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Shortening the MJK Dogbone Chassis

Hi, there are various ways to overcome the problem of the axle lining up with the mounting screw holes with the MJK Dog Bone chassis. One is bending the screw mount tabs over 180 degrees & notching the chassis to clear. The other is to angle the screw tabs so the wall plug misses the axle. This means that the wall plug may be at up to 45 degrees to the body contact point. Both these methods work but I decided a different approach. In this case the chassis was too long for the project body anyway.

This method I used a car body tool used in rust repair. The rust is cut out and the remaining metal is stamped in a "Z" with this air tool to form a recess so the new metal plate is flush with the original panel ready for welding in place.

I put the chassis as original in a plywood and angle plastic jig. The plastic angle was drilled for the axles at the desired wheel base ans also at the correct height for the chassis resting on the plywood base. after squaring up the plastic angles were screwed to the base with the chassis in place and the angle pieces fitted on the axles

I marked the chassis at the cut on the point. I then marked at 11mm from the cut on the chassis piece I wanted to end on top at the "Z' join. I did these wit a small square so they are right angles to the center strip of the dog bone chassis.

The chassis was then cut with a normal hacksaw with medium teeth. The piece to be on top at the join was then pressed to the "Z" shape by the Air tool. That piece was then drilled for 1/8" rivets. Best to take the hole jig & chassis to a drill press to drill. I then rotary filed the holes slightly so the pop rivets fitted in snugly. A snug fit is important to make sure the chassis can't move out of line.

The chassis is then fitted back into the jig with the axles inserted in the correct adjustment hole for the wheel base and the fit of the "Z" joint. I did not do this but I now suggest fitting 2 screws into the ply wood each side of each piece near the join. This should hold the chassis halves in alignment while drilling.

I would suggest doing one rivet hole first and fitting the rivet after removing the chassis pieces from the jig . Then replace the chassis in the jig and drill though the second rivet hole. Fit the second rivet then dress the rivet head with a file but don't take too much off- clearance should be OK . If not bend the chassis center slightly

Next - assemble the chassis & body & have fun - John

PS most crash repairers would have the air tool to do the "Z" hopefully they would do it for goodwill. If not contact me & I will do it for you. 

Chassis Alteration photos

Sleeves to fit 3mm Plafit bushes to the MJK chassis

Hi, The MJK Chassis only come drilled for the 1/8 axle size bushes. These Oilite bushes are larger in OD than the Plafit 3mm bushes.

I needed to use the BRM Porsche front rims for a project. They were the correct size and took the plastic kit wheel inserts. Also they are a very nice rim as they are light weight air rims. MJK only make tyres for the BRM rear rims at this point but you can fit the rear tyres by fitting them with the normal inside wall to the out side with the wider bead. This is a bit teadius but with patience and 5 dots of glue on each rim bead it can be done , But take great care to see the tyre is true after each glue dot. The completed mounting will need to go in a tyre truer. Maybe MJK will produce the correct size soon for the front rim - so check with them for supply.

Now back to the axle bush adaptor sleeves.

I found that the #132 brass tubing was near to correct for the Plafit 3mm bushes. with a bit of Locktite bearing mount - or epoxy glue the would be fine if left to set with the axle in position. This also ensures the bushes are in alignment for the axle.

I machined the OD of the tube down to 6.7 mm but left a 1mm flange at the original OD . The part that goes through the chassis was 2 mm wide .

Using the 3mm bushes and sleeves allowed the choice of using the Plafit range of gears as well .

I will machine sleeves if people require them.  

Bracket for PLafit Fox 2 Motor - in MJK Le Mans Chassis

Bush sleeves to fit 3mm Plafit Oilites.

The #132 - 9/32" Brass tube is machined to 6.7 mm OD for the chassis bush hole .


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