differential oil

[ishbo03]

i have a 77 blazer 4x4 and was wondering how often i should change the oil in the differentials. what is the best oil to use? also, what is the easiest way to do this? do u have to take the whole cover off or is there a plug or something. thanx

[TXsizeK5]

You have to pull atleast the bottom bolts off the cover to drain it, but its better to take whole cover off and inspect for damage or wear.
I usually only change if i've gone through alot of mud or water crossings. There is a plug on the frontside of the housing, passenger side that you can unscrew to fill it up with.
Usually takes a little more than 2 quarts in a 10bolt.
80w90 synthetic is good.

[ishbo03]

aight thanx, any other general maintenance i should do on the truck, i bought it used and im not sure how well it was kept up. i bought it strictly for off road use, no daily driver.

[uglyota]

Originally posted by ishbo03
i bought it used and im not sure how well it was kept up.
Change every fluid and filter it has (fuel, tranny, tcase, engine oil, diffs, radiator) right now, then drive a few hundred miles and change them all again while it's all still hot (well, maybe not coolant). Take note of any glittery stuff or chunks that come out with any of the fluids.

If I had a diff that didn't have drain/fill plugs, I'd replace the cover with one that does...one of the easiest ways to prevent big $$$ repairs is to change your gear oil early and often. I wouldn't waste money on synthetic though.

ummm...squirt grease into every zerk fitting you can find, suck all the brake fluid out of the reservoir, fill it up with fresh and bleed master cyl, proportioners, and all 4 wheels (in that order) until everything comes out clear (this will keep your cylinders from blowing too soon). Same for the clutch hydraulics. Look in the owner's manual and do everything to the vehicle that it recommends up to and including 100,000 if you have no history of the vehicle's maintenance.

If you do all this and find something funny, sell it to someone you don't know and buy a yota :flipoff2:

[Chadnutz]

If you want good gear oil you can use Mobil 1 Synthetic 75w90 but expect to pay $6 or $7 per quart. It can be used in both diffs, t case, and manual tranny.

[uglyota]

Originally posted by ishbo03
what is the best oil to use?
Oh yeah, forgot this
whatever weight of Castrol GTX/Fram Tough Guard in the engine (good stuff, and if it hasn't had synthetic in 26 years, why start now?) and, whatever weight the manual says everywhere else. Don't have the manual? Try this: vehicle specs (http://www.autozone.com/servlet/UiBroker?UseCase=C002&UserAction=beginSpec)
$6/quart??!! Tractor Supply's el cheapo 85w90 is maybe $6/gallon! How hot do you think your diffs get?

[stx4wheeler]

i wouldnt change the tranny fluid if automatic, that aint to cheap to change it out then do it again, just run it a while and check the dipstick and see if it has any white frothy looking stuff on it that usually means water in the tranny or if it is not the red color it should be, then a change is in order.
also i would check and make sure the bearings have been packed recently i didnt do that on my 78 when i bought it and it costed me a crap load or cash and time to fix all the damage it did when they blew.

[JB]

I have got about $900 inside each of my diffs. You guys think that the cheap non synthetic stuff is ok? I was planning on running the Mobil One synthetic stuff.

[TXsizeK5]

Synthetic keeps it cooler, that's what I'd use.

Don't use synthetic if you're breaking in your new gears.

[JB]

Originally posted by TXsizeK5
Synthetic keeps it cooler, that's what I'd use.

Don't use synthetic if you're breaking in your new gears.

Why?

[redcagepatrol]

TRAIL ONLY RIG. (strictly off-road use)

he doesn't need synthetic if the truck doesn't see lots and lots of long highway trips.

water will get into diffs on a TRAIL RIG (what he bought it for). It is WAY too expensive to put synthetic in a trail rig just to change it after your first trip out.

[JB]

I get that.

My Bronco will drive to the trail, through the trail and back home again. That is my goal. It will also see around town and highway miles.

Does anyone know the difference between the synthetic v. non besides the obvious?

[TXsizeK5]

Well from what I know and what i've been told, bassically, when you're breaking in your gears, you want them to get hot and let the metal cool to make them stronger. If you're running synthetic your diff won't run as hot as if you used normal gear oil. And you only really need to run your gears for about 15-20min at a decent speed then let it cool for a while and you really only need to do it once. After that change it out to synthetic, and yea scott's rght, if you see highway driving synthetic is better if its mainly trail rig and ur changing out your fluids alot keep wiht the cheap.

[TXsizeK5]

I known someone who shattered his ring gear.... in a 10bolt though.

[eight]

Yes I said wore out. My little brother broke a d30 gear set and I hear busa's broka number of toy gear sets. Plenty of people do that. But to have one wear out cause of cheap oil is completely different.

[ishbo03]

ive never repacted my bearrings, how do i do that?

[stx4wheeler]

1 jack up the truck and take off the tires, then remove the small bolts in the face of the hub, should be outside of the dial.

2 remove all the parts to the hub not quiet sure what chevys look like but there will prolly be some type of spring, a snap ring that goes over the axle shaft, and either gears or a solid locking mechanism like warn hubs. REmove all of these parts make sure and keep everything in order or take pictures so that installation is easy.

