Author Topic: Hello from Unsubtle in Berkshire  (Read 395 times)

0 Members and 1 Guest are viewing this topic.

Offline unsubtle

  • Tiger Newbie
  • *
  • Topic Author
  • Posts: 11
  • Bike/Model: Tiger 1050 Sport
  • City / Town: Reading
  • Country: gb
Hello from Unsubtle in Berkshire
on: 07 December, 2021, 05:12:23 PM
Hi all - no pictures of the bike as I picked it up and rode it back from Wigan yesterday evening, and the weather has been dark and 'orrible. I'm new to the 1050, but I've done about 250k on Triumphs on and off since about '93, most recently on a 1200 Explorer. The rear UJ on that let go at 60mph, breaking the swinging arm in two and leaving me trying to keep bike and pillion upright while the very alert Polish driver of the HGV I had just passed attempted to avoid articulating us.

For some reason, I thought it might be nice to go back to a chain drive.

Anyway, I'm hoping to get some touring done on the Sport in SE Europe if quarantine allows.
Tiger 1050 Sport, Bonnie, Daytona 1200, Fireblade, TT250R

#1

Offline Paul2bikes

  • Tiger God
  • *****
  • Posts: 9261
  • Bike/Model: 2014 Tiger Sport 1050
  • City / Town: High Peak
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #1 on: 07 December, 2021, 05:51:58 PM
 :401: to the forum  :031:

Bet that was a scary moment. Any clues as to what caused that.
Also: '16 Tiger 800, '95 Yamaha Serow, '58 Ariel FH.

#2

Offline unsubtle

  • Tiger Newbie
  • *
  • Topic Author
  • Posts: 11
  • Bike/Model: Tiger 1050 Sport
  • City / Town: Reading
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #2 on: 07 December, 2021, 10:26:26 PM
*Originally Posted by Paul2bikes [+]
:401: to the forum  :031:

Bet that was a scary moment. Any clues as to what caused that.

Yes, I'm pretty sure about the cause. A problem with old shaft drive bikes (e.g. the BMW R100 of the late 70s and early 80s) was that the rear suspension would extend as more torque went to the back wheel, and collapse as the torque was removed. Not ideal if you panic in a bend as your ground clearance, but honestly not as big a deal as people made out. Modern shafties have two universal joints rather than one, a hinge in the swinging arm just forward of the bevel box, and a linkage above or below the swinging arm which completes a parallelogram. The bevel box now can't rotate around the horizontal axis under engine torque, which removes the climb/squat and makes the bike handle like a chain drive bike.

That's fine of itself, but there is no practical way of enclosing that rear UJ in the oil chamber of the bevel box. It is enclosed in the swinging arm, but that is not air or water tight, just sheltered from the elements. On the bikes with this system that I have worked on (BMW R1200S and Triumph Explorer 1200), there is no documented maintenance or inspection procedure, and on the Triumph I don't see a practical way to get at it.

Since the whole point of a shaft drive is that it should last the life of the bike (possibly with oil changes for the bevel box), I just rode the thing - shopping, commuting, off-road, on the track, down to Greece - using it as you are supposed to use an adventure bike. Anyway, at just under 70k miles, the joint was overheating, judging from blueing on the side of the one of bearings that  became readily available for inspection. It appears to be a plain greased bearing with no sealing, and I think it just ran out of grease. While it is theoretically possible that some heavy object was thrown up by the tyres of the lorry I was passing and smashed apart both sides of the swinging arm at that rear pivot and broke the shaft at the UJ on the way but left no other evidence that we could recover while waiting 6h for the break down recovery, that seems unlikely. It seems that one of the four bearings on the UJ ran hot, seized, and broke the UJ. This left the shaft flailing as the engine hit max revs in top. On this bike, the hinge in the swinging arm is two pivots built in to the swinging arm adjacent to the UJ, so the flailing shaft took them both out, disconnecting the rear wheel from the swinging arm.

It's interesting that Moto Guzzi appear to have found a way to have the whole swinging arm as an oil chamber, and BMW (and this year's Explorer) have the pivots external to the swinging arm, even though that is not the optimal geometry. I suspect that  this is a known problem they are designing around. Anyway - back to chain drive!
Tiger 1050 Sport, Bonnie, Daytona 1200, Fireblade, TT250R

#3

Offline Bugslayer

  • Tiger Newbie
  • *
  • Posts: 5
  • Bike/Model: Tiger Sport 1050
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #3 on: 08 December, 2021, 05:15:08 AM
I'm a newbe myself, but welcome to the board, and thanks for that thoughtful account of your suspension failure.  I have friends who ride Triumph shaft drive bikes and I'll pay attention to that. 

