brute4c : Front axle teardown q's

Front axle teardown q's
Post by brute4c on Sept 6, 2006, 11:16am

OK....after the fire, I found my diff lube to be very dark bluish in color...smoky blue I have been calling it...recall that I had a brake fire and lockout hubs were on the truck...the grease I had in the knuckles was black....my thought was that the grease had at least liquefied if not vaporized, toasted the seal inboard of the knuckle and made its way to the diff thus contaminating the fluid. Since the diff wasnt turning and the heat source was so far away and the lube is synthetic, I very seriously doubt that it could have gotten enough heat to the center section to boil the 3 plus quarts of lube for a long enough time to cause such a dramatic color change....we arent talking a little difference...but major!

In ordering parts, I wanted to get the seals that go between the knuckle and the axle tube....I thought they were just inboard of the knuckle to keep the grease in there...well no....there is a bushing just inboard of the knuckle that the axle shaft passes through and the seal is actually far inboard almost at the differential...just a bit outboard of the bearing caps.

In this view, #9 is the seal in question and #11 is the bushing.
http://www.m715zone.com/manuals/34parts/fig74.jpg

Not having torn into one of these before...I am wondering how much clearance is there between the bushing, #11 above, and the axle shaft? I am guessing not much...enough for a bunch of grease to migrate past on its own or not? Thinking back to Brians axles, he had a ton of grease down in there but that was done under pressure....seems that bushing should make a pretty fair restrictor or what good would it be....something like .1 inch or less maybe?

Also, with the seal being at the inside edge, the only way to change them is to take out the differential right?

I have to wonder if that was the source of my discoloration or not...so far away from the heat source, I doubt the seals got that hot...maybe the passenger side due to the offset of the housing but not sure that would happen....

I would like to have all the parts on hand and do the job once....but dont want to spend more than I need to or make more work than necessary....though it would really suck to get it together and find those seals leaking...

I take it those seals are there more to keep the lube in the center section than to keep the grease from the knuckles out?

THANKS!!

Re: Front axle teardown q's
Post by robertcowan on Sept 6, 2006, 11:32am

BRUTE, SOME LUBES I,VE SEEN HAVE A BLUE COLOR TO EM. AND FOR CHANGING THE INNER SEALS YES YOU GOTTS PULL THE CARRIER-RING GEAR ETC. TO GET TO THEM MOSTLY TO REINSTALL THEM. I,D PULL THE COVER AND CATCH THE FLUID AND IF ITS NOT COMTAMINATED ESPECIALLY SINCE ITS SYN. LUBE IT ISNT HURT. I KNOW OF SEMI TRUCKS WHICH RUN CONSTANTLY AT 225 -250 DEG. ALL DAY LONG FOR 250K MILES. OUR END PROBLEMS WONT EFFECT THE DIFF. MAKE SURE YOU GOT ALL PARTS TO REASEMBLE IT BEFORE YOU TEAR IT DOWN. SOMETIMES THERE HARD TO COME BY NOW. YOU OTTA WATCH EBAY AND PICK YOU UP A USED POWER LOCK AND INSTALL IT IF YOU TEAR IT DOWN. YOU WONT BELIEVE THE DIFFERENCE IT MAKES. 100.00 WILL GET YOU ONE PLUS S&H.
BOB

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 11:44am

This lube was translucent before the fire with no visible blue in it...Eaton synthetic 75W90 for semi axles....after, it was certainly not...not even close. Like a large amount was added to make it that dark and light impenetrable...
Due to it being synthetic and so far from the heat source, not to mention is was all in one big "vat" in the center section thus requiring a major amount of heat for a long time to raise its temp versus a small pool, it seems it must have been contaminated somehow....I just cant figure how....

I did change it out to new lube and discarded the old....just dont trust stuff that I dont know what is in there...

Re: Front axle teardown q's
Post by barrman on Sept 6, 2006, 12:06pm

Jon,
The outter bushing #11 is what holds the axle shaft in the center of the tube while the hubs are turned. Too much play in them and you will get vibrations and of course wear on your carrier and hubs. That bushing is what makes the axle full floating.

The seal #9 is where the grease was oozing past on Brians axles. I took the stripped axle tube with the seals and bushings still in it to the car was to power wash. My students had already used brake cleaner to get everything they could reach clean. I ran out of money before I ran out of odd colored gunk coming out of the space between the bushing and the seal. I personally think that yours has 40 years of old oil, grease, rust, etc between the seal and bushing. Getting it hot just loosened that stuff up enough to mix in with your good oil.

