I’ve finally finished the front suspension brackets and have started to set-up the A-Arm mounts.
I had one of those weekend ends where I ran out of everything. Sanding discs, sanding belts, grinding discs, band-saw blades, new lens for the welding hood, 13 amp fuses, etc. Every job I went to do the easy way, ended up taking hours. I hope I’m not alone in having these days! Be prepared; this blog is packed full of excuses.
The front end on this car is not standard – not even close.
The chassis is approximately 2″ wider than standard at the central drivers compartment, although standard width at the front. The chassis is about 2″ longer and the wheelbase has been stretched nearly 4″ to give the car a more aggressive look.
Coupled to that I’m using Audi RS4 19×9″ wheels all round. They are significantly taller than standard. If I were to mount these onto a standard Haynes Roadster, it would gain a jacked-up off-road style ground clearance. To counteract this, the suspension has been moved up-wards on the chassis, effectively lowering the body back down.
This car has got 25% anti-dive geometry (see anti dive blog here), so the mounts don’t even end up level to the base surface.
So that there is enough room for front 4×4 drive shafts, steering and suspension push-rods, the width of the A-Arms have also been increased, moving the chassis uprights backwards to match.
What I’m basically saying is, setting this up is going to a little tricky.
As you can see in the above shot, I’ve had a quick play. I made the mounts and brackets to a high tolerance in order to make this process as easy as possible, but even doing this, still means the process of getting everything right might take a few hours.
In the above shot, you can see a bar slid through the top suspension mounts (already slipped in picture). I’ll cut these bars down and turn them to a sharp point. Having a pointed tip on these temporary rods, will help me with accurate measurements. I have two digital spirit levels accurate to 0.1°, but even these don’t produce results as accurate as I thought they would. I found that you could move mount positions almost 0.5mm before they changed 0.1°. I’m a bit nerdie about getting suspension mounts 100% accurate, so I’ve devised a plan. Good old fashioned, bubble levels would normally give better results but unfortunately because of the anti-dive, things aren’t horizontal, so I’m stuck with digital.
The plan is to make special mounts for 2 laser spirit levels, so that they sit tightly and squarely onto 2 rods. These 12mm rods will be passed through the two suspension mount brackets on both sides of the car. The lasers both produce a large X-Y axis cross, which will be visible on the end wall of the garage. With the X-Y axis perfectly vertical / horizontal I’ll get 2 projected lines (Following me?) Hopefully these two lines will be parallel and the two points on the end wall at the same height.
I shone the lasers along the chassis table and marked a horizontal line on the end garage wall. A third laser is shining a line along the center line of the car. I’ll use this to double check any laser lines with CAD measurements. Any small error or movement in the height or width of suspension mounts will be amplified several times across the length of the garage and produce a large change in the height of the laser line at the garage wall. I can check all lines with predicted points and there distance from the projected center line.
Well it’s a good theory. I’m still to working on it and from just the brief try I had, clamping these bits in the right position was somewhat frustrating but promising. I also know, as soon as I move the MIG welder anywhere near, metal will distort and pull mounting points miles from where I want them.
There are fun and games ahead.
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