Sunday, 18 March 2018

Torque A Good Game

The stock AW11 torque mounts are famously weak. Not even strong enough to withstand road driving if you've put in a seriously powerful motor. We are certainly going to need to beef ours up quite a bit, even though we'll be sticking with the 4AGE. A 20-30G 'bump' in the road is certainly not uncommon in forest rallys.

I designed a little 'kit' for the front one and had the pieces lazer-cut to save us some time with the fabrication. here's how I did it.

First I drilled out the spot welds on the bottom and the sides, cut off the lower tab, re-welded the mount to the chassis to prevent it from moving and then ground it flush. Then did the same to the tabs on the side. I made sure I cut the sides of the mount back far enough so can slide a 3mm plate in behind it.

I've designed the main plate by very carefully measuring the spacing of the bolt holes on the existing mount. The bolt holes in the new plate are 10mm and the OE mounting bolts are M10 so this should make it center itself quite nicely as there is no room for it to move around the bolts. this will also help to center the captive nuts behind the additional holes.  The next job is bolt it in place. I had to chop a corner off it as there is a bump in the cross member where it meets floor pan. You can just about see I've used a 10mm drill to mark a perfect center for each of the new bolt holes on the cross member. Ignore the line of holes in the middle of the plate, they're for spot welds later on. Once this is done, I could unbolt the plate and add the captive nuts using a bolt to center them. Finally, using a hole cutter and the centers marked on the cross member,  I cut holes for the captive nut to sit in.

I bolted the plate back up and put a good run of weld all the way around the outer edge as well as filling in the spot-weld holes. The two smaller plates could then be slid into position behind the factory mount and welded into place. Those slits you can see are for the little triangular buttresses to slot into. Once they were done that's the chassis side complete.

Onto the engine side. The holes in these parts are 12mm to allow for wiggle room when installing the engine. Ours was very rusty so it needed a bit of a clean up with the angle grinder and the removal of the old rubber core. We have some sweet Woodsport Poly mounts to replace them with so I just butchered it out with a hole cutter, a hacksaw and a chisel.
To get everything lined up I bolted the stock mount into position making sure it was centered over the bolt holes. I then clamped the 'wings' into position, again, making sure they were perfectly centered. Once I was happy I tacked them into place. 
This could then be welded up properly on the bench. I used a straight edge to set the wings level to one another as they have a habit of bending down slightly as the tacks cool. It's really nice to able to put some juice into the welder and get stuck into some nice thick, clean steel after all that frustratingly contaminated seam welding.

You can see I've had stop short to leave enough room for the washers to seat on one side of the buttresses. I Should have thought about this when I designed it and moved them inward a little but other than this little over-sight and the bump in the floor-pan on the chassis side I'm really pleased with how this turned out. Once this has been powder-coated and has the PU core in it it's going to look epic.

I'm sure some of you will be thinking this is using a hammer to break an egg but from what I hear there is no such thing as too strong on a rally car. Like I say, it's not the torque from the puny 4AGE were trying to combat here, it's the fact that in a major crash or a massive bump the engine can briefly weigh in excess of 20-30 times what it normally would. This has also totally future proofed us with regards to hairy engine swaps in the years to come.