Rear differential leaking

[unbrokenchain]

Well I went to change the transmission and differential fluid on my newly purchased 68 C30... wouldn't be surprised if that transmission oil was original... but as for the differential, there wasn't much changing it because it was almost empty. I filled it up yesterday, and this morning I see why. It drips like a faucet (1 drop every 15 seconds or so) from just behind the u-joint on the front of the differential. Is this something I can fix myself? Anybody know where an exploded diagram is so I can picture this seal? Thanks!

I'm pointing to the leak in the diff pic. Also had to post one after I cleaned the lichens off the paint. Still need a bumper. And not sure where the seat in the truck came from, but who doesn't love a gold-sparkle steering wheel?

*edit: I guess this is called a pinion seal? I see where I can order the part, but should I tackle this without air tools?

[Davidf]

Hard to say if you can DIY. But, if you try, the important thing to know is the pre-load on the bearings is critical. A good way to do this with basic tools is:

1. Remove driveshaft
2. Mark (with chisel) the relationship of the pinion stud/shaft and nut. Go ahead and mark the position of the yoke as well.
3. Count number of threads showing between the nut and end of pinion shaft. The purpose of all this is to ensure you reinstall the nut in EXACTLY the same position as it was before you removed it. This will ensure the proper pre-load on the bearings.
4. Set parking brake (do this first actually).
5. Remove pinion nut.
6. Remove yoke. Should simply pull straight off (not pressed fit).
7. Remove old seal.
8. Reverse order of removal for installation. Ensure nut is replaced in exact original position.

Good luck.

[Mike C]

No crush sleeve used in one of these. Pinion preload set by the spacer. Just remove and r&r seal and torque back to spec from factory service manaul.

[Stocker]

Might find the right online manual here: http://67-72chevytrucks.com/vboard/s...d.php?t=558016

[Davidf]

Originally Posted by Mike C

No crush sleeve used in one of these. Pinion preload set by the spacer. Just remove and r&r seal and torque back to spec from factory service manaul.

Good to know, my '52 is the same way. But, I wasn't sure and my instructions would work either way...but simply torqueing to spec is best in this instance.

[unbrokenchain]

Mike C, are you saying that on this design it is less critical to have the nut in the exact position, as long as the torque is correct? Anybody know what size the big nut is? Thanks y'all!

[Wrenchbender Ret]

Ithink the big nut is 1 5/8". Your only problem will be getting it off without an air tool. There is a cotter pin in it also. After removeing the yoke (you might need a puller) you will need to remove the 5 bolts & remove the flange. The seal goes into the flange from the back side. There is a thick cork gasket that goes behind the flange but you can use RTV. Tighten the pinion nut real tight & go furthure enough to line up the cotter pin holes.

[mike16]

torqueing the nut is critical. check your service manual to deterimine if your torque wrench can tighten it back on properly. if not... get an extension and recalculate torque using the longer dimensions . Try selecting an extension that will put the torque you need in the middle of your torque wrenches range of operation. Torque wrenches are not too accurate at the outer extreames of thier range.( both th low end and the high end of thier range)

[unbrokenchain]

Thanks again y'all, and those service manuals are awesome. A little dense though, wish they had split them up by model! Trying to figure out what model differential this is and then I can hopefully find the torque spec on that nut.

[Stocker]

Originally Posted by unbrokenchain

Trying to figure out what model differential this is and then I can hopefully find the torque spec on that nut.

That is an Eaton HO72

[unbrokenchain]

You rock! Thanks. Still having trouble finding torque specs though, everything seems to have it in rotational/drag torque... I'm thinking though that if the vehicle is still sitting on the ground that I won't be rotating the diff... ? I haven't found a HO72-specific torque spec yet, but from all the manuals I'm scouring I'm thinking it's somewhere in the 150 ft/lb range? I'm also a little concerned about the need for a specific puller, I have a couple but not sure they'll work.

Hmm, new part is in the mail, may just take this one to someone who's done it before/has more tools. Wish there were a shop around here that specialized in older vehicles! This has been hugely helpful.

[Stocker]

It may not help, but just in case..... By most accounts, that HO72 is the same as an HO52 which came in 3/4 ton trucks, but for the larger brakes on the HO72. Also, all HO72s have the pinion pre-load bolt, but not all HO52s have it. Mechanically, though, the axles, housings, and drop-in units are said to be identical. Only mentioning in case you can find torque specs for an HO52.

[unbrokenchain]

220 ft/lbs, page 443 of 1968 chassis overhaul manual. Well, gotta see how I feel about it when the part gets here. I don't mind supporting other people's work, but there's just something about doing it yourself.. Thanks again

[Andy4639]

I'm fixing to do this same job on mine. Hope to get started on it Monday if not sooner. I start my 7 day break tomorrow and this is in my plan to do while off.

[Mike C]

Torquing the nut is critical but just to the factory manual spec. No need to try and align some marks.

Many older diffs were set up with spacers and not crush sleeves. It's more precise, but it is more time consuming. The crush sleeve lets the factory put diffs together faster that way.

[mike16]

two other pieces of advice, if you can locate a NOS yoke, you might consider buying it and installing it rather than the old one. The old one may be worn where the seal rests on the yoke.

Anoher piece of advice for you and others. The drain plug is ON THE REAR OF THE DIFERENTIAL COVER!!!! Its NOT that plug looking thing on the DRIVERS SIDE. Dont loosen that plug thing on the drivers side of the housing. All kinds of terrible things will happen to your rear end befor it self destructs.

Dont do it!!! the filler plug is on the differential COVER.