You have two options. Leave the seal and bushing alone, rebuild the ends, drive it and change the fluid after a hundred or so miles and see how bad it is.

or

You can tear it all down, clean everything, hope you got it set back up right, change the fluid after 100 miles and see how it looks and get rid of any new metal that has come off from the new parts meeting their new neighbors.

Either way, driving with lockout hubs disengaged you should be ok. For flat towing just go the extra step and remove your brake drums next time and don't worry about it.

Re: Front axle teardown q's
Post by porkchop on Sept 6, 2006, 12:14pm

The bushing #11 will allow oil past it. If the grease liquified in the hubs, which it did in your case, then it would go past the bushing with no problem. The seal to stop the oil from mixing between the hubs and the diff is #9 which you have to pull the diff to change (I have spares, PM me). The black burnt grease then would mix with the diff oil from a bad seal and cause your discoloration. It took me a total of three hours from what I can remember to do both shafts on the front.

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 12:40pm

So I take it there has to be enough clearance between the bushing and the axle shaft to send grease down there normally...not under pressure feed...

So just driving around, the grease gets hot in the knuckle and will be thin enough to migrate to the other side of the bushing as well?

That makes sense...so if the truck has 28,000 miles on it like mine and has been greased regularly, there is going to be grease past the bushing normally?

I thought the grease would want to be contained in the knuckle and the gear oil would be allowed to go from the diff to the bushing area...thinking thats where the seal would be....wonder why the grease is the one that can migrate in that tube area, unlike the rear axle....

Re: Front axle teardown q's
Post by tacomainoh on Sept 6, 2006, 12:48pm

Jon, the inner seal is the only seal on the later 60's. There is a company making outer seals now, don't know if they'll fit the 715 or not, but they are a double seal design and cost $55.

There shouldn't be anything in the axle tubes but the shaft. The bushing is just there to guide the shaft.

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 1:08pm

Wont some of the grease, when it gets hot and runny when driving, make it past the bushing? Brian was pushing grease past the inner seal but that was under pressure....obviously not my situation but there must be some clearance there in order for that to have happened right?
Cant be much though...

Re: Front axle teardown q's
Post by tacomainoh on Sept 6, 2006, 1:15pm

If all is well, nothing will make it past the inner seal. There shouldn't be any grease in the tubes unless those inner seals are compromised.

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 1:47pm

Hold on here now.....

the bushing is at the inboard edge of the knuckle....the seal is way down the tube by the differentail bearing caps....so some grease can get in the tube unless the bushing out there is so tight to the axle shaft that grease cant pass by....or what am I missing?

Re: Front axle teardown q's
Post by tacomainoh on Sept 6, 2006, 1:55pm

Holy crap.

I had totally forgotten about the closed knuckle. WOW>

In this case then, it really depends on how tight that bushing is??? And since I don't have one to look at, you tell me. Your theory is sound, grease can get past the bushing unless it's tight.

complete brain fart. Gee I ain't never seen these trucks before. Wow.

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 2:02pm

Thanks...I thought I was missing something major....like that would be a first...

So does anyone have a clue what the clearance is before I get in there? Probably measured in small decimals of an inch I guess?

Re: Front axle teardown q's
Post by hiker on Sept 6, 2006, 4:31pm

I'd guess that the shaft to bushing clearance would be 0.005 to 0.010 inch. Doubt that it will be worn out enough to replace.
Robert-ca

Re: Front axle teardown q's
Post by brute4c on Sept 6, 2006, 4:54pm

Thanks Robert!

Another thing that has been in my head is that the grease in the knuckles...best description I can give...looks like a bunch of pieces of a black crayon that has been cut in half and then split along its length....so depending how much may have gone past the bushing, the stuff down there would need to be cleaned out pretty well...maybe now I dont have to?

Re: Front axle teardown q's
Post by tacomainoh on Sept 6, 2006, 5:45pm

If your grease looks like chunks of anything at all it should probably be changed!

