hi guys i have a quick question. i have an 89 lo3 with 2.73's and i am gettign a set of 3.42's from a v6. will the 3.42's go right in the rear my car has or do i need to get the whole rear from the 3.42's? thanks

 

Your existing rear has a 2-series carrier, and the stock 3.42s will only work on a 3-series carrier. The difference is the distance between the ring gear mounting flange and the centerline of the pinion. The 3-series carrier locates the ring gear about .400" closer to the pinion since the higher ratio pinion necessarily has a smaller diameter than the gas mileage 2-series one.

Other than that, they'd be a bolt-in. However, there's nothing spoecial about your L03 rear as compared to the 6-cyl rear; it would be less work by far and a better chance of success if you've never set up rear gears before, to just swap the whole rear.

 

well i know a guy that builds rears and said he would help me if i got gears but i didn't know if the 3.42's would fit right in with the 2.73's


edit: what all would i need to do to the rear to get the 3.42's to work.. because the kid only said the gears cause he needs the rear

 

You need a 3-series carrier, or a ring gear spacer.

I'd recommend locating a 3-series posi carrier. Maybe SLP still has some of their take-off Torsens, I don't know; if so, for $100 it's hard to beat.

 

don't mess around, be patient and wait to see if you can find a complete rear end with the 3.42's. Once you start messing around between series-2 and series-3 carriers, it can get ugly.

 

well what about a 4th gen 3.42's? are they different? or will they go right in?

 

If you want to use those gears and do it cheap, then get a spacer from Speedway Auto. Part number 910-48305 $44.95
1-800-736-3733 or www.speedwaymotors.com

 

great

thanks

 

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You can probably order it as a 2 or 3 series. This means that if you buy that posi and you want to use a 3 series gear (3:08 and numericaly higher), you need the 3 sereis carrier. Which means you are going to have to get the 3:42 gear at the same time, because a 2 series gear (the one you have) will not fit a 3 series carrier. There is no way that I know of to make it work.

A 3 series gear can be made to fit a 2 series carrier using a spacer, but it doesn't work the other way around.

 

That is wrong. They are 3-series ONLY. They took them out of Z28s and replaced them with the Zexel heavy-duty one as part of making their SS model. So since Z28s all came with 3-series ratios, the take-off carriers are all 3-series.

You're right, you can't possibly use a 2-series gear with a 3-series carrier; since the ring gear mounting flange on the 3-series carrier is closer to the pinion centerline, there would be no room left for a gear; and it's possible that with some ratios, the pinion would be large enough that the flange on the carrier would hit it even with no gear at all installed.

Think about what you're spending and what you're going to get for a minute before you order anything. $50 for a spacer so you can preserve your one-wheel-peel, or $99 for a posi. Which one seems smarter? Hmmmm...... let me step outside the meeting and consult my financial adviser before I answer that.....

 

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The $99 posi is a 3-series. You don't need a spacer to make it work with 3-series gears. In fact, most of them came out of cars that already had 3.42 gears in them, that being a common Z28 ratio.

The only thing you need to make the SLP take-off posi work in your rear is carrier bearings. But, since you'll be buying a gear install kit for your gears anyway, you'll already have those, because they come in the lit along with the pinion bearings, shims, crush sleeve, seal, etc. that you'll be needing.

Don't think for too long about one of those posi units "in the future", because their future days are numbered with a very small number. 2002 was the last year of the F car and therefore the last year of the SS conversions. So, however many they have now, is all there will ever be; and once they're gone, they're gone forever. Better get yourself one ASAP before you lose the chance.

 

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Don't be so sure about that. I reaserched my
application before I built the rear end on my T/A. I found out from Moser that the most common axil ratio for all 82-92 F-bodies includng Z-28's and TransAms was either 2:73 or 2:77(9bolt) all other ratios were optional.

 

I know about the lame ratios the 3rd gen Z28s mostly got stuck with. I wasn't talking about those, since that has nothing to do with the issue at hand. I was talking about the LS1 Z28s that the SLP take-off posi units that I was talking about came out of, since it's the SLP take-offs that I was talking about, not 82-92 Z28s. And even what you said isn't entirely true, since the L69 cars got 3.73s. Only the LG4 and L03 cars especially, and the TPI ones especially the 350s, got the lousy gears.