[RedRoad]

IF you can find a yoke get it, I could not find one under $200 so I just used a National Ready sleeve #99259. You can get them from your local Oreiley or Rock auto

http://www.rockauto.com/catalog/more...nid=528&jpid=6

If you have the original seal in there you might find remnants of the felt washer that also helped stop leaks.

Here are the Napa part numbers

Pinion seal: NAPA 25970 / Victor 49428M

Pinion Felt: NAPA 528

Pinion Speedy sleeve: NAPA (CR/SMF) 99259

Not sure if Napa carries the felt anymore as my local idiots were of no help. I installed without it and no leaks

edit: found the felt at rock auto

http://www.rockauto.com/catalog/more...nid=468&jpid=1

[unbrokenchain]

Yeah Mike16, I actually didn't notice the square bolt on top/side of the diff til I went to investigate the leak, just used the hole on the cover like most other rwd vehicles I've had. Glad I read about it on here before I messed with it!

You know I didn't realize that NAPA made these parts, I ordered from partsgeek but hopefully it will be a good part. That speedy sleeve thing, does that remain in the pinion bearing area or just make it easier to install the seal like a shoe horn?

I swear there's more knowledge just on this thread than in any of the shops I've been to in the area.

[motorcritter]

I use NAPA for stuff I need immediately- they have a selection of quality, so I get the best they got. If I can wait, I usually (like 99 ties out of 100) I use Rock Auto- you can pick your supplier, get what you want and know what you're getting.
Posted via Mobile Device

[RedRoad]

the repair sleeve stays on covering the groove worn in the yoke.

Here is video from SKF

https://www.youtube.com/watch?v=09LiVbqL6ss

I hear you on the lame parts changers in the shops these days. No one is able to trouble shoot or even begin to think of repairing a damaged part. If they cant find the part they just give up and say to buy a new vehicle. No computer to tell them a trouble code? Deer in the headlights lost. The trade schools these days are pretty weak. I had a friend that went to one of the big ones and all it did was to familiarize him with the systems. $30K later all he could do was change oil.

This place is great, use the search and you will find plenty of threads to help. Keep it up and good luck!

[mike16]

Originally Posted by unbrokenchain

Thanks again y'all, and those service manuals are awesome. A little dense though, wish they had split them up by model! Trying to figure out what model differential this is and then I can hopefully find the torque spec on that nut.

funny you should ask that question about which rear it. is or whats it called.

I've heard it called an HO33, HO52 and the Eaton rear. Peop;e have been very polite about my cluelessness. What is this rear end called in polte company.

Another question I have, I dont want to hijack this thread but maybe we can consolidate all the servicing information about this rear end so future searches are simplified.

Anyway. I gave advice on torqueing nuts and which plug(?) to pull to top off the fluid level, and which one NEVER to touch under any circumstances.

My stoopit question...

drum roll please.....

is...........

How do you drain the old fluid from this rear?

All the fluds in my drive train need replacement. I am certain this does too. so....where is the drain plug on this rear or do you pull the cover. And presuming you damage the gasket removing the cover how do you distinguish it from the Dana 60 when ordering a new gasket. Clearly they look different but thats whenyou get it, How do you distinguish it when ordering it up.

[mike16]

Sorry, some of my questions were answered in previous posts.

So this eaton rear came as a 3/4 ton rear with out the preload adjustment, but came with the pre load adjustment as a heavy duty 3/4 ton rear and as the 1 ton rear.

Stocker:

Still trying to wrap my head around this:

Eaton rear:

HO ? was 3/4 ton standard rear/ no preload
HO52 was hd 3/4 ton rear and had the preload
HO72 was hd 3/4 ton rear (HO52) and had the preload and big brakes

[Stocker]

Originally Posted by mike16

How do you drain the old fluid from this rear?

....where is the drain plug on this rear or do you pull the cover. And presuming you damage the gasket removing the cover how do you distinguish it from the Dana 60 when ordering a new gasket.

You guessed it.... pull the rear cover. This also gives you a chance to clean it out and eyeball the innards. Any decent parts house should be able to supply a new gasket.

Pick up some Permatex Gear Oil RTV Gasket Maker. It's made specifically for use with gear oil. They say you can use it without a gasket but I prefer a thin coat on each side of a gasket. Good stuff.

Originally Posted by mike16

So this eaton rear came as a 3/4 ton rear with out the preload adjustment, but came with the pre load adjustment as a heavy duty 3/4 ton rear and as the 1 ton rear.

Stocker:

Still trying to wrap my head around this:

Eaton rear:

HO52 was 3/4 ton standard rear/ no preload
HO52 was hd 3/4 ton rear and had the preload
HO72 was hd 3/4 ton rear (HO52) and had the preload and big brakes Yes

Saying the HO52 without the load bolt was a standard rear, while the HO52 with the load bolt was a HD rear seems logical and *might* be correct..... but I don't know for sure, so let's just say probably so.
That caveat aside, your info is correct.

[RedRoad]

Ive read the difference was the weight /load designation (5200 lb vs 7200 lb).

The only difference Ive seen in parts manuals is reference to a 60 and later 3/4 and 1 ton with 7200 lb axle and a 1 ton with 11,000 lb axle.

Since the parts manual shows a bearing change in 1960 Id assume the roller bearing is 60 and earlier and the tapered is 60 and later.

[RedRoad]

Here are the two pics of the different pinion support bearings from the part sheet above. NOS pic is the 60 and earlier and the SKF is the 60 and later

Exploded view and big bearing part sheet

Some good threads as well

http://www.pirate4x4.com/forum/chevy...n-h072-37.html

http://67-72chevytrucks.com/vboard/s...d.php?t=401974

http://67-72chevytrucks.com/vboard/s...d.php?t=604173

I couldnt find a part number for roller vs tapered bearing, anyone know the number or cutoff?