Clutch thrust bearing on 8V's

[pete roper]

The factory released a service bulletin a few months back about the thrust bearing on some 8V's most notably early Stelvios and Grisos becomming noisy in service. While no further explanation was really given it was obvious that the bearings were failing in some cases and the sollution was said to be to replace the whole thrust assembley with a new one with two bearings that has a superceeded part number to the original.

Now MarkIII who posts here was having some problems with his clutch on his 8VG, we found out last week that they were in fact unconnected with the thrust issue but since it was something that had been mentioned by the factory I went ahead and ordered the new part that comes as a complete assembly, supposedly a new thrust cup and two bearings. Well, they weren't in stock so they went on BO and duly arrived a couple of week later. Unfortunately they only has ONE bearing in the kit!!!!

Last week when we pulled the swingarm on Mark's bike to get at the slave cylinder and thrust mechanism we found no problem with his thrust mechanism but in for a penny? In for a pound! We used the original bearing and the new one as shown on the service bulletin. His clutch pushrod length was correct but interestingly, even though adding another bearing effectively increases the length of the thrust mechanism by 4mm there is no suggestion that anything else in the system needs altering.

This is by the by, the whole thing went back together fine and we then found the source of the problem that Mark said he'd probably post about but I'd also bought a second thrust assembley to put in stock and today did a bit of measuring only to find that the actual thrust cup is identical to the 'Old' one, hence the extra length in the mechanism which means that rather than buying the $80 assembley from Guzzi all one actually NEEDS to do if you want to add another bearing is go to the bearing factor and purchase a 10 x 24 x 4 Torrington and while I have yet to purchase one it'll sure as shit be cheaper than $80

Pete

[DanPez]

The factory released a service bulletin a few months back about the thrust bearing on some 8V's most notably early Stelvios and Grisos becomming noisy in service.

The symptoms would only be if the lever starts to get hard to pull right?

We used the original bearing and the new one as shown on the service bulletin. His clutch pushrod length was correct but interestingly, even though adding another bearing effectively increases the length of the thrust mechanism by 4mm there is no suggestion that anything else in the system needs altering.
Pete

Are there supposed to be 3 bearing in all?

[pete roper]

That pic shows one bearing and two races. With the new set up you end up with a second bearing piggy-backed on the first so you get race, bearing, race, bearing, race.

Pete

[Phang]

So there is more than 4mm (bearing + race) introduced to the total length of the assembly?

I am quite surprise to learn that the clutch actuation assembly can accommodate the extra 4mm+

As the clutch push rod came in 4 lengths with 1.5mm increments, which I think allowing a +/- 1.5mm error. Wouldn’t the additional 4mm in the thrust bearing pack preload the pushrod?

Phang

[pete roper]

I think that the different rod lengths are there to compensate for different diaphragm spring preloads due to manufacuring tollerances rather than the abillity of the slave cylinder to cope with extra travel.

I could be completely wrong on that. The addition of an extra bearing will be for speed reasons rather than load but all I can immagine is that people who slip their clutches alot would be more likely to experience problems with the single bearing set up than the twin.

Pete

[Phang]

I think that the different rod lengths are there to compensate for different diaphragm spring preloads due to manufacuring tollerances rather than the abillity of the slave cylinder to cope with extra travel.

It make sense Pete

Do the later machines come with twin bearing setup

Phang

[pete roper]

Buggered if I know? Never had a look at one. I'd say a cautios *Maybe* on that. Given past history on 'Updates' the world is your oyster.....

Pete

[pedmondson]

I believe I have the same issue "thrust bearings". Is the main symptom a high pitch whinning sound coming from the area around the alternator?

It happens to me when I come off throttle. If I change gears while this sound is being made, the sounds stops.

Thanks,

Patric

[pete roper]

Thrust bearings are at the back of the gearbox. Logic would dictate that if there is a bearing noise from the region of the alternator it is most likely to be an alternator bearing. Having said that what you'te describing has the symptoms of belt slip. Have you checked the tension of your belt?

Pete