rear drive torque arm

[richard100t]

OK now I've ridden the bike a few miles at different speeds & I think the problem is solved. Almost surely the rear axle nut not being tight enough caused that bolt to fail somehow. In any case the bike runs as well as a Guzzi should & the fix was $1.63 for the nut/bolt/washer. The tow home however was $75 Gawd only knows how much $$ I saved not trying to fix it on the roadside & limp it home lol.

[Guest ratchethack]

Richard, congrat's on what appears to be a simple fix, but is there need for further concern here? Y'er scarin' me, my friend. It sounds to me like you haven't been torquing the spindle (axle) nut properly. It needs a fairly hefty 88 ft-lbs. or 120 Nm. Careful not to torque it much more than this to avoid crushing the stock wheel spacers, which are known to be cheesy, and tend to easily deform.

 

The bevel box "floats" on the axle per the parellogram design (preventing jacking under load), so the amount of torque on the spindle nut has no effect whatsoever on the movement of the bevel box and/or the torque arm.

 

As Docc mentioned, the likely answer to the broken bolt is that either it was under-torqued and loosened up, over-torqued and fractured, or it was defective to start with.

 

Again, glad you came out of it so well.

 

How many Guzzisti d'you figure ran out to check theirs?

 

[richard100t]

Well one time I had tightened the nut too far & it caused something that made the brake grab the disk or something like that. So after that I always made sure that I never over tightened it again. Once I tightened the nut this time I realized that it was just a little too loose so I am assuming that was the cause of the problem. The bolt that failed hadnt loosened up because there was plenty of bolt through the end of the nut & it was still plenty tight. I'm thinking the damage happened like a lever action with the stress starting at the wheel & moving out the torque arm when I gave it gas or was leaning the bike Eventually the repeated stress/relax/stress on the bolt caused it to fail. I could be wrong but thats my theory of what happened. Btw I had been riding the bike for most of the season this year with the axle nut at that torque level so it did take a long time for that bolt to fail.

[cash1000]

I've just had same bolt snap  for the second time! First time I had noticed it was loose and fixed it. This time  I was 150 k's from home and my wife had to come with trailer a rescue me.

Has anyone got further opinions why this would happen?

[docc]

For reference, this fastener?

[The Monkey]

I've just had same bolt snap  for the second time! First time I had noticed it was loose and fixed it. This time  I was 150 k's from home and my wife had to come with trailer a rescue me.

Has anyone got further opinions why this would happen?

Over tightened, poor fit or vibration

 

here are the easy things to look at/fix

Check the condition of the bushings in that arm, and the fit of the bolts into those bushings

Check your cush drive for freedom of movement.

Ensure the needle bearing in the nose of the bevel box (spindle starboard side) is in good shape 

Replace the bolt and Nylock Nut with Grade 8 material from a fastener supply. Do not use Stainless stock.

Don't crank on it, its not necessary the bolt merely need to be tight enough to hold itself in place.

 

The not so easy (to repair) is an excessive amount of vibration due to the needle bearing thats aft of the main support bearing for the drive yoke within the bevel box being shot.

Easy test- grab the shaft drive back near the bevel and stir it. If that needle outfit is shot then you will get lateral movement. A lot of it. 

[cash1000]

Yes that's the one

[cash1000]

Any suggestions how I replace the bush on the rear drive torque arm? See attached photo

Guzzi parts list appears to only offer complete replacement of all the arm.

[gstallons]

First , the rubber appears to be good. If it is o.k. then , take a flat file and file the surfaces flat on both sides of the inner portion and reinstall .Tighten the bolts to the correct torque and go !

[Scud]

I was looking at replacing those bushings myself, but I learned they are not available. Neither is the complete arm. A few months ago, when I talked with someone at Harpers Moto Guzzi, they said they were working with a machinist to create a new arm that would take a standard, replaceable bushing.

 

Ideally, though, the suggested repair will work.

[Rox Lemans]

I've just had same bolt snap  for the second time! First time I had noticed it was loose and fixed it. This time  I was 150 k's from home and my wife had to come with trailer a rescue me.

Has anyone got further opinions why this would happen?

I had a snapped one also . It's actually damaged the arm and needed a new one (thankfully Scud had one). Didn't think this was as common as it is.

[victor]

Cash,

that bush must be changed.Agostini has the replacement or you can buy this ones http://www.ebay.de/itm/Silentbuchse-Motorlager-10x30x30mm-/171945540992

For the bolt use this type of bolt 

http://www.ebay.co.uk/itm/M5-Shoulder-Bolt-Socket-Screw-Allen-Tool-Post-High-Tensile-Bolt-DIN7379-/300752788661?var=&hash=item8bb5edea12

obviously buy the right measure.

Replacement is very easy ,lot of vids on youtube.

Regards,Victor

[Scud]

Just noticed a complete arm with mounting hardware for $40 on e-bay:

 

http://www.ebay.com/itm/2001-MOTO-GUZZI-SPORT-V11-REAR-BRAKE-STAY-/361303623288?hash=item541f5fc678:g:POAAAOSwZd1VVkL2&vxp=mtr

[stewgnu]

Would it be possible to cut/chop out the old bushings and press a couple of spherical plain bearings in i wonder?

[gstallons]

You could....and you would have a stiff arm linkage for this to work with / against . Think about that.