3 Remove brake calipers and pads, now you will need some type of spindle socket tool to remove the bearing lock nuts from the spindle. then everything should come off with a little pull there will be two bearing one on the inside of the rotor assembly and one on the outside.

4 Now you are ready to repack them, just get a bearing repacker tool from local autoparts place of your choice it is usually to cones that has a greasegun fitting on the top, hook your grease gun up to that with the bearing in there and just follow directionson the package. Reassemble and you are ready to go. The spindle lock nuts sshould be torqued to spec from manufacture. would be a good time to do a brake job to since you already got it all apart.

anybody else fill in anything that i have missed, or if something is very different on a chevy.

[ishbo03]

if i had a brake job done on the truck, the bearings wouldnt of been repacked at this time would they?

[Graystroke]

depends...front or rear axle. fronts, I suspect, would have to be repacked. You have to remove the bearings to put the hub on the brake lathe and I would hope the shop you picked-the trusted competent shop that it is, would repack them..

[ishbo03]

aight thanx for the info

[ishbo03]

one more question, when i take the diff cover off to inspect for wear and tear, are there any parts that are gonna come out or just oil? basically, can i just unbolt the cover, let the oil drain out, look for an problems, then just put the cover back on and fill it up? is there a gasket or anything on the cover?

[fbronco86]

Originally posted by TXsizeK5
Well from what I know and what i've been told, bassically, when you're breaking in your gears, you want them to get hot and let the metal cool to make them stronger. If you're running synthetic your diff won't run as hot as if you used normal gear oil. And you only really need to run your gears for about 15-20min at a decent speed then let it cool for a while and you really only need to do it once. After that change it out to synthetic, and yea scott's rght, if you see highway driving synthetic is better if its mainly trail rig and ur changing out your fluids alot keep wiht the cheap.

I am gonna have to call BS on this one. I really dont think the gears get hot enough to heat treat them.

[AgDieseler]

There are quite a few guys that pull for several hours at a time, and some of them are bored enough to install temp probes in the read diff. Most of them don't get over 150F, unless there's a problem. Nearly all of us have a hypoid style ring and pinion, which runs very cool when compared to regular spur gears, but there is some heat generated. That's just the nature of gears, but it's what the break in process is all about. The change from hot to cold sets the shape of the gear making it more stable just like an engine block settles once it has a few thousand miles on it.

[BigRedFord04]

i use synthetic in my engine. mobil 1 only. but its a newly rebuilt engine and only switched to it after ~8K miles. my ZF 5-speed requires synthetic ATF for lubricant...$6/qt, but its what the factory specs call for. diffs get pennzoil usually b.c. its the shiniest bottle on the shelf. break in period for new gears according to Randy's R&P is 500 miles. I wouldnt switch to synthetic before then if you do at all. a couple points have been brought up:
1. its been that way for 26yrs, why do it now?
2. why bother spending the extra $$ on synthetic diff fluid when it will get replaced often anyway?

i agree w/ the 1st one, but to the 2nd...i say why not? its extra protection and i've never really bothered with changing diff fluid after a trip to llano....of course, i did blow up an 8.8....hmmm....your call :flipoff2:

just remember, trail rig only...do whatever makes you feel comfortable driving it on the trail

[fbronco86]

Originally posted by AgDieseler
There are quite a few guys that pull for several hours at a time, and some of them are bored enough to install temp probes in the read diff. Most of them don't get over 150F, unless there's a problem. Nearly all of us have a hypoid style ring and pinion, which runs very cool when compared to regular spur gears, but there is some heat generated. That's just the nature of gears, but it's what the break in process is all about. The change from hot to cold sets the shape of the gear making it more stable just like an engine block settles once it has a few thousand miles on it.

Yeah 150F that is one hell of a heat treatment:flipoff2: :flipoff2:

haha I called your BS

[Graystroke]

Originally posted by fbronco86
Yeah 150F that is one hell of a heat treatment:flipoff2: :flipoff2:

haha I called your BS

Your wrong Mike. There is a break in treatment.
www.richmondgear.com
BREAK IN

A new ring and pinion installation, especially a high numeric ratio with new bearings, can cause an excessive heat buildup in the rear end and cause softening of the gear teeth and bearings if a break in is not performed.

Street vehicles should be driven at normal street driving speed for approximately 10 miles, then stop and let cool for 30 minutes. Do this 2 to 3 times. Towing vehicles need approximately 200-300 miles of normal street driving before being used for towing.

On circle track race cars make approximately 6 to 8 laps at slow speed, then let cool for 30 minutes. Make 6 to 8 more laps at slow speed, then 2 to 3 laps at full speed, the let cool again for 30 minutes.

Drag cars need only an initial run-in since they are driven short distances and heat is not normally a problem with proper lube and backlash allowance.

NOTE: If after the above break in is performed, overheating of the rear end is suspected, repeat the final portion of the break in procedures.



what a dumbass! :flipoff2: