Front & Real Differential Fluids

[nfpgasmask]

So, I wanted to start a thread for info on our differentials and what kinds of fluid to put in. I know we need some LSD in the rear, but I have no idea what to buy or how much.

I also would like to get a good step-by-step from someone who has done their diffs so I can do mine. I did a search and couldn't really find a solid thread about this.

Ldub, I nominate you to write this up for us!

Bart

[ZEUS]

I'm running Royal Purple in there too - check the manual for rec. weights and amounts.

[nfpgasmask]

I'm running Royal Purple in there too - check the manual for rec. weights and amounts.

Yeah, I printed the whole thing out last month, I might as well use it, eh? So RP diff fluid in the front and rear, and what about your LSD fluid? What did you put in? Are they easy to drain and fill? Do you need to pump it in or syphon it in like the tranny?

Bart

[ZEUS]

Everybody keeps forgetting I have an open rear diff - no LSD. But to my understanding, Royal Purple has qualities in it comparable to an LSD additive already. Check it out. The front is easy to drain and fill - the rear I think is easy to drain but a little more challenging to fill. The front is just a bolt that is removed - it is the bolt at the very bottom of the 3rd member. It acts as a bolt and a plug. Once fliud stops coming out, put the bolt back in and fill er up until fluid starts coming out of the fill hole then plug it again. I think we had to pump fluid into the rear diff but it has been over a year and a half ago, so I forget.

[nfpgasmask]

Everybody keeps forgetting I have an open rear diff - no LSD. But to my understanding, Royal Purple has qualities in it comparable to an LSD additive already. Check it out. The front is easy to drain and fill - the rear I think is easy to drain but a little more challenging to fill. The front is just a bolt that is removed - it is the bolt at the very bottom of the 3rd member. It acts as a bolt and a plug. Once fliud stops coming out, put the bolt back in and fill er up until fluid starts coming out of the fill hole then plug it again. I think we had to pump fluid into the rear diff but it has been over a year and a half ago, so I forget.

So there is a drain and fill plug, just like everywhere else. I bet the syphon method will work good.

Hopefully some others will chime in with what fluids they are running in their diffs. Thanks, Justin.

Bart

[JHarris1385]

I forgot the brand but I used syn with lsd in the back. Better to be over than under on your lsd. I forget the amounts and numbers but I swear I have a thread on this somewhere. MAKE SURE to be on a level ground. I did not have to use any funnels or syphons at all. I just cut the tip of the bottle to an angle.

[nfpgasmask]

I don't like doing things unless I am 100% sure.

Can someone point out which is the drain and which is the fill? I assume the big plug that is high up is the fill port. Now, according to Dub's earlier post, the lowest bolt should be the drain, so which one is it exactly?

Fill???


Drain???


In the above photo you can clearly see the dripping problem I have also. I think Jharris might be right about it being the seal there. The manual mentions this as a potential problem.

Bart

[Ldub]

I don't like doing things unless I am 100% sure.

Can someone point out which is the drain and which is the fill? I assume the big plug that is high up is the fill port. Now, according to Dub's earlier post, the lowest bolt should be the drain, so which one is it exactly?

Fill???


Drain???


In the above photo you can clearly see the dripping problem I have also. I think Jharris might be right about it being the seal there. The manual mentions this as a potential problem.

Bart

It's hard to tell from this angle, but I think it's this one...



In any event, it's the one closest to the ground.

And you are correct in your assumtion that the upper ones are the fill/level check holes.

[nfpgasmask]

You're the best, Dub. I figured that was it, but with your red circle, now I am certain.

Thanks -Bart

[nfpgasmask]

One more thing, does anyone know the size of the socket needed for the diffs? I need to get one I think.

Thanks - Bart

[Ldub]

One more thing, does anyone know the size of the socket needed for the diffs? I need to get one I think.

Thanks - Bart

Don't know the size, but you could give it a shot with a large crescent wrench. Snug it up tight & give it a few persuasive gestures with the heel of your palm......

Worst case scenario, you bloody up some knuckles, learn new swear words, & have to clean up the head of the plug with a file...so a socket will fit.

[etlsport]

hmm i forget the size.. i want to say the rear is 24mm.. but it could also be 25

word to the wise... take the fill plug off first... its unfortunate to get the fluid drained out only to realize you cant get the fill plug off

[nfpgasmask]

hmm i forget the size.. i want to say the rear is 24mm.. but it could also be 25

word to the wise... take the fill plug off first... its unfortunate to get the fluid drained out only to realize you cant get the fill plug off

Good tip, Etl, thanks. I was going to do everything yesterday, but I just didn't get to it. Next week hopefully.

Bart

[VCrossfan]

Royal Purple front/rear...No LSD needed

[johnnyapollo]

I wanted to add that there are actually 2 pans in the tranny - the larger covers the filter - there's a smaller pan (adapter pan) up front that covers the tranny solenoids. Best right up I've seen was done by Joe Black:
http://www.antiquecaterpillar.org/vx...l/4L30E_01.asp

Call around and ask for a tranny-pan filter kit for a GM4L30E- comes with both gaskets (pan and adapter pan) plus the filter - runs right at $50 and the gaskets are shrink-wrapped to cardboard so they come flat.

-- John