Using a spot welder

In between sorting the rear end, the disc break mod, drawing up parts to be machined and collecting the bits needed to finish off the panel work, I've been trying out my new toy.

It has taken me a while to get around to buying myself a spot welder, 1) because of the cost, £370 for a 6Kw (max 2mm thickness weld) or £495 for a 13Kw (max 4mm weld) 2) because I've made do by mig welding holes together. But now I've got it, I've realised I should have purchased it way before I started cutting my van to pieces.

I managed to get my 13Kw as a used display model for £380 from eBay but having to wire up a 32amp socket, plugs and cables so it would work cost me an extra £50 on top.

Once I was all wired up and running I started practicing straight away, like a child with a hot and dangerous Christmas present. Reading the instructions carefully I set up the rod gap thickness to the metal, adjusted the required pressure and set the welder to the required power and material thickness, pulled the trigger and sparks went flying. As the instructions said to leave the rods closed for a few seconds to cool the weld and then release, behold my first spot weld, easy.... I thought.

The instructions did not mention that you have to set the gap with the trigger set just before the pressure spring starts to work, this meant I started spot welding the lower bulkhead to the forward cross support with no pressure reacting on the metal, and what this does is spark erode the material away, (burn a big hole) after a few burnt through welds that I later MiG welded and cleaned up with a grinder, I managed to reset the spot welder and squeeze my way under the rest of the van to weld along the lower bulkhead.

Although there are still a few variables, power, pressure, gap and timing the welding is pretty easy, apart from the weight of the welder when as you lie on your back and hold it up to the van above you, and also that the material is spotlessly clean.

Now I'm able to fit the front jacking points and cross pieces.

944 IRS Conversion A arm trial fit

With the all the dimensions we previously measured, my mate drew up a comparison drawing on CAD overlaying the VW set up over the 924 rear end. This gave us a better idea what would need to be cut away from the rear end and any issues with clearance. I had also measured the old 924 spring plates and transferred the holes using a pillar drill for accuracy on to the van spring plates, I did nearly make a mistake drilling in the wrong place, luckily I caught myself by measuring twice (and only cutting once). Once both plates were drilled off I cut one to the desired length. Not knowing for sure how thick the spacers would need be I also cut out a recess for the A arm casting to clear but I realised later from trial and error I didn’t need to.

The A arm was first trial fitted with 26mm shims made up from £10 worth of cut-to-length steel tube, 14mm nuts, washers and threaded rod, this clunkingly amateur set up gave me an idea of where I needed to cut the chassis for clearance.

So now the point of no turning back! I got to work grinding away the chassis to get the clearance needed for the travel of the A arm.

With the A arm remounted with 26mm spacers you can see the hinge just inside the horn.

Then with the wheels mounted directly on to the hub, with no discs or caliper spacers, the rim clearance on the wheel arch was too close for even the tyre to fit.

I did fit the discs and calipers to the hubs to see how they would look then try to fit the wheel, this reminded me I needed to shim the caliper lateraly to the disc (placing spacer washers inside the caliper mounting holes and onto the arm mounting position) and space the wheel off the disc about 6mm to clear the caliper, (see previous blogs) this meant spacing the A arm even further in than expected. But don't the disc and caliper look lovely?

With several hours spent fitting and dismantling the spring plates, grinding out the chassis a little more, cutting tubed spacers and threaded rod to length then refitting it back on the van, I finally decided to use 57mm lengths of tube to space the A arm in from the spring plate. This gave the 205/60 /15 tires about a 24mm clearance gap from the wheel arch and 18mm gap from the face of the spring plate. The problem now is that I can only fit the wheel over the disc and hub when the spring plate is set on the original spline (touching the bottom stop). I also need to work out where the damper mount and bump stop will fit. It's a good job the wheel and tyre aren't heavy...

Rear corner lower repair

I've always known there are a few mysteries hiding in the rear corners of my bus so armed with a grinder rather than an archeologists' trowel I fought my way through the layers of ancient filler to unearth all the rust demons hidden beneath.

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I wasn't too surprised with the left side- a few small holes around the shelf line and plenty of dents under all that filler but the right side revealed this maze of holes on the inner corner of the deck lid seal line and covered by a channel section on the inner skin. This could be a little tricky to fabricate a patch for. But I like a challenge...Not

944 IRS conversion

Taking a break from all the welding and body work, I managed to drag my mate Tim from working on his own van to spend the day removing my rear end and measuring up for the sexier back side. On the VW not my own body. He's not an amateur surgeon. Just to clear that up... This is a Porsche 924s (not a 944 as stated in the title but I think they are the same) rear axle that I ordered from Porsche Apart and it arrived in a box as wide as my garage, doing a little VW to Porsche IRS conversion research online I've found that there are two types of 944 aluminium A arms, one shorter than the other, I hope I have the right one. I've also had a few comments that this can't be done so lets see if they're right.

I've played with the hubs and discs previously (usually when I'm alone in the house) but it was now time to get the serious stuff sorted out. So a quick spray of penetrating oil on all the bolts and the original gearbox and reduction boxes pop out after 40 years with no bother.

Here are the A arm mounting points on the 924s beam, this beam is the same diameter as the bus one at 90mm. I may try and use these mounts if I can't work out how to make a fresh pair.

The mornings' work gave us the measurements we needed to calculate the size and shape of the A arm and most importantly if they would fit. I've drawn up a plan of the measurements to get an idea of how things are going to fit (the arm on the drawing is a bit fat). The Porsche axle wheel offset including discs worked out to be 1497mm across, the Bus axle with the original reduction boxes and drums came up as 1445mm across. To keep the outer wheel rim in the original position under the arch and using wheels with an extra 40mm offset means I'll need to locate the A arm mounting points 46mm closer to the center line.

I've also stolen a couple of photos from the SSVC 'For Sale' forum of a 944 rear end and edited them to show the comparison of the different length arms below. Please don't sue me if you hold the copyright of these pics. The longer arms have no bump stop molded in the arm and a longer reach from the spring plate mount.

Before we removed the spring plates I marked their position across the spline shaft with a junior hacksaw then carefully slid them off making sure the inner portion of the splines stayed in position, if the moved I'd have to waste a lot of time later setting the ride height to the correct set up. The 924 spring plates are a lot shorter and made of two plates, the outer plate has the inner spline tube poking out (the spline is smaller than the VW one) the tube is slid through the inner plate and held in place by the two bolts one is elliptical used for adjusting the ride height, the plates are sandwiched by rubber bushes and bolted on in the same way as VW do it. With the reduction gear boxes out the way we decided to see what sort of ride height would look good. These are 205/60/15 unfortunately they are touching the top of inner arches. But you must admit it does look good! (No the grass isn't real, I R Photoshop King)