Sleeve Gear Bearing Failure

gortnipper said:

Out of curiosity, would Redline Lightweight ShockProof be any different?

Click to expand...

I doubt it, but I don't know for sure.

Maybe you should ask Redline.

I have been told it is the extreme pressure additive used in gear oils that attacks the plastics.

Did a quick dig, and found some quotes from the rest of the article

“Polyamide (PA) is playing a key role in enhancing fuel economy through its usage as cage material for tandem pinion ball bearings… The 30% glass fiber-reinforced grade Stanyl TW200F6 PA46 from DSM Engineering Plastics…"

"Stanyl TW200F6, [however], demonstrated acceptable resistance to Hypoid Gear oil up to 150°C, as well as an appropriate balance of stiffness and flexibility necessary to insert the ball bearings into the cage and retain them,” says Burnham. "

comnoz said:

I doubt it, but I don't know for sure.

Maybe you should ask Redline.

I have been told it is the extreme pressure additive used in gear oils that attacks the plastics.

Click to expand...

Is a bugger cuz I put one of these in a couple thousand miles ago since was ordering other things too
http://www.tritonmotorcycleparts.com/297620485/product/517742/sleeve-gear-bearing?catid=146825

There are some plastic composites that can do the job -but they are not common or cheap. They are generally only going to be available for certain OEM applications. Definitely nothing in an imperial size bearing.

I stay with steel cages for everything except the layshaft bearing where I insist on brass.

Finding a decent ball bearing for the sleeve gear is getting tough. Either they have plastic cages or the radius on the edges is too small and they will not seat on the shaft or in the case.

I fitted a roller layshaft bearing back in the 1980's, it had a plastic cage and its still in the bike and I have no reason to consider opening the gearbox as it shows no adverse symptoms.

It is virtually the same as the current AN replacement other than being German made.



I had been using EP90 GL4 and now use EP80w90 GL5, now there are different ways to get EP oils, the earliest was using Sulphur based chemicals but they caused problems with yellow bushes and a lot have been reformulated. So either FAG use a EP proof plastic (they describe it as being nylon PA6) or the EP oils I have been using do not contain plastic destroying chemicals.

Nylon PA6 is not generally approved for Hypoid gear oil. Time and 150 C. temps will generally cause cracks in nylon in older formulations.

PA6 is the same as Polyamide 66.

Maybe some of the newer oils don't cause problems?

But Niagra850's failure is not the first failure I have seen with the bearing he used. I have seen a couple others that appeared to be cage failure and ended with the same result.

swooshdave said:

The next gearbox I do is going to get a ball bearing on the layshaft.

Click to expand...

That is Mr. Hemmings recommendation (using a phenolic-seal high quality ball bearing) and he's done a few hundred GB's and lots of racing applications....hard to argue against that IMHO.
I believe he states in his GB tear down video something to the effect of rolloer on layshaft tends to increase rigidity and he has seen shaft breakages with them.

Tornado said:

I believe he states in his GB tear down video something to the effect of rolloer on layshaft tends to increase rigidity and he has seen shaft breakages with them.

Click to expand...

Sorry, I don't buy that one.

PA6 is the black plastic used in FAG ball or roller bearings

A quote from Zydeco Racing.

"PA6 or
Polyamide 6,6
For the majority of injection moulded cages polyamide 6,6 is used. This material, with glass fibre reinforcement or without, is characterized by a favourable combination of strength and elasticity. The mechanical properties like strength and elasticity of polymeric materials are temperature dependent and subject to permanent changes under operating conditions, called ageing. The most important factors that play a role in this ageing behaviour are temperature, time and the medium (lubricant) to which the polymer is exposed. The relationship between these factors for glass fibre reinforced polyamide 6,6 is illustrated in diagram 1. It appears that the cage life decreases with increasing temperature and the aggressiveness of the lubricant.

