New M923a1 owner. All help appreciated.

[absolutemoon]

Good morning everyone, Well I can tell ya, I have spent a lot of hours reading through these threads and have gained a lot of knowledge doing so. So, for that, Thank you to all who take the time to give such insightful answers for all of us who need help. So here goes: I am the proud owner of a 83 M923a1 and it is a match made in heaven. My kids and I have had a blast cruising the streets until yesterday. The drivers side axle boot has split and the grease is running out. Now I have already downloaded the TM for removal/replacement but the thing I am having difficulty with is deciphering which grease to add back. I will be using the zipper style replacement and RTV for sealant. Question is how do I regrease and what type to use?

Thanks in advance. Bryan

 

[Coffey1]

Welcome to the M923 club. I have a 1984 M923 .
It's a fun truck if you need anything don't hesitate to ask.

 

[brasco]

Bryan,

Welcome to Steel Soldiers. I assume you are talking about the steering knuckle boot. I had one tear when I first got me M925A2 and had the same questions. After doing a lot of research, I started using Valvoline Cerulean grease. See my post #74 at http://www.steelsoldiers.com/showthread.php?1936-GAA-Grease/page8 Most people seem to just use a good commercial grease from the local auto parts store.

You really don't need to pack grease back into to boot. The grease is just what squeezes out of the upper and lower bearig pivot points. You can see the grease zerks on the top and bottoms of the knuckle. Squeeze some grease in there with the boot off and you will see what I mean.

I think the boot on my truck actually tore becaue it had too much grease in it and was driven while really cold - we picked it up in Little Falls, MN. The grease was probably too stiff to move and tore the rubber boot.

PM me if you have any other questions.

Don

P.S... you really do need three hands to get the zipper boots back on! I struggled for hours until I could get my brother to help and it went right on after he held one side.

 

[absolutemoon]

Thanks Coffey1

 

[absolutemoon]

Don, I appreciate the heads up. This will be the first repair for me with this rig. I'll update when she is back in order.

 

[Another Ahab]

Hey sorry about the breakdown, and hope she's up and running again chop-chop.

And welcome from Virginia!

 

[Capehenery]

Welcome from Virginia Beach. Good luck with the boot.

 

[R Racing]

Welcome aboard. What part of MD are you from?

 

[absolutemoon]

eastern shore

 

[Another Ahab]

eastern shore

Lot of territory:

- Trappe?

- Salisbury?

 

[73m819]

The knuckle is GREASED by TWO fittings that are in the knuckle NOT the upper and lower king pins, turn the wheel all the way then look for a plug, REMOVE the plug, turn the wheel the other way, remove the plug, install a grease fitting, fill till grease comes out the other hole, remove the fitting, install the plugs, do the other side. The grease lubes the ball and socket axle coupling NOT a U joint.

The real trick fix is to redo the axle coupling to a GREASEABLE U joint. This along with some trick seals will eliminate the boot.

Installing the boot is not that hard, EVERYTHING CLEAN AND DRY helps a lot,

 

[Artisan]

When you do your boots, only do one at a time so you have
a reference to look at IF it was installed right to begin with.
It is a little tricky but the TM does a good job
of telling you how to do it. Once the light comes on
and you realize how it is supposed to work you will
have it done in no time. CleanCleanClean everything IMO.

Get all that old grease out of there...do not repack it w/ grease.
You only grease the upper and lower knuckle zerts and there
is probably one zert buried in there for the Cardon Joint
and YOU DO want to give it a squirt, read the TM to verify
all I say and what others say.

PS, you can drive the truck that way, just don't go muddin'
or down dirt roads to keep rocks out.

I suggest you do them both, get it over with.

I recently started using Kendall L-427 Blu grease. I found where
to buy it cheap and I believe it meets all requirements for a
Lithium NLGI-2 type of grease. I was looking for a disc brake wheel bearing
grease and I believe I am correct in saying it is OK for most
all GAA type use.

It would be great if a grease guru researched it and approved it for us!

 

[Artisan]

The knuckle is GREASED by TWO fittings that are in the knuckle NOT the upper and lower king pins, turn the wheel all the way then look for a plug, REMOVE the plug, turn the wheel the other way, remove the plug, install a grease fitting, fill till grease comes out the other hole, remove the fitting, install the plugs, do the other side. The grease lubes the ball and socket axle coupling NOT a U joint.
The real trick fix is to redo the axle coupling to a GREASEABLE U joint. This along with some trick seals will eliminate the boot.

Boy I would LOVE a pictorial on that!

 

[73m819]

Bryan,

Welcome to Steel Soldiers. I assume you are talking about the steering knuckle boot. I had one tear when I first got me M925A2 and had the same questions. After doing a lot of research, I started using Valvoline Cerulean grease. See my post #74 at http://www.steelsoldiers.com/showthread.php?1936-GAA-Grease/page8 Most people seem to just use a good commercial grease from the local auto parts store.

