ok guys so I have a 89 2.8 camaro...it's modded but I want to change out the rear end for a posi. I plan to drag race it so I want some short gears... I thought about the 3.42 posi or the 3.73posi but I'm not sure which to go with. which one would be better for my motor. or if you guys have any input on other gears that would work for me. I need to know quick because I plan on getting the rear end in about 3 weeks. any help would be appreciated!

oh and just incase you're wondering it has about 150rwhp. and no haven't dynoed yet. plan on doing that after my first race on the track in may!

 

you're going to drag race... with a 150hp 2.8.

Let me wrap my mind around that for a minute....

 

haha im more interested in how you think you have 150hp at the wheels on that 2.8

but on topic, are you running 1/4 or 1/8th

i prob wouldnt go to high on the gears as the 1st gear in these cars is pretty short as it is 3.42 at most

 

I'm only racing it to see how fast I can get a slighty modded 2.8 to go since no one has done it. and those who have can never seem to find the papers or remember far that case. so yeah I'm racing it for me and for those who wanted it answerd for so long. And
i said "about" 150 like I said idk for sure haven't had it dynoed it could be less who knows. but i run side by side with a stock 5.0 ( and not the new either, before you get smart" light to light. but that's besides the point. this thread is posted for one reason only either help me with some suggestion or leave this thread be. I don't need your b.s.

 

lol no one has done it? do some searching...it has been done

as for the HP....its less, i can assure you at best you might have(and i stress might) 130hp, and running with a 5.0(which you didnt say which 5.0 but ill assume TBI) it was probably a short light and you have way higher gears in your car stock than most v8 cars.

despite all this i did answer your question take it or leave it... you might have a 17-20sec 1/4mile

im running a posi with the stock 3.23 gears and as i said if you go up to much you will have no first gear at all and taking off in 2nd isnt an option with no hp

 

from the sound of it i think he means a foxbody 5.0, it which case im calling BS

as for the rear, a 98-02 4th gen rear would have better brakes, be newer and have decent posi units. That woudl be the way to go, but i dont think you need it.

 

ha i just always assume being on a thirdgen board people are talking about thirdgen 5.0s....however if its a mustang i agree with you

a 4th gen rear swap probably isnt worth the trouble for a 2.8....i dont even think i would bother to do that on my v6, and it has plenty of power

stock gears and posi on a v6 is really all most people need

 

yeah sorry about that response towards you pillsb. my computer never loaded the rest of the response you first left. I've look all over the web and haven't found anything. if I do it usually has a turbo or it's a hybrid. I will take into consideration about the gears and probably just get the 3.42posi or try and get the 3.45 that I saw a week ago. but as far as your statement the 1/4mile....20sec! is outrageous. I've seen stockers run 17.1 to 16.9's
oh and the 5.0 was a mustang I only beat him once but other than that we're side by side majority of the time. but yeah btp

 

naw i beat him once, barely...but i won't lie it was only because he missed 3rd gear. you could hear it loud as hell. usually only beats by a car and a half 2 at the most.

 

ive seen stockers in the 20sec range lol i only know of one v6 car(a 3.1 highly modified) that ran a 14.97...unfortunately that car went boom

 

heres a vid someone posted up online with a stocker running 17.06 1/4mile
<iframe title="YouTube video player" width="480" height="390" src="http://www.youtube.com/embed/05APaRXlVZw?rel=0" frameborder="0" allowfullscreen></iframe>

 

i think i will go with the 3.42 posi...only reason I need the posi in the first place is that i cant keep my damn car from spinning/chirping on a dig. I had 205 65, then stock 215 65, now I just got 225 60's put on the rear and it's still spinning/chirping when i take off

 

you might be better off with a little spin and a chirp instead of it getting complete tracking and just bogging out

im not a huge drag racer so i could be wrong on that

 

well I have an automatic so not to much worry on it bogging. and it's all about hooking up. i don't need slicks cuz it's not going that fast but traction is a must.

 

I've often wondered what my car would do going 0 to 60 and the 1/4 mile, but I wouldn't want to do it in front of anybody

 

(deleted post becuase SOOOOMMMEEEbody cant keep track of his windows)

 

sorry, posted on the wrong thread.. too many windows open..

fixed

 

hahaha we could arrange an all v6 night at a drag strip

 

at the national V6 gathering!

 

EXACTLY lol

 

My 3.1 was a 17 second 1/4 iirc.

Get LCAs, that really helped with my traction. A set of drag radials would give you enough traction to not need a posi rear end.

 

was it stock... and wat are lca's? right now i have on falkens

 

Lower Control Arms

Get Drag radials and have them mounted on a set of cheap rims.

 

DR's are expensive, my friend got some M/T's for his 67 stang. way to much. but i will consider it in the long run

 

Expensive compared to what?

A set of Nittos is ~300 bucks. 50 bucks for a pair of rims so you don't need to drive around on then. My 555rs have a lot of passes on them... they don't wear out if you are just running them at the track.

 

i see wat you're saying...then it would really be a matter of just getting the damn rims. for some reason there expensive out here. and if you go to the jy you will be lucky to find one

 

one more question all the rear ends are compatable as a complete rear end right? I'm pretty sure just want to double check

 

Sort of... on a true budget, no. You need one with drum brakes so the e-brake and brake lines match up. Also, your speedometer will be off if you change the rear end ratio.

 

As far as run times go, its a fairly known fact that a stock 2.8 will run 17s provided its running good, modded without boost or nitrous 15s is about the limit for a 2.8 or 3.1, you could get one into the 14s on iron heads, but the fact is most people that serious about power go hybrid or boost so it hasn't been done afaik.

