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Gearbox input shaft cush drive

organfixsing

organfixsing

Cruisin' Guzzisti
GT Contributor
Joined
Jan 10, 2013
Messages
133
Location
ROMA
BREVA V1100, 2005 Has anyone had experience of the cush drive on the input shaft of the gearbox failing. I cannot be sure that this is the problem, however, but I have a lot of slack in the gearbox which I think varies a little with gear selection. Perhaps there is another problem. Just to give you an example, when I had the rear wheel on, the slack was at least 2"/50mm at the wheel rim. The CARC box doesnt seem to have any play and neither does the cardan shaft. Any experience please!!

organfixsing : :?
 
Hi organfixing, welcome to the forum.

I haven't experienced a "cush drive on the input shaft failing", but I have about 2" of slack at my rim and have no problems. I don't certain what the input assembly of the input shaft does but I don't think its a cush drive since the drive shaft itself has a cush incorporated into it. My guess would be that it is a gear change shock absorber.

What's the bike doing that makes you think there's a problem?
 
G'day Raphael & Pete. Thank you for your prompt replies. The cush drive, in the gearbox, I was referring to is shown in 'BREVA1100_12055_Atel2(GB).PDF page 96)'. It shows the idler gear (which is not connected to the input shaft) and the driven double dog (which is splined to the input shaft). The dogs can ride up ramps in the idler gear, thus compressing the Bellville washers, so providing some antidote to shock loading on the gearbox. (Bellville washers are spring steel convex/concave [depends which side you are looking from] washers which when placed edge together {like so () } make a limited movement spring. By putting multiple pairs in series, the amount of maximum movement is multiplied by the number of pairs. The above reference says 8 Bellville washers (4 pairs).
I am having a bit of trouble with low speed riding. It probably has to do with the light throttle control, the transmission slack and the fact that I haven't ridden for about 43 years. My previous bikes were Triumph Thunderbirds, 2 off (Amal carbs) and briefly a 42 WLA Harley.
Cheers
oerganfixsing
 
How low is low speed (engine rpm's, not mph)?
With a shaft drive bike like a Guzzi there is a technique to the balance of clutch and gas. As well as keeping the rpm's mostly above 3K.
There were some issues with driveline noise as I recall, and that was dealt with by a recall for certain vin#'s. I don't remember the details of that and could have it wrong.
What I do know is it is normal, as Pete said, for there to be some slack in the drive line. That slack will increase (as I recall) as you go through the gears. And as mentioned, there is a knack to riding a shaft drive bike, especially at lower speeds.
Maybe you can compare yours to a known good one to see if it differs.
Also, try to adjust every last bit of slack out of the throttle cable, right up until just before the point of not enough.
 
Thanks for your reply GuzziMoto. I can't remember what the revs were but I would think that they were too low. I cannot check at the moment as I have the swingarm and CARC out. What would you suggest greasing the splines with? I have some molybenum grease here? (Pulling it apart was relatively easy. Putting it back together may be a little more difficult!!)

Cheers and thanks

organfixsing
 
The issue with the Cush drive related to a few very early B11's and the problem it caused was a loud rattle at idle. If this machine idles quietly it doesn't have the problem.

Yes, I'm very familiar with the face-cam shock absorber and how it works but will re-iterate that the backlash you are feeling is from clearance of the dogs, not anything to do with the Cush drive.

Pete
 
Thanks Pete. I will just have to get used to it.
I have a further problem in putting the bike back together.
I have two flexible pipes I am not sure of where they go.
The first pipe is a fairly long black (rubber?) pipe which I thought went through the P clamp on the right hand cover but it appears to be too long and hangs out the bottom. It comes from a T piece.
The second pipe, I think, should be where the black pipe is now?
The pipe is a clear plastic pipe with a pipe clamp on one end. It is marked with a part No 8144038.
In the parts list, this pipe appears in two places, one being the oil drain from the air cleaner box but the other one is hard to see where it comes from in the parts diagram Rear Body - Mudguard.

