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correct wieght gear oil for rear gear box?

1

1st V7 classic

Tuned and Synch'ed
Joined
May 24, 2011
Messages
27
85-90w or 85-140w?? Thanks in advance ,I put the first one 85-90 syn. in gear box is that right??
 
1st V7 classic said:
85-90w or 85-140w?? Thanks in advance ,I put the first one 85-90 syn. in gear box is that right??
Click to expand...

Rear drive(transmission) the lump at the end of the swing arm, 85W-140. The gearbox(transmission) ( the box that changes gears) 85W90
 
Pulled the 75-90 syn. out of rear transmission hub and put in the 75-140 syn. in. Thought I had it backwards and thanks John for the correction. Only ran it 5miles on the wrong stuff and it flushed it out anyway and cleaned magnet again. Get to go!!!!
 
Good info to know. Owner's manual is unclear.
I need to top off my final drive fluid as I've noticed some oil on my rear wheel. Can't quite tell where the leak is from just yet. I re-torqued the drain nut and cleaned the wheel and final drive off last night, and no leaks as of yet from sitting over night.
 
If you aren´t using full synthetic then don´t forget the moly additive. It makes a noticeable difference to the operating temperature of the drive.

90% of the time a leak out of the rear drive is due to over filling.
 
My first service was done at Rosefarm Classics, and I'm sure Jim used Agip synthetic and put in the proper amount.
After a 2 mile test ride, I noticed a drop from the inside of the hub assembly.
 

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Morizzi said:
If you aren´t using full synthetic then don´t forget the moly additive. It makes a noticeable difference to the operating temperature of the drive.

90% of the time a leak out of the rear drive is due to over filling.
Click to expand...

Not a fan of Moly. I've seen it cause etching on the bearings. For that reason, fully synthetic is best. Also even with non synthetic I wouldn't use moly. Airhead BMWs have similar rear drives and never recommended moly.
 
I used Valvoline syn-blend,works fine! Just got back from 200 mile run,smooth,shifts easy,not noisy! I,m changing it out every oil change. Plenty overkill and protection. Oil-syn gear blend best of both worlds.
 
john zibell said:
Morizzi said:
If you aren´t using full synthetic then don´t forget the moly additive. It makes a noticeable difference to the operating temperature of the drive.

90% of the time a leak out of the rear drive is due to over filling.
Click to expand...

Not a fan of Moly. I've seen it cause etching on the bearings. For that reason, fully synthetic is best. Also even with non synthetic I wouldn't use moly. Airhead BMWs have similar rear drives and never recommended moly.
Click to expand...

My experience is different to yours John. I´ll continue to use it. I´m interested to know how you could tell it was the moly causing the etching?

The easy test to see if what you are using is doing its job is straight after a decent ride. Put the back of your hand against the drive and feel the temperature. It will be hot but if you can´t hold your hand there then I´d be looking for an alternative.

Cheers
 
Morizzi,

Moly is molybdenum disulphide. If the sulfur breaks away form the molybdenum molecule, you can get sulfuric acid formed. The race for the crown bearing (the roller bearing not the ball bearing in a big block bike) was completely pitted by the acid that formed taking the bearing with it. BTW, BMW has used a similar rear drive forever (old airheads) and they have never recommended adding moly to any of their oils.
 
Thanks John.

Interesting! I´m wondering if any contaminants came down the swing arm. Unlike the small blocks, big blocks don´t have a seal between the drive and the shaft. If the rubber boot ever split or a vent was fitted then this may be an alternative explanation. Don´t know just throwing something up there to contemplate. Water and moly disulphide would be more able to convert to sulphuric acid than air, I´m thinking. (Needs ample hydrogen and not a lot in air, H2SO4)

I´ve never had the issue but I change the oil in the rear drive every 10,000km as per recommendations.

I´ve actually gone to Tungsten disulphide now and still no detrimental affects to be seen. I must admit I don´t go into the drives very often, only when the inner seal has finally died but I´ve never had a bearing failure in there or seen a sign of pitting in the lubricated space.

The reason that moly has got so expensive is the demand for it in heavy industry and mining. A gearbox in some of that stuff is worth more than a showroom of Guzzis and under much higher loads.

I´ll stick with it. At 160ml of oil in the rear drive I´ve got 120,000km worth of 80W140 in a 2 litre container and I have a lifetime supply of Tungsten S2 so I´m set for a long time considering I mainly ride my LM III.

I also use moly fortified grease on the splines. I find its the duck´s guts. :woohoo:

Stick with what works for you is my attitude. B)

Enjoying the discussion.

Cheers

Rod
 
My rear cover gets luke warm to the touch after 30 minutes or so. Running Valvoline SYN-Blend 75-140,oil and syn. the best of both worlds. Perfect protection. I,m not sold on 100% syn.
 
1st V7 classic said:
Running Valvoline SYN-Blend 75-140,oil and syn. the best of both worlds. Perfect protection. I,m not sold on 100% syn.
Click to expand...

Allow me to wonder; how much synthetic and how much mineral? 50/50 ? 10/90? 73/63 ? :whistle:

I also wonder why Guzzi makes recommendations for which oils to use where, as many users knows so much better. :dry:
 
Re: correct weight gear oil for rear gear box?

Plain gear oil in the right wieght is fine and has been used for near 90 years in Guzzi,s and the reputation of Moto Guzzi,s long lasting dependible service was made with reg. oils and gear lubes. Agip made a deal with Guzzi and they market it. Its not the answer to all aspects of lube. And for sure not best out there. If the oil meets the spec,s its fine. Beemers,Honda,s, and the more costly cars and trucks do fine on spec oil and lubes. Come on a 10-15 thousand dollar bike is cheap to a 30-40 thousand dollar car or truck. Change it ,drive it right and you will get good service. Thats the magic and follow it.
 
Thanks for the discussion.

I bought an '07 Breva 750 recently that came with a final drive leak. Following good advice here, I found the vent was frozen, free'd it up and all was good. Just got it back from the dealer who did the first scheduled service and put 75W-90 syn in the final drive - and it's leaking again. : - (
I've ordered another vent (even though I think this one is venting) but thinking I will just go ahead and try the heavier 140 weight fluid and viva la difference.
I'll report back my results.
 
Did the dealer replace the two seals? If not, then a seal may be damaged and will leak no matter what weight you use.
 
When I brought the bike in, I had freed up the vent and there was no leaking. I suspect it has closed up again. I have another on order. I understand that oil weight will not fix leaky seals.
 
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