1970 ambassador throw out bearing

[harrytief]

I think the clutch throw out bearing in the new to me 1970 ambo has collapsed. the bike started to show symptoms of hard shifting and clutch creep before suddenly
.freezing in gear in the middle of an intersection. Quite the adventure that. Back in the garage, with the battery plate out I saw that the outer body has receded 2-3 mm back into its port. The clutch shift arm looks to be from a later ambo(?) as it has an adjustor screw added. That shift arm operates on the left side of the transmission so I know it is an ambo arm but I thought all early ambos used non adjustable shift arms. Anyone clarify this?
In any case, I need to pull the outer body and get at the throw out bearing. I tried a magnet lowered from above and slid up alongside the swing arm with no luck. Is my only option to pull the transmission and push back on the clutch push rod. Hope not. Any ideas?
Thanks
Harry

[pehayes]

The receding of the outer body is indicative of bearing failure.  But, freezing in gear is not.  The bearing may have failed some time ago.  Now, the pushrod has been ground shorter or the receiver cup in the clutch has been bored through.  Have you pulled the swingarm as yet?  Do that and you may be able to use  much stronger magnet for a straight pull aft to pull the body.  Use a "rare earth" magnet for more grip.

What happens when you pull on the hand lever?  Any resistance?  Fully locked?  Can you shift the bike with the engine off and turning the rear wheel by hand?  More data please.

Also, there is a very active and knowledgeable discussion forum on yahoogroups at Loopframe_Guzzi.  Ask there for more advice.

And read here:

http://www.thisoldtractor.com/moto_guzzi_loopframe.html

Patrick Hayes
Fremont CA

[Antietam Classic Cycle]

The clutch shift arm looks to be from a later ambo(?) as it has an adjustor screw added. That shift arm operates on the left side of the transmission so I know it is an ambo arm but I thought all early ambos used non adjustable shift arms. Anyone clarify this?

AFAIK, only the V700 and earliest ("A-series") Ambos had a clutch arm with no adjuster screw. By '70 it would have had one.

[harrytief]

Thanks charlie. The right side shift ambo I also have has a shift arm without an adjuster so I thought the 70 might be the same.
Patrick. I can shift when I adjust the clutch cable for more pull but a few hundred yards and the cable begins to go slake and the clutch starts to drag. All this looks like throw out bearing failure and hopefully I caught it before worse. I want a quick repair but that may not be in the cards. I'll try a better magnet and even pull the swing arm. Is there any room around the lip of the outer body to get angled needle nose pliers into? I don't want to score the wall the o ring runs on. Any other ideas?

[Antietam Classic Cycle]

Thanks charlie. The right side shift ambo I also have has a shift arm without an adjuster so I thought the 70 might be the same.
Patrick. I can shift when I adjust the clutch cable for more pull but a few hundred yards and the cable begins to go slake and the clutch starts to drag. All this looks like throw out bearing failure and hopefully I caught it before worse. I want a quick repair but that may not be in the cards. I'll try a better magnet and even pull the swing arm. Is there any room around the lip of the outer body to get angled needle nose pliers into? I don't want to score the wall the o ring runs on. Any other ideas?

Here's a "wild-a$$ guess" idea that I've never tried, but that might work. It might be possible to pressurize the transmission slightly (5 psi or so) and pop the outer body out. To do this, you'd need to plug the vent plug on the side above/behind the starter and then fit a spare fill plug with an air valve. Like I said, I've never done it, so try it at your own risk.

[TOMB]

Yes you can pressureize the trans and the bearing should pop out. There was two different types of   bearings one ball early type and roller type  fewer. I've seen both in ambassador 4 speed. The 5 speed have the roller type. You don't need to pull the swingarm
If the  push rod is frozen to the pressure plate then yes the trans needs to come out. If you go this route consider during the clutch

TOMB

[pehayes]

Three other ideas.

1-clean the outer body fastidiously with strong solvent and then use superglue or jbweld to attach a pulling device.  Like an inverted bolt.  Once the outer body is out, a good machinist could clean the outer body surface back to normal.  If it doesn't work, you'll have to pull the transmission with the puller glued in place.  No loss since you'd have to do that anyway at that point.

2-the rapid change in action is disconcerting.  While it points toward the bearing, the loss of the bearing can also cause a grinding damage to the pushrod tip so be prepared for resolving that as well.  It is actually possible for the front tip of the rod to weld itself into the clutch receiver cup.  If so, the rod will then continuously spin with the engine even though you haven't pulled on the clutch.  Rod seals won't last long under that condition.  Once you get the bodies out, make sure you can pull the rod backwards just a mm or two to verify it is free in the forward cup.

3-The recessed outer body is a problem.  But, could you also be losing the clutch cable core?  The cable filaments are a wound up, springy affair.  If one strand breaks, the others relax a little an the cable lengthens slightly.  Cable gets longer with each broken filament until it fully snaps.