I look forward to any replies,
Cheers
Organfixsing
 
I know where the black pipe goes now. I had taken photos of same!!! (I might forget my head if it weren't screwed on tight).
Just need the location of the 'clear' pipe which looks like a drain pipe as it has only one clamp and the other end is dirty.
Cheers
organfixsing :( :?
 
I think I have found the place for the 'clear' dirty pipe and it is a drain pipe for the battery box? :D

Cheers
organfixsing :D :oops:
 
Hi Organfixsings,
My fuel injected Norge feels a bit snatchy at very low revs when compared with my carbed R80R Airhead BMW - as if it had the driveline play you describe. I don't think thare is a problem with my bike, more that I have to ride it in a different style to the BMW. It may not be good for the clutch but my solution is to slip the clutch a little when riding at slow speeds (ie at walking pace) and keep the revs above tickover.
AndyB
 
Thanks Andyb. That seems to be the only solution, keep the revs up and slip the clutch. Part of the problem I have is that of confidence. I haven't ridden for about 43 years and also I am having trouble adapting to the right foot brake / left foot gear change. :) :)
 
Earlier in this chain it was suggested that you remove all the slack you can from the throttle cables. Has that been done?
That can make a big difference in the snatchy feeling.
You want only enough slack so that when you turn your handlebars left and right the idle does not rise. To do that you can remove the slack to where the idle does rise and then back it off until it no longer does. Make sure the push cable is loose during this and then tighten that back up to where it should be.
 
Having re-read this thread I have to ask has the bike ever had its throttle bodies balanced and its TPS re-set? Also has anybody tried to alter the idle speed by messing with the throttle stop screw on the left hand throttle body.

Pete
 
Sorry about the delay Pete. I don't think anybody has messed with the throttle bodies, it idles reliably at slightly above 1000 revs.

I have the DVSTS software coming from Todd in the US and I am contemplating making a differential oil filled manometer so I can balance the carbs properly. I took it for a run recently (6Ks only) and I found that it does 100KmH at around 3600 revs, but it did seem to me that I had a small amount of surging at that speed? Could that be due to a poor state of tune?

The original problem with driveline snatch is no longer much of a problem, having adjusted my riding technique and having adjusted most of the slack out of the twistgrip control.

Cheers
Brian :) :)
 
Just balanced the throttle bodies. They were not far out but the TPS was 6.0 which probably contributed to the bike running rich.

I was toying with the idea of making an oil filled manometer but instead bought an intriguing manometer from the UK. (Took a while to come. Aus Customs Inspection?)

The device is sold on Ebay under the title of "UNIVERSAL MOTORCYCLE CARB BALANCER VACUUM GAUGE TOOL" for a price of 22.99 English Pounds (free postage). This translated to AU$34.10 via PayPal.

The device consists mainly of clear plastic tubing and a couple of ball bearings and a couple of restrictors in the vacuum tubing. It comes with 5mm & 6mm manifold adaptors.
I was surprised as to how easy it was to use. One ball bearing (in a separate upper tube) is the reference point and will acommodate the device not being quite vertical. The other tube contains the measurement ball bearing.

With the motor idling (around 1100 revs) the measurement bearing varies rapidly over about an 8mm (5/16") range, however, it is easy to visually centralize it to the reference bearing.

The 3000 Rev setting is very stable and is set below the reference bearing.

The only query I have about the device is that it does connect the two vacuums together, albeit via 2 restrictors, so I suppose that has a minimal effect.
All in all, Impressed!!!
Cheers
Brian :eek: :) :D
 
pete roper said:
The issue with the Cush drive related to a few very early B11's and the problem it caused was a loud rattle at idle. If this machine idles quietly it doesn't have the problem.

Yes, I'm very familiar with the face-cam shock absorber and how it works but will re-iterate that the backlash you are feeling is from clearance of the dogs, not anything to do with the Cush drive.

Pete
Click to expand...

Hi Pete, just happened across this thread, and I have been trying to figure out what that rattle was at idle for my B11.
What is this issue with the cush drive? and can it damage anything?
 
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