Posi - Out a of 1977 Monte Carlo

[getchasum]

Had a guy call me tonight trying to sale me a posi rearend out of a 1977 Monte Carlo. Says it an 8.5 with 3.42 gears. Thought it may be the same rear end as the GN's.

Was wondering if any one knows for sure?

 

[charlief1]

It's the same Scott. Just make sure to measure it.

 

[DR BOOST]

It's the same Scott. Just make sure to measure it.

say what?

 

[charlief1]

say what?

The 8.5" GM is the same except for the trucks.:smile:

 

[getchasum]

It's the same Scott. Just make sure to measure it.

Charlie, Tell me what all I should measure and what should it be?

 

[xcessiv6]

its wider than a GN by 1" or so

 

[charlief1]

its wider than a GN by 1" or so

Huh? Then why do the parts books list the 8.5" GM carrier as all the same except for the trucks? The gear may be different but the carriers are the same.

 

[xcessiv6]

carrier is the center section, the axles are longer because the car is wider but check with Moser to be sure I had a 77 regal and pretty sure I am right plus older camaro and firebirds had 8.5 gears in the 70's you can use it but your wheels should stick out more. Just measure your 7.5 from the backing plates and the one out of the Monte carlo. plus the rear drums might be bigger to since it was a heavier car.

 

[pacecarta]

carrier is the center section, the axles are longer because the car is wider but check with Moser to be sure I had a 77 regal and pretty sure I am rightplus older camaro and firebirds had 8.5 gears in the 70's you can use it but your wheels should stick out more. Just measure your 7.5 from the backing plates and the one out of the Monte carlo. plus the rear drums might be bigger to since it was a heavier car.

a posi carrier is the section that the ring gear bolts to , and no they arent all the same there is a two series and a three series depending on the ratio of the gear needed , 2.73 up is 3 series and will work in the gn with 3.42s, many firebirds of mid 70s-80s(the most common years) were 2.41-2.56 (even most trans ams)

and the trucks were different in that they were govloc style posi and the carrier is totally different , it is a posi and will bolt into a gn but its design is not intended for what we do with a posi , its designed to switch to an open style above 35mph .. good for a 4x4 driving slow through mud but not good at the track , besides they are 30 spline so they require an axle change since our stock are 28spline


and all center housings (the section the axle tubes go into) arent the same either , the cam/firebird 8.5 rear wont work ..it was leaf spring w/ no perches for coils or shock mounts and most different in the housing has no upper ears for the bushings for the g body upper ctrl arms

on the 77 posi rear it has the ears and mounts the same as the gn rear ( besides the width i beleive the ears are spaced differnt like when you go to a 12bolt from the 70s cars which requires a special set of adjustable upper ctr arms .. you say 3.42s ..are you sure its a 77 rear and not a gn rear someone put into a 77 monte

 

[getchasum]

I posted all the info the guy gave me, at this point all I can do is go on his word. I guess I need to go look at it but it's an hour's drive one way. Says it has 60k on it & was stripped to bare metal & painted. I don't need it as I just sold a spare rearend I had but he offered me a heck of a deal.....cheaper than I can buy an open 8.5 Even though it's cheap...If it will not work in a G-body I have no use for it. Think I'll give him a call back to see if he can send pictures to save me a drive.

Anyone want to put a value on it based off of the info I posted up to this point?

 

[pacecarta]

if its a 77 , assembled unless they are fully rebuilt and someone will stand behind it ..as pulls they are only worth 100 bucks
if he pulls the posi and its a 3 series (not a 2 series with a spacer behind the ring gear) the posi brings around 200 an ebay and even here .
as a used rear if it was in a 77 (heavy car) even with just 60k the posi might already be used up beyond just clutches (clutch kit 130) if you need to replace the posi (400+ for an eaton) and for that matter the gears and the rest of the rear parts (bearings /races/seals) may need replacing and rebuilding and setting up a rear even if you are capable of doing the work isnt cheap , the gears(ring and pinion) are 220 and up , rebuild kit to install gears 100 , axle bearings and seals and possibly even the shafts might need replacement (another 250 even though with a gn the moser axles would be first on the list of things to do) and youve still got the brakes to redo (wheel cylinders/pads/hardware/drums/lines/ ebrake cables maybe even backer plates )