89 is the changeover year between 26 and 28 spline axles. It's impossible to predict which spines your rear has. From what we've seen in ohter people's posts on this board, you have about a 80% chance it's 26. Maybe higher, since the ones that seem to have the 26s the most are the 2.73 and 3.08 rears, the most common V8 ones. I would strongly recommend that you take an axle out and count splines BEFORE you buy parts; and if you find you have 26, locate a 90-92 rear to get axles from. Nobody in his right mind will sell you axles only. They'll sell you a rear, and let you leave everything but the axles behind; but you'll pay for a rear. They (junkyards) all know that they can sell that rear, and they're not going to destroy it just for you and accept less money just for the axles.

Yes, you'll need bearings. The easiest cheapest way to get what you need to install a gear set is to buy a {drum roll please} gear install kit. It contains the pinion bearings, pinion seal, carrier bearings, crush sleeve, an assortment of shims for both the pinion and the carrier, new ring gear bolts, a cover gasket, and gear marking compound. It's about $100 at your local speed shop or from Summit or Jeg's or wherever.

What's in your pic is the ring and pinion. You don't have to upgrade those because of your carrier; rather, you have to upgrade the carrier because you're going from 2.73 gears (2-series, with a huge pinion and the ring mounting flange on the carrier relatively far awy from the centerline of the pinion) to 3.42s (3-series, with a much smaller pinion and the ring mounting flange on the carrier reltively closer to the centerline of the pinion).

Gears are the same regardless of the axle spines. The rear in your car is a 7.5", or 7.6", or 7-5/8". They're all the same, just called different stuff. Not 8.25" or 8.5". The number of splines on teh pinion, where the yoke goes onto it, is 27 in this model of rear end.

3.42d is a good choice for an otherwise unmodified 305 TBI car. 3.73s are probably too much, because the car will accelerate quickly in each gear but not be going very fast when it reaches the "top" of each gear, and by the time the trans shifts, it will have spent a couple oif seconds just sort of hanging at the highest RPM it can reach. Too much gear will slow the car down if the engine can't rev enough (like a TBI motor can't) to produce meaningful power at a relatively high RPM. Plus, gas mileage can suffer drastically from over-gearing.

Yes, a carrier is often called a differential. Here's what one (this one is a stock posi, made by Auburn, out of about a 91 or 92 10-bolt). Imagine the ring gear bolted onto the big flange you see on this.

 

yes the differential is the carrier unit assembly

same difference, difference name/word

thats all


side gears of the diff assembly and also the axle shafts are the things that are splines 26 or 28 depending on the year

the pinion gear neck has another count of splines on it for the pinion yoke- in which is splined the same count as the pinion gear neck

if youve never completely disassembled an axle before then i suggest you find illustrations of an exploded view of an axle

find ones for a GM semi floater 7.5 8.2 8.5 or 8.875

they are all same construction and same parts palcement and such

only diff is size of the parts and spline counts and thats about it

other than if its posi unit or not

i could scan you some tech book illustrations if you cant find any with google images search,

http://www.google.com/imghp?hl=en&tab=wi&q=

but im sure google has all kind sof results with illustrations by now, there billions of info on the net now

good luck

 

I'm guessing he's probably done or gave up by now..

Oh, and RB, you rock.

 

im guessing all of the slp takeoffs are gone now??

 

I'm pretty sure I saw them in the latest summit catalog.

I ended up doing 3.42's the "hard way" You need the 28 splined axles form a 90-92 third-gen rear.

In hindsight, I should have just scored a 90-92 v6 rear-end, though I did luck out with a maintained, low-miles one for $10 and gave it an overhaul, with axle bearings and seals, all new brake components, and new brake lines, and synth lube.

3.42 gears and housings are in nearly every v6 car 86-92



Here's what I did. https://www.thirdgen.org/techbb2/sho...highlight=3.42