1974 /6 14mm front axle, upgrade???

[kstoo]

I have done little or nothing on my 1974 R75/6 project for the longest time but . . . the other day I got a pretty good price on a front fork assembly on eBay and I want to use this on the /6. Trouble is that the 1974 first disk brakes used a 14mm axle as opposed to the 17mm used on just about all others including this 1976 fork assembly that I now have. I know that it can be done but does anybody have advise/hints/stories/comments to tell me about how to adapt the front hub to 17mm? I visited snowbum's and Duane Asherman's (sp?) site and read up there but I was wondering if anybody else has done this and has some tips. I am going to take the hub apart and look at it, maybe it will be really obvious. or not.

[20774]

I tried to find something in the beeg Airhead list archives and didn't find anything that said one way or the other. One thing that Tom Cutter wrote was that during the change over from 14 to 17mm axles for the early '75 models, they used 14mm axles, but put bushings in to get up the 17mm size needed for the hub. So, you could go in and remove the bushings and just use the 17mm axle.

That suggests that the '74s had no such bushing and that only way to go would be to drill it out (if it can, but it might (?) probably significantly weaken it), or buy a spare 17mm wheel/hub and go that direction. There might be someone out there who could use a replacement/upgrade to their '74.

Not much help...

[lostboy]

You're going to have to either replace the front hub or have it bored out. The center of the early hub has only enough room for a 14mm axle and bearing adjustment shim. A good used front wheel is probably the easiest way out.

[krehmkej]

The 17mm hub would be a very cheap item. I had one that I didn't need. Put it on evil bay for 5 bucks and got no bids. Just tossed it into the recycle bin.

[kstoo]

The 17mm hub would be a very cheap item. I had one that I didn't need. Put it on evil bay for 5 bucks and got no bids. Just tossed it into the recycle bin.

Krapp!!!! I always wondered what happened to those parts that were left over.



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:nono
:nono

[kstoo]

It really does not look that bad. I took the hub apart today and just seeing what is in there calms most of my fears. At the very center of the hub the I.D. is just big enough to hold the 'wedding ring' in place for the 14mm axle. If that were bored out just big enough to fit the 17mm components then everything else should be fine. I know that is what some of you already said but seeing it for myself it all becomes comprehensible. If I had enough money, this would be a good excuse to find a set of Lester mags to rebuild . . . hmmm?
I will just monitor eBay, IBMWR and this site for 17mm axle and components and sooner or later they will come available. The rest, bearings and seals, were going to be purchased new any way.
Thank you all for your responses. It is good to have you guys around for advice and . . . stuff

[GeorgeRyals]

Why not use bushings (if necessary) in the fork axle holes and use the 14 mm axle in the 17 mm fork? Of all the talk about the "weak" 14 mm axle, I never seen one bent.

[kstoo]

Why not use bushings (if necessary) in the fork axle holes and use the 14 mm axle in the 17 mm fork? Of all the talk about the "weak" 14 mm axle, I never seen one bent.

Excellent suggestion. You know, I had the same idea and I have a suspicion that there was just such a kit sold by BMW for a while:

"36311240987 supplementary set plug type axle (D17-D14MM)-Up to 09/1974"

Still, what really is driving me to modify this to 17mm is that I would like as much commonality between my bikes as possible and this is another morphidite. I have the 17mm axle now and I just need to get the spacer, bearings and seals, which have to be replaced in any case.
Thank you for you suggestion. I see that you have two (2) 1974's so you should know. I had a 1974 that I rode all the way down the Cajon Pass in CA on a rock road that sometimes was actual railroad tracks and I never damaged that one! Even with a sidecar on it, the transmission gave up first!!