You really don't need to pack grease back into to boot. The grease is just what squeezes out of the upper and lower bearig pivot points. You can see the grease zerks on the top and bottoms of the knuckle. Squeeze some grease in there with the boot off and you will see what I mean.

I think the boot on my truck actually tore becaue it had too much grease in it and was driven while really cold - we picked it up in Little Falls, MN. The grease was probably too stiff to move and tore the rubber boot.

PM me if you have any other questions.

Don

P.S... you really do need three hands to get the zipper boots back on! I struggled for hours until I could get my brother to help and it went right on after he held one side.

Not sure WHERE you got this INFO but I would SUGGEST that you READ the -12

 

[73m819]

boy i would love a pictorial on that!

-12

 

[absolutemoon]

Thanks for the info. Are you telling me I sat and looked at that giant piece of steel all day thinking I couldn't drive her the way she is?

 

[absolutemoon]

Ron, Please clarify. If I am reading your post correctly, you seem to be disagreeing with not packing the boot with grease again. Tell me what your thinkin please. B

 

[brasco]

Ron, Please clarify. If I am reading your post correctly, you seem to be disagreeing with not packing the boot with grease again. Tell me what your thinkin please. B

Bryan,

I think Ron is technically correct that the LO says to add grease to the knuckles via the plugs. However, I have't seen the procedure that Ron decribes (perhaps it is implied) and I'm not sure what the ball and socket axle coupling is that he is referencing. This may be a opportunity for me to learn something new too since I haven't had the whole axle apart yet. I would like see what it is if Ron can attached a reference or picture.

The point I was trying to make was that the extra grease pumped into upper and lower king pins will make its way into the same cavity enclosed by the boots so you don't need to pack grease back in - it fills up as you add grease to the king pins. Ron and others may disagree on this point. In my case, the knuckle was packed with a ton of old-stiff grease that appears to have caused the boot to rupture when cold. This is the main reason I don't re-pack mine full of grease -plus there doesn't appear to be anything in the immeidate area that needs to be packed with grease.

Having said all of the above, It's also important to note that I'm only referencing the immediate boot area. There IS a procedure to maintenace the front axle and u-joint from the outboard side. This procedure does say to pack the knuckle cavity with grease so you probably can't go wrong with adding grease. My question would be how much is too much? Maybe others can chime in an give some advice.

Don

 

[73m819]

The joint is a constant velocity coupling,

Yes OLD grease will get hard at times, that is WHY you keep fresh grease in the knuckle, that is also Why the old boot is R/R and the knuckle IS cleaned and dried, at this time you check the axle seals for leaks, bits of metal in the knuckle ect.

Please REMEMBER there is a WHOLE series of TMs that cover these trucks, not just the -10, For the 939 series truck, you WANT the 9-2320-272-xx series TMs.

 

[brasco]

The joint is a constant velocity coupling,

Yes OLD grease will get hard at times, that is WHY you keep fresh grease in the knuckle, that is also Why the old boot is R/R and the knuckle IS cleaned and dried, at this time you check the axle seals for leaks, bits of metal in the knuckle ect.

Please REMEMBER there is a WHOLE series of TMs that cover these trucks, not just the -10, For the 939 series truck, you WANT the 9-2320-272-xx series TMs.

Great discussion Ron.. I did more reading this morning and I think older trucks used some kind of ball joint that required them to be bathed in grease. The newer M939 trucks appear to have CV joints. The parts manual -24P shows only CV joints but the maintenance manual -24 shows both universal joint and CV joints noting that CV joints were the "new" configuration. As state before, I haven't had my entire assembly apart from the outboard side to see what exacly is in there but I think is has CV joints. I don't know if the CV joints are even servicable with grease and it's not clear that packing the knuckle with grease will do anything for them.

I agree with you on cleaning out all the old grease. The grease in mine was gritty and dirty so I cleaned out all I could get to.

This gets us back to Bryan's original question about repacking with grease - it sounds like was going to repack. But, do you really need to pack it full with grease if you have CV joints (or even U-joints)? My view on this is to "do no harm" and I think more harm will come from putting in too much rather than too little. This is based on my personal experiece with too much grease jammed into the knuckle.

The best solution for a M923A1 is probably to repair the boot now and put in whatever amout of grease you are comforable with. You probably can't clean out all the old grease anyway. You can then service the knuckle from the outboard side when able. At that time, the remainder of the knuckle can be cleaned out and you can determine what joint is in there and exacly where the grease is going and what it is doing.

I would love to see pics of a M939A2 knuckle from the outboard side if someone has them to share.