#4

Offline unsubtle

  • Tiger Newbie
  • *
  • Topic Author
  • Posts: 11
  • Bike/Model: Tiger 1050 Sport
  • City / Town: Reading
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #4 on: 08 December, 2021, 05:32:41 AM
BMWs seem more prone to break their shafts, but usually not the swinging arm. Having said that, I have seen a photo of a GS with a broken swinging arm. Guzzi UJs apparently grumble before they break, but a pre-emptive repair still costs about 650.
Tiger 1050 Sport, Bonnie, Daytona 1200, Fireblade, TT250R

#5

Offline Paul2bikes

  • Tiger God
  • *****
  • Posts: 9261
  • Bike/Model: 2014 Tiger Sport 1050
  • City / Town: High Peak
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #5 on: 08 December, 2021, 07:46:18 AM
*Originally Posted by unsubtle [+]
BMWs seem more prone to break their shafts, but usually not the swinging arm. Having said that, I have seen a photo of a GS with a broken swinging arm. Guzzi UJs apparently grumble before they break, but a pre-emptive repair still costs about 650.

Sounds frightening, could be fatal. Never had shaftie, never will, now. If similar to prop-shaft on cars, just sealed bearings. Only had one prop UJ bearing fail on a rwd, rattling/vibration, cheap fix kit from local auto shop & vice back in diy days.
Also: '16 Tiger 800, '95 Yamaha Serow, '58 Ariel FH.

#6

Offline Dusty ST

  • Tiger Supporter
  • Tiger Master
  • *
  • Posts: 647
  • Bike/Model: 2017 Tiger Sport 1050
  • City / Town: Brighton, Sussex
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #6 on: 08 December, 2021, 10:05:01 AM
*Originally Posted by Paul2bikes [+]
Only had one prop UJ bearing fail on a rwd, rattling/vibration, cheap fix kit from local auto shop & vice back in diy days.

Having had a Triumph Herald and Spitfire, been there, done that at least 6 times!
17 Tiger Sport 1050
08 Sprint 1050ST
01 GSX1400 K2

#7

Offline Paullie

  • Tiger God
  • *****
  • Posts: 5777
  • Bike/Model: Tiger Sport (2014)
  • City / Town: Back in Blighty
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #7 on: 08 December, 2021, 11:31:16 AM
*Originally Posted by unsubtle [+]
Hi all - no pictures of the bike as I picked it up and rode it back from Wigan yesterday evening, and the weather has been dark and 'orrible. I'm new to the 1050, but I've done about 250k on Triumphs on and off since about '93, most recently on a 1200 Explorer. The rear UJ on that let go at 60mph, breaking the swinging arm in two and leaving me trying to keep bike and pillion upright while the very alert Polish driver of the HGV I had just passed attempted to avoid articulating us.

For some reason, I thought it might be nice to go back to a chain drive.

Eek! Sounds horrible. So you went sliding down the road with no rear wheel!?

I have a 1970s Beemer with the original unelasticated prop shaft, so I know all about lifts and squats. Interestingly, a Guzzi of the same era doesn't seem to have the problem!

#8

Offline unsubtle

  • Tiger Newbie
  • *
  • Topic Author
  • Posts: 11
  • Bike/Model: Tiger 1050 Sport
  • City / Town: Reading
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #8 on: 08 December, 2021, 12:58:47 PM
*Originally Posted by Paullie [+]

Eek! Sounds horrible. So you went sliding down the road with no rear wheel!?

No, we had a lucky break. I had panniers on, so the wheel was captured by the top of the mudguard and the pannier frames. It was canted over about 30 degrees and not turning, but it did hold the back end off the ground. I couldn't steer, but I could use the bars to keep the bike upright from 60 down to about 20, at which point we bounced along the Armco a couple of times and fell over. Aforementioned Polish lorry driver brought his load to a stop, checked we were ok, and brought out a broom to clear the debris.
Tiger 1050 Sport, Bonnie, Daytona 1200, Fireblade, TT250R

#9

Offline Paullie

  • Tiger God
  • *****
  • Posts: 5777
  • Bike/Model: Tiger Sport (2014)
  • City / Town: Back in Blighty
  • Country: gb
Re: Hello from Unsubtle in Berkshire
Reply #9 on: 08 December, 2021, 02:46:14 PM
*Originally Posted by Dusty ST [+]
Having had a Triumph Herald and Spitfire, been there, done that at least 6 times!
Cheap fix for the Triumph Herald and Spitfire that I remember involved a thick leather strap for each rear driveshaft!

 



reconstruction