Gearbox question

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Rick, I believe Redline "NS" gearbox oils are "No Slip," not "No Sulfur." They're GL-5, in any event.

There's always Redline's MTL or MT-90, which are GL-4 (but much less viscous than their "Shockproof" gear oils).
 
Interesting, I used to collect TR3s and XK Jags that had the early Moss box. About the only problems I had with trannies were clutches in the overdrive on my ones that had that.
I didn't know Redline had a product that was developed for this sort of application.
Yup, the box is too small, the gears aren't very hard. I suspect having them coated or cryogenically treated would be more expense that it is worth. It does seem like the best oil you could get would be a sound investment.
 
The car box, as swoosh pointed, out is substantially larger than the AMC box. Therefore car gears are substantially larger than MC gears. This means that the contact stresses are spread over a larger area on the car box, which translates to lower contact stresses between gears. And lower stresses mean less chance of spalling, which is the damage you see in the photo -not brinelling.
 
GavinJuice said:
Here's a good article that explains Spalling...

http://www.machinerylubrication.com/art ... icleid=664
Click to expand...


It is common for initial pitch line spalling (usually labeled initial pitting) to occur soon after gear drive commissioning and then stop suddenly and for the gears to continue a long life of service. It is a relief mechanism for small-tooth geometry errors. In some cases, however, more severe geometrical errors can continue, leading to premature tooth cracking and early failure.
Click to expand...

Two very interesting sentences together. On one hand, it may last for ever, or it may fail. Not very reassuring. :mrgreen:
 
GavinJuice said:
Here's a good article that explains Spalling...

http://www.machinerylubrication.com/art ... icleid=664
Click to expand...


It is common for initial pitch line spalling (usually labeled initial pitting) to occur soon after gear drive commissioning and then stop suddenly and for the gears to continue a long life of service. It is a relief mechanism for small-tooth geometry errors. In some cases, however, more severe geometrical errors can continue, leading to premature tooth cracking and early failure.
Click to expand...

Two very interesting sentences together. On one hand, it may last for ever, or it may fail. Not very reassuring. :mrgreen:
 
swooshdave said:
Two very interesting sentences together. On one hand, it may last for ever, or it may fail. Not very reassuring. :mrgreen:
Click to expand...

Yup! Lots of spalling reported on the AMC box, but I've still to hear a report of the tooth fairy actually paying a visit.
It would seem that the layshaft flexing causes the spalling on the gears, and is inevitable.
My 100K+ miles old Bonneville gearbox shows none of this :roll:

So the question is...will the gear fail?
 
After the way I beat them in the 60s I'd have to say they were a good design at the time. As folks have mention the hp went way up. I have little concern for my gearbox as the way I will treat it these days is far kinder.
 
Redline got back to me. I had heard this same thing before but wanted them to confirm it. I have a friend who threw a gearbox bushing into some Redline a couple years back. It is still there and the result seems to be that the bushing is just oil covered, not disolved. Another one for Mythbusters.

Richard,


Thank you for contacting Red Line Oil, the Red Line GL-5 gear oils are certainly not corrosive to brass, bronze or copper, our gear oils will not cause pitting or metal removal. In the Norton Commando transmission I would recommend the ShockProof Heavy, a good choice in those older British bikes offering improved performance and protection as well as reducing the clunk.


Regards, Dave
Red Line Oil
 
Jason Curtiss said:
The car box, as swoosh pointed, out is substantially larger than the AMC box. Therefore car gears are substantially larger than MC gears. This means that the contact stresses are spread over a larger area on the car box, which translates to lower contact stresses between gears. And lower stresses mean less chance of spalling, which is the damage you see in the photo -not brinelling.
Click to expand...
Hi Jason,
That's how it was explained to me also. Spalling similar to the breakup of a concrete roadway, but it's not abrasion. The harder exterior material fractures and separates from the softer core, in pretty big chunks. It's a given. If a design is showing spalling the gear face just isn't wide enough.

The issue of raising the overall gearing has come up before and the feeling was that putting on oversized final drive trans sprockets is asking for trouble. You would think that if the actual ratios between crankshaft and rear wheel were identical in two setups; one with the ratio changed in the primary and one in the final drive that the loading on the gears in the transmission would be the same. But it turns out it's easier on the transmission to spin it faster by using a higher ratio in the primary. The problem is that the only way to do that is with one of the belt drives. Oversized engine sprockets were available once but not anymore.
 
Thanks, Cookie, for posting the definitive response from Redline Tech on gearbox oil. My previous posts on the value of Redline's NF series applies only to synchronizer transmissions, such as in my TR3A, and has nothing to do with corrosion, as it turns out. I found a recent response from Dave of Redline Tech to a Harley forum in which he stated that the NF product line was NOT appropriate to our dog ring transmissions, He recommended Redlines standard GL-5 75W90 product (Harley provides a quart of this oil with all new sportsters). The Redline site unambiguously states that they make NO oils, GL-5 or otherwise, that corrode copper alloy parts below 150C. So, it seems that we have a winner for our classics, Redline's GL-5 ShockProof Heavy. Now to find it locally.

This has been a valuable discussion.
 
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