I have a chance to put some 3:23 gears in my trans am which currently has 2:73 gears. Do you think this swap is worth it. The numbers on the axle tube is 2hg for the 3:23 and 2hp for the 2:73 is this also correct??

 

I made the swap a few years back out of necessity.. the increase in acceleration is matched with a decrease in top speed. So figure this for the RPM it takes to run at 75 mph, you're only going 65 mph. basically Your speed is only 83% of what it reads. Now as for acceleration that gets a noticable boost, if you were just barely gripping the road before you'll chirp everytime now. Its not that bad for fuel economy and performance goes up. I don't have actual performance numbers in yet, but will have some by the 16th of the month.

 

If you're talking about switching the whole rears for a decent price, I would say go for it. But to buy new gears, install kit, and installing them, then I would say no it's not worth it.

 

what bout 3.23's to 3.73?? i was gonna do this with all new stuff... worth it?

 

Only if you have no intention of highway driving

The funny thing is that there are a fair number of cars doing 13s with just 2.73s. Your 357 has lots of torque, so I don't know if anything more, other than a posi, will be worth the considerable expense involved--especially for a daily driver.

 

IF you're running a modified engine. Worth every penny, in my book. If you're running a 700r4, with a 25 1/2 tall tire you'd be looking at about 2300 rpm at 70mph. I'm running a 410 and highway speeds are ok.

 

Hey, hows your car doing now with those 4:10s. Is your speedo still setup for the stock gears or did you ever get that changed?

Ben

 

what would it do for highway driving? someone was telling me that it would knock at least half a second of my ET. and since i have the th700-r4 tranny, i have the overdrive to cruise with on the highway and save my gas....would used gears be worth it? im gonna get the POSI for sure,, just not sure about the gearing.. then i dont even know whats involved to make the spedo right!

 

I swapped from a 2.73 peg-leg to a 3.23 SLP posi. It was a great mod. Plan on about 3 tenths dropping on your 1/4 mile. The car will lauch much faster and rev through the gears quicker. The gas mileage is not hurt too much, either. For a fairly stock thirdgen, with the 700R4, I would not recommend going any taller than 3.55's. Good Luck!

 

maybe ill just get rid of the peg leg unless i find some good cheap gears somewhere.

 

I would do the gears too, because if you buy a carrier you might as well get the series 3 so you dont have to buy a new one if you decide to upgrade your gears sometime. I would think it would be better to do it all at once. You might even look out for a used rear that already has posi and a gear set that you would like, because that would be cheaper most likely.

Ben

 

In the latest GM High Tech Performance they purchased a 4th gen Z28 Camaro with an LT1, 700r4 and 2.73 posi.

It runs 13s just like it is and gets great mileage.

So, isn't that what we're trying to achieve???

Sure you can go marginally faster with higher gears but it will cost you for gas in the long run.

If this is your daily driver, isn't the potential of easy 13s OK with you?

 

I was just gonna put the rear end from my 86 camaro in my 85 trans am. Since my trans am runs a lot better I want it to have better gears to. Thanks

 

im getting 11mpg as it is now.......ehh its jsut money

 

I had 2.73s in my 91 camaro and went to 3.73 and i like it but I wish I would have went with 3.42s.With the 3.73s you almost go threw first gear to fast and it doesnt stay in your power band long enough.But yea i would say going from 2.73s to 3.23s would be worth it.Youll notice a difference out of the hole and all aroung acceleration will be improved.

 

Yeah, if you want 3:73s, you really need an engine that pulls a little past 5k. Right now mine doesn't and it's doing nothing for me performance wise. I didn't lose any mpg either. I'm running 2k rpms @55 and 2500 rpms at 70. It's not too bad on the highway I don't think, unless you like going faster than 70 a lot.

 

my engine pulls till 6grand. havent had it past that yet. but i make it shift at 5500 cause of nasty belt squeal

 

Have you replaced the belts lately? Are they tight?

 

Hi Ben, the 410s are great. No more lope running 30 mph. Haven't been to the track yet though. I have to get some sfc welded in first. Speedo is fixed, although I feel it's still 1 or 2 mph off. I put in a 15/45 combo. The counter man at our local chevy dealer said they don't show a 46 tooth gear for camaros or firebirds.

