Driveshaft Lubrication 4wd

[cj80cruiser]

I know this has been covered several times but recently I read that some people are using moly in the slip yoke. I read many years ago that moly is designed for metal parts to slip past one another and not allow them to roll. Which wouldn't wouldn't be good for needle bearings in a ujoint but good for the slip yoke.

However, there is a diagram somewhere on this forum that shows NLGI #2 multi purpose being used in all slip yokes and all Ujoints except the 3 zirks aft the Tcase on a 4wd. In which case moly is used in the latter.

I've been following the diagram against my better judgement but I'm thinking that moly should be used in the slip yokes and multipurpose in all the Ujoints including the ones aft the Tcase. Curious as to what the masses here are doing.

 

[Baja Runner]

I'm a mechanical engineer and I don't fret over things like this... Maybe I need to go back to school but I just use all purpose lithium chassis grease

 

[TheDurk]

I know this has been covered several times but recently I read that some people are using moly in the slip yoke. I read many years ago that moly is designed for metal parts to slip past one another and not allow them to roll. Which wouldn't wouldn't be good for needle bearings in a ujoint but good for the slip yoke.

However, there is a diagram somewhere on this forum that shows NLGI #2 multi purpose being used in all slip yokes and all Ujoints except the 3 zirks aft the Tcase on a 4wd. In which case moly is used in the latter.

I've been following the diagram against my better judgement but I'm thinking that moly should be used in the slip yokes and multipurpose in all the Ujoints including the ones aft the Tcase. Curious as to what the masses here are doing.

I just used moly all around for the first ten years. Then I saw that diagram and the whole rolling/slipping moly discussion and realized that none of it made sense. So I used up my moly and switched to lithium all around. I figure I will be 50% right on all of them in another ten years. At least I grease the dang thing twice a year.

 

[Brilliant]

Its a safe assumption the engineers at Toyota specified it a certain way for a reason.

I am also am an engineer and understand its 2 grease types for some reason. A reason I don't need to understand completely. What I do understand is that the expert on the 4runner driveshaft determined it was 2 grease types.

I have little doubt there was a discussion at Toyota about this very issue. It drove extra complexity into the drawing, the assembly, the maintenance documentation, parts inventory requirements for the model, etc, etc. A company, especially one like Toyota, would not add complexity unless it was required to meet some performance or life threshold.

... off soapbox.

- cheers

 

[TheDurk]

Its a safe assumption the engineers at Toyota specified it a certain way for a reason.

I am also am an engineer and understand its 2 grease types for some reason. A reason I don't need to understand completely. What I do understand is that the expert on the 4runner driveshaft determined it was 2 grease types.

I have little doubt there was a discussion at Toyota about this very issue. It drove extra complexity into the drawing, the assembly, the maintenance documentation, parts inventory requirements for the model, etc, etc. A company, especially one like Toyota, would not add complexity unless it was required to meet some performance or life threshold.

... off soapbox.

- cheers

Probably the same guy who said we had to torque the bolts on the propeller shaft every six months. Almost 13 years and 143,000 miles and I still haven't done it. I can't get a torque wrench on it, I tried.

Several people have posted that their dealers use one type of grease (of varying types).

 

[cj80cruiser]

It seems the lithium grease I used last time wore off pretty quickly and the clunking came back prematurely. It must have been application error on my part since you guys are doing fine running any type of grease in there.

 

[Millerad1651]

I did this yesterday. I too read that you should use two different types of grease. After talking to my dad, he explained that all purpose would work just fine. He said unless the joints create a lot of heat, all purpose would work, so thats what I used. It immediately took the thunk out, and time will tell if it keeps it that way.

 

[Gerdo]

I use moly grease on the slip yokes and regular on the u joints.

 

[Drcoffee]

Probably the same guy who said we had to torque the bolts on the propeller shaft every six months. Almost 13 years and 143,000 miles and I still haven't done it. I can't get a torque wrench on it, I tried.

Several people have posted that their dealers use one type of grease (of varying types).

