Clutch slip 69 GT

Yellybanany

Yellybanany

New member
Location
Scotland
I have an odd clutch quirk with my 1969 750GT in that sometimes while out riding and I go over a bump on the power it induces a bit of clutch slip, easily remedied by backing off a tad before giving it the beans again. I don’t experience it at any other time and can’t induce it myself on purpose, it’s only ever a bump that will set it off so it’s not a terrible nuisance just slightly irritating. It’s not regular either, it might only happen once or twice during a long run of 100+ miles. The clutch action is otherwise fine, cable set with slack etc. and I’ve done nothing to investigate, I just wondered if anyone else had experienced this and if so was anything done to successfully rectify it?
Cheers
Bruce
 
Its hard to believe a 750 GT even has enough power to slip the clutch! Anyway has the clutch ever been apart? If not you have 53 year old clutch springs and friction discs which are probably due for replacement.
 
Haha it’s a beast. Clutch had new springs in 2014 according to an invoice but it did sit about for a few years before I got my hands on it. New plates are probably in order, I was really just curious to see if this had manifested itself with any other machine out there in case it was a common mis-adjustment issue or easy to sort out with a bit of tweakery.
Cheers
Bruce
 
Yellybanany said:
I have an odd clutch quirk with my 1969 750GT in that sometimes while out riding and I go over a bump on the power it induces a bit of clutch slip, easily remedied by backing off a tad before giving it the beans again. I don’t experience it at any other time and can’t induce it myself on purpose, it’s only ever a bump that will set it off so it’s not a terrible nuisance just slightly irritating. It’s not regular either, it might only happen once or twice during a long run of 100+ miles. The clutch action is otherwise fine, cable set with slack etc. and I’ve done nothing to investigate, I just wondered if anyone else had experienced this and if so was anything done to successfully rectify it?
Cheers
Bruce
Click to expand...
My ‘69 GT does that very occasionally and if I go uphill ( turn right out of my house!) when the motors cold on a cold day, when hot it’ll pull like a train. Mine is on original clutch, just turned 25,000km. They only thing I’m watching Is one pitted exhaust valve where the tappet sits, apart from that I’m trying to wear it out!
 
Hitting a bump while under load usually is right in the fat part of the torque curve. If you pop the clutch a bit under those circumstances it will probably slip a bit too. New plates, and ensure that all the rest of the clutch actuating system is good.
 
What clutch is in there, steel or alloy?
Of course springs and plates need to be within specs but unless used by a wheelie hero, they should last hundreds of thousands of km. My SF2 is on its original clutch with 140 000 km.

Wear of the bronze bush in the clutch drum will induce slip for a reason unbeknown to me.

Paul
 
The original steel hub clutches weren't phased out without reason! I've come across quite a few that would slip, despite being in obviously perfect condition. Only recently swapped a steel-type that would slip as soon as the torque built up a bit, admittedly a very healthy "S" motor, all-alloy jobbie works perfectly! Same levers, basket, rods and cable, diffence only in the actual clutch. Also now has a more difinite and lighter pull! Friction area and specific pressure are almost the same, despite the later type having an extra friction plate. I'm suspecting the steel pressure plate not being up to the job.

piet
 
Thanks Gents. Feels like I will live with it and monitor over this summer and if it gets worse and I do go in then new plates and a good look at the drum and mechanism will be the order of the day.
Cheers
Bruce
 
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