Wednesday, February 25, 2015

Rear Axle.

Once the decision to irreversibly modify an otherwise marginally sensible car had been made, we tried to think of the desired outcome and how to get from where we were to where we wanted to be. Of course, the big picture just needed to be distilled down into small(ish) tasks that, once complete, would (not doubt) produce a cohesive Whole. Right.

The first thing to address was the rear axle. As you probably know, old Volvos used tapered halfshafts that were (and still are) known to break off at unfortunate moments. When this happens, the wheel, brake drum and the little stub on the axle end depart the car.

Our first choice was to find the rear axle from a '70-73 1800E or ES, as this would have stronger axles as well as the benefit of disk brakes (which are strongly encouraged for LCP). We were unable to find one in the time we'd allowed ourselves but we did find a '74 142 that was being dismantled. And this donor showed a scant 86K on the odometer, which had us thinking that the parts we were taking probably had lots of remaining life.

Apologies to fans of the 140 series. In my defense, though, the car was heavily scavenged before I arrived to harvest the last bits.

Fitting the rear axle was really pretty simple. The old one came out without any fuss, and because the axle itself is held in place with really  primitive bushings and brackets, all we had to do with the new axle was remove all the suspension brackets with a grinder. The panhard bracket had to come off the axle so that it could be relocated to the opposite side... we'll get that welded later on...

On the left of the photo, no brackets. On the right, brackets.

Because the 140 axle tubes are larger in diameter than the 444, the bushings won't fit. Unless you have a hole saw and a rasp. It's messy. Keep  in mind: if you do something like this, you want the bushings to be so snug you can barely get them into place. Also, if you do something like this don't hold me accountable for your results.
The ID of the bushing on the left has been enlarged. It makes a powdery mess, which is a bit of a nuisance -- but much less of a nuisance than metal shavings. More on that later.

Once we were done cutting things and hogging out bushings, we put the axle into the car. The PV torque rod arrangement simply will not interface with the 140 rear axle, so we made up a bracket that secures to the diff cover bolts and holds the original (PV) torque rod bracket in place. We had to make a few of these before getting everything to line up the way we wanted - the one in this pic is one of the early (and crude) attempts.
The recommendation on wheels for LCP is to use big heavy steel wheels. Not because they're good for racing, but because this event is really about endurance, and big heavy steel wheels are apparently more robust than pretty alloy wheels. Because the 140 has a 2 inch wider track (and a different bolt pattern) than the 444, we also had to consider offset differences in wheel selection. After a lot of thinking and looking online for something that might work, I finally went to the nearest tire store and picked up a 15x6 steel wheel that's typically used for snow tires on the front wheel drive Volvos. It fit nicely, so I bought a set. Readily available and surprisingly affordable.
There really isn't much to mention about fitting rear disks to the car, as they bolt right onto the axle like they belong there. Because they do belong there. The only other adaptation that had to happen was to have the driveshaft fitted with a larger flange that would match up to the new rear axle... which is a really simple thing for a driveline shop to handle. Of course, we got a new bearing and ujoints at the same time, then this piece just fell into place under the car.
Things were going so well that I started thinking the car was going to just put itself together. The axle went into the car in less than a day working by myself, and I spent another day futzing around welding up brackets and making 3D templates for the torque rods.
I'd realize later (and repeatedly) that the axle swap was just about the easiest part of the whole process.
Next: it gets more complicated.

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