489 pinion bearing install?

[port-holio]

Is the front pinion bearing cone supposed to be a slip fit over the pinion shaft on a 489 case, or does it have to be pressed?

I'm setting up a TrueTrac w/ 3.23s, and trying to set pinion depth. The problem is that the front bearing won't go down over the pinion shaft. I've tried this with two Timken bearing sets, and two different OEM 489 pinions.

I've set up a 742 before, and the front bearing was a slip fit, so this has me scratching my head. Any hints on how to proceed would be really appreciated.

Thanks,
PH

 

[SGBARRACUDA]

Should just slip on with minimal effort. Might need to pollish the shaft a little. No not that one, the pinion shaft! LOL

 

[fishy68]

I've ran into a couple that were pretty tight but never had to press one. Like SG said, polish it and give it a try.

With tight ones like that I keep an old (but good) bearing handy that's been whittled out a little so it slips on and off nice and easy. Get the depth set then install the new one.

 

[Bad Sport]

Hmmm, Yup it should slide on with minimal resistance, try some emery cloth on the shaft and clean it up some more.

 

[SGBARRACUDA]

Yup it is a pain to pull the inner bearing off every time to change the shim. That is why I made a bearing tool out of a new bearing by honing the bore till it would slip on and off till I set the pinion depth. I have one for the 489,742 and 741 pinions.

 

[port-holio]

....... I keep an old (but good) bearing handy that's been whittled out a little.......

LOL. I was thinking about wallering the front bearing enough for it to lightly tap down, and just running with it that way!

By waller, I mean hone it out with a brake cylinder hone. I was worried that if I have hammer it on (or use the nut to draw it home) if I have to hammer if back apart, I'd dent up the races.

I gave the threads and the bearing journal hell with a drill & wire wheel, and deburred the edge with a stone. Dressed it lightly with a diamond file, and didn't find any high spots.

I have honed out an extra new rear bearing to minimize pressing it on and off. The old bearings, with a little wallering sure make good tools for tapping down the new bearing cups.

Thanks alot guys.
PH

ps is it true the factory just looked up the gear ratio, picked the right shim off the chart, and just put them together? Can I really just throw in a 0.015" shim for 3.23 gear, and hope to be close, as claimed in June 2010 CarCraft? I saw a July 2011 Mopar Muscle article about measuring pinion depth, but there aren't any dimensions on my gears.

 

[fishy68]

ps is it true the factory just looked up the gear ratio, picked the right shim off the chart, and just put them together? Can I really just throw in a 0.015" shim for 3.23 gear, and hope to be close, as claimed in June 2010 CarCraft? I saw a July 2011 Mopar Muscle article about measuring pinion depth, but there aren't any dimensions on my gears.

I don't know about that but I do know they are pretty touchy on setup. By that I mean if they aren't right they'll howl. My factory serv. manual goes through the process of measuring the setup but rarely will you find dimensions on factory gears. It must be referring to installing brand new gears that had the dimension written on the box or in a piece of paper in with the gears??? It also says that on the pinion it'll be marked how much to vary from the measured depth but I take it those marks were done with a grease pen so they probably got washed off.

coming from a heavily Chevy biased magazine (that's why a lot of guys call it Chevy Craft) it wouldn't surprise me if the writer hated Mopars and wrote that to try and make them look stupid. I had a 489 with a 3:23 gear and it had a real thick shim in it. Don't remember the exact thickness but I know it was at least .050". That disproves his saying all 3:23's in a 489 housing take an .013" shim.

 

[port-holio]

now now, say what you will about Camaro Craft, but I'm not ready to chalk everything up to willful slander & reckless sabotage. Jeff Smith might not be the sharpest tech, but he at least finds experts and attempts to quote them accurately.

Here's the article with pics & shim chart:
http://www.carcraft.com/techarticles/ccrp_1006_mopar_83_4_inch_rear_axle_assembly/viewall.html

I notice two things their gear expert says:
1. he uses this shim chart, which varies by ratio
2. he mentions finding shims under the rear cup inside the case, and that you should put them back in the same place you found them.

Note - my gears have painted numbers, but had NO shims inside the case. Could it be there were two assembly methods, and Jeff Smith just mixed up the translation?

The first pic is an OEM 489 Mopar 3.23 ring gear. Both ring and pinion are paint-penned. The ring gear seems to read "-03" when the teeth face down. The same number is written counter-clockwise on the pinion head. sorry no pinion picture - the marking washed off.

The last two pics are from OEM 489 Mopar 2.76 gears I pulled out. If placed teeth down, it seems to read "-021". The same number is written counter-clockwise on the pinion head.

If read as thousanths of a inch, these both would be in the ball park for a shim pack. Would also make sense if they were serial numbers to keep the two parts mated together.

