The Stovebolt Site Forums The Parking Lot Big Bolts T170 2speed rear axle fluid questions?

So I'm cleaning up the "new" 2 speed rear axle for my dump truck and figured I'd change the gear lube and I also noticed the eaton high/low 12v selector has a oil reservoir for itself. What gear lube should I put in the diff? the selector says sae10 on it but is there a specific lube for these things?

Also what is the actual way to drain the diff lube to refill? Since I have axle off truck I'm gonna just spin the axle to where the fill plug is down and drain it like that for now but later on down the road when I want to change it again and its mounted to truck. do I just take the lower bolt out of front and it drains like that or do I have to pull the whole gear plate off front of diff and reseal it everytime fluid gets changed? And if that's the case most rear ends like this probably have the original gear lube in them cuz that would be a pain to do every 50k miles or when ever you changed it.

Thanks mike

I believe the lower bolts are the drains, don't know about the selector. If it says sae 10 however, I think 10 weight engine oil would be fine. Anyone else who actually knows for sure?

Isn't the selector lubed by splash?

Ed

Here's the info I got from it....

Mike,

The lower cover screws are the drain holes, but if it were me I'd remove the rear cover and clean the old gunk out...there may be chunks of metal in there.

Mike B

Forgot to say, I use 1 in One Oil in my Eaton Electric Shift motor. I believe it's 20w oil, but it works for me. I've put 30k miles on my fire engine that has a 2-speed Eaton...

Mike B

Well my axle is a GM t170 so the back cover is solid which threw me off but I looked them up and they are made like that so it wasn't some crazy hillbilly with a welder haha... but if I were to do that I'd have to take the whole (center)gear section out the front. What's the correct term for that section? But I'm not really wanting to do that but if when I drain it and there is some chunks and/or metal shaving in the gear lube maybe I'll take it off and check things out.

And yeah the high/low selector has the eaton logo stamped in it so maybe that selector isn't original, idk much about the two speed rears other then splitting gears, and fortunately for me it will also give me a 5-8mph top speed gain according to the calculator on the spicer website. And this axle has the dayton style rims which are tire shop serviceable so that saves me a lot on rims/ tires cuz these tires also have decent tread on them.

Glovebox codes...

Here is the gm code on the center section with a eaton selector.... is this normal? One thing I've been wondering will my old h150 axle center section 7.20 gear ratio fit in this axle center area? I'm not expecting to ever change back to a single speed but if I get metal oatmeal back there I'll have no choice. And having the spare parts would be great or should I sell that section if no fit. since the axle housing is ruined due to the right spindle threads are stripped might as well part it out right...

One other thing I have been thinking about when I put it back on my truck, should I put a piece of inner tube between the axle and the bracket as a gasket/spacer/bushing type thing so this wear doesn't get worse... I'm planning to paint it all up nice before installing. And my sandblasting really dug out the corroded metal from the metal2metal from u-bolt bracket to axle so realized I should probably take some sort of action, what do you think?

You do not what any gasket or rubber at the U-bolts connection, it could crush and squeeze out over time leaving the connection loose and dangerous. The corosion you have was due to road salt over many years. Paint the area with your favorite rust preventing paint and torque the new U-bolts to spec and call it done.

Mike B

Ok so I was thinking that it would eventually crush as well but just wanted to see if anyone has tried to figure something out for this issue. Cuz I didn't really wanna just put it back on in the same pitted spot. How thick is the walls of these axles? And I guess to try to keep the salt outta that area would it be ok to put some sort of gasket sealant on the clamp bracket so that the crevice between there is already filled with a material so new road salt doesn't get in my fresh paint job and corrode ? Kinda like a oil seal but a corrosive road salt seal in my case...

Did you clean up the bottom of the rear end good. It seems to me there is a plug at the bottom to drain it. If the center section is held on with bolts & not studs/nuts it might drain through the lower bolt. The electric shift uses 10W oil up to the level of the plug. Those shift a lot better then the vacuum shifters.
George

Well there she is, oh black Betty "bam ba lam" whoa black Betty "bam ba lam" hope she's still rock steady!!! Haha my rear end overhaul remix. But never mind my last thought of the gasket sealant to seal off that junk collection pocket.... what if once I mount axle and tighten u bolts to spec, if I just slapped a glob of wheel bearing grease to fill in that area so water and road dust gets deflected by outer grease layer so it can't penetrate that pocket????? Other wise only way to keep stuff out would be to spray gunk out of there once a month and who has time for that!!! Lol

How do you drain oil from high low selector? Take off the triangle thing on bottom or just one of the 3 bolts holding that on? Or should I just drain it outta the fill hole by rotating the axle then rotate back up to fill? That's probably how I'm gonna do the axle lube...

If it were me, I'd remove the rear cover and make sure everything inside is nice and clean. It will also allow you to see how everything inside works. The three screws on the bottom hold the bottom bearing in place...

As for protecting the axle housing at the spring perches, I think your sand blasting and painting will provide many decades of added life to it. Remember, it took 60 years to get the way it is now and that's with no one caring for it! Don't overthink it...

