Lock lube, snake oil?

I think we are in danger of violently agreeing. I agree, the dimple key is particularly prone to getting blocked by debris bonded by the surface tension of liquid lubricants. Nylon rowlocks respond well to water lubrication, at least in part because of the low elastic modulus of nylon. In my biking days, some 40 years ago, the preferred chain lubricant was Lynklife, a very waxy grease which you cooked on a stove, then immersed the chain. This was very good at displacing any moisture, and filled the clearance with something not too sticky, which did not collect too much road dirt. I believe modern chains and lubricants are rather more clever.

At the risk of stating the blindingly obvious, one of the reasons that simple unrefined mineral oils are so good in general is that they contain fatty acids which provide really good boundary lubricants to both iron and copper alloys. So that even if life gets hard, because the oil attracts sand or other similar contaminants, the lubrication is usually better than it would be otherwise.

Hehe.

Ok.

I think we also got some lube that was supposed to be good but safe with nylon but I can't remember what it was.

I've still got my tin (and contents). ;-)

Yes, once cooled it left a fairly waxy finish.

Yes, 'O' and 'X' ring motorcycle chains are supposed to have their pins lubes for life but you still need to lubricate the rollers on the sprockets. The best for that was my old MZ ETZ 251 where the chain was

100% encased and because of how well they could be lubed and much of the cr*p was kept off, they (and the sprockets) would generally last for years. The Old C50/70/90 were similar but not quite as well 'sealed' if I remember correctly.

Not obvious to me so thanks for that. ;-)

Understood.

Cheers, T i m

Chaincases were the answer, I remember riding a Venom from London to Buxton in heavy rain all the way in the late 60's. Started off with a properly adjusted chain, arrived with at least four inches of movement.

I had an MZ 250 with the leading link fork as a "town" bike for a while in the 70's.

but shaft drive is best.

I think it has it's advantages to be sure (and why 3 of our bikes are shafties) but it also brings with it added complexity and another fairly complex point of failure (as anyone who has had a bevel-box, rear wheel bearing or uj go will confirm).

I got my first shaft drive bike *because* of what I mention above. Uncle took on Dads Lambretta LD150 (shaft drive scooter) and a rear wheel bearing went. He was warming the final drive casing with a blowlamp and a neighbour went and got his blowlamp at 'help' and melted the rear (ally) casing. Uncle dragged the scooter back into the shed and that's where it stayed for the next 5 years. I finally managed to convince him to let me have it when I was 15 and (long short), got a replacement rear end off a mate at college and got it back on the road. ;-)

The smallest shaft driven motorbike bike I've ever had was a Yamaha T80 step through (like a Honda 90 Townmate) but that wasn't such a good solution as on the BMW's as with the BM's the engine was already 'in line', so you only needed one bevel box.

And then you have the issue (as I did on my R100RT) of the (dry) clutch splines wearing away prematurely (35k miles) and having to be AA'd 175 miles home on the first day of a 2 week motorcycle / camping holiday. ;-(

Cheers, T i m

remarkable when you consider how long it has been about (100 years or so) that it is not yet perfect.

Less efficient, though.

only when chains are perfect, as time and wear take hold the efficiency goes down, and the cost benefits of shaft become apparent. I sold thousands of chain and sprocket sets (many of which were in the 200 quid area in the 80s), but never even a single shaft drive component, even though there were many shaft drive Suzukis that came through our shop, including several 650gts that were used for courier work and clocked up

150k plus.

Nissan Leaf has been having problems with hub spline wear. Have to remove drive shafts from hub and re-lube every now and then.

Interesting. Do you know what lubricant is recommended? (I would go for something with a high Moly Disulphide content).

Surely there should be/is no movement that on hub splines? Hub nuts are done up very tight to prevent any movement. Or is there some strange new design being used? Axial movement on drive shafts is taken up in the cv joints.

This is what some recommend for the old Airhead motorcycle clutch splines:

(Which is indeed a Moly mix). ;-)

Cheers, T i m

It's called fretting. "Normal" drive shaft splines are "parallel", this means that there must be some torsional clearance otherwise you would not be able to assemble them (OK you could make them a drive fit, but you don't). So even if they are bolted up tight axially, there is still scope for some torsional vibration leading to normal impacting of the drive faces. That sort of contact gives you quite similar "fretting" to that which you will also be familiar with in tight sliding contacts, for example things like exhaust clamps, you can also get it between ball bearing races and the shafts or housings.