 

[fishy68]

now now, say what you will about Camaro Craft, but I'm not ready to chalk everything up to willful slander & reckless sabotage. Jeff Smith might not be the sharpest tech, but he at least finds experts and attempts to quote them accurately.

Let's clarify things since my comment seem to rub you the wrong way. I said "

it wouldn't surprise me if the writer hated Mopars and wrote that to try and make them look stupid

". I didn't say he DID say something. Just that I thought it was possible he said something because I have seen that before. Since you didn't post a link to the article (until now) I had not read it.

Here's the article with pics & shim chart:
http://www.carcraft.com/techarticles/ccrp_1006_mopar_83_4_inch_rear_axle_assembly/viewall.html

I notice two things their gear expert says:
1. he uses this shim chart, which varies by ratio

I read it and see the chart is not from Smith, but it doesn't make sense that it is spot on since I have torn apart several units with 3:23 gears, 3:55's, 4:11, and 2<76's and found much thicker shims most of the time. Only once did I find a thin (less than .020" under the pinion. Just sayin my personal experience

.

2. he mentions finding shims under the rear cup inside the case, and that you should put them back in the same place you found them.

I have never found shims under the pinion bearing cup but have heard other guys say they did.

Note - my gears have painted numbers, but had NO shims inside the case. Could it be there were two assembly methods, and Jeff Smith just mixed up the translation?

The first pic is an OEM 489 Mopar 3.23 ring gear. Both ring and pinion are paint-penned. The ring gear seems to read "-03" when the teeth face down. The same number is written counter-clockwise on the pinion head. sorry no pinion picture - the marking washed off.

The last two pics are from OEM 489 Mopar 2.76 gears I pulled out. If placed teeth down, it seems to read "-021". The same number is written counter-clockwise on the pinion head.

If read as thousanths of a inch, these both would be in the ball park for a shim pack. Would also make sense if they were serial numbers to keep the two parts mated together.

As I said earlier, it's my understanding (by what I read in the factory serv manual) that those markings were how much to vary from the stated pinion depth. So the 03 would vary .003" from the depth. The 021 would vary .021" from the stated depth. I am not an differential expert so you can take that any way you like, or consider it trash. I'm bowing out of this discussion because I am not a diff. expert and I don't feel I need to waste time defending myself over some silly thing I said about a Chevy magazine.:wack: Maybe someone with more knowledge than me can help you.

 

[port-holio]

fishy, I was kidding too. Appreciate all responses, especially from senior members. rayer: All I meant was Smith's heart is in the right place, vs most other media guys. I still think he got something confused in his notes.

So I take the "0.021" painted on my gear, subtract that from the nominal pinion depth, and then I shim it until I get the actual measurement to match (like the Richmond method)?

I added pics to support what you said - the manual mentions numbers on the parts, but I nearly washed them off myself with just a toothbrush. If these hadn't been low mile cases, marks might be gone.

I wonder if people find shims in the case because it's easier for a hack like me? If you don't have a press, hard to press the pinion cone on & off to make corrections. There's not much on the cone to grab on, and I'd probably screw up the basket trying. Sounds easier to tap the race out of the case, refreeze it & tap it back in with a shim behind it?

PH

 

[SGBARRACUDA]

I agree with what ph says. I've built countless 8 3/4's and I find rears that have shims behind the cone to be done for ease and I don't think the factory ever did this. On a used R & P the most important pattern is on the coast side of the gear set. Your looking for a mesh pattern in the center of the tooth as possible. But Hell sometimes no matter how hard you try some set ups are going to whine.

 

[fishy68]

fishy, I was kidding too. Appreciate all responses, especially from senior members. rayer: All I meant was Smith's heart is in the right place, vs most other media guys. I still think he got something confused in his notes.

Just pulling your leg too, LOL

So I take the "0.021" painted on my gear, subtract that from the nominal pinion depth, and then I shim it until I get the actual measurement to match (like the Richmond method)?

Ummm... Not sure if I'm follow you. Mainly that part about the "nominal pinion depth". Maybe because I don't know the Richmond method?? What I meant earlier is there is the depth a pinion is stated to be set at and whatever # (+ or -) is marked on the pinion is how much to vary it. i.e. lets say you have a pinion stamped 1.710 and has a -003 on it. You set it to 1.707. I'm not a differential expert by no means so I might be interpreting it wrong but that's how I read it.

I added pics to support what you said - the manual mentions numbers on the parts, but I nearly washed them off myself with just a toothbrush. If these hadn't been low mile cases, marks might be gone.

I wonder if people find shims in the case because it's easier for a hack like me? If you don't have a press, hard to press the pinion cone on & off to make corrections. There's not much on the cone to grab on, and I'd probably screw up the basket trying. Sounds easier to tap the race out of the case, refreeze it & tap it back in with a shim behind it?

PH

Your probably right about the shims behind the race. It does work and is easier. I'm lucky enough to have a press to press it apart to change shims when I don't have the setup right but a lot of guys don't.