Newb Question - Rear Diff Gasket/oil

[dudeiwin86]

sorry for the newb questions to follow, but i cant find my owners manual... and im new to trucks (used to late model IRS dodge charger)
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Where is the best place to source a rear differential gasket?
does the dealer still supply/stock these? (for a 1990 k5)

OR

should i just RTV it? thinking orange RTV everywhere might be kinda fugly.


but im looking for the quickest possible fix, and dont want to wait on shipping for ordering a gasket online.
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what weight oil goes in the rear end? im pretty sure its still stock. no limited slip modifier correct?
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i think its a GM 10 bolt, but im not 100% sure.

i bought the truck recently and the rear end is howling and the diff is seeping out the bottom of the case.

im hoping the gears arent damaged and some fresh oil will help with the howling.

(only howls under load in forward gears)

if not... it will be time for some 4.10's soon i guess because this truck is missing some grunt with these 35" tires on it.

thanks!

 

[76zimmer]

Is there a G80 code on your glove box sticker? Any Napa store will have the gasket, and 85-140 gear lube, they can tell ya whats supposed to be in there and how much. Do a real good inspection of the diff parts while you got it off. If its a gov lock, check the pinion bolt (the small one that holds in the pinion shaft) and the gov lock assy, and the clutch discs.

 

[MNorby]

get a lube locker gasket

 

[Hogback Fabrication]

RTV and 80W90

And the pinion bearings will go long before the gears, is it leaking from the cover or from the pinion seal?

Differentials fail VERY quickly without enough oil.

 

[xCaliK5x]

I used black RTV and a gasket, 90 weight in my 14 bolt with a gov loc, and open D44, works great.

 

[82355]

Silicone and whatever gear oil is convenient.

Martin

 

[dudeiwin86]

thanks for the tips guys!

time to hit up the parts store. lets hope the R&P looks good. but i dont have my hopes up very high.

btw, it looks like its seeping out the bottom of the cover. and a little more quickly that i would like to see from any leak. so im a little concerned.

oh well, its a small price to pay considering how good the frame was on this truck. absolutely no rust.

i think its the rear end that is causing my intense clunking between reverse, nuetral and drive.

need to finish rebuilding the engine on my toy so i can get this baby into the garage

 

[USSkoval]

I personally like Permatex Ultra Black (not regular black), it works very well.

 

[Can Can]

I personally like Permatex Ultra Black (not regular black), it works very well.

I agree with this. Ultra Black works great, and unlike the bright orange stuff, doesn't make you look like you're from Oklahomo..........

 

[dudeiwin86]

10/4 on the ultra black... i just got the OJ stuff from the last time i sealed up my timing cover when we put the cam in my charger.
but ill get ultra black - if i need it -

i went and peeked under there after work today..

its leaking from the FRONT SEAL where the U-Joint enters the front of the differential...
it seeps out of there and runs to the bottom edge of the rear cover and drips down...
(since the differential is angled up from my lift..)

there was absolutely ZERO rotational lash in the driveshaft... but im wonder if i need to have the T-Case in nuetral first?

is it just a matter of replacing the front seal?
what are some possible causes of this leak? i wouldnt expect that seal to just.. up and fail? or ?

looking forward to more input,
you guys are awesome,
thanks

 

[BoondocK5]

I agree with this. Ultra Black works great, and unlike the bright orange stuff, doesn't make you look like you're from Oklahomo..........

Don't think that your sly little harassment will go unnoticed by a certain LEO from Okie. He's hot on that ****!

 

[noJeepshere]

thanks for the tips guys!

time to hit up the parts store. lets hope the R&P looks good. but i dont have my hopes up very high.

btw, it looks like its seeping out the bottom of the cover. and a little more quickly that i would like to see from any leak. so im a little concerned.

oh well, its a small price to pay considering how good the frame was on this truck. absolutely no rust.

i think its the rear end that is causing my intense clunking between reverse, nuetral and drive.

need to finish rebuilding the engine on my toy so i can get this baby into the garage

Yup, your pinion seal is leaking, and if you know what you're doing, not a hard fix.

As for the clunk, that is lash on the transfer case end of the drive shaft. The splines on the slip yoke are developing space between them and when you go from drive to reverse, the splines change faces and "clunk!" Not a huge deal, and fairly common on older GM trucks.

 

[dudeiwin86]

would a fix be as easy as swapping in a lower mileage driveshaft or replacing the input shaft on that slip yoke?

i guess i mean... is the wear on the male or female side of the slip yoke?

it looks like it would be relatively easy to replace the male side(drive shaft side) than it would be to replace the piece hooked to the t-case..

but thats going off memory from 4 hours ago.

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i can do a head/cam swap on my latemodel hemi

does the pinion have to come out to replace that seal? i dont have the proper tools to set up a rear end(gears/lash/etc)... but if its just pulling and swapping parts, its i can do it easy.

im concerned about how much and the quality of oil left in the rear end, tho... might have to pay some one to set it back up anyway... ill look into it more this weekend when im not strapped for time

thanks for all of the help!

 

[Chevy305]

you dont necessarily have to remove the pinion, but to do it "propperly" you need to replace the crush sleeve. The crush sleeve is a collar on the pinion that applies a preload to the pinion bearings.

You can just do it by feel though. I mark the exact possition of the nut and number of exposed threads. Then remove it (easier said than done) pry out the old seal. Tap in the new one after pre-oiling it. Put the yoke back on and tighten the nut until its in the exact same position, then feel the resistance for it turn. If it feel loose, tighten little by little until the same "feel" is achieved as it was before. Also a little rtv under the pinion washer is a good idea to prevent oil seapage through the splines.

 

[Hogback Fabrication]

you dont necessarily have to remove the pinion, but to do it "propperly" you need to replace the crush sleeve. The crush sleeve is a collar on the pinion that applies a preload to the pinion bearings.

You can just do it by feel though. I mark the exact possition of the nut and number of exposed threads. Then remove it (easier said than done) pry out the old seal. Tap in the new one after pre-oiling it. Put the yoke back on and tighten the nut until its in the exact same position, then feel the resistance for it turn. If it feel loose, tighten little by little until the same "feel" is achieved as it was before. Also a little rtv under the pinion washer is a good idea to prevent oil seapage through the splines.

I know of people that have had success with this method (at least as long as they had the vehicle or last I heard) and some that killed their rear end shortly after.

Beware that by doing this by "feel" you're putting lots of faith in your concept of how much is enough, especially if you haven't setup gears before.

Also, the pinion nut is a VERY important locknut that is one time use. If it comes loose it usually takes the whole rear end with it.

Your call as to risking it doing it the easy way or doing it the right way. This gets argued on here all the time.