‘72 Commando Front Axle Spacers

The only reason for two washers here would be to help get the front and rear wheels to line up. Which possibly means that either there is something bent......frame, stanchions or rear swinging arm or one of the wheels has the wrong rim off-set.

Those look like stainless spokes so rebuilt if so, that disc front wheel has an extreme offset to the disc side that inexperienced wheel builders can get wrong or experienced ones that cannot bring themselves to under tension a spoke. The disc side spokes should be nearly vertical and the tension high, non disc side angled with lower than normal tension.

The wheel is supposed to be pulled up against the RH fork leg by the shoulder on the spindle, when you tighten the nut — that's why there's a hole to put a Tommy bar through (which I see in your picture is being done).

Assuming the wheel is correctly built its alignment with the rear one should then be correct (or as correct as it ever gets with a Commando … ).

You shouldn't need any washers at all. Perhaps a p/o failed to understand how the assembly works?

There is no need for additional spacers on the pinch-bolt side. A spacer, usually incorporated with a dust cover, goes on the disc side and sets the offset of the wheel in the front fork. The shoulder of the axle then sits hard against the dust cover on the pinch-bolt side which 'floats' on the axle to the correct width. There is a risk that additional spacers could pack out the fork legs and space them wider than they should be.

The only reason I can think of for your spacers would be to compensate for an axle that has been shortened - often done on race bikes to save a bit of weight, bringing the outside of the axle flush with the fork leg.

Neill, woud you elaborate.

Spacers can only cause the fork end to be further apart. Too thin a spacer on the pinch bolt side should make no difference to fork width because the fork 'floats' on the axle's larger diameter until you tighten the pinch bolt. The only possible reason I can think of as to why this might happen is damage (abuse, corrosion) to the end of the axle preventing the fork moving freely over it. Yes, the tommy bar hole might disapear into the fork end but the distance between fork ends should be self-adjusting.

It's not easy to measure, but centring the wheel rim in the forks is probably, in my opinion, the most important step in creating a stable Commando...No matter how good the rest is, if that disc side is not pulled upright beyond most of the laws of physics then you'll be forever fighting the rubber-hinged whole which under normal circumstances just follows along...

Spot on Richard and the correct spacers and hub width are essential to front wheel alignment and free suspension movement. The wheel rim must also be spoked central in the forks as you say.

It wouldn,t surprise me if failure to check this has had an influence on the many handling problems reported on Commandos in this forum and elsewhere. Ironic considering the legendary handling woes of early Japanese Superbikes.

As Julian mentions the hub and spacer are pulled up tightly against the axle shoulder and slider on the pinch bolt side and effectively become a solid assembly once the axle nut and pinchbolt are tightened. There is only a narrow range of movement for the optimum axle position, if your tommy bar hole has disappeared into the slider you have not fitted the axle correctly!

Note that the spacer in the second image is wrong. I replaced it with the correct 06- 6034 Mk3 one which is 4mm longer between the bearing and dust cover. Possibly accounts for Richard Potter,s additional shims.

I,ve deleted my earlier post as it seems to have caused some confusion.

You,ll need to check the centres of the two sliders are 7 3/8" or 187mm to be 100% certain. The spacer in my photo is possibly your 06-3918. It,s 9.0mm thick.

Your extra washers may be the missing 4mm of the Mk3 06-6034 I bought to replace it which will be around 13mm overall although I didn,t measure it.

The extra 4mm is on the inner bearing side of the 06-6034 by the way, possibly because of the circlip arrangement of the later hub. Outwardly they look identical fitted with the spacer against the slider as in my photo.

No idea why the washers are there if you have the correct spacer (unless you have the circlip hub) but if the forks work smoothly, the tyre is centred between the forks and the bike handles well you,re probably very close anyway.

Hi Richard, the spacer part of your dust cover is missing and needs replacing. Someone has put the washers in to emulate the missing spacer. I also have a 72 disc braked commando and have put washers in mine to make up for the missing spacer. Ive attached a photo of my bodge up and a photo of the correct dust cover with spacer attached to the outside. You can buy the correct dust cover with spacer from RGM or AN. If you dont have the correct spacer in the fork legs get pinched in too far and stop the fork sliders moving up and down properly. I should really order a new dust cover myself but the washers are doing the same job for now. I hope this explanation make sense.

Donald

The spacer 06-2448 in your screenshot is the stainless RGM version for the disc side not the pinch bolt side Richard shows in his original post. It seems to be the same part for all 750/850 disc braked models from 1972-75.

He also says his bike is fitted with the 06-3918 pinch bolt spacer for 750/850 1972-74 models so it obviously needs checking to see why the washers are there. You appear to have the same non O.E. setup so his checking data may be of use.

Your right Neil, I feel a plonker now. I don't know why i have a large gap on the pinch bolt side but without the washers to fill the gap the forks legs are not straight and don't move properly when I tighten it all up. As far as I remember the dust cap is the original one as ive had the bike from new. Im going to get some new wheel bearings soon so I will get a new 'correct' spacer to fit on the bike. Anyway, I'm off for a ride on it now to Squires Cafe.

Our late Atlas fork legs  never seem to be in a happy relationship ,I'm suspicious that the Damper rods  are not equal or the top nut threads  are  damaged and not pulling up the same. Does the axle on the Commando have a shoulder to  trap the bearing cover/spacer against the hub bearing ?. Is the axle a smooth sliding fit in the pinch slider?.Very neccessary if you want to get a nice free action of the forks.

Does the axle on the Commando have a shoulder to  trap the bearing cover/spacer against the hub bearing ?.

Yes, both spacers have an internal diameter equal to the bearings and the smaller diameter on the stepped axle.

Is the axle a smooth sliding fit in the pinch slider?

This is the larger of the 2 diameters on the stepped axle, how smooth the surface is needs careful inspection and rectification if not. The pinchbolt leg should float on this portion of the axle so you can bounce the front end to align the legs before the tightening of the pinchbolt. The spacers are not part of this process, one aligns the hub and the second gives the axle the right position so the nut does not bottom out on the threads.

If the spacers are needed to stop the fork action sticking then you might want to check the mudguard is not loading up the forks  with this issue being resisted by the extra spacers.