Mike B

MikeB, do you mean remove the selector and take the back cover off it or are you saying take the back cover off the diff? Because my axle housing is solid on the rear(right pic), only way to open black Betty is the front center gear section(left pic). But if you mean the back cover of the selector? then I misunderstood you before when you said that, I thought you meant the diff. I haven't actually inspected the selector to much I did notice its bolted to the center by 3 bolts and the bottom triangle thing.

And I'll try not to over think it. I'm just thinking I have it off if there is anything I need to do to it, now is the time cuz she ain't coming back off till it falls off lol. hints why I just gave it the fresh paint job, and sandblasted ALL the corroded metal off to just fresh pitted metal. The shackles took quite a bit of sand to blast, the axles metal that corroded off to the shackles was on there good!!! That little $40 craigslist sandblaster has come in handy with my old equipment restorations I've been diving into, it makes me feel good to bring crusty and rusty old stuff back to life.

Sorry for the confusion...I'm talking about the "front" cover on the 2-speed selector motor...the one held on with 6 screws and the little tit on it. No need to remove the selector motor, just take that cover off and inspect everything inside.

The "triangle thing" is the selector shaft bottom bearing retainer.

As for the differential, in my earlier post I thought your rear had a removable cover, that's why I said to remove it. But, since you have a welded on cover there's either a plug in the bottom of the housing or the bottom bolts holding the pumpkin in are removed to drain the fluid out of the rear.

Mike B

Ok glad we cleared the confusion. Haha. The diff lube draining out bottom bolts makes sense so I got that issue figured out now.
So the front plate on the selector, that has the fill plug and the brand stamp comes off to drain oil?

That makes sense I guess but why did manufacturers forget how the oil pan was designed, with a drain plug Haha. Almost all daily driver trucks and SUVs have rear diffs and transmissions with no drain plug and only way to change fluid is to remove pan/plate destroy seals so you have to reseal just to change fluid what a retarded design flaw, causing ppl to neglect their fluid changes because of the hassle manufacturers created. I guess they figured ppl should be checking the internal components but come on how many of us remove our oil pans to check our pistons out while changing our oil.... we just assume by keeping up on our regular fluid changes the internals should be in good shape since were taking care of the internals lube when needed.

One of the bearing screws on the bottom may allow you to drain the 10w oil, but I'd still take the cover off as now is a good time to make sure everything inside looks okay.

You can also test the motor and make sure the limit switches and linkage are all working before you install the rear back on the truck. The motor will have 3-wires (12v)...Ground, High and Low.

Mike B

Gotchya I'll try the lower screws first to see if they drain it. But yeah it probably should be opened up and checked. But yeah I was debating if I should hook that up outta truck and hit the selector button to see if it clicks or whatever it does, to make sure I don't need to do anything else before installing. But one other thing I just noticed about this thread, nobody has said the best type of gear lube to put in the diff? I got the 20w engine oil for the selector motor...

Gear oil options readily available to me.... Lucas conventional 85w140, Lucas synthetic 75w90,Lucas synthetic 75w140, a cheaper brand masterpro conventional 80w90, masterpro conventional 85w140, masterpro synthetic 75w90, masterpro synthetic 75w140.... what do you guys think is the best brand/viscosity/oil composition or does it really matter that much??? I'm kind of a learn as you go kinda person if that hasn't resonated with some of you Haha. Hands on learning is the only way to go for me.

Some pics of the swap out...

I'm just a little nervous about those CMU jack stands. Be careful.

SimS

It was only like that for 10mins tops as I rolled "new" axle under to sit her back down on. And by the way I did have some logs just in front of the blocks as a back up if they broke cuz I had same thought. Now the logs were about 3inches shorter so she could have dropped 3inches but it worked. And before I took old axle out from under it it was sitting on the blocks like that while i took a lunch break. So I did somewhat test the strength of the blocks. But heck all mobile homes are sitting on blocks for years so why couldn't my truck sit on them for a hour or so.... was my thoughts.

But to make all of you feel better I do plan to make some heavy duty jack stands outta some 2in square tubing that slides in and out of some 2.5" squaretubing as the base and drill holes threw both tubes for some tractor pins to set the height of the jack stands. So for my future repairs I'll be a bit more safer then concrete blocks and firewood log jackstands.

If the Masterpro is rated GL-5 I would use it in the conventional 75W140

Gotchya and I believe it is. So I'll defiantly pick some up because tomorrow is the day I'll get my new u-bolts according to fedex. Yay. So I'm gonna bust but to get her ready like fluid change and wire up the selector so once u bolts come in I can bolt it down and take it for a spin with the 2speed rear in it. It's gonna be like a totally different truck.

So they only had small jugs of that fluid so I went to ruralking and got there brand of gear lube "harvestking" gear lube 85w140 conventional GL-5. and I have my old gear lube draining still.... it's about 20°f outside so its draining like molasses on a cold winter day. But it seems to be in decent shape not milky and no metal chunks or flakes so far, it is obviously pretty used tho as its rust brown in color.

