Meet “Frankenstein” and the Mad Scientist

Planning out “Frankenstein”

This blog “Building the Monster” is being produced on behalf of Brent Mayfield, who is a CCM team rider and renowned custom motorcycle builder. His creations have been featured in magazines all over, from Ironworks Magazine to Easy Rider and have won numerous accolades at events all over the world.

For his 2014 Cannonball Ride, Brent is attempting something that is anything but easy: building a motorcycle that Harley Davidson never produced. Using a 1920s JD model frame, Brent is shoehorning a powerful VL flathead motor into it to create a hard-riding, bad ass custom bobber. Without further adieu, here’s part one of Brent’s custom build blog. Let’s meet the beast and the mad doctor behind its creation.

Brent Mayfield with his 1935 Harley Davidson VJ-the bike that never existed.

Brent Mayfield with his 1935 Harley Davidson VJ-the bike that never existed.

I entered the 2012 CB (#77) with a bike I had purchased and then totally redid. It was a 24 J motor in a 25/27 chassis. It was my first attempt at a J-series bike as most all my experience is with UL’s, knuckles & pans. I really enjoyed building the bike and it came out great. The bike ran great and was comfortable to ride. I was impressed with how light it was and how it handled (for a 88 year old bike). I did not finish the CB but it was not due to the performance of the J. Our Team Leader, Mike, is now the owner of the J and will be entering it in the 2014 CB.

When I started hearing rumors that there might be a 2014 CB, I started getting the itch to build another bike. Not finishing to 2012 CB had really bothered me and even my wife said that if there was a 2014 I should go for it or not finishing the 2012 would haunt me forever (what a gal). If you remember, the first rumors said the route might go from Key West to Seattle and the bike year had gone up to pre 37. I called the promoter and asked him : will there be a 2014 CB, if so, what’s the route and what is the bike year cutoff.  He said there would probably be a 2014, the route may be from Florida to Washington but the bike year was going to stay at pre 30. After this conversation, I knew there would be a 2014 and started looking for another J or JD. I did not want a complete bike ($$$$) and was looking for a basket case or just parts. Over the next couple of months I found and bought a 25/27 frame, 28 frame, 27 transmission, 30 VL transmission, 28 JD motor, 28 fork, 25/27 fork and boxes of various bits and pieces.  I figured when I got the bike done, there would be parts left over that I could use for spares and then sell off after the CB. I had just started getting into the 28 motor when I heard that the acceptable year had been raised to pre 37. I called the promoter and he confirmed that it was now pre 37. While the J/JD bikes are great, I would have liked to build a VL. I started looking for a VL basket case and figured I could sell all my JD stuff or sit it aside for a later project. I was having a hard time finding the right VL project for the right price. Seems like Cannonball fever had hit everyone that had any VL stuff and the prices had really gone up.

After some careful attention and skilled welding, the VL motor now fits smoothly in the JD frame

After some careful attention and skilled welding, the VL motor now fits smoothly in the JD frame

While at Wauseon this year, I ran into a good friend of mine who is mainly into Indians but I told him what I was looking for. I couldn’t believe it, he had a 1935 VD motor complete that he had bought many years earlier and had never used it for anything. He offered me the motor at a great price and I bought it. OK, now I have a motor and I had a 30 VL trans, just needed a VL chassis. I was sitting in my easy chair in my shop surveying all the stuff I had accumulated and it struck me. I had the V motor and trans and I had an extra J frame and fork. I really liked the way the J handled and how light it was. Why not marry the V motor and trans to a J frame and fork (easier said than done). After reviewing what it would take to build this hybrid, I thought, we have the technology and skills (file, hammer and welder) to pull this off. I started picturing the finished bike in my head and thought, this might be some little bobber/hot rod style bike that some guy would have built in the 30’s. I got excited and thought this is it, my 2014 Cannonball bike will be a 35/25 VD/JD. I had  to shorten that name. Since the bike is titled as a 35 (titles go with the motor), I’m calling it a 35 VJ (yes I know). The plan is set and now to get started.

Compared to the relatively small space occupied by a Harley J model engine, the flat head VL is massive

Compared to the relatively small space occupied by a Harley J model engine, the flat head VL is massive

First I had to make sure there was enough real-estate in the J frame to accept the V motor. The J motor is taller and has the generator in back. The V motor has the generator in the front. The J motor mounts horizontally and the V mounts vertically. I decided to use the 25/27 frame as it had already had its rear motor mount modified to fit a pre 25 J motor so it was not a good original frame. I wanted to keep the 28 JD motor, 28 fork and 28/29 JD frame together for a later project. When I built my last CB bike, I had made a small cradle to hold the single down tube J frame while I built the bike. I used this to hold the 25/27 frame. I then used blocks of wood to hold the V motor (with generator) in place just to see if it was going to fit. There were some parts of the frame that got in the way but I could see there was enough room. I then cut out the old motor mounts and some other small areas of the base casting. I then made a small sub-frame for the V motor to sit on while I positioned it in the frame.

Starting to modify the J model frame to house the custom touches in building a VJ

Starting to modify the J model frame to house the custom touches in building a VJ

When I got the motor where I wanted it in the frame, I made patterns for the new motor mounts. I did not want to weld the new mounts directly to the old frame tubes so I decided to make some sleeves to fit around the old tubes to weld to. This would also strengthen the frame much as Harley did on the 28/29 frames. I made patterns for sleeves for the top and bottom of the seat-post tube, the bottom of the front down tube and the top and bottom rear frame legs at the rear casting. We made the sleeves by taking mild steel tubing with an appropriate OD and boring it out to the proper ID to fit the frame tubes. The angle was then cut, cross holes drilled  and the sleeve cut down the middle. The 2 halves of the sleeves were then clamped around the frame tube with the one end up against the casting. The sleeves were welded to the casting, through the drilled plug holes and the seams welded together.  The new motor mounts were then welded to the sleeves. Should be pretty strong and it looks neat. Since I was going to use the 25/27 rear fork leg, I also made patterns for reinforcing sleeves to go under the lower tree and ribs on the rear of the lower area of the leg. I figured this would help strengthen the fork for using a front brake. The fork sleeves were silver soldered in place and the ribs welded. While I do some of my own welding as I can make 2 pieces of metal adhere to each other, it’s not always very pretty.

Mayfield's friend Doug is a master welder, and is seen here modifying the JD frame

Mayfield’s friend Doug is a master welder, and is seen here modifying the JD frame

 I have a friend, Doug Times,  who is an artist when it comes to welding. When I have some welding to be done that I feel needs more expertise than I have, I take it to Doug. That’s him in picture .3 and you’ll have to admit the welding on the motor mounts and sleeves is a thing of beauty.