Servicing Rear End

[Rodimus_Prime]

So I am unsure of how long its been or even if the rear has ever had new fluid put in it. I would like to drain whatever is in it and put in new lubricant however I am unsure of how to do this or even what type of stuff is in there. Any how tos on this?

 

[80/89TTA]

Easy Job , I usually do drain and fills on low mileage or well maintained vehicles you will need a tube of RTV sealant, 2x cans brake clean (you can get a rear cover gasket if available or just use RTV instead of gasket) 3x qts axle lube, you can use what manufacturer recommends. I use 75/140 Synthetic on most vehicles BUT on my F-Bodies (3rd & 4th Gen = small rears) i use Amsoil Shockproof rear gear fluid and a bottle of GM rear diff. addittive.

vehicle on lift or on jack stands, Jack stands must be on all four corners.
So parts needed:
RTV and or gasket
3 x qts rear fluid - you will not use it all
2 x brake clean
1 x GM Rear addittive.

Remove rear cover bolts with drain pan underneath - pull as much old fluid out as possible then spray down rear with brake clean - while doing this inspect ring and pinion gears and diff. gears for chips and such. you can inspect gears while rotating tires by hand. Once all clean inside go clean the cover and apply a generous bead of RTV on cover surface (RTV should be applied around the bolt holes and outer edge- I like to shape it with my figure so that when i install cover most excess goes to outside of rear) let cover set for 15 or 20 minutes to get a skin on the rtv. re-install cover on the rear add new fluid through fill hole i usually add the additive first and then the gear lube...because you squeeze in the fluid it is just easier to get it all in by adding to next bottle. fill until fluid comes out fill hole.

if vehicle has alot of miles and original fluid then I would also remove axles to clean axle tubes thouroughly.

 

[Quiky One]

Just remove the rear end cover and let all fluid drip out.

For the rear end I just use Lubramatic 75w-90 with the little bottle of posi additive. I have tried Amsoil and Mobil 1 and both of them create more noise.

Make sure you use 75w-90 as that is what GM calls for. Dad made a mistake years ago on a Limited and put in 80w-140 Amsoil and the rear end chattered and groaned! That fluid was taken out after 20 miles.

I just used regular Castrol rear end fluid or the Lubramatic as stated above with the posi additive/friction modifier.

I also used blue RTV and a rear end gasket to make sure it didn't leak. No issues here! This is how I have done all the cars. If I can help let me know!!

Jason

 

[Rodimus_Prime]

So just remove all the bolts and it dumps out then refill through the top. Is there a fill cap or something at the top? I have zero knowledge of these things since this is the first non FWD car I've had.

97k on it and I know little about the history of it. For my own peace of mind I'd like to service everything on it I possibly can. How does one remove the axles? Also where can I order one of these rear end gaskets?

 

[Quiky One]

So just remove all the bolts and it dumps out then refill through the top. Is there a fill cap or something at the top?

Ya, there is a rubber looking plug. Use a paint scraper to remove it.

Jason

 

[Rodimus_Prime]

how much 75w 90 should I get so I know how much to buy?

 

[turbo nasty]

Pick up and install and mag drain plug kit while you are in there. One hole to drill and you no longer have to fight with cleaning the gasket po the cover off BS.
Drain kits are less than 10 bucks are normally on teh shelf

 

[Quiky One]

Buy two quarts and the posi additive which is 4 ounces and you will be set! Make sure you pour the posi additive first!!

Jason

 

[Rodimus_Prime]

ah ok, while we are at it, what is the correct color for the cover, if its dirty i was going to paint it

 

[Scott89TTA]

ah ok, while we are at it, what is the correct color for the cover, if its dirty i was going to paint it

rust :biggrin: seems they don't paint much under these cars...front frame, upper/lower control, spindles, rear, rear control arms, panhard bar, etc.

I plan on painting all these parts satin black with POR15 and be done with them pretty much forever I have seen a lot of muscle cars that have used POR15 and it looks awesome.

 

[Rodimus_Prime]

yup thats the look im going for, i dont want to wait to do it too long i know the subframe braces have some surface rust on them, not gotten a chance yet to get it on a lift and spend a day under there cleaning things up and seeing what I have to deal with.

 

[Jan Larsson]

I had my rear end cover along with all suspension pieces (swaybar, aftermarket tubular control arms, adjustable panhard rod etc) all powder coated satin black.

I would get the complete rear axle powder coated as well at some point but just cleaned it up with a wire wheel and painted it years ago and it holds up pretty good.

Even had the GM OEM sticker reproduced that goes on the rear end diff cover ... looks pretty good

 

[Quiky One]

I had my rear end cover along with all suspension pieces (swaybar, aftermarket tubular control arms, adjustable panhard rod etc) all powder coated satin black.

I would get the complete rear axle powder coated as well at some point but just cleaned it up with a wire wheel and painted it years ago and it holds up pretty good.

Even had the GM OEM sticker reproduced that goes on the rear end diff cover ... looks pretty good

Is it possible that the rear end was painted from the factory or were all the cars sent out with it unpainted? My rear diff cover cleaned up pretty nice!

I guess it is more likely that the original dealer had it done.

Jason

 

[Jan Larsson]

Is it possible that the rear end was painted from the factory or were all the cars sent out with it unpainted? My rear diff cover cleaned up pretty nice!

I guess it is more likely that the original dealer had it done.

Jason

What I've seen from low milage cars (53 miles and up) it looks like the rear end was painted black ... only thing back there that did not get some paint looks like the swaybar and the mounting brackets for it but the other bits had some paint on it but very thin and flaked off easily