And my selector had some red color oil in it. Could have been "atf" or some brand of oil that adds a red dye to it.?.?.?. Anyway I added 10w30 engine oil to it and also carved a new gasket out for the front plate as the old cork one ripped when I took it off. And everything seems to be in good shape inside of there.

You know the oil is thick when it forms a pile as it hits the drain pan!

Oh yeah I bet it took a hour to drain. And I'm not sure all of it drained out, it just got soooooo slow and a thin stream that it was flying all over the ground missing my pan cuz it was windy. Since it's so easy to drain the gear oil maybe I'll drain it again at the end of 2021 summer. while it's still hot out so I can get all that built up gunk out that I'm sure was froze/so thick it wouldn't drain out. Kind of a waist of gear lube cuz I know it last longer then that but it was cheap so I'm willing to refill again to be sure all the particles and old fluid gets out.



On another note there was one thing I did notice about this axle swap.... when I was hooking up driveshaft, at the yoke end with the splines it slides/adjusts on, with this new axle there isn't as much splines length showing. My old axle I'd say there was about a 1-1 1/2inch of splines showing and now there is only 3/4-1inch of splines showing. Is this an issue I should worry about ?? Does this actually move enough to cause a problem?

I would look at the old wear pattern on the splines to see how much it moved before. That should be visible on the male spline. Of course, the shaft will have to be out in order to see it. If the wear pattern indicates less than the 3/4 - 1 inch you see showing, all is well. My guess is it will be OK but its too easy to pull the shaft not to check it.

If it moved before, it pulled out I believe. My worries were if the rear could somehow push forward when hitting bumps sliding it forward but the shaft had thick grease/dirt build up on the splines that were showing. so I'm assuming the rear end moves away making the nice and greased splines show when hitting bumps and then hides away when riding smoothly... not sure but if they were dirty they obviously weren't getting used. I actually cleaned it off so can't use that for referance. Lol
But I had to get a box cutter to basically cut the dirty grease outta the grooves then used a flat head to fine tune my cleaning so I could move it all the way down the splines without major force. So my guess is it doesn't move much cuz I have been hauling rock down a pretty bumpy road. so I would assume that rock haul would move the driveshaft on the splines cuz I know my springs are close to overflexing at times with a load and some of the bumps but I try to go slow in the real bad spots now that I know them better. And will take it even easier now that I know about this if it's actually an issue.

There would be a wear pattern in the steel that reveals the movement. The crud may have built up during times of light loads after the last heavy load.

Well this said crud was ancient so it had been there for quite some time wasn't just dust from driving unloaded but I'll check and see. I'm guessing you mean the worn area will be like chrome and the rest will just be the grayish metal color.

Yes to the shiny part, and look on both sides of the splines, one will be driving, the other coasting, but one might be clearer and easier to see than the other. There may be a step worn at the end of travel if the joint was not lubed often. Sounds like it had plenty of lube though so the witness marks might be faint.

Yeah I just cleaned it pretty good and there isn't really any shinier section on it so I think when I cleaned it and ran it back and forth on there, before thinking about this issue, I may have ruined my movement evidence. Lol. I would screw something up by cleaning dirt out. That just seems to be how my projects go sometimes. And I spent about 30mins cleaning that out and using all my might to slide it back and forth as far as it would go to make sure it would slide good haha.

The spline movement is directly related to the load on the springs- - - - -more weight, more spring flex, longer stroke on the splines. A quick way to monitor spline movement is to snug a zip tie around the spline, and push it up against the yoke. As the spline moves in and out the zip tie will get pushed back to the maximum point of travel and stay there. It's the same way we would monitor suspension travel on the race car by putting a zip tie on a shock absorber shaft. Three big guys jumping up and down on the front bumper couldn't move the suspension as far as a couple of hot laps around the dirt track would!
Jerry

But yeah I have been religious with the grease gun since I got this truck I've hit every zerk every fall when I change the engine oil for the past 4 years I believe that I've owned it. So yeah the grease buildup on the end is mostly my own fault I'm sure but at least the goods are greased up.

Hmmm I didn't think about that but that would have worked great if I done that on my old axle so I knew how far it moved before I took it out and put new one on. But I'll do it anyway to see if it moves or if it gets crushed, that'll be a bad sign so hopefully that doesn't happen but if it does I'll know I need to fix something somewhere before something bad occurs.

And btw what would happen if my driveshaft bottomed out on the splines of the yoke?

Im guessing it would send a shock toward the front into trans and then into engine like dominos correct..... Or would it put force on my trans/motor mounts? Or both I suppose.... Hopefully I'm ok on this issue. but I'll for surely keep a close eye on this issue.

I would expect u-joint damage or bearing damage at either end of the shaft first. More problems farther along the drive line later on if it continued or was severe. One bad bump with a load on and you will likely know what is going to break. There really is no good way to predict where or when bad things are going to happen. I had not heard of the zip tie thing, that sounds like a very good idea.