How to remove ring and pinion gears

[biffidun]

Ok, so I have finally narrowed down my power divider issues to mismatched drive axles. Front drive axle is 4.17 and rear is 4.5

I have counted the bull gears in both diffs and they are both 55 teeth. I have opened the rear diff at both sides and removed the plates with 3 bolts that appear to center the top shaft.

My plan is to switch the rear drive to 4.17 It appears as though I have CDR92, CDR93, CDRPC92 or CDRPC93 - all information on the axle has rusted off so I'm guessing two things, 1st is that it doesn't really matter, 2nd is that I have a CDR93 rear... I figure once I have the gears in my hands I will know what to order (fine vs coarse etc...)

How do I get the gears out? Do I rotate a wheel and tap the top shaft towards the passenger side to slip the transverse gear off the key?

Do I pull the yoke?

I'm worried that if I tap the top shaft too far over I will drop something into the bowl.

Any tips would be nice.

[NY-B61]

Ok, so I have finally narrowed down my power divider issues to mismatched drive axles. Front drive axle is 4.17 and rear is 4.5 ........ Any tips would be nice.

I'd start by having a chat with the person who sold you the truck.

[biffidun]

Not worth calling a lawyer and no they won't own up to it. The truck drives like a bucking bronco.

I'll just chalk this one up to a lesson learned.

[terry]

Sure would be easier just change the rear carrier to a 4.17, there are plenty out there.

[biffidun]

a used rear carrier is about $1500 ... the 45's (ring and pinion gears) are about $300

[Vladislav]

I have taken some of the diffs apart but haven't put back together any yet.

For the first you need to remove the yoke nut, than bolts wich fix the pinion body to the main housing and remove whole the pinion assembly.

Press or hit the pinion out of. For the ring gear you take the side covers off and those 3 bolts at the shaft's end. Than pull out the ring wheel with the shaft wich is also a small mating gear to the big 55 teeth bull gear. To remove the ring gear off the shaft you need a press. That's where I stopped at the moment. But to me that's a hobby.

When apart you'll see the splines are coarse or fine etc. If I'm not wrong CDR32/33 are coarse and newer CDRPC92 and CDRPC93 fine.

Don't forget you'll need to set up the gear's position to each other and pre-load of bearings. Looking the style those carriers done it might be alot of job. Vlad

P.S. You can find a manual about CDR32/33 on ebay. I'd buy one if not well experienced with diff repairs.

[biffidun]

Thanks. I'll tackle it ASAP. If I think of it I will post some pictures. There is next to nothing on the net about this stuff.

[biffidun]

OK, so I have the gears out and now I have to figure out what to order. The gears that came out have 47KH3397 stamped on them, which (given my luck) does not match up with anything at the local Mack Dealership.

From what I can tell this is a late 70's to early 80's axle.

It's the rear axle, so I am going to assume the axle is a CRD93.

I am trying to swap the gears to make the axle a 4.17 to match the fron axle.

Could someone help me figure out what gear set I need to get a 4.17?

I looked up a PAI/Excel part number of 7540, which corresponds with a Mack PN 27KH1915

So what is the deal with the part number that came out of the axle (47KH3397)?

[Vladislav]

At least I can tell you they must be 14 teeth pinion with 17 teeth crown.

[biffidun]

That much I have figured out, thanks. I am pretty sure I have the right part number from Mack for a 4.17 gear set - just looking for some confirmation.

[Phase 1]

As Vlad said, it will need to be set up when assembling it. That will require a service manual and measuring instruments and is "a lot of job".

If it is not done, you will be doing the job again in a short time, and it could take a lot more parts.

[biffidun]

I'm not sweating the setup. Just the part numbers. I'll do a better job than the knuckle draggers that have worked on my truck in the past at the stealership.

[theakerstwo]

Please keep us posted on how it holds up.If you can do it I may try it to.

[biffidun]

Out with the old and in with the new. I have to press the "ring" gear off the stub axle. The PAI part number was 75400.

The 4.5 gears look great - just not the right ratio. Anyone want to buy them? It would help offset the $400 for the 4.17 gears

[Vladislav]

How do those PAI parts look perfect?

I'm also going to convert my 5.02's into 4.17.

But need both front and rear sets.

Too difficult to import heavy used stuff overseas so go for new stuff.