Re: Front axle teardown q's
Post by fisherman on Sept 6, 2006, 8:58pm

Brute, I did my front axle last winter seals, bearings, added disc brakes and lockout hubs. I wouldn't worry about it. Do you hub bearings and seals and add new felt and seal to your knuckle, clean and repack with new bearings. The grease looking like crayon as you described was the same in my axle. There is some clearance in there and I believe if things get hot enough grease my leak into axle tube and visa versa. I don't think the bushing and inner seal change would be necessary a pita if you ask me. Clean everything well, new seals, repack or new bearings fill with new grease, I like the kendal blue grease and or Lucas oil red grease, the next time you need to repack or look in there you can tell if something has contaminated or changed the color of the grease. It is a good indicator as to how things are wearing. Was pretty straight forward, I wouldn't do my carrier or disassemble the ring and pinion unless you have to. Good Luck

Re: Front axle teardown q's
Post by jed on Sept 6, 2006, 9:20pm

I am now in the process of installing front locker, so carrier is out and new oil seals will be installed tomarrow. I had a little grease in my axle tubes as well. Once front axle is done, time for paint and to throw this thing back together, just in time for fun in the snow I hope!

Re: Front axle teardown q's
Post by robertcowan on Sept 6, 2006, 11:14pm

A LOCKER IN THE FRONT AND SNOW ?? THIS WILL BE INTERESTING. CAN YOU SAY RATCHET ON SLICK ROADS ?? SCARES ME TO THINK ABOUT IT. HOLD ON MA HERE WE GOOOOO

Re: Front axle teardown q's
Post by brute4c on Sept 7, 2006, 9:04am


Quote: <TABLE class=bordercolor cellSpacing=1 width="90%"><TBODY><TR><TD width="100%"><TABLE class=quote cellSpacing=0 cellPadding=2 width="100%"><TBODY><TR><TD width="100%">If your grease looks like chunks of anything at all it should probably be changed!</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>

I am tearing it down to completely scrub the insides of the knuckles and make them like new...thus removing this mess...its just how far do I have to go to get all that I need to worry about that I am wondering...

Re: Front axle teardown q's
Post by jed on Sept 7, 2006, 10:36am


Quote: <TABLE class=bordercolor cellSpacing=1 width="90%"><TBODY><TR><TD width="100%"><TABLE class=quote cellSpacing=0 cellPadding=2 width="100%"><TBODY><TR><TD width="100%">A LOCKER IN THE FRONT AND SNOW ?? THIS WILL BE INTERESTING. CAN YOU SAY RATCHET ON SLICK ROADS ?? SCARES ME TO THINK ABOUT IT. HOLD ON MA HERE WE GOOOOO</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>

Thanks for your concern. Have you tried it? Or is that just what you've heard? It's just for fun, man!

I'm not sure I would have put a locker in the front if my truck were a daily driver.

Re: Front axle teardown q's
Post by brute4c on Sept 7, 2006, 10:51am

On a serious note here...I have thought about the front locker and, with lockout hubs up front, why not? The only time I would use the front axle on road is when it is completely covered with snow...or else I am gonna bind the tcase...and in that case, it will be because the road hasnt been plowed and its too deep for cars....so speed would be low and caution taken...just like on the trail.

If a car can go through it, then I dont need 4WD...and if I do, then it will be at low speed because everyone else will be at low speed and it would be reckless to be flying along "just because I can" and rearend someone.

I did once drive home in about 1.5 feet of snow when cars were going like 20-25 mph and I was doing like 50...thought it was cool to be the fastest vehicle on the road...but it was dumb to do...just because one can GO faster on that stuff doesnt mean one can STOP any faster....and that would have been a bad ending....

I did pass a cop that evening too....didnt realize it was a cop till I was passing...snow was coming down pretty hard still...I thought for a second....CRAP!! He will get me for too fast for conditions or something....so I took my foot off the gas...then I thought....he's doing like 20 on the highway and I'm doing 50....how could he possibly catch me...and I hit the gas again....

I'm older now...

Re: Front axle teardown q's
Post by tacomainoh on Sept 7, 2006, 11:17am

with lockouts, there is no reason not to run a locker. You won't know it's there until you lock the hubs. BUT if you do and it's snowy, have fun LOL .

Re: Front axle teardown q's
Post by fisherman on Sept 7, 2006, 7:44pm

Just lock in one hub if it is snowy or slick out.

Re: Front axle teardown q's
Post by robertcowan on Sept 7, 2006, 10:06pm

why not put a power lock or a track lock ? i,ve had all 3 . a detroit even in the rear end jerks the whole truck and eats tires like crazy. in the front end its too extream inmy opinion. but put in it what you like. most that have voiced opinions have never had one in the front also my opinion. wanna buy one for the front ?? might as well put a spool in it.......

Re: Front axle teardown q's
Post by fisherman on Sept 7, 2006, 10:23pm

Even with a spool you can still just lock in one hub, which ever one you choose.

