Saturday, 11 August 2018

Caged Animal

Well it's been tough finding days we can both keep clear for putting a solid shift on the MR2 but the roll cage is finally taking shape. We decided on 8 points in the end, you can't be too safe, or two stiff, so fore-stays and back-stays. Rrule changes for stage rally cars as of 2019 mean we also need A-pillar bracing and two bars in the roof. Probably a traditional X in our case.

So without further adoo lets have look at some piccie's. Click to view full size
The Main X with Harness Bars
Two Raked door bars instead of an X. We decided entry and exit would have been nigh on impossible  with an X.

Fore-stays. well pleased with how these came out. we just need to do a tidy job re-paneling around them now. These could make one of very few if not the only AW11 currently competing (in the world?) with an 8 point cage.

A-pillar bracing. Mandatory for 2019. I would have been nice to have these bent to clear the steering wheel a bit better but we don't have the budget.

The notch on the top of the A-pillar brace. The biggest one we had to do at just 22 degrees. This was done with paper templates and the angle grinder as it was too big for the tube notcher in the drill.

Boom! howdya like them apples?. the plan is to 'rectangle' the rear window with small plates of sheet steel welded to the ends of the window aperture and the back-stays. This makes it much easier to seal up that trying to pass them through polycarb. It wall also tie the cage to the shell very nicely indeed.

Definitely 'Notch of the job' this one. All the notches are bevelled back so your welding to the full thickness of the steel.

Top corner node in the main hoop. 

My Kind of office. Because we took the time to perfectly level the shell we can now use spirit levels to set stuff like the dash bar perfectly true

The floor has to be cut beforehand and then the feet slid over the holes so that when we need to we can drop the cage to gain welding access to the hard to reach spots up against the roof.
Back-stay re-enforcing plate.
The rear bulkead ad to cut to build the Main X
We also needed to install the seat mounts so we could judge where certain bars needed to be before we installed them

he sunroof had to be massively minimized for head room. Even with the seats as low as we could get them its super tight.
The solution was to cut out everything. and jut leave the aperture with a 3-mm (the thickness of polycarb) return on it. I took a template of the hole and had it scanned at my laser cutting place
from that template we produced this flange. with all the rivet holes pre-cut. I can now use the same CAD drawing to have the plug made. Again, with all the rivet holes pre-drilled in exactly the same places. Too easy. the plug itself will be either smoked or solid-black polycarb. This should look really smart when it's in.

Oops moment with the angle grinder when cutting out the old framework.

Just the roof X left to now. these will need to be bent to push them right up against the roof itself. so we just need to wait until we have a bit more spare cash. The next session will be spent on the seat belt anchors.

We have also been working on installing Corsa-C electric power steering which is coming along nicely. I'll do a seperate post on that though.

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.

Saturday, 10 March 2018

Better Seam Than Heard

It's taken a while but we finally finished the seam welding the other day.

What a truly miserable task, compounded yet further by the huge number of body panels MrT saw fit  to use to build such a small car. You know it's going to be shitty work when you have a respirator mask, ear-defenders, goggles, cap, hood up and your welding gauntlets on. There's nothing skillful or thought involving about it you just need to have clear vision of how much better off the shell will be when it's done and belligerently move from one seem to the next until there's none left.

The rule of thumb is you only need to do everything between the suspension turrets but we also did the foremost bulkhead too.

First job is to get a knot-wheel on the angle grinder and get all the easy access stuff off. minutes and minutes of that special kind of drone that only an angle grinder can make as you get peppered with high velocity spikey bits of metal and gross semi-melted seam sealer

Then get your blowtorch and soften up all the stuff in the nooks and crannys at either end of the seam as you pick it out with a screwdriver/paint scraper. Smokey but it just feels like a woefully slow and inefficient way to to do it after the knot-wheel.

Another wire brushing, this time with the smaller, softer one in the hand-drill. this gets deeper into the seam than the knot wheel and also gets the paint off really well. Cup brushes and end brushes also come in really handy for the tough spots. By now it should be looking pretty good. Any last little bits can be finished off by hand with the screwdriver and the scraper.

Finally a wipe with a old microfiber and some clutch cleaner.

We're not going to fully seam weld the whole thing, just the suspension turrets and pick-ups. Everything else will be 25mm 'stitch' welded. That is to say a 25mm runs of weld, spaced by 25mm of unwelded seam.

It looks a lot smarter if you take the time to mark it out. I used the width of a steel ruler and a Sharpie. Make nice big marks as they get sooted over as you weld your way towards them. This is where you realize that the last 20 minutes of misery 'cleaning' the seam was only marginally more productive than punching your self in the face. In fairness the interior seems weren't too bad but the exterior one were loaded with sealer really deep into the seam so trying to lay nice clean weld beads is near impossible.

Crappy welds produce lots of spatter so inside the wheel arches was the worst. It's massively frustrating because your welds are so contaminated and you're just getting huge globs of spatter raining down on you and getting under your clothes.

Another brush with the drill before the primer and then onto the next one.

We also fully welded the joins in the sills and the roof. The only kind of accident that really worries me is broadsiding a tree. I fully appreciate that if that happens at speed your in big trouble but if these seams fail the whole car will split open. Luckily they cleaned up really well and they were some of the best runs I laid down.

In other news. I've stripped the engine down and sent it off for a pro measure up. It could use a re-bore but it's going to have to do without. A set of 0.5mm oversize pistons are north of £400. What it will be getting is:

Head skim: 10 thou
Deck skim: 4 though
Performance big end shells
Performance main shells
Thrust washers
Bronze exhaust valve guides. The originals were worn out

I also plan to do a my own very mild porting job on the head. Just to remove the casting flash and tidy up any misalignment between the casting and the factory machining of the head. Maybe a bit of a polish.

We will also be getting all the stock internals lightened and balanced as well as the cam-pulleys, fly wheel and clutch cover. So we should have one of the sweetest running stock-trim 4ages out there. The total cost of all the engine work so far is £830.

We're toying with the idea of a thinner head gasket and maybe some mild/fast road cams so if anybody has any advise in that regard it would be gratefully received. The stock injectors and ECU need to be able to cope though as we don't have the budget to upgrade them. If we can get to 150-160BHP that would be a massive win.

And we picked up a sweet AE86 tubular manifold on Ebay for peanuts. Made by BTB exhausts these things usually go for mega bucks but we picked it up for £50 as they were clearing old stock!

The plan is route the exhaust over the gearbox and into the boot (the battery will be in the frunk) to give us as much ground clearance as possible . As you can see with some relatively minor surgery this little beauty is absolutely perfect.