1982 Maxim 400 Complete Tear Down and Rebuild

Thanks Mototrooper, holy is that ever one clean Virgo.

I got the frame cut down today, I decided to keep the gas tank bracket as I like the stock gas tank and I'm thinking about mounting a solo seat off of it once I get it reinforced.

Some pictures!



and the Swingarm:



I dropped the swingarm off at a local machine shop today along with a case of beer. Asked to get it extended 6" and dropped by 2" next I'll have to match everything up and see what I need to do to get the monoshock to fit.

Wow, you really tore into that. Hopefully there wasn't much 'springing' apart when you cut it. Sometimes frames have innate tension from the factory welds. Interested in your tank mounted seat though, seen it done on some modern sport bike builds.

I don't understand what you mean by the 2" drop in the swingarm mod though. Is it 2" in ride height? I might've created a scale cardboard template before chopping that into bits first. The way the swingarm is designed, changing the length by 6" radically changes the geometry/trigonometry so the request for a 2" drop may be a more complex task. Also the longer lever of the swingarm may easily overpower the rate of the shock spring. I'm not bashing the way you did it -I'm bringing up stuff that occurs to me when I see what you did and the direction you are headed.

There was next to no springing apart that I noticed when I cut into the frame, it just kinda fell apart when I cut it all off. I was aiming to get about 2" lower of a ride height, and I agree that I should've maybe taken my time and made a cardboard cut out first. I'll definitely make sure to slow down when I think about altering the frame. If the swingarm doesn't work out too well then I guess it's just a lesson learned and hopefully I'll be able to correct it without too much hassle. I'll make sure to read up on shock leverage ratios and do my best to understand it. And don't worry, I'm not super sensitive so I'm really not offended, you're offering great feedback so thanks!

If you cut and weld without a jig, shit will be fucked up

I'm glad I took it to a machine shop then, my welding skills are pretty much non-existent

Well I got my swingarm back today, I called them last week and managed to cancel the whole 2" drop bit and just stick with the stretch. Thanks motoTrooper, I might've had to buy a new swingarm there. The cost was a bit higher than I expected, I thought the job would run me around $260 max but it came to $400 after they dropped the price cause I paid all in cash. This kinda puts a hold on all the other parts and fabrication I was going to have done and I'm definitely wishing I could weld and fabricate right now. Oh well though, just gotta start saving again!

Picture!


Also got some fancy forks on the way

With respect to the rear suspension, I honestly would probably buy another swingarm and go back to stock. When you see stretched swingarms that have been properly modified, you see that the extensions occur at the rear axle mounts. Had you done that the geometry of the arm would've stayed intact and you could mount it right up and possibly the added extension leverage would've compressed the stock shock the amount you wanted to begin with. But building things like this is a fantastic learning opportunity that most people can't be bothered to figure out.

Did the shop who did the welding show you how they jigged up the swingarm to keep everything in line and straight? You may have to do some careful measuring and check alignment. I'd find a level area in the garage and set the forks, swingarm, and frame assembly on some blocks, checking that the front and rear axles are level and straight with respect to the frame.

At this point I'd also suggest looking on Craigslist for a used MIG welder. You can usually find good ones for $400-500. Welding with a MIG is incredibly simple and the skills you learn will transfer to so many other projects. Yes there is a bit of initial learning curve but you can find all sorts of resources online to help. The guys at the fabrication shop aren't geniuses so you don't have to be one too to attain their skills. And it feels really good to do this stuff yourself and not have to rely on someone else and their timetables to get things accomplished. Best of luck man.

*it double posted my comment for some reason

For the money you spent it better work perfect. Hope they used slugs inside the tubes.

I'm definitely looking to get a welder, I think it'd be really satisfying to have done the whole bike myself. I am going to try this swingarm just cause I want to be sure it doesn't work before accepting that I spent $400 on a real heavy paperweight. According to the receipt they only used 1-1/2" square CF bar and 3/4" DOM tube, so I'm guessing there's no slugs in there. I'll probably go back tomorrow and ask to see how they jigged it up if that's possible. As for the extension occurring at the rear axle mounts, I'm not super clear on that. Do you mean they cut the mounts off and then just extend back from there? I'll attach some pictures I drew up real quick to hopefully get a better visual idea of what you mean.

Stock:



Thought 1:



Thought 2:



Sorry for not being very well informed on this stuff, got lots to learn!

Yep thought #1 is what I was referring to as shown by what these racers did to this magnificent CBR1000 swingarm.


That said I prefer thought #2 as it provides a direct load path from the rear axle to the shock. But as light as these bikes are #1 is probably ok.

Try the one you've got first. This isn't going to be a track machine or ever leave the ground. You'll probably find it will work just fine for what you're going to ask of it.

I also doubt they slugged it as it doesn't look to have rosette welds and at the front the tubing angles back in towards the swingarm pivot so they would have had to match the angle to fit a slug in there. I just don't think they would have done that.

With the swingarm design I don't feel slugs would be necessary anyways, but that's my non-professional opinion so take it for what it's worth. But if you felt unsafe about it you could add a gusseted piece between the lower tubes and vertical support pieces.

I'm curious, did you try the extended swing arm? I agree with previous post. I would be surprised if those welds broke given the design of the swingarm and the stresses involved. It would be something I would monitor by checking for cracks in the tubing right next to the welds. Most likely on the underneath side of the tubing. In my experience these type of welds don't fail abruptly, they usually flex enough to start a small crack that gets bigger and starts a crack on the opposite tubing before it actually comes apart. Two cents.

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Hey, I'm going to be trying the extended swingarm cause I think it'd be a big waste of money to just throw it out. The welds look good and clean to me. I'm still waiting on some parts and whatnot before I give it a go, but I'll be sure to post the results as soon as it's all together!

Hows it going, Oops? I'm thinking about doing a tracker build with my Maxim 400. I have a similar plan for my seat, and I'd love to see how yours is shaping up.

Hey Sprout, build is slowly coming along! I met a welder/machinist through work who said he'd help me out with the project so I've got the frame and seat all done up now. The frame is HEAVILY modified though. We welded in a bracket to attach to the new shock and extended swingarm and then built the seat pan off of that. The bracket goes all the way up inside the hollow neck area in the DOHC frame. I decided to get rid of the stock tank, and replace it with an old Harley tank instead. Here's a picture of how it's coming along, please excuse the messy garage

Very innovative, man. Looks really good. Hope you keep us updated, this bike totally stands out.

Ooookay, been gone a while again. I've made some more progress on the bike too! I've been plodding along trying to get parts and everything organized and good to go. First off, here's how the bike looks as of a couple weeks ago:



Some new things here! First off, the Aprilia rs125 front end that so many of our friends across the pond use.



Next, the MAC 2-1 exhaust system, I had a bit of difficulties fitting this for some reason. The headers required a bit of persuasion to fit in the head.



Rear fender is also mounted, along with a chain guard, side mount license plate, keyed ignition switch, and 1927 style Ford taillight, none of which are really visible here aside from the fender.

Next up I've got to put bars on it. We're machining a set of risers to bolt up to the Aprilia rs125 Tuono top yoke, which come pre-drilled for risers. Gonna throw some drag bars on 5" risers. I'm thinking chrome, thoughts?

Also have to get a speedo, I like the 2" speedhut gps style ones, but I'd like an odo so I can keep track of my fuel ups.

I'll get some more pictures when the bars are on. Feel free to ask or comment on anything!

looks great! love the USD forks wish i had the time and money for a front fork swap

Did you get those from the UK?