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1970 450 Scrambler Front wheel binding

Posted: Sun Dec 12, 2021 12:00 am
by Carnaggio
Any thoughts as to why tightening the nut on the front wheel spindle would cause the hub/wheel to lock up?
I replaced the hub which was bent, described in a previous post, and replaced the stanchions in each leg.
The spindle is fully seated so that the arms are tight against the fork. it also appears that the wheel is slightly shifted to the left/clutch side of the bike, but I cannot determine if anything is bent in the frame.
Thanks!

Re: 1970 450 Scrambler Front wheel binding

Posted: Sun Dec 12, 2021 9:42 am
by ducwiz
Snap 2021-12-12 at 10.31.21.png

The wheel gets blocked when the distance tube 290 between the inner races of the wheel bearings 060 is too short. By tightening the spindle 330 an axial force ist applied to the races, moving them towards each other until the free play in the bearings is zero; from this point onwards the force strongly increases, hence blocking them or even destroying ball races or balls in the bearings.
To extend the distance between the bearings, you can add some steel shims between one bearing and the tube, in order avoid the axial force. Or you get a longer tube machined on a lathe.

Hans

Re: 1970 450 Scrambler Front wheel binding

Posted: Sun Dec 12, 2021 12:48 pm
by Ventodue
Carnaggio wrote: <snip> The spindle is fully seated so that the arms are tight against the fork.

As per Hans. In addition ...

(While I'm not sure exactly what you mean by the "arms"), on the right side, there should be a gap between the fork leg and the brake hub.

Front wheel gap.jpg


Front axle gap.jpg

Re: 1970 450 Scrambler Front wheel binding

Posted: Sun Dec 12, 2021 3:02 pm
by Carnaggio
Thanks guys, I will pull it apart and adjust the tube spacing.

By arms I am referring to the two perpendicular rods on the opposite side of the fork from the wheel.
Originally it was spaced as in your image but now they sit against the fork.
Thanks again!

Re: 1970 450 Scrambler Front wheel binding

Posted: Sun Dec 12, 2021 6:54 pm
by Bob_Matthews
One side of the hub should be tight up against the fork slider when you tighten up the wheel spindle nut. The other side fork slider on the opposite side should be free to float sideways (with a gap, as posted above) until you tighten the pinch bolt on the slider.

Re: 1970 450 Scrambler Front wheel binding

Posted: Tue Dec 14, 2021 12:59 am
by Carnaggio
Thanks Bob,
I have to wedge the fork apart, there is no free play.
I think it was a nasty tumble that bent the original hub and probably created some of my difficulties.

The inner tube is the exact length of the distance where the bearings are seated so I will try an increased tube length and see what happens.

There was originally more space between the two perpendicular arms and the fork before I replaced the stanchions, so it is all a bit puzzling.
I appreciate the knowledge,
Richard

Re: 1970 450 Scrambler Front wheel binding

Posted: Tue Dec 14, 2021 12:42 pm
by George
Hi measure forks centre to centre top and bottom. Should be the same and parallel. If not that's a problem. As stated before you should have a gap between right stanchion and hub.