You can also make tapered, or conical, splines and you would normally bolt them up tight in the axial direction. But, there is still scope for microscopic sliding in service as the structures flex under load.

In most common examples of splines (for example clutch plates) fretting is kept to acceptable levels by good geometric design, plus use of hardened steels, often without lubrication. But wipe a bit of tissue down the splines of a used one and you will get some fine black or brown debris, sometimes called "cocoa" in the trade.

Perhaps with electric drive there are relatively high frequency fluctuations in torque, hence in the nominal contact load between the parts. Maybe any fluctuations from IC engines are more effectively damped by the clutch and/or the gearbox lubricant.

I'm trying to think where else I've seen fretting in automotive parts (it's been a long time since I did much serious spanner work). I think I have probably seen it in places like fans, alternator pulleys, and associated threaded joints. With incorrect design or assembly, fretting can remove material at a remarkable rate, and sometimes in strange ways. I'll see if I can find any images (but most of the examples which come to mind are not currently digitised).

Good old Molykote, I think I still have a small pot in my workshop! Rocol products are also good.

My Austin 1800 (landcrab) stripped the splines in a front hub twice. Despite the splines on the driveshaft looking perfect. After the second time, I bought a complete assembly used from a breaker's yard. Not sure how long that lasted, as I sold the car shortly afterwards.

To be fair to the car it got thrashed with no mercy. ;-)

It sounds like there is something seriously wrong with the design spec of the leaf shafts: "On another note they still haven't managed to fix the clicking from the front end of the car, opinions seem to vary between brakes and driveshafts. It has now had more grease applied to the driveshafts than the Queen Mary's anchor chain, latest grease is £340/Kg as well!. Brakes were stripped and cleaned too but the noise is still there. This is five times it has been in to rectify this and at least twice I have been assured it had been rectified. The first time they told me it had been fixed I didn't even need to drive it more that 8' to determine it was still there so I drove out in the loaner AGAIN. If I thought the range when driving the car was bad it is nothing compared to when the Technicians are driving it, make of that what you will."

and that is just one of many. The only time I have ever heard noises from drive shafts is when the hub nut is loose, Metros particularly suffered from that, but it was nothing to do with lack of grease, just loose hub nut/washer, if they were correctly tightened with a new nut and a new washer (both lubricated at assembly and correctly torqued they never had the problem again.

Anything sliding is obviously very different, but that does not apply to drive shafts.

Fretting can only occur where there is movement.

Agreed. Something not right.

Remember, the reason we have splines is that it is normally not possible to secure a shaft in a bush just by tightening the nut on the end, except in the special case of things like Morse Tapers, and for these you don't even need the nut.

I agree, "clicking" does imply something not tightened properly

Yes, BUT no material is perfectly rigid. You don't normally notice movement from elastic deformation except in components like leaf or coil springs. Once you apply stress to steel parts, they deform following Hooke's law. It's very interesting to look at finite element stress analysis computer models where people sometimes multiply the deflections by (say) a factor of 100 or more, to help the designers to visualise exactly where movement is occuring. In the case of splines, the applied torque means that both the male and female splines bend very slightly (they are actually short, very stocky beams) and this means there is sliding between the male and female drive faces.

On rolling element bearings, you will sometimes find brown patches, usually sharply delineated, on the radial seating faces. These occur when there is in-service "slip" over part but not all of the contact surface, between the race and the shaft or the housing.

Apologies for the lecture!

In that case, why doesn't every modern ford engine have the cam timing go out on a regular basis?

Sorry, you will have to explain the geometry to me. Are you saying that it relies on a nut on the end of the camshaft pulling a step on the camshaft on to an axial face on the drive pulley (or something equivalent?)

Perhaps I oversimplified. Obviously, there is *some* torque level which can be sustained without slipping with that geometry, and I guess that torques on camshafts don't match those on crankshafts and driveshafts, where you typically have splines or keys. I would still maintain, that in principle, that is not a good way to transmit torque (unless of course you want something which will slip on overload). There may be good production engineering reasons why Ford build it that way and obviously, since it works, it is good enough.

Are you sure that the Ford doesn't have a slight (matching) taper on the camshaft and the pulley? That is the relatively easy way to make a strong (but easily released) frictional joint which is actuated by axial load (like a Morse Taper).