i have 2.24 gears now in the stock rear end. id love to see disk brakes and 3.73 posi in it for the future. what is involved with this kinda swap? is there somewhere i can order this stuff or do i piece if together at junk yards? what is the best way to go on a limited budget and what parts will i need.
1985 pontiac grand prix rear end
- Thread starter PiZZaMaN
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Well, it all depends on your level of patience and the kind of junkyards you have available. If you find a Monte SS, you have a 3.73 axle ( unless it's an 83, then it's a 3.42). If you want an axle to take abuse, the rare 8.5 axle out of either a 84 or newer 442 or turbo Regal is the best choice. Not the cheapest, but the best junkyard solution. For brakes, you can get a kit or fab it yourself on the 7.5/7.625 axle. For the 8.5, you can use the brakes off almost any GM car with rear discs. The flanges are the same, but I don't know if the axle length is too. I know on some Ford 8.8's, the axles are a little longer than their drum brake counterparts. If you could figure out how to adapt a Ford 8.8, you'd have a good axle for cheap with potential to swap factory brakes too, but you'd need to redrill the axles and rotors to a GM pattern.
what kinda money would i be talkin about if i just bought everything new to do this swap, entire rear end all thats needed for this to bolt right up to the factory mountings
Cheaper - Easier way to convert to 3.73
Hi,
I switched my 83' GP with 2.24 one wheel peel to 3.73 posi for about 10% of the last cost posted. I used a replacement posi unit and gears bought on e-bay.
If you are going to posi you can pick-up a used posi and gears on e-bay. Shop carefully and be willing to wait for the right set. Or, you can buy replacement gears that bolt to your stock carrier (need a thicker after market gear since your unit is a 2 series). This way you can split up the costs but the gears now, install them, drive for a while and buy the posi later. Just remember to buy a matching 2 series posi unit. This is more work so if you can afford it, doint it all at once is best, and actually cheapest.
For rear breaks, get a set of 4th gen rear discs. With a minimal modification to the flange at the axle, they basically bolt right up, add an adjustable pressure regulator and you should be able to dial it in.
My guess is with some pacience and creativity you can do this whole conversion for about $500.00 +/-. It might be more work but it is cheaper and do-able. If I can change a set of gears and a posi anyone can do it (I am Stoopud). Get a book, buy the tools, and take your time.
Good luck whichever way you go.
Stoopud
Hi,
I switched my 83' GP with 2.24 one wheel peel to 3.73 posi for about 10% of the last cost posted. I used a replacement posi unit and gears bought on e-bay.
If you are going to posi you can pick-up a used posi and gears on e-bay. Shop carefully and be willing to wait for the right set. Or, you can buy replacement gears that bolt to your stock carrier (need a thicker after market gear since your unit is a 2 series). This way you can split up the costs but the gears now, install them, drive for a while and buy the posi later. Just remember to buy a matching 2 series posi unit. This is more work so if you can afford it, doint it all at once is best, and actually cheapest.
For rear breaks, get a set of 4th gen rear discs. With a minimal modification to the flange at the axle, they basically bolt right up, add an adjustable pressure regulator and you should be able to dial it in.
My guess is with some pacience and creativity you can do this whole conversion for about $500.00 +/-. It might be more work but it is cheaper and do-able. If I can change a set of gears and a posi anyone can do it (I am Stoopud). Get a book, buy the tools, and take your time.
Good luck whichever way you go.
Stoopud
My current rear axle is a 3.23 open diff unit that I paid $50 for at the local U pull it place( they were optional on 3 speed 231 V6 cars for high altitude. Look for option code GU5 on the trunk lid data sticker). I also have a old Gov Lock posi out of a Monte SS that I plan on using, and I paid $75 for it. I found the disc brakes from a 94 Camaro ( and foolishly didn't pull them!) and the price was $10 per caliper, $12 per rotor. The nice thing about the new parts route is that it will likely get you a Ford 9 inch from somewhere like Currie that will bolt in and be almost bulletproof. The bad thing is that you have a 150hp 305 that will never use the strength of that 9 inch, so it's not money well spent unless you plan on significant upgrades. I have around 350hp/425 ft lbs of torque according to Dyno 2000, and my engine almost exactly matches the test engine on Comp's web site for the cam I have, so I know it's a fairly accurate figure. I run the 7.5 just fine, and my G body was (unfortunately still is sometimes) also used as a pizza delivery car with the current setup, so you know it's been beat on.
If, as your screen name implies, you use this as a pizza delivery car, you will hate the 3.73's with the TH350. It will kill any hope of fuel economy. I get 16mpg around town right now with a TH200-4R and the 3.23's spinning 225 60 16's.
If, as your screen name implies, you use this as a pizza delivery car, you will hate the 3.73's with the TH350. It will kill any hope of fuel economy. I get 16mpg around town right now with a TH200-4R and the 3.23's spinning 225 60 16's.
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