Advice-PROPER way to service rear diff

[RLDSL]

Or get one of these puppies and then you'll never have to pull the stinking cover to change fluid and take a nasty diff fluid bath again and have to scrape all that crud off the gasket surface to get it ready to mount back up. Just open the drain plug and drop it When you consider how short the diff fluid life is if you tow, it's something to consider. Even with the heavy duty Amsoil in mine, under severe service towing, I'm changing at 50k intervals ( it *does* keep the posi clutches acting like new

 

[Wicked97]

Tilting the truck with a jack is unnecessary also. Just fill it and drive it.

 

[riotwarrior]

Ok, never serviced a rear before (lest wise not on a truck.......hehehe)

Want to do mine soon. Watched a bunch of youtube videos and some folks just remove cover, drain, clean cover, seal with RTV and fill.

Some do the above and use carb or brake clean on the gears. Yes/No?

What is the preferred method on our trucks? Can i just use RTV, or is a gasket needed?

BTW I bought the Pennzoil 75-140 synthetic lube and a tube of friction modifier. Is this correct?

Thanks in advance for the pointers..............Frank

Riot warrior- If you help me I am NOT paying you............LoL

Oh why was I not the first to respond...when I read that I burst out loud laughing so hard my dog jumped and wondered WTH was going on....I'll chime in on details shortly!

THAT is EXACTLY why I posted this. I kinda feel that if you do not get ALL of it out it will break down your new lube. However, I am no expert.

What small amount left in the diff is no different than that which is left in a transmission, transfer case, or engine for that matter. Anyway you slice it there is residual oils that mix with the replacement fresh oil in any of the above mentioned parts...diffs inclusive!

I always use a gasket on rear ends, and have never had a leak. Gasket and rtv both sides. maybe its going overboard but my track record for leaks is better then my friends locally who dont want to spend the extra 10 bones.

Gasket or no gasket both work, and if I can get one I prefer one, as it is nice to have! However one caveat I use elephant snot, not RTV

Tilting the truck with a jack is unnecessary also. Just fill it and drive it.

Most of the time this is not needed...most people have enough sense to go and drive slowly and maybe side hill a bit both sides and let oil get down to the bearings and then once back home / shop on flat..check fluid level and top up as required!

Ok so my chime in time...

- Start with visual inspection for issues, pinion seal? Vent tube NOT blocked...bad brake lines...loose ujoints...etc

- Pull all the bolts but one or two top most...loosen them...only

- With catch basin under diff, pry bottom of cover off and let material pour out somewhat controlled into basin...once completely drained, remove upper bolt/s and remove cover.

- once mostly drained, you can get in there with fingers and kinda swipe the oil out of the bottom of diff, get as much as you can out...nothing wrong using some brake clean to wash it all down...nothing wrong at all...maybe even have diff blocked up off ground and turn drive shaft so you can clean all the gear teeth etc...again swipe the oil out with hands...get it out ....as much as you can...

- Take and carefully..watching for sharp burrs...run your hand/fingers around the inside of where the cover bolts on...looking for NUGGETS of RTV that get pushed into bolt holes and hang on in there....get em all out! Don't want that ***** in there when your driving do ya? small bits can be ground up and get caught up in seals....

- Once no NUGGETS ...take brake clean and blow the bolt holes clean...ya...clean!

- Clean gasket surface of diff...this needs to be surgically clean I tell ya....absolutely spotless...no slow weep of oil out a lower bolt hole...if there is..you will never get cover to seal...make sure all oil is out of diff...paper towel or good old feminine napkin or oil sorb sheets...placed in bottom of diff to collect it. Again get it all out.!

- Remove said paper towel shop rag what have you and blast diff cover area again...ensuring bolt holes are clean and NOT leaking...

- Prep diff cover same...remove all RTV and or gasket...clean with brake clean...again SURGICALLY clean...remember we can heal ourselves...trucks cannot!

- go back and check diff...not leaking out of bolt hole...ok...proceed to button it up...

GASKETLESS METHOD

- thin 3/16" dia bead of silicon around diff housing start at top and in ONE continuous bead if possible, go around the diff INSIDE of bolt holes....then once you have an unbroken bead, go and encircle the bolt holes...basically close them up with U around them from bead around bolt hole and back to bead...NO MORE THAN 3/16" dia....

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- Now for me...I usually have an old longer 2" bolt or two floating about with no head on them ...I take and thread these...HOME made guide studs one on each side in diff cover...slide cover over studs and down against diff...thread bolts in all around finger tight....and gently tighten down..not fully tight. remove studs install bolts and gently tighten down....let set for 20-40 minutes... then do final tightening of bolts to torque spec!

