750 SF1 rear brake problem.

gibbo-123

gibbo-123

Full member
Location
Warwickshire,UK
Help/advice required please.

When i stripped my SF1 down I noticed the rear hub was in a bit of a state, some of the reinforcing webs having broken at some point in a previous life. I applied crack detection spray and it didn't look too bad and I was confident a bit of rework could make things good. I discussed this with a customer of mine that carries out a lot of tig work for various industries and he suggested passing it onto a mutual friend who lectures in all things welding for a 'red brick' University here in the UK. He would be the man to sort it, or so I was told...... What I got back, to me, is a complete mess. I'm no expert but I guess this has been welded without being preheated, hence the cracks that can be seen?

So, what is the general consensus of what I should do next? Is it salvageable, can anyone help or point me towards someone that can? Does anyone have a spare for sale?

I didn't pay anything to have this done (luckily) as it was a favour. Damn annoyed though as now I think I should have left it as it was.

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I have all the bits cleaned up and want to get the wheels built so I can get a rolling chassis together for a dry build. Sorting it all out over Christmas has put the fire back in my belly again to get it sorted so it doesn't look such a pile of scrap next to my SF3.


Cheers, Stuart
 
Looks like a gonner Stuart - If you've got the equipment - maybe you could make a flanged aluminium boss and bolt or weld it on - not too hopeful I know and way too expensive to get done as a paying job. Just proves how crap our universities are. You should be able to source another hub somewhere - but they're not that cheap now - rtegards - Phil
 
Stuart

Not sure I would ever trust the components integrity after that butchering but you could give these guys a shout. Not them in particular but they have a guy next door called Richy who is a master of all things Alloy welding. He works closly with them. Sorry I haven't got his number.

He gives an honest opinion on whether it would be a viable repair or not, & not just say "AYE." No Problem mate!!

http://lochnessrestorations.com/

 
Should have got a welder to do it.... "those who can do, those who can't teach...." Even with a pre heat the ribs were going to crack after welding.

Could be fixed with a bit of machining and welding by someone who actually knows what they are doing. I could sort it for you. It will either take a while or be expensive.  ;)


  Keith
 
laverdakeith said:
Should have got a welder to do it.... "those who can do, those who can't teach...." Even with a pre heat the ribs were going to crack after welding.
Click to expand...

Unfortunately I found that out a bit too late?!

I think i'm going to look at the machining route. We use a couple of subcon toolrooms at work, i'll take it to them and see what they say. I'm thinking maybe machine away the ribs completely down to a clean diameter and fit a stepped boss in there place.

Keith, if I get no joy locally I may use your 'take a while' service, I'm in no rush. At least all is not lost.

Stuart
 
Hi Stuart.

I think I'd be more inclined to send it to Keith in the first instance if I were you. He's a Laverda specialist and resourceful fabricator/repairer of fucked-up alloy parts. He's posted photos on this forum of some impressive recovery work.

Keith has said he can fix it so I suspect he already has a workable solution in mind.

A general machinist will be trying to dream up a fix which may not end up being optimal, or even workable. The "stepped boss" idea (if I understand your meaning - make a solid ring to drop over the bearing tube and weld in place) seems to me a good example of a non-optimal repair. I can think of several arguments against such an approach. For example, full circle welds around the bearing tube and hub flange have the potential to induce weakness in the heat-affected area. A full circle crack in the hub while enjoying a bit of twisty road could ruin your day.

Cheers,
Cam
 
Maybe a bit  of a different way out - I used an old Ariel/Bsa full width hub - immensely strong and only ?50ish on fleabay - as you have access to machining facilities - this could be an answer. - Regards - Phil
 

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I seem to remember seeing those photo's on the forum a while back Phil. An option if i'm stuck. As if by luck I'm working in Glasgow the next two days so hopefully popping in to see Keith with it.

Stuart
 
Dellortoman said:
Hi Stuart.

I think I'd be more inclined to send it to Keith in the first instance if I were you. He's a Laverda specialist and resourceful fabricator/repairer of fucked-up alloy parts.
Click to expand...

Dropped it off with him today  :D.
 
Smart,we all seem to be running into the Unobtainium Conundrum a lot these days.Hard to replace,must repair
 
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