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Diff cover off, what should I look at/for?

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misweetrevenge

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I'll be getting my tranny serviced today and was going to have them do the rear differential at the same time but decided to do that part myself to save some money. First time doing this and am curious as to what I should look for while I have the cover off. Signs of wear or signs of something going bad.

I have a 91 suburban 3/4 ton. (14 bolt if I remember correctly)
 
Can't tell you much on the 14FF, but if it's the 14SF, I'd at least rotate the carrier while watching the side/pinion gears, to make sure they weren't moving excessively before the carrier moves. Look for wear on their teeth, check the ring/pinion gears for missing/chipped teeth, pitting, etc. Check oil for metal flakes or chunks. Pull the pinion shaft out and check it for wear. If into it this far, not a bad idea to pull the axleshafts out a bit and check the bearing surfaces for wear.

Replacing axleshaft seals as preventive maintenance at this age wouldn't be a bad idea either, particularly if the axles are coming out anyway. Bad seals will ruin the brakes.
 
If its a gawdamn 14bff.... Shake it.
If sh*t doesn't fall out, yer good to go.

The carrier bearings are BEAST's.
The pinion bearing is a BEAST.
The wheel bearings.... You get it.

If the carrier ain't loose, the gears look good, and there is NO milky fluid, yer fine.

Usually 14b's don't experience "minor" issues.... It's more catastrophic failures in the gears.
 
Sorry to HIJACK this thread a little but when I removed my diff cover (10 bolt) There was a big chunk of white stuff at the bottom, I am assuming this is friction reducer? Also should I put friction reducer after I change the oil. Already changed it but I've driven about 20 miles so I can still add it...
 
How would I go about checking the level in my differential and tcase? Got busy with cleaning and prepping the bathroom for paint so I couldn't get to it today but I'd like to check the levels because iv noticed spots in the areas I park but haven't had any spots on the cardboard I put under it so I'm worried it might be low or close to empty. Also what gear oil should I use if I do need to top them off?
 
For the diff you remove the drain plug and stick your finger in it, it should be level with the hole...If it is low fill until it starts to come out. T-case I am not sure sorry
 
wilpetty said:
For the diff you remove the drain plug and stick your finger in it, it should be level with the hole...If it is low fill until it starts to come out. T-case I am not sure sorry
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If I remove the drain plug wouldn't the fluid drain out?:dunno: are you referring to a filler plug or is the fluid actually supposed to be lower than the drain plug?:confused:

Carcinogen said:
Transfer case is the same way but you check the fill hole.
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[Both of The Above]
Sounds the same as a manual tranny. thanks guys.

[Everyone]
What should I be using in my diff and tcase? I read somewhere its different but can't remember for sure nor can I recall what it is.
 
Yes, no drain plug on the diff, fill plug.

Fluids are listed in my service manual, sorry I don't have time to check right now, t-case I'm sure is whatever version DEXRON they are on now (there is no T in DEXRON!).
 
Yeah, if you have an auto trans, run atf. If you have a manual, run gear oil. It'll help prevent cross contamination. Unless you have a manual and chain driven case, then run atf I'm pretty sure.

Axle always gets gear oil, though.
 
dyeager535 said:
Yes, no drain plug on the diff, fill plug.

Fluids are listed in my service manual, sorry I don't have time to check right now, t-case I'm sure is whatever version DEXRON they are on now (there is no T in DEXRON!).
Click to expand...

Looked it up in my Chilton. Says "API GL-5, SAE 80W-90". Any brand preferred by anyone? When it comes to mustangs (I've had a few and currently have a Cobra) I know some people swear by Royal Purple for gear oil BUT will NEVER use their engine oil.
 
xenomarine said:
Yeah, if you have an auto trans, run atf. If you have a manual, run gear oil. It'll help prevent cross contamination. Unless you have a manual and chain driven case, then run atf I'm pretty sure.

Axle always gets gear oil, though.
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I'm pretty sure it started with gear oil in the transfer case and was changed later by GM to ATF for fuel economy or something like that... I just use the same fluid because its easier, and I only have to buy one kind of fluid / have one kind of fluid behind the seat in case of emergency.
 
Carcinogen said:
I'm pretty sure it started with gear oil in the transfer case and was changed later by GM to ATF for fuel economy or something like that... I just use the same fluid because its easier, and I only have to buy one kind of fluid / have one kind of fluid behind the seat in case of emergency.
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Bingo. I am about to start running atf in my 205 so I don't cross contaminate my 700r4. Gear oil in the trans wouldn't be nice. I don't know how well gear oil would jive with a chain driven case honestly.
 
the 1991 Chevrolet trucks service manual says to use Dexron II automatic transmission fluid.

the NP 241 has an oil pump with a long, skinny suction tube that has a screen at the end to filter the oil. I do not think gear oil would suck through this arrangement very well.
 
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