Never let an old girl die – bike restoration blog – and general bike gibberish related to keeping your girl on the road

’75 RD350B update: beginnings of an R6 Front end conversion

There’s a veritable tonne of lug converters for cars and trucks but there’s practically none for Motor bikes and for good reason.

Motorbikes tend to have a very limited amount of room in between swing arms and forks, in fact, there’s basically no room at all to insert a spacer/converter.

This of course isn’t the case when it comes to converting a bikes front end from one set of forks to a completely different set, if you change your triple set that is, as it is ultimately the triples that determines the width between your forks.

As part of my restoration (modification) RD350 project I decided to update the front forks with some that I’ve had for my FZ6 project, a set of 2008 R6 USD forks.

If I wanted to just bolt an R6 front end on, it wouldn’t be too difficult, steering stem on the frame might need some attention and the frame might need some strengthening as the R6 forks wont flex like the old ones.

However I have plans to put on the RD400 Mag wheels on this conversion and wish to maintain the use of the R6 discs as well as the calipers… which means I’ve got to learn how to use some sort of CAD program, design up some lug converters that double as spacers, get them printed in plastic to check sizing, then get them machined and put to use.

A friend who uses 3d printers and the like pointed me at Autodesk 123D and I’ve just had my first attempt at using it.

After a few hours playing around I have come up with the following caliper/spacer – it’s not complete yet but it gives you a good idea none-the-less.


It’s a fairly basic spacer/adapter at this stage and it basically allows me to bolt an R6 disc on the outer 6 holes and then bolt the converter itself to the wheel via the inner 6 holes.

It will be 8mm thick in the center – the same thickness as the RD disc and thicker on the outer edges to put the disc where it needs to be.

There’s sadly a lack of tutorials for 123d that I could find but I worked out most of what I wanted eventually.

I’m tempted to design up a seat/cafe hump in 123D and trial 3d metal printing… still, I should probably get the rolling frame sorted first 😉

Next up, need to sort out what axle I can run with this… ie if an RD400 axle will be sufficient in width with the R6 forks…

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Comments on: "’75 RD350B update: beginnings of an R6 Front end conversion" (1)

  1. How did it go? Did you have the part made?

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