With all due respect to GRBrown and Evo Dresser Swingarm Upgrade and Howard at Motorcycle Metal for their pioneering work and documentation of the 2002-2007 swing arm upgrade, I had one question ...

The swing arm pivot shaft (SHAFT, rear fork P/N: 47505-02) is ¾” in the 2002 & above. The pivot shaft in the 2001 models & below is 5/8”. And there exist a number of solutions for fitting the latter swing arm on the earlier shaft.

However ...

What are folks opinions/experiences at honing the transmission from 5/8” upto ¾” to use the later shaft?

If the actual hassle factor of stripping one's bike, and machining costs are not an issue, is it worthy or worthwhile upgrade?

And if so, what are the best bearings or bushes to use in the latter, e.g. I saw elsewhere discussion of using Aurora bearings in that place?

See also discussion, here.

In my situation, I was all set to to go with the 5/8” spindle and STA-BO blocks ... until I lucked over a second swing arm with 3/4" shaft complete. (NB, the shafts themselves are actually pretty cheap via H-D if others are considering this).

Now I am wondering if it's worth going up to the 3/4" and if, say, I can re-machine my STA-BOs to suit ... although we do have some Delrin in the shop where I work too, so I could have new ones made up.

The obviously sound warning Howard offers is to 'never hand drill the transmission' to take the bigger spindle ... that's clear ... but we have a mill and lathe so should be able to do it properly. He recommends a slip fit reamer.

But looking at the new spindle, the narrowest threaded part of it looks the same size as the old one.

I'm guessing the difference is going to be small but if it's also an opportunity to tighten the rear end up and improve tolerances then now's the time for me to consider it.

Thanks

 

I've been ridin' with my 5/8" for several years with complete satisfaction - been to Poland, Hungary and back via Slovenia, over the Alps and Vosges Mountains, all at a rolling weight of around 1200 pounds. I'd save the effort for doin' somethin' else!

 

Having recently done the upgrade with Howards kit, I cannot see any reason to create all the extra work of stripping the trans to properly bore it.. As a matter of fact, it seems to me that the extra beef of the trans housing would add more stability than the 3/4" shaft.. I'm with Graham, spend your money elsewhere..

 

Gonna agree with the above posts. I would not do it after all of their research. Jasper86 had recently completed his and I forget what he did but it is on his rererere build thread on this or the second page.

 

Thanks ...

The transmission is already out of the frame (... I'm in the process of welding it up, and re-powdercoating it anyway).

Costs are zero ... unless I have to buy a specific reamer.

In fact, I'll probably make more than a $150s from selling the STA-BO bushing I bought.

Would that make a difference to the equation?

I heard Howard machines them to a closer tolerances ... and note a few other discussions where individuals looking at and measuring up these pieces discovered they were machined as advertised.

It would be a chance to have it all done to spec.

 

All we can do is comment and make suggestions. In my experience of riding my own modified bike I can see no likely benefit of doing that mod. The negative is that it will take material away from an important casting. I don't know, but suspect the later spec casings are beefed up in that area.

 

I hear you ... I've just got a pile of unused parts and 'upgrade fever' during the boredom of waiting on a load of parts to come back from being painted ... You know, that terrible affliction only made worse by having an angle grinder and too much coffee.

From memory, the amount of metal at the transmission axle mount on an Evo is .435" thick.

As you might suspect, the axle is visibly loose in it hence the inspiration to "do it properly".

Perhaps I might compromise and just turn the new one down a bit to fit snuggly?

 

Here's a comparison ... as you can see, where they go through the donuts - weakest point - they are same diameter. So why the larger centre?

I'm thinking 'easier to machine more accurately cheaply'. If anyone has a measurement of a later one, I'd be interested.

 

I thought this is useful too ...

 

With the whole thing assembled that gap or red ? cannot do anything! The swingarm is restrained by the rubber mount clamps to the frame, at each end, and the trans casing in the centre. Once tightened up the gaps will still be there, but the other features render it/them harmless.