Moly grease OK on drive shafts? (2 Viewers)

[Hayes]

Is it OK to use moly-fortified grease on the drive shaft splines and u-joints?

I did this last time I had my shafts apart.

Seems like my clunk is back sooner than the last lube.

Hayes

 

[e9999]

can't imagine it matters much on the splines, maybe more on the Ujoints

 

[maximBJ70]

Molly's actually a great choice, reason being is that a layer of molybdium disulphide will always be around so...giver. Best thing to do though is check out an oil/grease manufacturor if you're really concerned. I know ARB requires moly grease for OME bushings because even if all the grease dissipates the moly still sticks around. The only really concern is in hubs were wheel bearing grease (the rd stuff) is really tacky and sticks to everything. Even still though, you can use moly grease and be in good hands. I am not certain about the temp variences for these greases though. This would be worth checking out.

 

[rbpearson4]

can't imagine it matters much on the splines, maybe more on the Ujoints

Molybden disulphide lithium base chasis grease is specified in the repair manual. You can use about any lithium base grease (NLGI No.2). Just make sure not to mix and match grease. Some components of different types of grease can chemically react and cause pre-mature breakdown. If you're not sure of what is in the component, purge the system until the good grease comes out or take it apart and clean all of the old stuff out.

 

[cruiserdan]

An engineer geek friend of mine claims that molly is not a good idea for a high-speed application because it may be possible for the needles to slide as opposed to roll like they are supposed to. Dunno if thats for real or not but I don't argue with him too much......

 

[rbpearson4]

An engineer geek friend of mine claims that molly is not a good idea for a high-speed application because it may be possible for the needles to slide as opposed to roll like they are supposed to. Dunno if thats for real or not but I don't argue with him too much......

When applying/repacking the knuckles with grease, do you remove the cap and pump it full? Looking at the Repair Manual (Maintenance Section), it doesn't specifiy how much to put in.

 

[Ting]

When applying/repacking the knuckles with grease, do you remove the cap and pump it full? Looking at the Repair Manual (Maintenance Section), it doesn't specifiy how much to put in.

You might want to start a new thread to get more attention.

 

[Hayes]

I've heard that too (probably from you ).
Do u-joints count as a high-speed application, though?

Like the ball-bearings in the birfs, the bearings in the u-joint just take up the motion needed to change the vector of the spinning shaft, no?

Not sure, that's why I'm asking about the u-joints.

The slip-yoke splines seem like a perfect candidate for moly.

An engineer geek friend of mine claims that molly is not a good idea for a high-speed application because it may be possible for the needles to slide as opposed to roll like they are supposed to. Dunno if thats for real or not but I don't argue with him too much......

 

[jonheld]

Depends on the amount of moly and the rest of the components in the grease. I had a lengthly discussion with an Amsoil tech about the sliding bearing theory, which can be a reality. I used to use 2 different greases (moly and GP). Now only the Amsoil GHD moly grease for everything.

A previous post mentioned that the chassis service manual specs moly grease. That's true but only for the steering knuckles. All other apps call for GP grease. That said, I use the GHD for all. Makes a great waterproof seal for connectors, makes great thread lube, good in the budoir, pretty good on sandwiches too.

 

[MikePL]

From what I know, moly grease should be used where there is friction/sliding and not rolling. Molybden creates a slick surface so anything that has balls or needles will slide instead of rolling. Sliding balls in bearings become uneven and no longer round so molybden defeats the purpose of rolling bearings.

But in all applications that have sliding bearings (bushings, knuckles, u-joints, driveshafts etc..) moly is the way to go.

The term 'high speed application' is not quite good here as speed doesn't matter but the type of 'work' matters. A driveshaft may spin like hell but the real movement within it is minimum so it's not a high speed application.

To summarize:

Moly is good only where there is sliding, not rolling.

 

[e9999]

IMHO, in the big picture, the type of grease matters less than whether you grease things up enough or not. I would rather have a non-optimum grease and do them every couple of months than using the "perfect" one and do it once every couple of years...

 

[MikePL]

e9999, you are absolutely right. Two thumbs up for you, or even four

But if you have a choice of grease it's even better to know which one goes where.

If I were to save a part on the trail from damage then I would grease it with anything I can... Grease, engine oil, cooking oil, butter, whatever... But in prepared conditions it's always better to hop on a bike and get the right grease than to do a job and finish it by putting the wrong one. The wrong grease won't do immediate harm but it won't help either.