As for the OPs question, to be perfectly honest, unless you plan on building your car up a lot, then getting a new rear end is pointless, you really don't need posi, and 3.42s as many have said is about as high as you should go with a 700r4 because of the first gear ratio being pretty low, I have a 3.4l in my car that probably puts out 200 hp and 240 tq at the crank, and it really doesn't spin bad at all with the stock diff, also posi isn't as good as 90% of the population thinks it is, it only adds about 10% traction increase, suspension setup is the most important thing for launching, tire choice also only makes about a 10% difference, not saying it doesn't help, just that suspension setup is more important, how bout instead a new differential you get some SFCs(subframe connectors) they will stiffen up the car letting it transfer power better and launch harder, will help handling and reduce chassis flex as well.

 

hmmm...I honestly never taught about the frame connector. trac bars and such yeah but not that. I had no clue on that one. thanks. but I won't lie I do plan on going crazy with it in a few years... just want to do N/A with it to see where I can push it you know. but thanks again...I know what's going on my list of things.
Oh and don't worry I've made up my mind I'm going to use the 3.42's as well. and will the 82-85 3.42 rear end fit my car without any problems? cause I'm doing a full on rear swap

 

All the 3rd gen rears will bolt up, as well as 4th gens, its different brake setups that will complicate things, but even if you do go crazy on mods, I would wait to do the rear swap, unless you're pushing 300+ hp its just not really necessary imo.
And a 4th gen is slightly wider, still bolts up, just that the wheels will stick out like 1" on each side.
But yeah, def get SFCs, imo they should be on every car, esp ones that get modded. As soon as I get my floorpan replaced I plan to get them.

 

will do on the sfc. and thanks for the reply on the rear ends really needed that

 

yup, I got one pass at 14.97. that was the only sub 15 sec pass that I am aware of for an iron headed n/a v6 in a 3rd gen. The car didnt go boom...just the motor. lol. All of the parts from it are sitting in the garage, too bad most of them are no good.

search for v6 camaro vs corvette z06 on youtube. thats a 15.13 pass, but still...

I would def go with some aftermarket lcas.

 

i have 3.73s in my rear end and a posi spend ur money on other things first and 373 are god but u run out of top end way to fast and to AM91Camaro_RS
im the 2ed on to run a 14.89 to be sed and nice vett race

 

14.89, maybe but, you were sprayin...i wasn't

 

Wish I had money to put mine back on the road and find out what mine will run....and 92camarov6, if you are running out of gear you should have your transmission built to use 4th at wot, just make sure you have it built strong enough to handle that as well, these cars top out at 120 with 3.42s and a typical tire size of 26", because they can only go into 3rd at WOT, gm figured they didn't have the power to go past 120 so why bother building the transmission to use 4th for wot, just uses it as OD for economy.

 

no 700r4 will shift into od at WOT from the factory...its not just the v6 ones. and yes, OD is designed for economy, not for racing.
my problem was running out of motor, not running out of gear. I ran 4.10s for a while then I changed to 3.73s. the change to 3.73 helped but it still seemed like it just didn't have the motor to really pull on top end at the strip.

 

o ye that would help its been built to the hillt so idk maybe im holding it in gear and AM91Camaro_RS ur right i do spray

 

hi, i would go with the 3:73 for sure. the engine will handle it no problem. just pay attention to find a good shift point.

 

would finding a good shift point matter with an auto? I dont think it should since it has a tvc and what not

 

Of course it matter, you always want to try to stay in peak power and or your powerband, regardless of transmission type.

 

I understand that...but wouldn't finding the shiftpoint only matter for when I'm manually shifting the auto? i'm asking only for knowledge. I don't know everything.

 

If you are trying to go fast its a given that you would be manually shifting....you should be anyways, especially if the car is modified at all.

 

Its alot of work but my rear end in my 3.1 was going out so I bought another from a junk yard. I swapped that into my car so that I had time to rebuild the origanal one. Im swaping a torsen differential into it, along with installing 12" rotors onto it. Probably overkill for my 3.1 right now, but im going to turbo it in the future. I have been slowly collecting the parts I need.

 

well I haven't dynoed my car yet nor gotten the gears...money issues came up. going to p.a.p this weekend to get the rear end. finally got the money...again. I still have one question that wasn't answered before. from 82 to 85 which rear end would be the best to get for the 3.42's. I've been going over a lot of my data as well for my horsepower. My math was wrong on a lot of stuff do to the fact that I was multiplying by 14%. which is way to high.I should only have about 125 at the RW's. but I did get the tranny done over. stge2, vette servo, tc and all. pulls real good. never new how much a weak link the tranny was until i swapped it. ran another 5.0 as well, my buddies 67 302. beat him by a car an half from a dig, but from a roll he just flat out murders me by three cars. but yeah input on the rearends please. going to get it this weekend. Imma get the 3.45 but only if I'm lucky enough to find it. other then that just the 3.42's

 

u have a 2.8 car it already has 3:42's dont waste ur money
take 110 bucks and goto the founders performance website and buy urself a set of tubular lcas and lca relocation brackets and make sure the rear shocks are good

pulling a rear end out of a v8 car even if its a posi will more then likley only have 2:73 or 3:23 gears and putting those in well u think u car is slow now those gears would kill any acceleration u do have

and btw stoock 2.8s in decent condition only put down about 100rwhp on a dyno

 

I don't think there is a 3rd gen that came with a posi 3.73, most if not all of the posis were on v8s, which mostly got highway gears. Unless you switch to 4.10 gears theres not much to be had in the swap imo, and even then, you don't need the whole rear end, just the gears.

 

Your 3.42's are fine, just toss in a spool or a LSD and call it a day...

 

82-85 3rd gens got 3.73's. and I'm doing the whole rear end because I don't have the time to really mess with the gears and all. sunday's are my only days off. so a quick swap is all that I really need.

 

Yeah, but 3.73 opens, or posis?