VBC driveshaft questions
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1964 VNB, 1966 VBC
Joined: 02 Nov 2020
Posts: 5
Location: Northeast PA
Mon Nov 02, 2020 2:38 pm quote
Iím wondering if someone out there maybe able to shed some light on a question Iím having? Iím in the process of rebuilding a previously running 1966 VBC engine and discovered significant wear on the splines of the driveshaft and hub. Iíve already decided to replace them both along with rear bearing and selector box. The mystery/ question being, why they donít seem to fit properly together? With everything removed from the casing, and the bearing remounted on the shaft, fully seated, and the hub then mounted on shaft splines, there seems to be, Iíd say, about an 1/8 inch space before shaft reaches flush with the hub face. To me it seems the shaft should be nearly flush, and in fact that distance corresponds with stepped wear on the inside of the hub. With the bearing removed (which is 14 mm the correct width I believe) and the hub mounted on the shaft it sits exactly flush, as I would imagine it to be. Is that 1/8 inch space normal? Could the hub be improperly milled( as in the hole is somehow too long) or the driveshaft be incorrect? With the bearing in place the wear between splines is significant enough that the hub simply spins on the shaft. My thought is that itís normal with this type of wear and the new hub and driveshaft will fit together better, but would love to have this seeming incongruence resolved before goin forward. Iím gonna try and throw some photos in if that helps clarify the question...Any thoughts or answers on this question would be much appreciated. Thank you

Without bearing in place

With bearing in place

1964 VNB, 1966 VBC
Joined: 02 Nov 2020
Posts: 5
Location: Northeast PA
Mon Nov 02, 2020 3:19 pm quote
Further aspect to question above...
Also ....sorry to add to the already long and perhaps pointless question above, but I wanted to add and ask that the driveshaft is approx. 34mm from shoulder to the end of the splines and the hole depth of splines on that 8Ē VBC super hub is approx. 25mm. Iíve been looking for a source for exact dimensions on those two parts to help resolve this but have been unable to find. If anybody has those parts on hand to measure or knows of a source it would be much appreciated. Also Iím gonna include a picture of the shaft end to show the splines wear. Thanks again...

Spline wear on driveshaft

2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
Joined: 26 May 2013
Posts: 4001
Location: That bushfire place
Mon Nov 02, 2020 3:38 pm quote
What does the INSIDE of the hub look like?
From the outside it looks suspiciously bumpy... like someone had welded the thing back together!

The THREAD that holds the nut on is of the most concern... get a new shaft!

There's a bit on the VBC1 shaft at top of pg4
modify VBC 2-port - Speedy has a VERY cranky clutch! (Page 4)



1964 VNB, 1966 VBC
Joined: 02 Nov 2020
Posts: 5
Location: Northeast PA
Mon Nov 02, 2020 8:40 pm quote
VBC driveshaft issue..
The inside of the hub seems fairly normal, but very worn, the splines are toasted , not smooth but on their way....up to the other side where that approx 1/8 step is, at which point the shaft splines didnít seem to reach the front face of the hub, the last 1/8 inch seems lightly worn. The back face where the hub passes through the seal and would have probably been in hard contact with the bearing is quite deeply grooved. Iím assuming the rear bearing has been dead for awhile, the shaft is not pressed but worn loose on the bearing, and shaft has been moving in and out. It has to all be replaced...but still having never looked closely or worked on this particular hub/ driveshaft / bearing combo the measurements donít seem to match up.....Like the driveshaft splines must need to come further forward towards the hub face? Like the bearing should be narrower...? That gap towards the front of the splines may be normal, and I guess Iíll figure it all out when I get the replacements....

Inside of the hub

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8331
Location: The state of insanity, SoCal
Tue Nov 03, 2020 2:31 am quote
shaft is roached. those threads are totally pulled.

i'd go for a new shaft and a fresh hub, just in case.

my guess is that you've got deeper issues lurking about.

whole thing has a whiff of bodgery to it.

1964 VNB, 1966 VBC
Joined: 02 Nov 2020
Posts: 5
Location: Northeast PA
Tue Nov 03, 2020 9:30 am quote
Ya ...well this is just the second half of engine rebuild ...already did the top end... replaced crankshaft, flywheel, crank bearings, seals, cylinder...blah ....On first engine split...Was unbelievably blind to the driveshaft and all this...On first round went nutz trying to get the rear bearing retaining nut off..couldnít , and I think went blind to all other issues down there I was having. Put it all back together and realized my major issues were down in the drive. So now Iím back with everything apart again, got real serious with stupid bearing retainer, finally got it off...and have now realized I probably should have STARTED with looking at the driveshaft which needs replacing. Also if anyone has a suggestion on a driveshaft Iíd love to hear. It looks like there are 2 available for this 1966 VBC, one reinforced and one I guess not? Seem to be the same price...anyone know of any reason to go with one or the other?
Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
Posts: 627
Location: New Zealand
Tue Nov 03, 2020 12:30 pm quote
looks like you have not pushed (or pulled)the drive shaft all the way into the bearing....put a small pipe over the push rod tube and hit it in a bit further until you here the sound of the driveshaft acting on bearing (the sound will change)

I do this over a hole in the bench so that the case half can sit on a hard surface and drive shaft can move as you tap tap tap gently down till you here the sound and it wont travel any more

agree the thread is munted and wont hold the nut properly (dangerous) so get a new one

good luck
1964 VNB, 1966 VBC
Joined: 02 Nov 2020
Posts: 5
Location: Northeast PA
Tue Nov 17, 2020 12:14 pm quote
Re: hmmm
[quote="Bluecati"]looks like you have not pushed (or pulled)the drive shaft all the way into the bearing....
Thanks for the response Bluecati, but this was one of the first things I considered and confirmed the bearing was fully seated on driveshaft using installation pulling tool..before I considered completely resplitting the cases...

Since first making this post, I have now finally received my new hub and driveshaft and can confirm that nearly 1/8 inch space does exist between the end of the splines on the shaft and the face of the hub. This being even without the bearing in place and with brand new unworn parts. Confirming the idea that the unusual fit I was describing was due to worn drive shaft splines and hub splines. I will include a picture of the brand new parts that maybe can can illustrate this gap to anyone else who might be wondering. Thank you to all who responded.

Spline end/hub face gap brand new parts

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