Dewey316

well, i just installed New Richmond 3.42's and an Eaton Posi.

man, what a blast the car is to drive now, the 3.42s put me right in the powerband, after the change i am wondering if 3.73's would be too steep for TBI.

the posi is great too, sideways in 2nd gear is mucho fun!


anyway, the techie stuff, the install went really smoothly, i actualy used all the factory shims and we were dead on with those, richmond spec'd the gears at .008" backlash, and with the factory shims we were just a hair under .009", not worth trying to find shims that are a .001" diffrence, so we left it there. also with the factory pinion shim, the wear pattern was perfectly centered on the forward side of the gear, the reverse side was a little bit to the inside, but that happens.

anyway, for anyone still sporting 3.08's or those of you blessed with *eek* 2.73 , upgrading to 3.42s and posi is def. worth it.

i am going to the track on saturday night, so i will have track times and gains up sometimes next week!

r90camarors

Awesome to hear man. Good job on the setup as well.....the rear end is the only thing in the car I am not willing to mess with other than changing the gear oil. Gears and Posi are the biggest sotp improvement aside from an engine swap or spray

Dewey316

ya know, i was really scared to do it to, but my mechanic friend helped me, showed me what to do, let me use his shop/tools, and it really isn't that big of a deal, you just need to make sure you check the specs.

now if the shiming hadn't been dead on, it would have turning into alot more work, as we would have had to keep trying diffrence shims to get it correct. but he said usualy the factory shims are dead on, because the manufacturing diffrences are usualy in the housing, and not the gears.

IROCaholic

Congradulations man, yeah I normally find the jobs that are supposed to be the most complicated turn out to work out better, and it feals really good to try something new . I need to put a new gear in mine , my 3.08 is killing me . Let us know about your times later. Good luck.

SilverSub122

my 3.42's are sitting in the garage cause i havnt had time to put them in yet, i also need to figure out what spline axles i have so i know what posi to get, im really looking foward to getting them in and mashin on it. should i get an install kit from summit when i go to put them in?

Dewey316

yes get an install kit.

i got the ratech deluxe install kit, because it included axle bearings and seals. but any install kit would work. i would also recomend getting new axle bearings and seals when you do this, all you need to get the old ones out is a slide hammer, and then you can use a hammer and a socket to tap the new bearing in, and the seal i used a hammer and tapped in as well.

miacamaro305

my 89 camaro rs has a stock posi in it i plan to put 3.42 gears in it by the end of the summer.do i have to buy a diffrent posi unit?or just install the gears?how much does a shop charge to put the gears in because i dont know how to do a gear swap or anyone in miami florida willing to help me out?

Dewey316

it depends on what carrier you have, and what gears you get. if you have a 2 series carrie, you need to either get gears for a 2 series (aftermarket companies make them in high ratios) , or you need to get 3 series gears and a 3 series carrier.

i would guess a shop probably charges quite a bit for a gear swap, it really is quite a bit of tedious work.

btw, i didn't know that RS's got posi from the factory..hmmm.

miacamaro305

well mines it a v8 5.0 tbi and all the ones i have seen or ask people they came with 2.73 posis.i have a second series carrier and richmond sells 3.42 for this series for 170 bucks,now how much is the install kit and how do i know if my 10 bolt is 7.5 or 8.5?about how long it takes to do a gear swap?

Dewey316

you have a 7.625 rear, but richmond will sell them a 7.5" and the two sizes are innerchangable.

the install kit is about $90, plus you need gear oil and posi aditive.

it took me the better part of 2 days to do it all, since i took the rear completely out of the car. also if you are going to do it, you need a dial-indicater for checking backlash, and access to a press for the bearings.

miacamaro305

whats a posi aditive?do u know how much a shop charges?

Dewey316

posi additive is just a little bit of fluid you add, it is actualy a friction reducing agent, so that the posi clutches will slip a little.

i have no clue what a shop charges, but there is alot of hours of labor into doing it, so i would guess a few hundred dollars.

avro206

cool--I would be very interested to know the differrence in your e.t. I have the deaded 2.73 open--I know where I can get a 3.27
9 bolt posi intalled for $550---thats Canadian $$...sure would be nice to get even tire wear!

miacamaro305

i have a 2.73 posi why is it that other rs camaro dont have posis but all my freinds rs have it?

SilverSub122

that is odd, the RS's (including my 89 5.0 tbi) that i have seen or heard of didnt come with posi from the factory. did the previous owner put it in there? if you have rear disk brakes then that would be a good indicator that the whole rear was switched out. but if not i guess you just got lucky.

miacamaro305

nope drum rear end i think it original from factory

Dennis91RS

little does everyone know as far as a stock TBI 5.0 motor goes a 2.73 rear is just as good as a 3.42 in the quarter mile
think im kidin not!

yes a 3.42 rear is quicker out the hole but thats it

with 3.42 gears a TBI 5.0 will be done by the 330 foot mark

with 2.73 the car is a slug out the whole but it pulls at the top of the track

i wish i had of gone to a 3.08 or 3.23 rear on my RS that way its a bit quicker of the line at still pulls to about the 1/8 mile

MrDude_1

theres one way to check.... look at your RPOs... look for a G80..

miacamaro305

what do u mean pros?

SilverSub122

the RPOs are all the codes on the sticker in the center console glove box thingy, ya?

tbfirebird

Thats what i was thinking because its like a mountain bike the 3.42 are like 1st gear on a pedal bike and the 2.73's are like 6th gear at first the 1st gear gets you but then you start to pull at the top so is it really going to drop your times alot if i were to switch to 3.42 but then i dont think i need that because im gointo get a 383 stroker.Maybe supercharged :hail:

89fastlookinRS

Yes, 3.42's would be the biggest you would probably want to go in a stock 305 tbi setup. But if you plan on major engine mods such as cam, heads, intake, etc. etc. Then 3.73's or even 3.55's would be better because you still have the power to pull that kinda gearing at the end of the 1/4. So when looking at peoples results and thoughts on their gear choices also look at their engine mods and see if they have the setup to match the gears.

It's all about getting a whole setup to work together the best...

spatter1

I don't know about a RS having a posi from the factory. I believe that it was an option on the IROC not the RS. I have looked at many (worked in a juckyard for a couple of years as well as a tech) and I have never seen a RS with a stock posi unless it was swapped in.

pat12spe

I was thinking about doin the posi switch also. I have an open ended rear - tires spin opposite when you rotate one side. I was told to go with a 3.73. I'm kinda clueless when it comes the the rear part of the car. Is this all I'd need to do the changeover? I was told to get:

10 bolt 7 1/2" carrier
3.73 motive performance gears
install kit

I have a 305 tbi with a lot of mods like headers, hollowed cat, flowmaster exhaust, ram air II hood, open element with k&n air filter, and a burned chip. I am planning on either going with a 350 or a 383 sometime next year so the big gears would work better with those engines. I was just told that these items would just go right into my existing 10 bolt rear. Is this true? or would I need to go with a whole new rear? Any help would be appreciated. Thanks.

spatter1

There are aftermarket posi units that fit in the stock housing in place of the spiders.

Chuck!

2.73 gears are only useful if you're driving 800 miles to work everyday. I was barely pulling into 3rd when my car was stock on the 1320, useless.

AJ_92RS

I have.

AAMOF, there's one in Kankakee at ACME Auto Parts (scrap yard). It's an '88 coupe with GU2 and G80 in the RPO codes.

We asked the owner (Mike) how much. He said $250, and we didn't even tell him it was posi. We said "Fuq that!!"

I can't say that it's still there though. That was probably 6-7 mos ago.

spatter1

Must have been really rare!