So I'm trying to set up gears for the first time...

[pvfjr]

...into an AMC M20. I know most of you probably aren't too familiar with this axle, but it seems fairly normal. It uses a crush sleeve, so no shimming for the pinion bearing preload, which is nice. I also noticed that there was no shim under the inner pinion bearing, so I was wondering what sets the pinion depth. Well it seems that they have placed the shim between the inner pinion race and the carrier. I suppose that that also makes sense, but our superior master install kit came with no shims that size. There was only one shim behind the old race, and it broke when we were punching out the race. It was .100" thick too. So is there a place to get the shims we need quick? Would and auto parts store carry something like that? I hope I don't have to order it from Randy's R&P, I wasn't planning for that much down time here. Another stupid thing, we made "setup bearings" before we realized that the shims don't go on between the pinion and the bearing, which means that you only have to press the bearing onto the pinion ONCE, which means that we completely wasted our time making that setup bearing.
So does anyone have any experience or tips for this axle, so far nothing has gone well.

 

[readymix]

Sometimes the original gears do not use the same type of shims as a new set. One example of this is some of the TOY axles I have done.

Toss the broke pinion shim you had......I bet that some of the shims in your set-up-kit will fit behind the pinion bearing. Hence: you will need the set-up bearing you made.

At least I hope I am right here....

 

[readymix]

And if I am wrong, you can get shims form Napa in most any size

 

[pvfjr]

Well I'll have to look into that, thanks. That gives some hope at least, I'll let you know how it goes. There'll probably be more questions too. I'm following Billa Vista's D60 gear setup article. Different axle, I know, but I figure it's got all the same procedural stuff in it. So far it looks like I can make do with what I've got (broke down and bought a 12 ton press today); with the exception of one thing - an inch pound beam style torque wrench. We don't have one, and it seems to be a bit important. Got a ft-lb beam torque wrench, but that won't do us much good. Since I don't have "the feel" for this yet, hopefully we can get one scrounged up. More to come...

 

[Hogback Fabrication]

Unquestionably shims set the pinion depth. The shims (for pinion depth) are in one of three places. Under the pinion bearing (by the "head" of the pinion), under the outer race of the "head" pinion bearing (the one that presses into the housing), or in the case of a removeable pinion support housing (which an AMC 20 is NOT) between the housing and pinion support. Saying that they put the shim in between the inner pinion bearing and the carrier makes no sense to me (unless you mean the shims are under the outer lower pinion bearing race like most dana axles are).

 

[pvfjr]

Well it seems that they have placed the shim between the inner pinion race and the carrier.

Please be more careful when you quote me. What I said makes perfect sense. There are two bearings on the pinion, the inner (by the "head") and the outer (by the yoke). I'm speaking of the inner pinion bearing race, which is the race that goes to the inner pinion bearing, which is also the race by the head which you speak of. We're talking about the same thing. In fact, I think you should be a little more careful with your nomenclatures. You speak of a "outer lower pinion bearing race"? Well my pinion is horizontal, so there is no upper or lower involved. Also, I wouldn't call it the outer race for the inner bearing, I would just call it the race for the inner bearing. I know each bearing has two races, but the inners are one piece with the cage and rollers, so that entire assembly can be referred to as the bearing. If you keep saying outer all the time people could think you're talking about the outer pinion bearing, rather than the "outer race" of the inner pinion bearing. Sorry if this seems like a rant, but much like this guy...

I’m a real stickler for accurate and consistent naming conventions

This guy writes very clear and concise articles, a quick flip through here can easily get everyone on the same page.

 

[Hogback Fabrication]

Yeah sorry I was out of line. I can't imagine why they wouldn't have included those shims but you probably won't be able to get them from a parts store. You will probably need to speak with a driveline shop or any 4WD shop that does gears (they probably have extras lying around). Good luck

 

[ntsqd]

FWIW I prefer to shim pinion bearing preload. Crush sleaves can and do relax or get crushed more. I've done it myself to two of them, one a 8" Ford (same exact part is in a 9") and one in a turbo Yota diff.

The inch-pound part is simple to solve. I use a quality fish weighing scale and a lever that bolts to the yoke. Carefully measure for the hole that the fish scale hooks to and you're off and running.

 

[pvfjr]

Yeah sorry I was out of line. I can't imagine why they wouldn't have included those shims but you probably won't be able to get them from a parts store. You will probably need to speak with a driveline shop or any 4WD shop that does gears (they probably have extras lying around). Good luck

No problem. That's a good idea about checking with the 4wd shops to see if they have extras, you never use them all anyway. I'll have to try that. Napa has told me that they're limited on the shims they have, and they don't think they'll have what I'm looking for. A different Napa may be better, but that's what I have to work with. After checking, they did include some shims that fit between the pinion and bearing, but the whole stack adds up to only .065". Since we pulled .100 out from behind the race, I don't think that .065 is gonna work for us. I would like to get something behind the race if I could, but I'll see what we can scrounge up from some shops around here.

 

[pvfjr]

The inch-pound part is simple to solve. I use a quality fish weighing scale and a lever that bolts to the yoke. Carefully measure for the hole that the fish scale hooks to and you're off and running.

Ah yes, the old force x distance. I'll have to see what we have for scales around here. Thanks for the idea.