V50 Stem/Top Yoke Nut

I am currently rebuilding my 1979 V50 in the style of a cafe racer. I have recently renewed the steering head bearings and refitted the top yoke, with the lock washer. However, the stem nut (the one with the eagle emblem on it) will not tighten down and touch the top yoke. Looking at parts diagrams suggests that there is only the one washer, yet there is this gap of under 1cm between the bottom of the nut and the top of yoke. Any ideas if it should be like that or am I missing something? Many thanks.

Are you using the original set of yokes that came off the bike ?Certainly with the big block models, there are different lengths of stem available to suit different models.

Hi The yokes are replacements from a reliable MG specialist who said they were for a V50. I guess there’s the possibilty that I have been given the wrong ones. If that is the case, is there anything else that would definately clarify whether these yokes/stem are for the big twins? Is there a different stem nut I can use that will seat down onto the top yoke successfully? thanks

Do the fork stanchions fit the holes in the yokes?

yes they do Brian, perfectly.
I am hoping that a longer stem nut might be appropriate or a suitable spacer as the bottom yoke is nicely polished and I would like to use it.

The main stem will have 2 short machined sections where the bearing races are designed to fit and form a close tolerance. if the stem is a different length, ie designed for a longer frame tube then these will not be in the right place.
Do you still have your old yokes? If so compare the distance apart of these sections.
It may be possible to swap the stem from the old to the new yoke. They are only an interference fit, so long as the diameter is correct

I will check this out…thanks for the advice.

I am not sure about machined sections but have a couple of pictures which might say more than a 1000 words of mine. The stem and lower yoke combined on the donor bike is exactly the same length as the one fitted in the frame…which makes me think that it is unlikely they are both wrong. Here is the yoke/stem from the donor bike that I am not using… And the two yokes/stems together… Here is the gap between the stem nut and the top yoke… Under the top yoke… The bottom yoke… I assume that having the stem nut screwed down onto the to yoke is not essential as there are 3 pinch bolts holding stuff together and that the top nut has almost all its thread used. However, for asthetics I would like to sort this out or get a spacer made up. Any ideas? Thanks.

Does the inner race have a thread on the inside as I would expect to see a machined section where it is designed to sit. It looks like it sits on the threaded part. This is a loose ball race with cups and cones. The large castellated nut should tighten down onto the top of the inner bearing cone, then a washer then the top yoke and finally the top nut should clamp it all down. The top yoke should be squashed onto the castellated nut but the top nut but it appears to be too long. Is this an aftermarket Shaw Stainless top nut by any chance, in which case that is too long and needs to be shortened to suit the depth of your yokes. Maybe the top nut is off a big block model with thicker yokes? Just guessing. The problem does appear to be the top nut being too long.

I am not sure about the inner (lower?) thread…it does all appear seated well and is the same as the comparison donor one in the photo. The top nut was either Chris Shaw or Gutsibits…can’t remember which. The inner thread on the top nut does not go all the way to the top of the nut. I have an original top nut from the donor bike, I shall try that, although they do look the same. Thanks for all your advice Don…yes the problem does look to be with the top nut. If it does not squash tightly against the top yoke would that be a problem safety wise?

Just had a look at my V50 - it’s exactly the same as yours and has been always.Do the top nut up tight, clamp it and forget it.

The important bit is that the castellated nut is set correctly so the head bearings are just right. In this case, it is the long nut above it is acting as a lock nut to prevent things coming undone again.
As Brian says, clamp the top yoke onto the long nut and then nothing can move.

Thanks Don/Brian…your help has been invaluable and is putting my mind at ease.
The castellated nut is set tight enough that the steering moves freely with no notches and no play up and down or backwards and forwards.
When you say ‘clamp the top yoke onto the long nut’…do you mean to suggest that I ensure that pinch bolt closes the gap up on the top yoke around the long nut completely or should there be some gap? I will have to check to see if there is a torque setting for this or not.

You will need to asemble the forks into the yokes and try and settle them in nice and straight, best done with the front wheel and any fork brace / mudguard in place. Then tighten the pinch bolt up. Not sure about a torque setting for this. It is only into the ally casting so not too tight or you will strip the thread. A gap at the back of the yokes is to be expected, so long as the pinch bolt is tight. Don-Spada2013-09-25 13:21:31

Don’t attempt to close the gap at the back with the pinch bolt, it just needs to be tight enough to stop the long capped nut turning.

Thank you

Oh yes! Now me I’d think that was obvious, but not to everybody I bet…

leaving the stem nut loosely connected undo all clamp bolts on forks, including the pinch bolt by the top yoke stem nut, tap the underside of the yoke at the pinch bolt area with a rubber mallet , dont tap it all the way up to the stem nut but a bit closer than it is now, you will have then to re aline the front forks, so this job is best done with the wheel out.just done the above on my V65SP.
northwest2013-10-05 15:02:00

will that not make the top yoke not lock into the locking washer? a photo of yours might be good? or two?

The top bolt / cap, is NOT meant to touch the top yoke anyway. It sits proud of it. As long as it engages with the thread of the stem, and bears down on the top race sufficiently to take up the slack in the races, that is fine.