Author Topic: A7 crinkle hub issue  (Read 587 times)

Offline Stefu

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A7 crinkle hub issue
« on: 29.04. 2018 17:59 »
Last autumn a colleague took my bike out for a ride and came back pushing it, saying that there is no more transmission on the rear wheel.

Now I figured out, that there seems to be an issue with the crinkle rear hub. Actually the inner part of the hub (Part No. 67-6126,) that should transmit the rotation of the driving flange (Part No. 67-6101) to the hub, turns inside the hub shell (see foto). I think this thing should be fix, am I right?

Now, how can I fix that problem? I guess it isn’t just because I didn’t grease the hub through the nipple for the last five years (I know I should have), although this could probably be the reason that thing broke…

How is that inner part originally fixed in the crinkle hub shell? Is it possible to fix that thing by welding it in there or by tapping some threads and fixing it with screws? Or do I have to replace that hub?

Thank you very much for your help guys!

Online chaterlea25

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Re: A7 crinkle hub issue
« Reply #1 on: 29.04. 2018 20:50 »
Hi Stefu,

The steel rivits holding the hub components must have sheared ?
Nothing to do with grease, just old age and Swiss mountains
When you remove the bearing retainers and bearings you should find the broken parts inside
Some people repair with bolts/ nuts or make new rivits and replace the broken ones

John
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1963 RGS (ongoing)

Online morris

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Re: A7 crinkle hub issue
« Reply #2 on: 29.04. 2018 20:59 »
Hi Stefu it's been a while since I have been in there but if I remember well it's the rivets that hold the outer hub (crinckle part) to the inner shaft that must have sheared.
They can be drilled out and replaced by bolts and nuts or be riveted again but both options will need a complete wheel dismantle.

Just noticed that chaterlea John types quicker than me  *smile* but posting this anyway for confirmation...
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Online berger

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Re: A7 crinkle hub issue
« Reply #3 on: 29.04. 2018 21:52 »
I have not been to the pub,a good few years ago I noticed my rivets moving a tad so I had a *bright idea* zapped the buggers with weld *wink2* *grins* been fine ever since. yours could have been a lot worse result  than the rivets another guy I knew [ the cadwell kid deceased *sad* ]stripped all the  teeth on his goldie *pull hair out*

Offline duTch

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Re: A7 crinkle hub issue
« Reply #4 on: 29.04. 2018 22:39 »

 Mine was a bit loose too, so as morris, I zapped it (them)....one of the bearing retainers has a  *ex* LEFT HAND thread *ex*, these bikes have a few of those where the activity may loosen; eg- L/H footpeg stud/oil pump worm drive nut)...the bearing can be challenging to remove, a special puller *may* be needed...that'll do for now, I have a spare I can take pics of later if need be...

  On the other hand, *conf2* It may be possible that the six bolts that hold the brakedrum/chainwheel have sheared or fallen out (fairly unlikely but strange things DO happen.... )
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online Rex

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Re: A7 crinkle hub issue
« Reply #5 on: 30.04. 2018 10:42 »

 Mine was a bit loose too, so as morris, I zapped it (them)....one of the bearing retainers has a  *ex* LEFT HAND thread *

Strangely, IIRC, they both do. I had all three (two rear and one front) in the parts washer and they're identical.

Offline Stefu

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Re: A7 crinkle hub issue
« Reply #6 on: 07.05. 2018 13:18 »
Thank you all for your help; very much appreciated!

Good to know that there are rivets holding that outer hub and the inner shaft together. I think I gonna try a weld.

Did I get that right, duTch and berger fixed the rivets in there with a weld? So you removed the bearings, and welded it from there, fixing the rivets to the inner shaft, without fully dismantling the wheel?

Do you guys think, I could also leave all the stuff in there as it is and go for a weld all around the inner shaft; so basically welding the inner shaft directly to the outer hub? Actually just where I drew the blue line on the picture in my first post (I’m after a fast fix, that lasts for the summer).

I have not been to the pub,a good few years ago I noticed my rivets moving a tad so I had a *bright idea* zapped the buggers with weld *wink2* *grins* been fine ever since. yours could have been a lot worse result  than the rivets another guy I knew [ the cadwell kid deceased *sad* ]stripped all the  teeth on his goldie *pull hair out*
what teeth do you mean? I don't really get that point.


 Mine was a bit loose too, so as morris, I zapped it (them)....one of the bearing retainers has a  *ex* LEFT HAND thread *ex*, these bikes have a few of those where the activity may loosen; eg- L/H footpeg stud/oil pump worm drive nut)...the bearing can be challenging to remove, a special puller *may* be needed...that'll do for now, I have a spare I can take pics of later if need be...

  On the other hand, *conf2* It may be possible that the six bolts that hold the brakedrum/chainwheel have sheared or fallen out (fairly unlikely but strange things DO happen.... )
...I think on the brakedrum/chainwheel everything's fine...



Offline duTch

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Re: A7 crinkle hub issue
« Reply #7 on: 07.05. 2018 23:28 »

 Hola Stefo....
 
 
Quote
Do you guys think, I could also leave all the stuff in there as it is and go for a weld all around the inner shaft; so basically welding the inner shaft directly to the outer hub? Actually just where I drew the blue line on the picture in my first post (I’m after a fast fix, that lasts for the summer).

 It *may* work, but I doubt total success unless they're good welds and it may be irreversible (carry on), but you'd need to weld both sides, as;......   The hub is a composite of three (3) separate parts; The 'crinkle' part is actually two halves, with the splined sleeve through both, and there's (I think) four rivets in each half.
 You'd need to check that the two halves haven't slipped sideways or slid apart on the inner as that may affect the spokes (probably unlikely), but best at least to locate the holes in the inner and align all holes- probably easier to pull the bearings and retrieve the rivets (they might rattle around and drive you crazy) and then you have rivets to plug the 'oles, locate the bits and something to weld on to.

  I've actually welded the rivets on two wheels, but I don't remember if the first (which I think was/is a early swing arm wheel) ,was done in situ, or if I pulled the bearings out or not, and is easier than the plunger hub which was a bugger to remove the bearings. This was a bare hub that I bought, welded and had chromed and is in almost daily use ...(but I noticed the other day a fair amount of backlash in the splines- off topic )


  (I'm not sure if this is finished, but have run out of steam/cells)
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online berger

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Re: A7 crinkle hub issue
« Reply #8 on: 07.05. 2018 23:47 »
by teeth I meant drive splines on a crinkle swing arm wheel that mate with the sprocket/brake drum, it must be the case that the swing arm wheel is easier to weld the rivets than the plungy, apolagies for confusing things

Online orabanda

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Re: A7 crinkle hub issue
« Reply #9 on: 08.05. 2018 00:00 »
I have replaced the rivets on several hubs, following the advice of a gold star owner who has always done this.

Make new rivets, drill out /grind off & remove old rivets, install new ones, put a solid steel bar (from memory approx 2"diam) into the middle of the hub. You need to machine the bar so that it is close sliding fit inside the rivets. The close fitting bar will prevent the rivets from sliipping backwards into the hub when you are belting the shit out of the cherry red rivet.
The bar needs to be supported at both ends; one end held and supported in a vice or (preferably) a hole drilled through and bolted to a bench. After the hub is slid in, the outside end should be supported with an adjustable pipe stand.

You need to rotate the hub after each rivet is heated and peened over, so that the next one to be done is on top.

Get prepared, and have a bang (as the actress said to the bishop).

Richard