Patrick Hayes
Fremont CA

[harrytief]

Charlie, Tomb.
Just for the giggles and 'cause I am a pushover for anything "McGiverish", I will try to pressurize the transmission case and see if that pops the outer body. Possibly will spit out the inner body with bearing as a good will gesture.
Patrick
I tried cleaning the face of the outer body as well as a magnet and got a mm of movement before the magnet releases. Air pressure as above with a little help from the magnet might do the trick. If not, I will try to "glue" up a puller to the cleaned face of the outer body tho" I am getting the sinking feeling that I may find those other issues that will require the transmission to come out.
Here goes...splash
Harry

[harrytief]

So first the good news. Pressurizing the transmission WORKED!
Thanks Charlie, Tomb. I replaced the vent cap with a bolt of the same dimension and used a rubber cork to plug the filler port. I predrilled the rubber cork to take a thin air wand  and fitted up a line set and air gun to the wand and back to my compressor. I metered air into the transmission SLOWLY and grew a little concern when the bladder around the U joint blew up like a July bullfrog. I let the air out to deflate the bladder but outer body had moved. Repeat twice and it pooped out!
Now the bad
No throw out bearing had been fitted. I can see the inner body with its concentric groove for the early style ball type bearing (I assume) but no throw out bearing or any debris of one. Luckily, little to no scoring or heat bluing on the mating faces of the inner and outer bodies so likely not run long in this mode so no overheating? Am l whistling past the graveyard? What should I check now?
The diameter of the outer body is smaller than I seem to recaller those fiited to my tonti. True? Different throw out bearing?
Harry
Thanks guys!

[MotoChuck250]

So first the good news. Pressurizing the transmission WORKED!
Thanks Charlie, Tomb. I replaced the vent cap with a bolt of the same dimension and used a rubber cork to plug the filler port. I predrilled the rubber cork to take a thin air wand  and fitted up a line set and air gun to the wand and back to my compressor. I metered air into the transmission SLOWLY and grew a little concern when the bladder around the U joint blew up like a July bullfrog. I let the air out to deflate the bladder but outer body had moved. Repeat twice and it pooped out!
Now the bad
No throw out bearing had been fitted. I can see the inner body with its concentric groove for the early style ball type bearing (I assume) but no throw out bearing or any debris of one. Luckily, little to no scoring or heat bluing on the mating faces of the inner and outer bodies so likely not run long in this mode so no overheating? Am l whistling past the graveyard? What should I check now?
The diameter of the outer body is smaller than I seem to recaller those fiited to my tonti. True? Different throw out bearing?
Harry
Thanks guys!

Harry,
As I remember the diameter of the outer body on the Eldo and later trannys is larger than the outer body on the Ambassador throw out bearing.  So unless you do some machine work to the rear tranny cover you can't fit a later model throw out bearing.  The later model bearing is a radially arranged caged set of rollers with a centering peg in the middle of either the inner or outer bodies. Typically the Ambo throwout bearing cage dissintegrates and the balls dig a channel into the aluminum of the rear tranny cover.  You might check for this groove.  I have filled the groove with a very thick grease and carefully assembled everything and had the bearing work for many miles. 

[Antietam Classic Cycle]

The diameter of the outer body is smaller than I seem to recaller those fiited to my tonti. True? Different throw out bearing?

Early 4 spds. had a 20 mm throw-out assembly vs. 22 mm later. In place of the original caged-ball bearing, use a needle bearing like the later bikes. There's cross-reference info. on Greg Bender's site. http://thisoldtractor.com/moto_guzzi_loopframe_throw-out_bearing_cross-references.html

If you end up having to pull the transmission, I'd recommend sending the rear cover and triangular selector cover to Patrick Hayes to have the throw-out bore sleeved in stainless steel and an o-ring groove added to the selector shaft bore like on 5 spds. This will eliminate leaks from both areas.

[harrytief]

It is always amazing to me how this technological age has revealed the world as library where  previously remote and dispersed ideas can be accessed almost spontaneously. This little forum is like that. The magic is that the data bases are people with ostensibly only a passion for the same motorcycle but as they share their information, some of what is best about the "us" shines through..
Thanks!

Charlie
Thanks for the lead on the bearing notes in Greg Bender's site. Turns out that they have a storefront here in Toronto. I'll call Monday morning. I'll likely pull the engine/transmission over the winter and send the covers to Patrick. Thanks for that lead
Is it worthwhile to try and pull the inner body and push rod now as well? I can't see signs of excessive heat that may have welded the rod to the inner body or clutch cup but how can I check without removal. That looks like a pain with the transmission in the bike.
Harry

[Antietam Classic Cycle]

Is it worthwhile to try and pull the inner body and push rod now as well? I can't see signs of excessive heat that may have welded the rod to the inner body or clutch cup but how can I check without removal. That looks like a pain with the transmission in the bike.
Harry

While you're in that far, it sure wouldn't hurt to pull the inner body and pushrod if you can. The inner body should come right out, nothing is holding it in other than gear oil. You might try using forceps to grab them.

This would be a good time to replace the original plastic sleeve type "seal" with the 6 o-ring stack. I can send you the o-rings for free. You may also find that the plastic sleeve has worn away the pushrod, so pulling it out will give you a chance to inspect it. 

[harrytief]

Hi Charlie
Pulled the inner body and pushrod with a magnet. No bluing or other signs of heat damage. I thought I might find a small ball bearing inside the inner body acting as a throwout bearing as in early v700 but found nothing. The pushrod seals show very little wear so I assume that when they were renewed, someone forgot to install the throwout bearing. Thanks for the offer of the o rings. I have one set left and they will go in along with a new bearing. I'll reuse the bodies and push rod as the seem undamaged.
Harry