- let RTV cure for about another 20 minutes....top up with appropriate gear oil.....use thread sealant on fill plug...NOT Teflon tape...DO NOT USE Teflon tape.

GASKET METHOD

OK so up to this point same prep...

- paint diff housing with thin coating elephant snot...AKA Permatex Aviation Form a Gasket...

- paint diff cover with thin coating elephant snot...

- place gasket on diff cover

- use alignment studs if you have them....bolt down...pull studs...install last two bolts..

- Torque to spec

- Add fluid....and do tipsy thing if you like as above...

These would both work well I've done both, never had a problem what so ever in 30 + years of wrenching!

Now...I'll say this much, these methods are mine and work well and are proven, they may not prove to work for you...why that would be I don't know...

NUMBER ONE RULE Surgically clean

JM2CW

Al

- You can tip axle with jack...seems like lotta work to me...or go find a side hill nearby and drive up and park on it tipping the truck. Then if you like swap ends so truck tips other way....drive home, recheck diff fluid level and top up if needed...

- Check the oil container as it may NOT need a friction modifyer....some don't for posi....some do. Do whats required if you have a posi...add if oil says to. Don't if it says it's not needed.

 

[79jasper]

^^^^^^He knows his stuff. Experience will teach you everything the right way.

 

[jayro88]

^^^^^^^ Good write up. I just did mine about a month ago. I used brake cleaner and just let it dry for a couple of minutes. I used a gasket on mine. The only thing I did different was use RTV also. Put a bead round the rear end (like shown), centered the gasket, put a bead around the cover and torqued it down. No leaks here. I was wondering what gear oil you guys recommend. I looked it up and was told it took 90W. I refilled with 2 bottles of Valvoline Synthetic 75-90w and a 1 bottle of Lucas HD oil stabilizer. What do you think?

 

[Bashby]

Couple things I do different than the above writeup, I find it easier to put the rtv on the diff cover rather than the diff housing, and that looks like the standard rtv black. I prefer the ultra black for most applications.

 

[Dave 001]

You probably have a Ford 10 1/4", however, I'll through this out there anyway......per the Dana manual, if the gasket surface on the cover is flat, use RTV and no gasket. If there are reinforcing ribs from bolt hole to bolt hole, then use a gasket and no RTV. The first picture is a ribbed cover. The second is a flat cover.

Personally when a paper or cork gasket is required I use Permatex #2 or Aviation Formula.

75w-140 is rather thick. 75w-90 or 80w-90 is recommended.

I don't surgically clean the gears with brake cleaner....it's simply not neccessary. You don't drop your oil pan and pull your valve covers to clean the inside of your engine everytime you change the oil. Why get every last trace of the old oil off the gears when the hubs are still filled with old oil. Also brake cleaner will evaporate very quickly when exposed to air but it does not evaporate very well when it runs down between then side gears and the differential housing or the spider gears and the cross pin. It makes lousy lub when it gets left behind in these areas. Obviously you do need to clean the gasket surface with brake cleaner before assembling.

Tilting the axle after refilling is not neccessary since pulling the rear cover will not drain the oil out of the hubs. The only way to drain the oil from the hubs is to pull the axle. (I'm not recommending this as it's simple not neccessary.) Even if you roll the truck over on its side and the axle housing is pointing straight up and down, the oil will not drain out of the hubs. Check out the third picture and you'll see why the oil won't drain from the hub.

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[riotwarrior]

I'm not saying surgically clean the gears....

I AM SAYING.....SURGICALLY CLEAN ALL GASKET SURFACES....my bad for not specifying that...

Al

 

[Black dawg]

You dont have to clean the diff out, but the amount of crud that you can get out of a neglected diff with a can of brake clean makes it well worth the time.

You guys dont service the wheel bearings when you service the diff?

 

[lilredtdi]

Wow Al! That was one heluva post I almost feel like I have to pay or at least tip ya for such through info. I will be tackling this soon and wil try and take pics. Can you be more specific about the elephant snot? I remember back in the day when my Dad had a small engine repair service, we used that Permatex stuff with the indian chief on the bottle. It was a dark brown/black stuff that smelled horrid and if ya got it it on you or your tools it never went away.....Lol BUT, it worked great in concert with a fiber gasket. Is that the same stuff???

 

[riotwarrior]

Wow Al! That was one heluva post I almost feel like I have to pay or at least tip ya for such through info. I will be tackling this soon and wil try and take pics. Can you be more specific about the elephant snot? I remember back in the day when my Dad had a small engine repair service, we used that Permatex stuff with the indian chief on the bottle. It was a dark brown/black stuff that smelled horrid and if ya got it it on you or your tools it never went away.....Lol BUT, it worked great in concert with a fiber gasket. Is that the same stuff???

