As I have previously said I am going to experiment with a different diff. Of course the diff has a different offset to the other one, and so I was forced to realign it somewhat! So that I can use the original diff I did not want to cannibalise the original diff plates. This meant a bit of a rethink, but I think I now have a pretty nice solution to the problem. I have decided to hard mount the diff to the engine cradle, this removing a link in the train from diff to engine to aid alignment, and should mean that the diff wont move when power is applied and then removed, BUT does mean it has to be aligned correctly.
The first thing then was to draw up some plates. These should get the diff in the same place as the original, and so everything else should fit.
I wasn’t brave enough to draw in the holes for the mini bearing jobs, so I just did that by hand afterwards
The next thing to do was to push the bearings into the plates and to align the diff with the engine cradle. In fact what I did was to heat up the aluminium plates and cool the bearings in the freezer, they then just dropped straight in no problems! This then allowed me to measure the difference in offset, when the plate was hard bolted to the engine cradle. I then made up the spacer welded in as below. Its actually is spigoted all the way through the box section and welded both sides. This should increase the strength of it.
I then had a think as to how best support the other side. I had a rummage through the offcut bin and found a small length of similar box section to the engine cradle. This I thought would do nicely for the second plate support and so I tried to place it in position as below. Here things started to go wrong. The mounting plate for the reverse mechanism was fouling the box section by about 7mm. I had a look at it and the only real solution was to reduce the thickness of the mounting plate by 7mm or so. I don’t think this has reduced the strength critically but we will have to see!
Then there was another small problem. The lower mount for the reverse plate went straight through the box section. Again I had a think and decided to cut an arc out of the box section as in the picture below.
Below is a pic of it loosely bolted together. There is extra clearance on the reverse plate as I was a bit of a plonker and miss measured! As you can see though it is all quite tight!
Next I just patched up the box section to give it back some of its strength.
I then decided that I could regain some of the lost stiffness on the reverse mechanism if I bolted through it into the box section. This massively helped the flexing in it and I think it may be stiffer then before I started. Not that it needs to be massively stiff, but it cant harm.
I then bolted up the diff plates reasonably tight, checked for the plates alignment and tacked the box section to the cradle.
I then bent up a piece of think tin to use for the top support. This only needs to be very think as I am cross bracing the plates elsewhere, but that brace will also stop the plates shearing across each other.
I then made up some mounts for the chain tensioners. These allow me to rotate the diff plates, from a different centre to the sprocket, and thus change the length from the diff to the sprocket. Again, as these will take a reasonable load, although I have put them on the slack side of the chain, I spigoted then all the way through the box section and welded them both sides.
I then wanted to lose a bit of weight from the thing, so I got the plates machined away. Personally I think it makes them look a lot more ‘racey’ aswell!
Tags: Chassis, Differential, Engine
