im thinking about buying a used rear end out of a 85 monte carlo ss for my 85 el camino. i heard the monte ss rear end has posi track and 3.73 gear ratio.. i was told it would bolt up with no mods. at all . is this true . could anyone give my complete specs on the ss rear end including tire size, meaning my elky has 14" wheels ..thanks for any advice..
85 monte carlo ss rear end
- Thread starter hddave1
- Start date
- Status
Not all SS's came with a posi. It was actually an option. If the SS has the sticker in the trunk, check that for the code G80. G80 is the code for posi.
83-84 SS's have 3.73 and maybe 85 as well. 86-88 SS's have 3.42 gears.
SS's came with 15" rims, but your 14's will fit fine. It will bolt right in to your car.
83-84 SS's have 3.73 and maybe 85 as well. 86-88 SS's have 3.42 gears.
SS's came with 15" rims, but your 14's will fit fine. It will bolt right in to your car.
Jman said:
I think you typo'd that one Jay - it's the other way around (83/84 have 3.42's and 85-88 have 3.73's) 8)
And yes - posi was an option. In my experience, only about 30% of SS's had it from the factory.
ok let me catch up here.. if i want a rear end with a 3.42 gear i need to look for a 83-84 model ss.. if i want 3.73 i need to look for 85-88 models.. let me give you some more info about my elky.. its a 85 with a 250hp crate engine.. i have a th350 trans and the elky gear ratio is 2.41.. im getting super bad mpg and i was told it was my tall gears.. i was told if i went with a rear end from another g-body car with a gear ratio from 3.08 to no more than a 3.73 it might help.. im thinking a 3.42 would be a good match for my setup..the car, so i was told is very heavy and im working my engine to death with the tall gears im running..this is by no means a hotrod nore will it ever be but im just wanting a daily driver that looks good to cat around town or even hit the highway for a long trip.. this will be my first rear end swap for myself and im wanting it to be as painless as possible..so after all that being said what are my options, what should i ask for when looking for a rear end.. thanks guys
honestly with a th350 i'd look for a 3.08 axle. 3.73/3.42 will be too high (numerically) and your rpm's will be too high. it would work great for the drag strip though. if you swap to a 200r4 trans with 3.42 or 3.73 gears then you'll have overdrive with low highway rpm's and good acceleration. power and mileage. 
would i be able to tell the difference from the 2.41 i have now to a 3.08 gear..im looking for a gear that will move this heavy car and still give good mpg for a v-8 i mean..megaladon6 said:honestly with a th350 i'd look for a 3.08 axle. 3.73/3.42 will be too high (numerically) and your rpm's will be too high. it would work great for the drag strip though. if you swap to a 200r4 trans with 3.42 or 3.73 gears then you'll have overdrive with low highway rpm's and good acceleration. power and mileage.
The Th350 is not an ideal mileage trans. As for what ratio to run without an overdrive, it depends on what kind of driving you do. If it is mostly highway, stick with the 2.41 with these gas prices! However, it is not good for city mileage as it requires more throttle to get it moving. I have a 3.23 with a .67 overdrive and have found it a great compromise. Good acceleration and good city mileage. It is actually better with the 355 I have now than it was with the 231 V6 for city MPG! I have not had it on the interstate since I switched the axle as the car is now in auto body hell awaiting me to have time to finish it. The best part is I only spent $50 for the axle out of a V6 high altitude car. It is not a posi, but I will be fixing that soon... As for other ratios, my Frontier has a 3.54 gear and .7 overdrive factory with 215 65 15 tires on it and it revs pretty high on the interstate as compared with the Cutlass. It's a 4 cyl and can't even get 30 mpg hwy. For reference, 215 65 15 would be the OEM tire size on a MCSS, turbo Regal or 442 Cutlass. It was also used on F bodies with 15 in wheels like Z-28 and RS Camaros.
Also, the posi case that comes with a MCSS is not very good. It is an Eaton Gov-Lok which is not known for longevity.
Also, the posi case that comes with a MCSS is not very good. It is an Eaton Gov-Lok which is not known for longevity.
actually the posi varies but it is NOT the gov-loc. it'e usually an eaton or auburn cone type. the s-10's did commonly use the gov-loc POS though.
- Status