Re: Front axle teardown q's
Post by fredrader on Sept 7, 2006, 10:29pm

I had detroits front and rear in a CJ7 and never had any problems winter or summer..I had boggers on it and it never hurt my tires..I had it a year or so and drove it quite a bit..I liked them..They worked every time I needed them..

Re: Front axle teardown q's
Post by robertcowan on Sept 7, 2006, 10:48pm

go for it. i just offered my opinion. even a power lock is a handful sometimes off road and in winter. you better know what your doin is all i can say. if your on a slope and break loose the tires your goin the way of the slope and with a locker your gonna break the tires loose

Re: Front axle teardown q's
Post by jed on Sept 7, 2006, 11:02pm


Quote: <TABLE class=bordercolor cellSpacing=1 width="90%"><TBODY><TR><TD width="100%"><TABLE class=quote cellSpacing=0 cellPadding=2 width="100%"><TBODY><TR><TD width="100%">with lockouts, there is no reason not to run a locker. You won't know it's there until you lock the hubs. BUT if you do and it's snowy, have fun LOL .


</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>

Havin' fun, that's what it's all about, so Jon, If your workin' on the front end, put that locker in and you'll be diggin' like a mad dog!!! You'll never look back!

Re: Front axle teardown q's
Post by jeepistdougiowa on Sept 7, 2006, 11:13pm

"my theory"...LOL

With one lockout unlocked you will still have some issues..it's not quite like an open dif.

For starters, if you happen to be spinning your tires on ice or snow, then hit a clear spot of pavement where the tires can hook...the shock to the front can't be shared by both axle shafts. SNAP.

Second, the open allows power to both front tires to be unevenly split as you round a corner(inside tire travels less than outside...blah blah) Anyway, with one locked, it has to travel the same speed as the rear tires are traveling (assuming you're still running a stock t-case and not a Q-trac) Result, that tire IS going to spin in a corner pretty much all the time, you will have the opposite side trailing to help keep you straight, just not as effective as an open dif IMO.

To me, if you have a front locker in you really prevent yourself from using 4wd in the snow at any "road" speeds.

Wheeling, in the snow, fun but on side hills, you're gonna go down..no biggie as long as you're at trail speeds and can correct as needed.

Re: Front axle teardown q's
Post by fisherman on Sept 8, 2006, 8:33am

Personally I like an open front axle and a mild locker or power lock in the rear axle.

Re: Front axle teardown q's
Post by bigwheelbob on Sept 8, 2006, 8:40am

Another thing about a front locker is if you are ever off road in a set of ruts on a 2 track or something, you cant hardly pull yourself up out of the ruts, the truck will just want to follow them.

Re: Front axle teardown q's
Post by bbm715 on Sept 10, 2006, 10:12pm

I've had trucks with both and in sand/mud the only thing better than a set of lockers would be spools. But when you hammer down (or maybe I should say "rubber mallet down" with a 230) lockers at both ends can be squirley to say the least - practicing ahead of time is a must unless you like being in the ditch or worse.
That being said when I decided what to do with my CUCV axles (already have a Detroit in the rear) I went with a posi. Tuned and tightened by reider racing, but a posi none the less. Using a locker in the front in slick conditions can be scary at times and I just felt the posi would fit MY driving style better.
Jon, from the way it sounds like you use your truck I'd leave the front open and just go with a locker in the rear. If $$ permitted then go with a normal posi.

Re: Front axle teardown q's
Post by bbm715 on Sept 10, 2006, 10:17pm

BTW, this is the one I used.
http://www.reiderracing.com/pgpowerlok.htm

But an E-locker like Lee had might be the best of both worlds. Spool when on and a decent posi when off. Bit pricey though, and I doubt one would work in a stock axle.

Re: Front axle teardown q's
Post by kwai on Sept 10, 2006, 10:37pm

I'm with Ron on the posi. My CUCV front 60 has a posi in it. I have driven a bronco with detroit lockers front and rear and it was hard to steer in mud. A selectable locker or posi is a much better option. Just my 0.02.

Re: Front axle teardown q's
Post by robertcowan on Sept 10, 2006, 11:01pm

i,ve got a power lock in my black m715 and still its a handfull. boy it goes as long as you got grip . i,d still prefet a trac-lock i think except for the serious off roader. never a locker in the front. its extream even in the rear. when it ratchets it jerks the whole truck. first time it did it i thought the rear end broke honestly.