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Topic: Rear Axle Oil (Read 744 times) previous topic - next topic

Rear Axle Oil

Hello everyone,
Was looking to have a swap change out my rear axle oil for Amsoil 75W140 severe gear that I have sitting here.  They mentioned on the phone to ensure compatibility with what's there, otherwise they would pull the hubs to ensure all the old oil got drained.  So my questions are:

1) are we sure that 75W140 oil is what is in there?  Amsoil claims mixing is fine but it reduces service interval.  I would just want to have a sort of reasonable assurance that the same weight is in there and it looks to be the case based on other forum posts.
2) When you guys do the service, do you pull the drain plug only or do you pull the rear axles?
3) Folks who switched to synthetic without draining the hubs - any issues?

What started this is a slight but perceptible vibration at 45-50mph which isn't present at higher or lower speeds.  We ran over some mostly plastic accident debris on the last trip but I am heavily leaning towards it being a u joint issue, especially considering I haven't maintained them properly.  I figure if I'm going to get trained eyes on the drive shaft I might as well get the gear oil done while I am in there as I've been carrying it around without doing the job!

Re: Rear Axle Oil

Reply #1 –
1. With the age of your coach the PO could have changed out OEM so what is in there would just be a WAG for me.
2. Drain plug 
2a.  (hope you ment pulling the axles and not just the wheels)
3. No

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Rear Axle Oil

Reply #3 –
I know of several coaches that have changed to synthetic (not all Amsoil though) and all that was done was drained through the drain plug.

Doing this change did result in a slight increase in our fuel mileage. We also run synthetic in the front wheel bearing hubs.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Rear Axle Oil

Reply #4 –
From my experience it will be a u joint.. The small amount of oil in the axel housing, to lube outer axel bearings is not very much, the effort to remove axels and possible seal damage dragging the axels in and out isn't worth the time or expense in my opinion.
Check the ujoint caps and see if they have been turning ... also if the joints have two grease nipples , BE Sure you grease them both ... only grease till a very small amount of grease appears at the seals. You can actually hear the grease make a small noise when the seal just starts to expand..I am careful that I don't stretch the seals...

Hope this helps.

Dave
2001 U320 40ft
Build #5867
2003 Tracker
VE7DOD

Re: Rear Axle Oil

Reply #5 –
Quote from: Dave Dunington –
From my experience it will be a u joint.. The small amount of oil in the axel housing, to lube outer axel bearings is not very much, the effort to remove axels and possible seal damage dragging the axels in and out isn't worth the time or expense in my opinion.
Check the ujoint caps and see if they have been turning ... also if the joints have two grease nipples , BE Sure you grease them both ... only grease till a very small amount of grease appears at the seals. You can actually hear the grease make a small noise when the seal just starts to expand..I am careful that I don't stretch the seals...

Hope this helps.

Dave

So the u joint is (potentially) salvageable with just grease?  That would really surprise me.  I guess it makes sense though if it's just binding up on dry grease and the rollers aren't obliterated.

Re: Rear Axle Oil

Reply #6 –
Would surprise me too but try it.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Rear Axle Oil

Reply #7 –
Actually, the two U joint grease zirks go to EXACTLY THE SAME "CENTER OF CROSS" PLACE.

There are two because one is generally easier to access.  Grease either.  Sure, you can grease both, but same result.

And, better if you grease until new, CLEAN grease comes out at all four grease cups.  Then wipe off excess.

And, agree, I would NOT pull axles when changing rear axle oil.  If really anal about it, after removing plug, lift each side one at a time.  That will allow a little more to drain from the sides.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Rear Axle Oil

Reply #8 –
With your coach being a 42' you have the long driveshaft but you still have the slip joint that needs to be greased while you are under there.  If this is neglected it can also cause a shaking/vibration.

Mike

Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Rear Axle Oil

Reply #9 –
Grease the drive shaft and look for a dent ..

AS far as the axle oil, some guys drive in a few circles to get the oil mixed at the hubs.

Re: Rear Axle Oil

Reply #10 –
Any visible red dust is a bad sign for U joints. I carefully rotated the driveshaft so I could access both of the Zerk (aka Alemite) fittings but totally unnecessary as the grease goes to the center as Brett points out. Yes, another on the slip joint.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Rear Axle Oil

Reply #11 –
I too replaced rear axle oil with Amsoil synthetic about 8 yrs ago. I am sure I used 80/140 though and just drained the oil from plug. No issues but it did stop a faint whine in axle gears so happy camper. I like some others use Amoil in every location, yes even Allison with Torque Drive. Way better than Transynd and it has been in there for at least 6 yrs (replaced with new of course) contrary to what the Chevron oil expert said, and not one issue except slightly cooler temp in tranny.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Rear Axle Oil

Reply #12 –
Thanks for all the advice guys.  I have an 8am appointment at a truck shop here in New Bern, NC that has good reviews.  The guy on the phone sounded extremely knowledgeable and said that he has many sizes and types of u joints in stock if it comes to that.  Looking at the photos of bad u joints it looks somewhere in the middle.  There is an ever so slightly rust color (but not dust) to the entire u joint as well as black grease residue at the caps.  It definitely looks good.  Wish I had a way to air up the coach before starting out tomorrow so I didn't drive the neighbors nuts.  My understanding of the joints is like what Brett said.  There are no seals so you grease it until all old grease/residue is expelled.  Maybe I have that wrong, but I suspect that's how they'll grease it.  I would do it myself but I didn't bring my grease gun.

Re: Rear Axle Oil

Reply #13 –
[quote author=Mark D
 I am heavily leaning towards it being a u joint issue, especially considering I haven't maintained them properly.  I figure if I'm going to get trained eyes on the drive shaft
[/quote]

I have made it a habit of greasing my U-joints halfway between the engine oil change interval, especially if I have been running in wet road conditions.

Doug W.
96 36' U270 CSGI #4946
04 Toyota Tacoma 4x4
PNW
 

Re: Rear Axle Oil

Reply #14 –
Quote from: Doug W. –
[quote author=Mark D
 I am heavily leaning towards it being a u joint issue, especially considering I haven't maintained them properly.  I figure if I'm going to get trained eyes on the drive shaft


I have made it a habit of greasing my U-joints halfway between the engine oil change interval, especially if I have been running in wet road conditions.



Believe me, I won't forget again ;)