The Engineer chose the two types of grease and the ATTORNEY added the propeller shaft nuts. CYA

my '99 SR5 has 159k and had not been greased by the PO. When I pumped some new Moly into the slip yoke on Saturday nothing would purge out of the seal. So for the past couple of days I have been spraying WD40 at the seal to help disolve the old crud at the seal opening. 3 days later, I'm finally seeing grease spray on the bottom of the truck which tells me the grease is starting to move again. This weekend, it'll get a few more pumps of Moly until I get the old stuff out. I'm not too excited about dropping the DS to clean it out. Fingers crossed hoping this works.

The U-joints, you should have seen the black crud that came out when I lubed them with Mobil1.

Somethings are so cheap to do as maintenance that if I need two types of grease, sobeit.

 

[Nelsonmd]

I know this has been covered several times but recently I read that some people are using moly in the slip yoke. I read many years ago that moly is designed for metal parts to slip past one another and not allow them to roll. Which wouldn't wouldn't be good for needle bearings in a ujoint but good for the slip yoke.

However, there is a diagram somewhere on this forum that shows NLGI #2 multi purpose being used in all slip yokes and all Ujoints except the 3 zirks aft the Tcase on a 4wd. In which case moly is used in the latter.

I've been following the diagram against my better judgement but I'm thinking that moly should be used in the slip yokes and multipurpose in all the Ujoints including the ones aft the Tcase. Curious as to what the masses here are doing.

I actually did a stupid amount of research on this topic and posted my summary here:

http://www.toyota-4runner.org/3rd-gen-t4rs/97006-drive-prop-shaft-greasing-guide.html

Toyota is inconsistent in what they specified. Toyota dealerships are inconsistent as well; it seems they typically only use 1 type of grease, probably MP. And there is a pretty good record out there of people using Moly grease in high speed bearings.

Its a safe assumption the engineers at Toyota specified it a certain way for a reason.

I am also am an engineer and understand its 2 grease types for some reason. A reason I don't need to understand completely. What I do understand is that the expert on the 4runner driveshaft determined it was 2 grease types.

I have little doubt there was a discussion at Toyota about this very issue. It drove extra complexity into the drawing, the assembly, the maintenance documentation, parts inventory requirements for the model, etc, etc. A company, especially one like Toyota, would not add complexity unless it was required to meet some performance or life threshold.

... off soapbox.

- cheers

Automotive engineer here; I used to think this way too, until I started working more closely with the car companies. They have not thought through every little detail of the vehicle the way we think they have. I think it is completely reasonable to believe that they specified different greases, but didn't really understand why they specified them. They do that kind of thing all the time.

Here's the conversation they probably had at Toyota... "Hey engineer, you need to specify a grease for the service manual." "Oh, uh, I used Moly grease in my testing..." "That's more expensive, is regular grease sufficient?" "Uh, probably, but I don't know for sure because I only used moly grease in my tests..." "Oh, well we better specify moly grease then."

Then a year or 2 later: "Hey, why do we specify Moly grease for the slip yokes? It's more expensive, we could save money be specifying regular grease" "Uh, I don't know, the guy that did the testing on this works for Honda now" "well shoot. We really want to reduce cost here. Can you see a reason not the use regular grease?" "No, but VW and Honda both specify regular grease in their's" "Oh, well then it's probably fine. Done and done, we just saved $30k per year. Bonus for us!!!"

Trust me, those kinds of conversations happen. I have heard them. I have been in them. It's engineering judgement, and there is no way around it.

 

[LittleCaesar]

+1 with Gerdo. I have been fine with that set up since 2009.

 

[Dagobah]

FWIW, I just went to a dealership two weeks ago to get a bunch of free maintenance (shh, my buddy is a lube tech there), and I asked to have everything freshly lubed since I was getting the unload "clunk" upon breaking to a full stop. I stood there and watched the whole process and while I didn't think to ask what grease he was using, it was pink, and he ran it through every fitting along the driveline.
(I know less than nothing about axle grease)

 

[Gerdo]

I can tell you that the LC guys have driveshaft thud, clunk or whatever you want to call it. They use Moly grease in the slip yokes to minimize and/or eliminate it.

Do a search over on ih8mud.

 

[Dagobah]

Oh, the clunk is gone now, I could tell from what came out of the joints that it had needed greasing for a long time.