 

The speedo gears aren't hard to change. Don't cost too much either. Lots of the v6 cars had 342s from the factory. Cheapest way would be to find a 91/ 92 v6 rear and go with the slp posi. Or put a locker in the peg legger.

 

the belts started to squeal bout a month after i replaced them. i have tightend them, loosend them, belt dressing...blah blah blah,,,,nothing works i tried lookin for them SLP posi units....couldnt find them anyone got a link?

 

http://www.slponline.com/view_produc...TNUMBER=64501T

 

99.95??????????????????????????????????????? what the hell is wrong with them?? thats a killer price! whats the quality of these? any problems?

 

im gonna need new axles now arnt I??

 

Yep, unless you have 28 spline already. Those take outs would probably be ok for a stock engine. BUT, you have to ask your self WHY are they taking them out. If you're planning on several mods, I'd pass them up. And go eaton first or auburn pro. Beings the rearend IS the weakest link.

 

The SLP posi units are meant for road racing, not drag racing. Keep that in mind.

 

hmmm well i just got some huge 275 bf goodwrench tires on the back, mounted on my 15's. i think im gonna go ahead and get the 3.73's now, and im still debating on the SLP posi, or something else. Its not like i drag race my car all the time, i have only been to the track once. i mostly just drive around messing with my friends off of lights and such.

 

I was wondering how gas mileage has suffered for people that did the 2:73 to 3:23 gear change......

I live in the City so gas milage would be needed............Also i take my car on road trips so a highway mileage would be great too....

Thanks

 

gas mileage...whats that?? i get 17mpg highway, 13-15 city without 3.73's and i plan on doing the swap. as long as your not on it all the time, you shouldnt see that big of a differance from what iv heard. my performance wise....i think ill have to saw WOW... i drive my car, then i get in my suburban that has 3.73's and i honestly think my suburban will kick my cars ***. but then again the burban has 340hp/400ftpounds out of a 496bb.

 

i get 21mpg out of my 83 CFi Z-28 with 3.73's and 700r4 trannie! the thing just keeps pulling.......................

 

when i switched form pegleg 273 to posi 323 it dratically helped acceleration and it didnt affect gas milage to bad that i noticed. It must be noted that i have a 2400 rpm stall as well but i still would recomend that kind of gear swap for a mostly stock car, plus then if you start getting really into mods, ditch the stock convertor to something higher and your back into the correct rpm range..

 

iv got a 2000 stall on my car and 3.23's and i shift at 5500rpm's 1st and 2ns and go through the traps around 3500-4000rpm's in 3rd i need gears!!!!

 

i had 2.73 inmy car and i enjoys not reving so high on the highway then i went to a 9bolt 3.45 and it is not to bad and the highway milage didnot suffer that much
then i went to 3.73 10 bolt its not that bad on the highway with the overdrive at 60 the engine is turning 2100 which is not that bad and at 80 it is turning 2700 which is still not bad with stock 245/50/16s

 

Swhaweet, run the 4:10's though a 94-97 T56 manual and you lug the motor on the highway. Problem (gripe) is that 1st is too steep and 2nd is too deep for normal steeet driving. I usually go 1,3,5 from a dead stop or 2,4,5 from a slight roll start. Another gripe is hitting all them gears quick w/o missing one. 2-3 is my binch but I got better now 3-4 is on my practice list. Such close spacing makes you look like a revvin' ******* (no offense) pulling from a red light next to a honda when all your trying to do is relax the right arm and left foot. They hear all the revs while your skipping gears and takin' it easy and they all the sudden asssume they can take you. Too bad an overly high street pullout IMO is taching (street wise 2,300rpm shift, loud exhaust) 1st at 5mph but 2nd is a little too much slippin for clutch wear... Hard to explain unless you've matched the combo. A bigger cam and 4:10's don't take to well to your CAGS (1st to 4th) shift at light trottle....


I guess i'm too bitchy... but I don't want to cook up the clutch doing 2nd starts.