I can order it locally for about extra 50% if I have part ##.

[biffidun]

Parts look good.

Assuming you have a CRD92 front and CRD93 rear;

Front axle: (fine) 24KH11073 (PAI7534) Coarse 24KH1917 (PAI 7530)

Rear axle: (fine) 24KH1956 (PAI7541) Coarse 24KH1915 (PAI7540)

Sometimes you add a "0" to the end of the PAI#

There might be an "A" or a "B" beside your Mack part# - don't sweat it, the newer versions of parts have a "B" ending indicating a minor improvement.

When I took mine apart the yoke was loose and there was endplay in the stub axle bearing. It must have been like that for some time. What was amazing was that the gears look perfect! no wear whatsoever. I think all the stress about setting the gears up right is a bit overplayed. I've got some paste I put on the teeth to make sure they are swiping properly, but I'm not too worried. I'll start with the shims that were in there to begin with.

Make sure you run Hypoid gear oil in youre axles - anything else will ensure rapid wear!

[theakerstwo]

Thanks and keep the info coming.Photos to

[Vladislav]

I use to work with hypoid gears on 4x4 off road pick-ups.

Have never done them just conicals.

They might be easier although I read in some book long ago that hypoids are a kind of self-setting.

You may (and should) apply some paste or just paint to check out the contact trace, it's described in many old books, probably on the net also.

Check out a gap in between the teeth mated, must be 0.07-0.18 mm for a big car, I thing 2-3 times more for Mack would be Ok. Better to find out the correct figure. For a car people used to put a piece of newspaper in between the teeth and if they start feeling jam it's Ok.

An important thing is bearings pre-load. In car diffs there's deformed pipe you just press when turn the yoke nut up and measure resisting torque of a pinion/bearings assembly. In CRD's there's a hard pipe between the inner bearing races so you need to grind it off (on a sand paper layed on a glass for example) to increase the pre-load. If you overgrinded you need to swap it with a longer one or maybe use a hard shim. Important note - if you want to go with the turn over torque that's specified you need to check it out with bearings washed and DRY. After you put oil in them they will start turn much easier.

Thank you for the PAI parts ##.

[biffidun]

Thanks for the info. I have the ring gear pressed on, but the bearing on the pinion shaft is being a B****. I don't have a bearing separator large enough, so I might have to pay someone to get it off or just buy a new bearing from Mack.

[41chevy]

Thanks for the info. I have the ring gear pressed on, but the bearing on the pinion shaft is being a B****. I don't have a bearing separator large enough, so I might have to pay someone to get it off or just buy a new bearing from Mack.

Chill it in the freezer for a few hours, some times it will give a small bit of clearance needed to remove it. Paul

[biffidun]

Well I had to break the bearing to get it off. The part number was on the covered side (or course). New bearing arrives tomorrow. Just in case someone is interested the main inner bearing on the spindle of the pinion is a Timken 5760.

The freezer trick won't work since the whole thing cools at once. I had to use a bearing separator, which due to the design of the spindle impacts on the bearing cage. The force to spread it deforms the cage.

A new bearing on Amazon is $65, I got one for next day delivery from a local supplier for $95. Not bad really.

[41chevy]

Tapered Roller didn't click for some reason. Probably better in the long run to replace it. Paul

[biffidun]

Well it is all back together. I had to reinstall the pinion shaft several times to get the lash setup. You can see in the photo how there are shims on the pinion carrier that set the gap. The new shaft ended up with fewer shims, so the machining is not identical.

Another tip for those who might tackle this, is to use the steel disc plate that bolts up to the ring gear axle (see picture). Pick up some 2.5" bolts (the stock bolts are 1.5" in length) and then use the longer bolts and the disc to pull the axle through. Once you are close enough swap the stock bolts in and tighten it up.

The job is not that bad. The big headache for me was pumping the gear oil into axle since I don't have a great pump. I just have some $10 hand transfer pump.

Anyone want to buy my 4.5 gears??

[Vladislav]

Glad to know you have it done.

Did you make a contact area paint test?

Gap is not what you only need to set up.

[biffidun]

I just looked at the whipe pattern left after spraying some dry lube (white). In the end, the whipe looked like it was even across the face. Should be good to go. Time will tell.

Mack dealership wanted ~$3000 to do this job.