Working on De-Dion Axle

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Working on the rear de-dion axle for the last couple of nights. Got one side rolling last night and the other side tonight. Had to weld the large black metal tubes onto the de-dion "ears" which needed very precise setting up before hand. I ended up with a jig consisting of two parallel bars on the flat (checked) building surface. The two axle tubes were set on these parallel bars and the de-dion axle with ears set on top. I was then able to space the tubes out to the track width I was looking for and ensure it was central. I then used hacksaw blades to act as spacers to create a small amount of toe-in. This is important for stability to void the back end sliding too much. It will slide quite enough due to the V8 without having toe-out to add to it further. I also positioned my caliper mounts by rotating the axle tubes to the desired angle before welding. I don't have any calipers yet so I am taking a chance here but I hope it will be okay.

Anyway, here are a few pics of the car as it stands tonight:

​Wagon's rollin' All I need now is a horse!

I have roughly measured the resulting camber and toe and it seems pretty close to ideal. I have about 2mm of negative camber and 1 or 2 mm of toe-in equally spread across both wheels which is close to ideal.

Side view showing axle detail. Note that I will need to chop the ends off the black axle tube so that it doesn't foul on tubes RU1 and RU2 but I want to leave as much as possible intact to allow me to weld a brace between the axle tube and de-dion tube. I intend to have this assembly welded professionally because I want it to be as strong as possible for obvious reasons. My welder just doesn't have the amps I'm afraid. If anyone in the Glasgow/Kilmarnock area is reading this and fancies welding it for me then drop me an email and give me a price. I'll be looking for someone shortly to do just that.

If you have a keen eye then you might notice that I've cut the left hand end off tube O1. This is because I am half way through modifying the left hand side to match the right hand side which you may recall I had to change to avoid tube O1 fouling the inboard trailing arms.

I've got some shock absorber substitutes to make up out of 1" tube with holes drilled at each end to mount to my shock absorber mountings (oh yes I'd better fit those too). I'll use these until I can afford the £250 for the real shockers and springs. I can then start working on the front of the chassis and get the suspension mounts fitted. I might get this thing rolling before the end of June after all!!

Four Wheels On My Wagon!

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Perhaps the most visible sign of progress yet...

As you can see I have four wheels on the ground although you may also notice that the chassis is resting on an old pallet. I have no shock absorbers and springs yet to make it all self supporting but they should arrive next week with a bit of luck.

The key to getting the whole thing on its wheels was the fixing of the front suspension mounting brackets. This was not a job I was looking forward to to be honest but it turned out alright. The accuracy is difficult to achieve because you are working effectively in free space and you have to continually go round and round double and triple checking everything and then do it all over again. I am very happy with the result and I feel that the accuracy I achieved is very good.

I meant to take some photo's of the process of attaching the brackets but I think I was concentrating too much on getting it right and forgot. No great secret though, I just used threaded rod and loads of nuts and washers to keep the brackets spaced out correctly. I started with the bottom mounts and used a block of wood at each end of the threaded rod to maintain the correct height above the building surface. I then placed the frontmost mount against the front assembly (LA/LB) and positioned the rear bracket so that the threaded rod was parallel to the chassis centreline before zapping it with the welder. I then made up two identical pieces of 20mm square section with holes drilled 204mm apart as per book. I bolted one end of each piece into the corresponding lower mounting bracket and then arranged another threaded rod across the top mounts with brackets held at correct spacing.

By the way, I figured out the correct castor angle/spacing earlier to ensure that I was close to the 5.3 degrees specified. I have washers either side of my wishbone tubes to that I can vary the castor +/- 1.8 degrees but I tried my best to achieve 5 degrees to start with, with my spacing washers centralised. Only once I had the front upper mount tacked loosely (one tack only) in place did I offer up tube FU1/2 which I moved in and out until I had the upper threaded rod parallel to the chassis centreline and also parallel to the plane of the building surface itself. I then tacked the FU1/2 tube in place and then tacked the rear mounting bracket to it. Note that tubes FU1 and FU2 sit well inboard of tubes J1/2 and F1/2 and actually straddle the gap between tube E and F1/2 on each side and between J1/2 and S and T on each side. On my chassis tubes FU1/2 are inboard by around 15mm from J1/2. Note also that my chassis suffers from the book error about wishbone design and my upper front brackets are not centrally located on LA/LB. I could have tilted the front assembly back by 1 inch to compensate but since my V8 engine needs every millimetre of engine bay length this is not possible. Having viewed a fellow builder's chassis to engine clearance I simply cannot tilt my front assembly back. I intend to make a little piece of 25mm square section to double up with LA/LB where the bracket is overhanging. This should take away any localised stress and should be better than a gusset. I'll do this when I am seam welding the chassis which should start soon.

Another few angles of the car. Note that I have measured my track widths from tyre contact patch centre to centre and it is 57.8inch rear and 56 inch front. I aimed to keep the rear track the same as the Sierra which I have and I am happy enough that the front is slightly narrower as this is not unusual.

Shot from above showing that I do have a healthy amount of castor...

Well that's it for tonight, I have ordered the shock absorbers and springs from GTS racing and they were sent last wednesday on 5 day postage so I hope to get them tomorrow or tuesday. I've also ordered some mounting brackets because I got very bored making up the ones above and they only cost £1.25 each. Hopefully I can get the shockers mounted quite quickly once they arrive and then the beast will stand without additional support...

One final thing, I have cleaned up my gearbox and differential using an acidic aluminium cleaner. It did a good job on the bellhousing but struggled to shift the corrosion on the differential. I think I might end up painting it instead. I also bought myself a Screwfix direct grinder stand for turning the grinder into a chop saw. It's a bit slow and noisy (and dusty) but it works! I got some 1.6mm thick cutting discs at the same time and they are quite good.