How much of a difference in feeling/power does a posi rear end make?

is 250$ too much to pay for a 2.73 Iroc posi rear end?

How hard would it be to swap this with the stock 2.73 rear end?

 

if the gear ratio stays the same you won't feel much differance, less spinning since both tires will be digging in instead of one. it's a direct swap.

 

if there's one thing I learned from drivetrains its that 2.73 gearing absolutely SUCKS. it's one of the lowest gear ratios GM has ever produced. Posi won't really show much help when you're still turning the rear 2/3 the speed you'd like to be at!

 

It will help with traction off the line since you are using btoh tires instead of just one. If you are sending power to just one tire, it is more likely that it will break loose and spin... get it to both tires, and you can have much quicker accelleration thorugh better traction with both tires spinning.

 

Yeah I never noticed how much different an open rear is than a posi until I got used to driving my 90 with a zexel rear then went over to driving my 89 2.73 open rear TBI car. The 89 turns easier when doing a U-turn but when you pick up speed it feels real loose like the tires are going back and fourth sharing traction.

 

in the last 2 weeks, ive swapped rears in my car 4 times....

gears make a huge diff... but the posi..


well it is un-noticable in a good way... let me explain..


say you're pulling out of a side street and you hit the gas... with a open diff you can very easily spin the one tire.... or atleast feel it slip a bit... annoying...

with the posi, you dont have that problem... both tires do the work, and the car just glides smoothly away.

i noticed no diff in low speed turning either... but when im banging thru the gears at the strip, the car goes straight.. none of that tweek to the side for a second stuff.....


now, its been warm and sunny for the most part these last two weeks... i havent driven it with a posi in the rain yet... but from your username, i'll assume you dont get much rain either...

 

hehe thanks guys, i think ill wait it out till i get a chance to bag a higher ration posi trac rear end.

what would the best ratio be for a total stock 91 rs lo3 though?

 

ratio depends on what you want... 273 is cruising/gas milage gearing, 323 is 1 on a scale of 1-4 level performance/good gas milage gearing, 342 is 2 level performance/ ok gas milage, 373 is 3 on performance (very desirable gear ratio probably the most popular)/ ok gas milage... people debate about 373 and 342 being the best all depends what you want... you could even go 411 on the ratio which is all out performance f' the gas milage

IMO 373 is the gearing to get... 342 is more abundant but you can also buy a posi unit and put gears in it yourself just make sure you get the right spline count

I went from a 90 Formula with 323 to 373 and loved the difference it takes off like a bat out of hell off the line compared to 323.... i now have a 91 RS with an open rear and i dont mind it but need posi b/c of the traction issues... in an open rear one tire gets power making the power distribution uneven... in a posi both tires will spin when loaded and you will get even distribution of power which means more traction and better 60' times(acceleration increase)

 

i run 4.11's and it pulls real good but i am lucky to get 16 mpg

 

I have 3.42's and it's a posi, too. It gets okay mileage but it pulls nice and healthy, too. Depends. You paying gas out of your own pocket, and with the prices here in Hawaii being what they are, I sort of envy you for the gears you got.... nah, I'll keep mine anyway.

 

mine's limited slip 3.23 and it's terrible in the rain. if i even touch the gas it slides the *** end around everywhere. but it is nice to have it grip from both sides and it does shoot farrely straight down the 1/4 mile

 

need I say anything?

 

HAHA

 

I have 4.11's in mine. You can be going 25mph, floor it & light both tires up. Care must exercised that you don't do a 180. Posi's can cause this especially on wet roads.

 

Yes, 2.73's definitely suck. But imagine having the 2.59 gears that are in the vette rear ends!!!

 

yeah man if you have the knowledge and $$$$ go and buy a aftermarket set of gears and do it yourself you will get more for your money .....

 

Don't 323s and up really suck for traction? I have the 2.73 posi and cant stop spinning tires now. Or is that the point?

 

on dry asphault i can barrely break em loose with my tranny/rear combo (TH400/3.23 LSD). but i also have 275.60.15's on the back....

 

Aren't all posi's limited slip? I'm pretty sure they are.

 

I know well what a 'one legged wonder' is like... I have a 3.73 rear and no posi... to make a long story short, one tire has alot less tread than the other... about 1/8" difference. (yes, I am getting new rubber soon)

I'd kill to have a posi.

 

dont say that, id trade my posi (2.73's) for 3.73s anyday

 

the 89 may turn easier doing a u turn but i'd rather have a posi for V turns lol

 

Posi's (positive traction full name) is GM's name for Limited slip differentials.

Well depends on the brakes partially, if they are PBR's then the rear is worth more money.

Swaping would be direct, (no speedo gear changes, no brake line changes) maybe a proportial valve if you change brakes.

 

technicly, its fullname is "Positraction".... thats the GM marketing name for a limited slip diff......

of course, now all limited slips are Posis... who knew marking names would apply to more then the orignal product?? now excuse me while i windex the xerox machine with a kleenex.......

 

Hope 91RS has made a decision by now, that was over a year ago guys.

 

Me too

 

perhaps he works slow?

id be lazy if i was in hawaii...... lol