similar way toward plus (+) shape.


This Ka is a stub

Now Ka chassis is as small as I like it to be:


Or at least I will not cut it any smaller before the frame starts to take a shape.

Unfortunately now this DIY Tractor project need to be a couple of days in hiatus since I need to install a couple of gadgets to my friend’s BWM. But I’m hoping to be able to continue this tractor project before the weekend already.