Frame crack

  • Thread starter Thread starter Davo
  • Start date Start date
sfcpiet said:
When reinforcing the 1000SFC frame, the factory added quite small and thin gussets above and below the "horizontal" tubes only, where they meet the front downtubes.  Obviously, the factory had become aware of RGS frames cracking and introduced these measures to prevent any future failures.  Only found on the last 50 or so 1000SFCs.  Seems they are quite ample, as I have yet to see such a frame showing the "normal" cracks.

I'm guessing the factory opted for an overkill repair solution to take weakened, cracked tubes into account.  Imho, too much gusseting may well show up weaknesses elsewhwere...

piet
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Piet, do you have any photos of the 1000SFC reinforcing? I'm getting ready to do my 83 RGS. I keep looking at the jobs others have done, and I have to wonder if the gusseting isn't often overdone, a sentiment you seem to share. On the factory SFC gusseting, did they only add gussets to the "horizontal" tubes, with no added gusseting between the bottom of the head stock and the down tubes? For what it's worth, there's no indication of any cracking on my frame, which has some 75,000 miles on it. I'm only doing it because I pulled the engine for a top end job and it seemed time to clean up the frame and give the RGS a fresh look.
Richard
 
Richard,

Check out this thread, Lothar posted nice piccies of a late stock SFC1000.

http://www.laverdaforum.com/forum/index.php?topic=87750.0

piet
 
"think there seems to be something loose in the front when i brake..... they all do that sir...no need to worry...." "we will just nip up the bearings for you.... your local all brands motorcycle shop...." Imagine being onboard.... yikes... you have ready by this afternoon Red? j. *** oh.... have you checked the front end also on the Miss M hooting machine Corvette in the background...might need a spot of welding also...
 
I'm sure there's a story in that red frame. It looks like a 120, given the rubber engine mounts. Clearly an opportunity to go wild with the 'while I'm at it...' approach...especially seeing what has been done already a la wheels and discs.
Cheers,
bazzee
 
bazzee said:
I'm sure there's a story in that red frame. It looks like a 120, given the rubber engine mounts. Clearly an opportunity to go wild with the 'while I'm at it...' approach...especially seeing what has been done already a la wheels and discs.
Cheers,
bazzee
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Concur Holmes, 120 Jota circa 1982. Must have been a wild seat arrangement, dig the "she'll do seat" support... Mechanical Tacho drive intact. Tyres on the high Rockwell scale, should be good for 100,000kms at least.... probably the instruments headlight and fairing are about 10 metres underground at the place of impact, around Mach 0,9. Brings new impetus to Front End dives a bit under brakes.... you do get them Red.... can see its an electric injected model, wiring diagram with air/fuel compensation would be in short supply.... regards Watson.
 
The 120 in the photos looks like it's just a long-cracked frame which has finally given way while in motion, perhaps with a minor crash involved but not necessarily. The forks look fine.
My 79 Jota came to me with a good 30-40deg bend in the forks (like twice the bend of the 81 Jota in the other thread presently) from a huge front end impact and the frame was bent but fine. With a new set of triple clamps and forks I kept riding it like that for another 15 years. I eventually got the full Dave Kellet treatment who was quite amused at the straightness or lack thereof!
The good thing about our old busses is that the frames are so solid that welding and repairing is comparatively easy. If anyone was motivated enough this one would be repairable assuming it's not on the insurance register of statutory write-offs. It may not make economic sense to do so but I'm sure it would be possible with enough skill and effort.
Probbly a parts bike now though. Should be a nice close-ratio gearbox in that one for your racebikes @redax5 !
 
breganzane said:
The 120 in the photos looks like it's just a long-cracked frame which has finally given way while in motion, perhaps with a minor crash involved but not necessarily. The forks look fine.
My 79 Jota came to me with a good 30-40deg bend in the forks (like twice the bend of the 81 Jota in the other thread presently) from a huge front end impact and the frame was bent but fine. With a new set of triple clamps and forks I kept riding it like that for another 15 years. I eventually got the full Dave Kellet treatment who was quite amused at the straightness or lack thereof!
The good thing about our old busses is that the frames are so solid that welding and repairing is comparatively easy. If anyone was motivated enough this one would be repairable assuming it's not on the insurance register of statutory write-offs. It may not make economic sense to do so but I'm sure it would be possible with enough skill and effort.
Probbly a parts bike now though. Should be a nice close-ratio gearbox in that one for your racebikes @redax5 !
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Gearbox no good for race bikes, is similar to an RGS box so totally different to the race bikes

Owner wants the bike repaired so dropped it off to Dave Kellet yesterday
He was slightly amused when he saw it and then started to tell me about similar issues with various other brands

Story I was told about the 120 Jota is owner took off from a set of traffic lights and then hit the ground when main spine broke
Obviously the down tubes had been broken for sometime prior to the main spine breaking as well
This is why we always brace the headstock and straighten the frames as the first step in any restoration that we do to avoid this issue
Don't understand why other Owners doing a complete frame up rebuild do not do the same, seen far too many triples now with cracked down tubes
 
Old, hard raced original featherbed Nortons are starting to do it now too. Few years back a guy was idling up to the start line, braked and the frame broke very like the one in the pics. He was lucky to be left standing over his broken bike. Made us look hard at old frames still being raced.
 
redax5 said:
and the 120 Jota is back in the workshop, in one piece
inner sleeves installed in both down tubes and the main spine and welded in place, headstock also braced
our frame man believes it has had a few different crashes as he struggled to find a straight tube anywhere on the bike

10th Jan in one piece 2

10th Jan in one piece
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That seat bracket adapter almost looks like the one for the Formula Mirage kit. I'll have a look at mine later.

Jim
 
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