Shop Teacher Bob: March 2025

Friday, March 7, 2025

Eureka! Quick-Change at Last

The Quick-Change for the jitney project came in yesterday morning. I didn't know what the deal was going to be as far as how it was going to be delivered but I got a phone call on Wednesday from the shipping company - straight truck with a lift gate some time between 8:00 and noon. All I needed to hear. The driver put it on the gate with a pallet jack and then rolled it into the garage for me. Nice guy, great service. Thank you, Dayton Freight. I did get a chuckle out of the fragile sticker on the carton. This thing is supposed to be good for 600 horsepower. Not what I'd consider fragile, but it made it here safe and sound and that's all that matters.

Page from the 1972 Motorcycle Repair Manual that I've had since 1972. There's a wealth of knowledge in the book. While much of the stuff for individual bikes is outdated, unless you happen to be restoring one of those particular models, like a BSA 650, the math in the back is most helpful. And math never goes out of date. So it's time to do some cipherin', Jethro.

The ring and pinion in the differential is 4:33. The transmission is 1:1 in high gear and the rear tire is a tick under 32" tall. According to the formula MPH = rpm x effective rear wheel radius / overall drive ratio x 168. That gives me 5000rpm x 15.75 /4:33 x 168 = 108 MPH. The effective rear wheel radius I figured for a tire 31.5" tall to account for it getting a little shorter with the car weight on it. So if I put quick change gears in the differential with a 1:1 ration, that's what I'd be looking at.

23/25 gears would give 117 mph on the high side, 100 mph on the low side

22/25 gears would give 123 mph on the high side, 95 mph on the low side.

All of these numbers are figured at 5000 rpm and make no allowance for horsepower numbers. The car is going to be pretty light, so the Slant Six should be able to pull to a 5000 rpm redline in high gear. When I looked into going to Bonneville, as long as you stay under 125, a regular operator's license is adequate, so the 22/25 change gears would be right in the ballpark.

Even though the diff is tagged as having a 4.33 ring and pinion, I'm going to double check that. The catalog listing says3.78. When I'm sure of what I've got I'll order the change gears, a couple of gaskets and some oil. I've already got the brake parts and axle studs, so I don't need much more to get it under the car.

Wednesday, March 5, 2025

State of the Union

I watched the State of the Union address last night. I don't normally sit through them, but I figured in light of what's been going on, it should be interesting. And it was. Say what you will about President Trump, the man can work a room.

I liked that he addressed the need for building ships for the Navy. I've read quite a bit about that situation and commented on it a couple of times here. It's good that there will be action forthcoming and it will put a lot of craftspeople to work. It'll be interesting to see if they can find enough qualified people in the various trades to get the job accomplished, however. They just might have to start paying the welders a better wage.

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No word yet on the delivery date for the quick-change. I'm not in any hurry, just want to know when the delivery is scheduled so I can plan to be here.

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A photo of pipe weld a former student of mine sent me recently. I'm not sure when he graduated but it was probably something like 25 years ago. Always nice to hear from him. Teachers and coaches often wonder how much impact we've had on our students. In his case, there it is. One fine looking multi-pass MIG weld. Makes me proud.

Monday, March 3, 2025

This & That

David Johanssen, aka Buster Poindexter, passed away a few days back. He was just a few months older than I am. I'm looking for at least another 5 good years. If I make it to 80, I'll reset the clock and shoot for another five. RIP Mr. Johanssen.

The photo is from the Rivendell bike email I received. It has a very much 1940s look to it, other than the electric fan. I especially like the welding hood with the riveted leather flaps top and bottom. The photo was taken at the Nitto factory recently and Rivendell is selling a series of 5x7 prints at a bike show in Philly currently and if they don't sell out of them at the show, they'll be on their website.

They are also selling Ilford black and white film in 35mm and 120 now in addition to complete bicycles, parts and accessories. Theirs is a different business model than most bike manufacturers but their website is worth a look. We all should be a cyclist of some stripe - good, low impact form of exercise and cheap transportation for short hops. A Rivendell bike is not necessarily cheap, but my touring bike that has taken me on several long-distance tours cost me only eight dollars from the local church rummage sale. I spent some money on a couple of upgrades, but there are lots of cheap bikes out there.

Frankie Flood at Handverker has some interesting stuff up on his blog. You need to scroll down and see the '36 Ford. The car was built at Rad Rides by Troy. Surly and I took a class from Ron Covell that was held there several years ago. They do great work, but I don't think this one can be topped. Check it out here.

Sunday, March 2, 2025

Linkage

I worked on the trials bike yesterday and finished the linkage. The only thing left to finish the frame is the piece to hold the rubbing block for the drive chain. Actually, I already have a piece made, just need to fiddle with it a bit then tack it on. I get that done, I'll weld everything finish and either paint it or powder coat it. It's getting close to being done.

Looks like it'll work - just needs some tidying up. Surly's coming down today to discuss a few things. The BSA project will definitely be one of them. The quick-change for the jitney, hence the Chuck Berry song, will be here this week. I need to get that to the stage where I can roll it in and out of the shop. I did a little think time on a way to turn the drum on the bike wheels if need be. I made a sketch, but I'll hold off on machining any parts until I need it, if I do. There's plenty of other projects on the list as well.

I got a call from the boss man at the college. I'll be teaching MIG 2, instead of Stick 2. And the nights will change, which will work in my favor. I'll be able to go to the boxing gym and the ham radio club meetings now. Don't know if I'll want to be busy four nights a week, but I do enjoy going to the gym and I definitely need the exercise.

Saturday, March 1, 2025

True Dat

I went to the massage parlor yesterday morning. In addition to working on my back, she tried getting the leg muscle to relax some. She did some cupping, so now I've got big hickies on the side of my legs. Not a problem since I won't be going to the beach anytime soon. In fact, I put my long underwear back on as soon as I got home - and I'll keep wearing it at least another three weeks, maybe even until April 1st.

It was fairly warm yesterday but the wind was gusting above 30 miles an hour, making it pretty chilly in the shade. I turned the heater on in the shop and made the piece to hold the dial indicator for checking the run-out on brake drums. Works really well on the junk wheel in the photo - should work equally well on the BSA and the Sportster.

Next up is finishing the shift linkage on the vintage trials bike.

Shop Teacher Bob