Ok i bought some 3.42's off my buddy after he swapped in 4.10's in his SS. After pondering about it i got to thinking maybe it wasn't such a good idea to put in used gears with 75k miles on them in my car. After all when installation is so expensive that would really suck to go through all that trouble and then end up breaking a tooth off the gear. But before i bought them i looked them over VERY carefully and they checked out altleast to my standards. But i just wanted to get some of your guys' opinions on this subject. (Experience with something similar etc.) thanks alotin advance.. you guys are awesome

 

for gears as cheap and easy to find as 10 bolt gears I wouldn't have bought them used. But for that matter, with how cheap and easy to find complete 10 bolts are in junkyards I would have just pulled a 3.42 geared posi rear end out of a junkyard and called it a day.

 

they'd be nice and "seasoned" by now though

I wouldn't worry about it. If you want you can run a magnet and some iron filings over it, and do a quicky mag test.

I'd run 'em.

 

I would rather but in a posi disk 3.42 rear end but i have had a hard time finding one in my area (Missouri). However i got the gears for $60 so i figured what the heck. But since i have a 2.73 carrier i have to buy a $60 spacer so they will fit so i will be up to $110 on a used gear setup. I know it sounds screwy but i already have the gears so im kinda stuck

 

Help us understand why it matters whether you already have the gears or not.

A set of brand-new gears costs about $180-200. Let's call it $200 for the sake of argument.

Since you're asking this question, we can easily assume that you don't know how to do a gear swap yourself, and don't have the tools, meaning you'll have to pay somebody to do it for you.

Given that you can't install the gears yourself, it'll cost you about 3 hours of shop labor time to get somebody else who knows what they'doing, to do it for you; IF you take it out of the car. Probably another ½ - 1 hr if it's still in the car. So, figure on labor being in the $200-350 range; let's call it $300 just for round numbers.

In addition to the gears, you need a "gear kit", which has bearings, shims, and so forth in it. That's another $100 or so.

There'll be about $50 of incidentals; fluids, other things you take off that are worn out enough to need replacing like brake pads, and so on.

You've already found out that you need a spacer to install those gears; another $60 there.

If your 2.73 is not posi, then no matter how much money you spend on it without putting posi in it, .... it's still not posi. Kind of like putting a $10,000 custom paint job on a Kia Rio; doesn't matter how nice the paint is, it's still a Rio.

OK, now I'm looking at that, and I see $510 up there so far IN ADDITION TO THE GEARS, AND YOU STILL DON'T HAVE A POSI.

Is the risk of failure of the gears, which would of course pour $450 of that $510 into the trash, REALLY worth taking? Think about it.... $510 to take what you've got now and assume a HUGE risk of getting to re-spend almost all of it again; or, sell the used gears to the next "greater fool" you can find, and spend the same $510, plus the diference between new and used gears ($140) and have something with NO risk? (keeping in mind that NOBODY will warranty a gear installation of used gears, for some odd reason or other)

It would be different if you could do the labor yourself; but, compare $510 and HUGE risk that you assume all of YOURSELF, vs $650 and NO RISK.....

I think you'll quickly see that those used gears are worthless to you. They're only a drop in the bucket of the total cost, and will cause you more headache than they'll save you money.

 

sofakingdom: I guessed you guys could obviously infer that i was paying to have someone do it when i said installation would cost so much. but maybe that was to much to ask. The gears were (60), installation labor is (200), and the basic installation kit is (30), plus the spacer (60), and like you said some unmentionables like fluid and what not (5I0) Im not the greatest at math but that only adds up to 400.....And what is all this talk about not having posi. I have a posi rear end so why would a gear swap change this (no kia rio here dude) thanks alot for the input

 

Right, I included that you were going to have to pay to get it done, and stated so in my little analysis. Just so we were all clear about that, since you didn't come out and say it.

You also didn't tell us that your existing carrier was posi. Which is a bit unusual in itself, not the high-probability combo, since most of the cars that got the low-performance grocery-cart gears also got the low-performance carriers.

We're not mind readers here, you know. If you don't post it, all we can do is guess. Like I said, "If it's not posi...." and "Since you're asking...."

OK, all that aside: I'm hearing you say you're going to pay somebody to put it together somehow with NO NEW shims and NO NEW carrier bearings; and you're going to get NO WARRANTY (unless whoever is putting the gears in is willing to warrant somebody else's used gears, which I or anybody else I know who knows how to set up gears SURE AS HELL wouldn't do); and you think you're going to have about $400 in it. Stop me if I'm wrong anywhere there.

As opposed to doing it RIGHT: same $200 of labor, $100 FULL kit with ALL NEW BEARINGS AND SHIMS, and $200 for NEW gears WITH WARRANTY. And at the end, a completed job WITH A WARRANTY (the low-bid guy DOES guarantee his work if he uses new parts, right?).

The basic situation remains the same. The used gears are only "saving" you a couple of pennies off the price, and they're making sure you're getting NO WARRANTY OF ANY KIND.

So it's your call.

Still doesn't sound very smart to me. Not that I would know "smart" even if it slapped me in the face though.

But if that's what you're already determined to do, as it sounds like from the overall attitude of your reply, then there's not much point in your asking for, or my giving you, an experienced opinion. It sounds like you're only looking for validation and reinforcement (somebody to tell you what you want to hear), and you aren't interested in common sense if what you've already decided doesn't agree with it. And that's OK with me too, since after all, MY GEARS are just fine. There's nothing that says you have to do what I say. You can do whatever you want. It's your stuff and your car, after all.

Good luck!!! You're going to be needing it.

 

help me understand why it matters whether or not i have a posi rear end or not? considering that had nothing to do with my question about installing gears i dont understand why you would use that as part of your "analysis". And it obviously is not that rare of a combo because i know several people who have it as well...but it my just be a huge coincidence. But thank you for your advice

 

Many 3rd gens didn't come with a factory posi, don't ask me why, I would never make a "sports car" without a posi... Then again I also wouldn't make one a V6, or... g0d forbid, FWD, but hey they exist
Most TBI cars didn't get posi, some TPI ones didn't, I don't think any V6 cars did, etc etc....

He assumed you didn't have a posi, such that a gear upgrade is only half the battle, getting the posi (assuming you didn't have one) would be the other half. You'd have to redo the install later when you got the posi, so it'd make little sense to do all the work of an install, only to have to do it again when/if you decided to get the posi unit.