MG TDs didn't come from the factory with an alternator to recharge the battery. In 1952, an old generator was good enough. In fact, it was probably still good enough in 2019, but in that year, Jake Roulstone and I collaborated on a blog post on how to convert to a modern alternator, which became Part 45 of the Beck TD saga. The installation documented there has worked perfectly ever since, so of course this winter I decided to redo it. What good is a project car if you don't have projects!
The reason I wanted to move the alternator had to do with the cooling system. The other winter project is to make several modifications to Beck's radiator, hoses and fan, all of which will be documented once I actually do that work. It wasn't absolutely necessary to move the alternator to do that, but doing so would make the ongoing maintenance of the cooling system easier. I saw this good-looking setup on the Volvo Powered MGs group, done by a fabricator named Steve Studer. I wanted to do something like that.
I started the process by making a slide for the top mount of the alternator. Sure is nice to have a big milling machine to make slots like that. I later did a bit more trimming at the mounting hole to improve clearance at the valve cover.
For the lower mount, I decided to use these two holes that are present in the later Volvo B18 blocks, and the B20 block as well. I did some careful measuring, and determined that the hole centers are exactly 40 mm apart. I just changed the Digital Readout on my milling machine to metric when I was drilling those, easy-peasy.
This was proof of concept - I drilled a short piece of wood for those two holes, and set the alternator on it, and attached the top slide. Visual alignment looked good, so I set out to make a heavy steel bracket.
The top of that bracket was to be a U-shaped piece that would allow the alternator to be held and adjusted. Emailing with Steve, he suggested to make it with some slack to precisely adjust the belt, and to make some precision spacers to hold it in the right spot once I knew what that was. I used my 20-ton press and a homemade bending jig to bend that U shape.
And here's the finished bracket, along with a spacer that fits behind it to ensure it doesn't lean on the front cover of the engine. Looks good, right? I thought I was basically done, right up to the point that I installed it and realized that it stuck out too far on the front side, and would hit the fan belt. To be honest, I wasn't totally happy with the bent design anyway. It was impossible to get the ears exactly at 90 degrees, and I had difficulty aligning front and rear holes in the U shape. I started over.
There were several benefits to making the ears separately and then welding them on. I could use thicker metal, since I didn't have to bend it. The precision of the milling machine made getting the holes aligned almost trivial, and I could use the mill to help keep the threaded hole straight also.
I still had to do some making and re-making, but my technique improved with each try, and finally I had this one, which was well-aligned, and sized to avoid any interference with the belt.
It only took me two tries to get the right fan belt to fit. At least in my market, the NAPA store is the one to visit. They are used to special requests, and actually understand their stock. At Autozone, for example, if you can't tell them exactly what car it will fit, they don't know how to look it up.
With the belt in place, I spun the engine briefly to make sure the belt was tracking properly. I could move the alternator a bit to get it just right, and then I measured the gaps from the alternator frame to the bracket. I had previously drilled a 1" steel rod, and used that to make two custom spacers.
With the spacers in place, the alternator is precisely located, and will stay there.
And it all worked! Even though the radiator is out of the car, I could run it for a minute or so and carefully look things over. The belt runs with nary a wobble, the alternator charges, and it's all good to go. I'll close with these pictures to remind me just what belt fit, in case I need to get another someday.
Continue on to Part 81....
No comments:
Post a Comment