Therefore, whether polyamide cages are suitable for a specific application depends on the operating conditions and life requirements. In table 18 the classification of lubricants into "aggressive" and "mild" is reflected by the "permissible operating temperature" for the use of cages made from glass fibre reinforced polyamide 6,6 in various lubricants. The permissible operating temperature in this table is defined as the temperature, which gives a cage ageing life of at least 10 000 operating hours.


Towards the low operating temperature side, also a limit can be set since polyamide loses its elasticity which can result in cage failures. Cages made from glass fibre reinforced polyamide 6,6 should for this reason not be applied at a continuous operating temperature below –40 °C.



Note
Bearings with polyamide 6,6 cages can be operated at temperatures up to +120 °C. The lubricants generally used for rolling bearings do not have a detrimental effect on cage properties, with the exception of a few synthetic oils and greases with a synthetic oil base, and lubricants containing a high proportion of EP additives when used at high temperatures "

So its a 'pre-unit' gearbox that is never going to get to 100C let alone 120C, the advice I got from Glacier Industrial bearings was if the sulphur EP additives were being used then it was only an issue above 100C with yellow bushes. So my roller bearing with its nylon cage and my yellow bushes will be fine. A unit gearbox would be different.

I have seen gearbox oil temps well over 100 C. with my Commando. About 100 miles on the interstate will exceed that easily on a hot day.

Here is what SKF says

"Cage materials
Phenolic resin
Cotton fabric reinforced phenolic resin is a lightweight material. Cages made of this material can withstand heavy inertial forces and operating temperatures up to 120 °C (250 °F). The material tends to absorb oil, assisting the lubrication of the cage / rolling element contact and providing a safety margin for run down, should there be an interruption of lubricant supply.

Cotton fabric reinforced phenolic resin is the standard cage material for most super-precision angular contact ball bearings.

Polyamide 66
Polyamide 66 (PA66), with or without glass fibre reinforcement, is characterized by a favourable combination of strength and elasticity. Due to its excellent sliding properties on lubricated steel surfaces and the superior finish of the contact surfaces, PA66 cages reduce friction, frictional heat and wear. PA66 can be used at operating temperatures up to 120 °C (250 °F). However, some synthetic oils and greases with a synthetic oil base and lubricants containing EP additives, when used at high temperatures, can have a detrimental effect on PA66 cages. For information about the suitability of cages, refer to Cages.
PA66 is the standard cage material for many super-precision cylindrical roller bearings and angular contact thrust ball bearings.
Polyamide 46
Polyamide 46 (PA46) has the same excellent material properties as those of PA66. Glass fibre reinforced PA46 has a higher permissible operating temperature than glass fibre reinforced PA66 and can therefore be used at operating temperatures up to 135 °C (275 °F). However, as with PA66, some synthetic oils and greases with a synthetic oil base and lubricants containing EP additives, when used at high temperatures, can have a detrimental effect on PA46 cages.
PA46 is the standard cage material for the SKF Silent Series angular contact ball bearings in the 719 .. D and 70 .. D series.
Polyetheretherketone
Glass or carbon fibre reinforced polyetheretherketone (PEEK) is popular for demanding applications where there are either high speeds or high temperatures or a need for chemical resistance. The maximum temperature for high-speed use is limited to 150 °C (300 °F) as this is the softening temperature of the polymer. The material does not show signs of ageing by temperature or oil additives up to 200 °C (390 °F).
PEEK is the standard cage material for some super-precision angular contact ball and for high-speed design cylindrical roller bearings.

Brass
Brass is unaffected by most common bearing lubricants, including synthetic oils and greases, and can be cleaned using normal organic solvents. Brass cages can be used at operating temperatures up to 250 °C (480 °F).
Machined brass cages are used in a number of super-precision double row cylindrical roller bearings and double direction angular contact thrust ball bearings and are standard for large super-precision angular contact ball bearings (d ≥ 300 mm).

Other cage materials
In addition to the materials described above, SKF super-precision bearings for special applications can be fitted with cages made of other engineered polymers, light alloys or silver plated steel. For information about alternative cage materials, contact the SKF application engineering service."

comnoz said:

PA6 is the black plastic used in FAG ball or roller bearings

A quote from Zydeco Racing.

