gear ratio in a posi rear end?

[blaqstar]

hey guys. i have a 79 malibu w/plans for 22in rims. my stock rear has 2.29 gears and no posi. theres a guys out my way selling a rear end, i believe from an 83-87 el camino, with a posi for $350. is that an okay price? anybody know what gears came in those? and also... i was thinking 3.08/3.23 were both good choices for my tire/rim set up that measures 29.5 to 30.5in diameter. any suggestions?

 

[Bad78Cutlass]

I'd go with 3.73's. Well with the 22's you will need 4.88's lol, just messin with ya.

 

[85 Cutlass Brougham]

I would go with no lower than a 3.42 with those 4x4 wheels you are using. I also would not pay that much for a 7.5 rear end. Try to find one off a Turbo Regal so that you get the 8.5 housing too. Those VERY heavy wheels will really tax the axles should you put any real power to them. People in Jeeps break axles with 4 cylinder engines if they go over 35 in tall tires and take them off road. Your axle will see similar stresses and shock loading if you choose to go with anything better than the lame stock engine.

 

[blaqstar]

haha... not quite 4x4. 22s with low pro tires. this is a weekend driver. also im working with a pretty cool 350 making about 280-290hp. can i get away with that? what upgrades would i need? (axles etc) or are you saying its a bad deal and start with the 8.5? a lot of guys think the 7.5 is okay and can take a fair amount of abuse.

any idea what gears are in those posi equipped units?

 

[85 Cutlass Brougham]

Depends on the axle. They can be anything from a 2.41 to a 3.73. They can take a fair amount of abuse with normal weight wheels and tires. Those 22's probably weigh 35-40 lbs each. For reference, my 16's weigh about 20 lbs each at most. You are talking about another 40 lbs of rotational mass you need to accelerate. Think of the axle like a fish scale. on one end you are holding it up, on the other end you have a fish. The fish is inertia keeping you from accelerating. You holding it up is engine torque. The drivetrain is in the middle. If you put too much weight on it, the spring in the scale will go beyond it's ability to spring back into shape and will break. The same goes for your axle, driveshaft, transmission, etc. It's a tug of war. Eventually, given enough force on either end without the other side giving in enough, the rope breaks. I have no experience with wheels that big on a G body because to me they do not make sound engineering sense (and I am going to college for Mechanical Engineering rt now...). It may well take it if you don't drive like I do. Then again, it may not. Remember that a heavier object resists movement more than a lighter one. So, it is easier to spin a lighter wheel than a heavy one. This is why many of the actual performance oriented import people run 15 in wheels that weigh around 9-11lbs each, like the Konig Helium or Volk TE-37 on their Civics and Sentras. They also run very light flywheels for the same reason. A Honda B16A (1.6 liter DOHC VTEC 4) with a 9 lb aluminum flywheel will rev VERY quickly, almost like a bike engine as compared to a stocker which has a iron flywheel that probably weighs 20-25lbs. Heavy rotating parts take a lot more power to accelerate vs light ones. Rotational weight reduction therefore is the best kind of weight reduction since it helps acceleration far more than static weight like hoods or doors. Also, with your 29.5 in tall combo, you are close to what a Jeep Rubicon has in stock tire height, which is 31 in tall, IIRC. The Jeep has stronger axles though, with a Dana 44 front, and a beefy rear. You have a GM 7.5.

 

[pontiacgp]

I'd be more worried about stopping the car with those wagon wheels...use the money to upgrade your brakes...

 

[blaqstar]

i have plans for the brakes for sure. i just wanna know what im gonna realistically be able to keep. id rather be safe than sorry but like most of us... im on a budget.

 

[blaqstar]

okay... so now im considering getting the 8.5 Grand National/T-Type rear end. how much should i be looking to spend on that? and is that my only option or my best option for something i dont have to worry about when i wanna occasionally mash the pedal?

 

[85 Cutlass Brougham]

It is the best option, but I have been trying to find one since 1996 with no luck in my price range. Expect to pay $500-1,000, depending on the seller, condition and whether or not it has posi. You could get lucky and find one cheaper, it's a luck of the draw thing. My advice is to run smaller wheels. Then, the car will look right, and people will be less likely to laugh at you. I dunno about everyone else here, but I laugh at people and point at them whenever I see a G body jacked up on large wheels.

 

[blaqstar]

personally im a fan, or an advocate even, of big rims on gbodys. its a growing trend out here in Calipornia. plus... i wouldnt take it personal if i saw you pointing and laughing saying 'That Doesnt Look Right' as i speed by you. i wouldnt hear you anyways. who cares about what the next guys thinks about the rims or paint or personalized license plate you might get? isnt that all personal? dont forget about one of the beauties of this whole car thing we love so much... choices! if i did my car to YOUR liking im sure i wouldnt be happy! and vice versa. haha...

so after all the hee hawin'... i saw the 8.5 w/posi and brakes on gbodyparts.com for $950! so i guess i'll keep looking too.

AMERICA!... F#%K YEAH!