Part X: A Trip to the Doctor's Office

Mechanical Meditations

Viewed from the street, John "the Frame Doctor" Fromberg's shop just looks like another crowded mechanic's bay in a busy industrial park. But walk past the racks of metal stock and rows of dusty bike frames into the back room and you'll see this is no ordinary chop shop. Dr. John's inner sanctum is dominated by a massive steel table on which he straightens the backbones and downtubes of badly bent frames. Stuff you or I would deem scrap metal the Frame Doctor restores to roadworthiness at the rate of two or three bikes a day.
And so I brought Dr. John the MB5 frame, which I had discovered was unequivocally and severely bent. John has been in the frame-straightening and fabrication business for decades, and in that time he's developed a closely guarded series of techniques and an arsenal of specialized tools. That massive steel table is the centerpiece of it all, and it's been drilled with a matrix of threaded holes to accept the myriad Medieval-looking jigs, fixtures, and braces that hang from the operating room walls. Bolted to one end of the table is a steering head fixture, a contraption that looks to weigh at least a hundred pounds. Hanging from the ceiling above the table is a winch for moving frames into position. On the table a Harley chassis awaits attention.

[To straighten a frame, John first has to figure out how it’s bent. To do that, he positions it on his table with the steering tube centered and locked into that anvil of a jig. Positioned in parallel with and exactly 12 inches above the table surface, it serves as the reference point for the rest of the frame. Just as the number 12 plays into our clocks, calendars, and the MB5’s ignition timing BTDC, so to it plays an important role here. Because until the center of the rear axle measures exactly 12 inches off the tabletop, the frame is not straight.

With the offending angles identified, the Doctor applies his secret blend of pressure and counter-pressure to bring the tubes back in line. Other critical planes such as engine mounts and swingarm pivots are checked and brought into alignment as well. It goes without saying, but don’t try this at home, or even in your well-equipped shop. Dr. John has years of experience and has invested thousands of dollars into the specialty equipment he uses in his trade. In all his time as a frame doctor, John has only come across a handful of frames he was unable to straighten. Even cracked and torn tubing can be repaired since the Doctor is also versed in welding and fabrication.

[As it turns out the MB frame was a full inch out of line from steering stem to stern. The bike’s backbone was stretched upward, a condition the Doctor attributes to the bike having been ridden while the upper engine mount (the engine serves as a stressed member) was out. Additionally, the subframe and swingarm were twisted, which was most likely the result of a violent tumble or rear-end impact.

But when I got it back everything was straight as an arrow. The rear wheel sits squarely in the swingarm and points directly down the backbone of the frame, and the engine bolts slip through the head and case smoothly. The Doctor even managed to do it all without marring the frame’s finish too badly.

Got a bent frame, or a bike that just won't handle right, no matter what you try? Take it to the Frame Doctor's and have it checked out. Don't live in SoCal? The Doctor ships. He's familiar with all manner of motorcycles from customs to cop bikes, and experienced with all levels of damage from minor tweaks to major carnage from racing wrecks. Dr. John also straightens wheels, forks, triple clamps, and brake rotors, and does custom fabrication and frame modifications as well. Check out his excellent website (if you're at work make sure to turn your computer's speaker volume down first!) for a full list of services and prices.

Resources:

Dr. John's Motorcycle Frame Straightening
Singlehandedly responsible for putting the MB5 project back on track!
drjohnsmfs.com

Sudco International
Replacement electrical components, Mikuni VM22 carburetor, perveyor of quality replacement parts for vintage bikes
sudco.com.com

Michelin Tires
Gazzelle moped tires
michelinmotorcycle.com

Caswell Plating
Epoxy tank sealant - the best there is!
caswellplating.com

Treatland.tv
Malossi 70cc kit. Moped parts superstore.
treatland.tv

Perk LLC
Case gaskets and technical advice. Supplier of hard-to-find moped parts.
perkllc.com
(317) 371-8530

Rusteco-Rust
Removal treatment for the MB5's gas tank.
rusteco.com
(800) 787-8326

Haynes Manuals
Invaluable technical information and diagrams.
haynes.com
(800) 242-4637

Huntington Beach Honda
Various OE parts such as gaskets, grommets, and seals.
hbhonda.com
(714) 842-5533

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A Trip to the Doctor's OfficeMotorcyclist
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A Trip to the Doctor's OfficeMotorcyclist
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