 

[Blanco]

I used MP all around on my last lube and all is nice. I have a brand new tube of moly but only one grease gun so I got lazy. I too have read all the threads around on this subject and could not find one convincing argument either way so, I'll likely continue to use MP unless I find a problem...or buy another grease gun : )

 

[TheDurk]

I use moly grease on the slip yokes and regular on the u joints.

I can tell you that the LC guys have driveshaft thud, clunk or whatever you want to call it. They use Moly grease in the slip yokes to minimize and/or eliminate it.

Do a search over on ih8mud.

But the Toyota engineers specified MP for our slip yokes. They only put moly in the double-cardan joints. MP in the rest. This is my big problem. If their spec made sense, I'd follow it.

My respect for engineers is not as high as some. For part of my career I was a utility management auditor. I was on the audit team that found that engineers had speced that half of Diablo Canyon nuclear plant be built backwards, and the company was in the process of doing it. That was just one, but admittedly the biggest engineering boo-boo I saw.

If I were to use two types, I'd do it Gerdo's way and ignore Toyota. Here's the famous TSB:

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyYXlkb3VibGUzNjB8Z3g6Mzc0MzcxMDU1ZTY4NjlhZQ

But the '99 Owner's manual, which predates the TSB says #2 in the spiders and moly in the slips and double-cardan. See p.208 here: https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyYXlkb3VibGUzNjB8Z3g6MmExYjU0ZTQ3MjJkMWU3YQSo we have three ways of using two types.

a) Gerdo's way: moly in the slips only.
b) Toyota pre-TSB: moly in slips and double cardan.
c) Toyota post TSB: moly only in the double-cardan.

and two ways of using one type:

d) all moly
e) no moly, just MP.



Matt--want to give us the thought process on the TSB change?

And, to top it all off, the 2002 owner's Manual, published well after the TSB, keeps the same spec as in '99, again p.208 https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyYXlkb3VibGUzNjB8Z3g6NjhiNDY0OGFjNGQ2Yjc1MQ

 

[Nelsonmd]

Matt--want to give us the thought process on the TSB change?

And, to top it all off, the 2002 owner's Manual, published well after the TSB, keeps the same spec as in '99, again p.208 https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxyYXlkb3VibGUzNjB8Z3g6NjhiNDY0OGFjNGQ2Yjc1MQ

Honestly, this is the point that confuses the heck out of me. The only thing I can think of is that they found a reason to issue the TSB (maybe due to warranty returns, or assuming that owners aren't going to obey the greasing intervals, or latent failures in one of the DS components), then forgot to include that update in the 2002 update of the FSM. But to that point, why would they update the FSM in the last year of the design cycle? I don't know, it confuses me.

I still fall back on my original conclusion after writing that grease page. If you are going to re-grease regularly, it doesn't matter. If you are forgetful and might let it go 50k without greasing, use moly.

 

[TheDurk]

I still fall back on my original conclusion after writing that grease page. If you are going to re-grease regularly, it doesn't matter. If you are forgetful and might let it go 50k without greasing, use moly.

This was my initial logic. I decided all moly was better than all MP because it cost more. I applied the old rule of "Who can do more, can do less". Then I did read that moly is indeed BAD for needle bearings in drivelines. So I switched to all MP, secure in that regular greasings would cover me (I grease twice a year and drive 12-15k).

I just was not going to use a 3rd grease gun. (My existing second gun is for the big tractor and bushhog, and is a big, really fast long armed pump that won't fit underneath the 4Runner. So I'd need two with a hose and short pump handle.)

 

[cj80cruiser]

I can tell you that the LC guys have driveshaft thud, clunk or whatever you want to call it. They use Moly grease in the slip yokes to minimize and/or eliminate it.

Do a search over on ih8mud.

Exactly why using moly in the DC end of my rear driveshaft and not in the slip yokes was against my better judgement. Ive been doing it the way you describe in my LC for years.

I didnt understand why the 4runner was different.

 

[Nelsonmd]

You got a reference for the moly being bad for needle bearings and driveline? If it's legit I'll add it to my grease thread.