Thanks...

YuuuuuuuuP same stuff..but likely different brand....

Permatex Aviation Form A Gasket

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Here is the stuff used on a fuel pump block off plate...

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Ya that's some Schticky stuff and get it on clothes...forget it. Not worth while washing it out...work clothes from that point forward!

You guys dont service the wheel bearings when you service the diff?

This is something that's open to discussion, I check the bearings as routine maintenance and look for loose bearings when I jack up and do my visual as I mentioned...able to rotate driveshaft and lube ujoints etc...

If I find that the wheel is loose and needs servicing I do so...and have a procedure for that too!

However I don't have time to write it up at this moment...and one thing that I do some don't...but us OLD school guys do...is pack WB's with Grease!!!!!!!

We had a member here whom serviced bearings on his rear diff and ate the new bearings in no short time because of dry...don't know if packing would have made difference, however at this point I have had ZERO failures to date!

EDIT
OH BTW...

75-140 Synthetic is the specific gear oil for the Sterling rear diff with Posi, not sure about non posi though...and the stuff I have does not need a friction modifyer...most don't now a day they are pretty well balanced for both posi and non posi rears.

JM2CW

Al

 

[jaluhn83]

Honestly it's a fairly simple procedure - no need to over think it.

I personally would use brake cleaner on the inside of the rear cover and all gasket surfaces. Possibly on the inside on the sump if there's lots of goop. I would most definitely *not* use it on the gears. The reason for this is because all the gears and bearings are still going to have a film of oil on them when you drain the diff. This film in turn provides lubrication when you first start it again. Cleaning the gears means you've now lost this and you've got metal on metal until you get good oil circulation again. Probably not that big of a deal, but why risk it? It's the same reason you put assembly lube on a fresh motor.

Also shouldn't be any need to tilt the axle unless you're doing wheel bearings too. The oil that's already in the wheel bearing pocket isn't going anywhere when you drain it.

My preference is to use a gasket with a light coat of #2 pemetex. Cleaner and easier to me.

Also, on the 10.25 axle, the fill plug is on the forward midsection of the pumkin, about halfway up and on the driver's side IIRC. It's a 1/2" drive (might be 3/8) plug and hard to find under the grime typically. On Dana's it on the rear cover.

 

[lilredtdi]

Here is the patient.

Any idea what animal I have from the bolt pattern???

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Let me begin by saying this is my first bigger truck and first ever 4wd. I do do most all of my own maintenance and even most large repairs but I am in NO way a great mechanic and like to ask others advice before tackling things I have never done before. I just finished R/R the head on my 04 TDI, even made a homemade valve spring compressor ( OHV engine) out of plywood, 2x4's, concrete form rod,and black pipe niples and tees. I was also a 63 Bravo during my stint in the ARMY. We worked on vehicles up to 5 tons. Well, not so much worked but were glorified Jiffy Lube mechanics. I have pulled more duals to repack bearings than one should ever have to do. I also am a logical thinker and my main reason for this thread is watching the youtube videos I was at a crux when I saw some using brake kleen on the gear pack. I was not sure if it would do more harm than good. My reasoning was that, if you did not remove it all (brake kleen) it would aid in breaking down the nice fresh lube you just put in.

I also saw some folks using RTV and some using a gasket. I saw you can buy one for our trucks but instead of ordering a $5 gasket and paying shipping or $$$$ in gas to go get one I perhaps could just use RTV which I can get 5 minutes up the street.

This brings me to my next question.

Axles- Are the ones on our trucks like the ole duce 1/2's and AM General's 5 tons the ARMY has??? Can you just remove the entire axel by removing all the fasteners from the center hub and pulling the axel shaft? I will assume yes. Are they hard to put bac in? Or do you just wiggle them till they find home??? If so, do y'all use the old manila folder, ball peen hammer and gasket punch to make your own gasket ? RTV?? I have not even taken one lug nut off of the truck since I have had it. It passed inspection when I got it and the previous owner had just replaced the master cylinder and booster before I bought it so I have not messed with any of the brakes as they work GREAT!!

 

[79jasper]

You are correct on pulling the axle shafts. I've only used gaskets and nothing else, NEVER had one leak again. But you should probably use the stuff riotwarrior was talking about above.

 

[Dave 001]

Permatex Indian Head Shellac......


http://www.permatex.com/products/pr...--indian-head--gasket-shellac-compound-detail

Also good sutff.

I remember back in the day when my Dad had a small engine repair service, we used that Permatex stuff with the indian chief on the bottle.