Click to expand...

Zydeco Racing is Charlie Cole and he certainly knows his stuff when it comes to Moto Guzzi.

I think that quote will be about the double row ball bearings in the Moto Guzzi gearboxes, one at the front of the clutch input shaft and one at the rear of the output shaft. (A roller and ball bearing the other ends)
I do not know the exact year but these were originally a 13 ball per race (26) , steel cage bearing, later the factory went to a 9 ball per row (18) with some from of plastic cage. (iirc) Those bearings have a reputation of failing (The cage)

When I rebuilt the gearbox in my 1973 Moto Guzzi that became something to consider, try and find NOS bearings or use the latest 9/18 ball version, that came in a complete bearing kit from HMB Guzzi in Germany with a plastic cage, which I ended up using. (I will hope that is the special material cage and what is being used on modern Moto Guzzi's which is quite flexible)

The problem is I would like to standardise oils if possible (Ducati/Triumph PU&U, Norton and Moto Guzzi)

I got Bel Ray gear saver for the MG, I swapped the front gearbox trust bearing to a needle roller so no yellow metal but am told later it will attack (GL5) the Norton bushes being yellow metal.

OK lets go to Redline Heavy which is supposed to be OK with yellow metal (no sulphur) but what if it attacks plastic which would be bad for both those MG bearings and the Norton lay shaft bearing rollers cage... (of course based on age that might not become my problem)

I had thought about the Redline GL4 but with online reading that was not really up to the task either.
Its not easy sometimes.

The original ball bearing (UK made) in my 750 had signs of the outer race starting to crack up so who knows what is going on with that shaft under load or abuse perhaps.

The Sleeve Gear bearing I acquired is more of a slip fit on the Sleeve Gear from spinning it out. I plan to lock the Outer race to the case and inner to the Sleeve Gear. What products should I lock it down with? I see Locktite Bearing Lock (green) online. Checked the local CTC and they have Permatex Red and Blue... I have a tube of Locktite Blue. Thinking I need something in between. Any suggestions?

The bearing will be clamped to the shaft by the sprocket nut.

The only thing that might help if the bearing is loose in the case would be Locktite bearing mount or JB weld. If it's not loose I wouldn't use anything.

comnoz said:

The bearing will be clamped to the shaft by the sprocket nut.

The only thing that might help if the bearing is loose in the case would be Locktite bearing mount or JB weld. If it's not loose I wouldn't use anything.

Click to expand...

Its a tight fit in the case and it will have to heated to get it in. So its okay of the inner race spins (somewhat??) with the shaft? The lip is banged up a bit should I smooth it out or leave it be and tap it in?

Niagara850 said:

Its a tight fit in the case and it will have to heated to get it in. So its okay of the inner race spins (somewhat??) with the shaft? The lip is banged up a bit should I smooth it out or leave it be and tap it in?

Click to expand...

I guess I would smooth it out a bit.

The bearing will not be able to spin once the nut is tight, so locktite will not make any difference.

They are normally a slip fit on the sleeve gear.

Getting at the rebuild - replacing the bearings on the Main Shaft and the Sleeve Gear bushings and 2nd gear bushings. Ist lay is okay. I see the Sleeve Gear must have had the Mk3 bushings. I ordered the the Mk2's from the parts diagram and they were much shorter. Pulled out the old and pressed in the new, with a little reaming they fit fine. The 2nd Gear Main has a lip on the new bushing but not on the existing one pressed out. It is a slip fit (as seen in other posts). I has a lip cut into one end. Which side of the gear does it go? I have it on the dog side currently.

Niagara850 said:

I has a lip cut into one end. Which side of the gear does it go? I have it on the dog side currently.

Click to expand...

I don't know. I'd guess it's right as it is. Not sure if you know but that "RS85" 2nd. gear isn't a genuine Norton part.