Jump to content
RMR110

DIY axle extension to fit 2.2 rims to a Vintage SRB

Recommended Posts

While my vintage buggy still has all the standard wheels and rubber, i wanted to take advantage of commonly available alternatives so i could put the original stuff away. The rear is simple if you have the re-re axles as they already have a pin layout allowing you to add a 12mm Hex adapter and fit most 2.2 wheels of your choice. However I was still looking at the best options for adding 2.2 wheels and tyres to the front of my Rough Rider, and wanted to share my journey and solution.

The twin challenges were getting rims that were bearing enabled, and extending the axle out enough so the new rim didn't interfere with the steering upright. I found some JConcepts rims for the front that are meant for Team associated models (they take an imperial bearing but a 5x9x3 with a small shim or loctite still works fine), but they still needed to be spaced out far enough that there were too few threads for the nut. So I needed an axle extender.

I could have ordered the CRP extenders but with the Sth pacific peso heading south daily, and me being too impatient to wait for up to 30 day delivery, I looked around for some alternative options. I usually start this kind of DIY bodge with the thought of "what can I repurpose" rather than starting from scratch. So I looked at the problem from 2 directions

  1. was there something with an M4 thread to screw onto the existing axle that had an OD close to 5mm, or
  2. was there something with a 5mm OD to match the axle OD, that could be tapped for an m4 thread.

In the end I tried both methods.

Option 1 - M4 threaded inserts

I found threaded inserts (rivnuts) with M4 threads and a 6mm OD at a local hardware store

19884796669_ef6583199b_c.jpg19883501930_d2af27e517_c.jpg

The rivnuts threaded on to the existing front axle just fine, but obviously the outer diameter was too big to allow my bearings to fit. Not having access to a Lathe, I was wondering how to manage this when it struck me that using a spare rear axle as a holder, I could put the whole lot in a drill, and with gentle pressure use a file to take the 0.8mm I needed off the OD. This turned out to be easier than expected;

20045233756_935c47a3b6_c.jpg

19884844309_04c85b8ebf_c.jpg

20071541905_a43ab47cf1_c.jpg

This worked out fine, but with a largish overhang from the part not reduced which I would take up with a washer and spacer.

Option 2 - 5mm OD spacers

Coincidentally I found a second option in an electronics store in the form of 5mm steel "stand-off" spacers. These hold a circuit board off another, and were hollow with a 5mm OD, so then needed an M4 thread in them. While I've never used a tap to cut a thread, I did have a set, so figured since they were so cheap, I could probably afford to mess around some. In the end it was again pretty straightforward and seemed to have worked fine. I threaded them full length so I could use an M4 bolt to hold a washer and spacer at the other end.

19883467538_edcd69415d.jpg19883480318_0d7e42928f.jpg

The advantage of this method is that I can easily cut the extension to size, which is not as easy with the rivnuts due to their shape. At the moment I have it at a length that means I add a small spacer and washer to hold the bearing in. I'm waiting until I get the slightly larger bearings before I cut it down to exact size, but have loctited them to the axle so they don't unwind on reversing.

The total cost of the rivnut method was ~A$5 (or 25c a piece if you made all 20 into extenders), and the standoff method was a little higher at ~62c a piece. This compares to about A$19 if ordered off ebay, plus i got to install and use them about 1 hour after i started the project..

Here's the end result on my buggy. Hopefully this helps someone else.

20076974241_3a5a5ba907_c.jpg

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...