help

[blackdogg442]

ok bought a posi rear from a MC SS. i know it will bolt up. but will i need to do anything to the u joints on the drive shaft. and can i use all the break stuff drums lines off the rear end in the car. the SS one dont have all that.
also want to swap in 200r4 have 200m read all kinds of posts. some say it will go in no mods other say crossmember must be longer. stuck on all that.

new to this and just need to get car back on road with little down time.
thanks Jrod

 

[Blake442]

What year is your car?

The rear axle assembly is completely interchangeable. The only difference would lie in what year your car is, and if it has SAE or metric wheel studs. I believe '78-'81 are SAE, and '82-'88 are metric. I might be off a year...
Everything else will swap over just fine.

If you're planning on swapping from a Metric 200 to a 200-4R, you'll need a different crossmember.

 

[patmckinneyracing]

It does depend on what your car is. I did the same swap in my 80 malibu. The car origionally had a 305 with a 200 transmission. Can't tell you if it was a 200R4 or not. Anyways, I kept the factory crossmember and modified it for dual exhaust but that was it. I put in a 350 with a 350 transmission. Came across a SS rear end and swapped it in. The brakes on it were old and I had already spent money on completely brand new brakes on the malibu's 2.29 dog leg rear end. So I just swapped all the brakes over with no problems.

The only problem I had came later when a tooth of the pinion gear chipped off and made one helluva noise. I had the whole rear end rebuilt just not the gears themselves. After that I had the same guy rebuild the whole rear end with Yukon gears.

Also, it depends on what year the rear end came from. 83-85 had 3.42 gears and 86-88 had 3.73 gears. Most came with auburn posi's, correct me if I'm wrong (mine did).

 

[Blake442]

'83-'84 had 3.42's because they had TH350's.
'85-'88 had 3.73's because they had 200-4R's.

 

[blackdogg442]

my car is an 1981 so i would have to change wheel studs. the rear end has 3.73. still would need only a cross member to put in the 200r4? all should bolt up?

 

[custom442]

my car is an 1981 so i would have to change wheel studs. the rear end has 3.73. still would need only a cross member to put in the 200r4? all should bolt up?

That's if your driveshaft is the correct length. Some people are lucky, others arent. After you install it and have all 4 wheels on the ground check how much clearance you have on the yoke. If it's much less than an inch (closer to 1/2") then you need to shorten the driveshaft

 

[Blake442]

my car is an 1981 so i would have to change wheel studs. the rear end has 3.73. still would need only a cross member to put in the 200r4? all should bolt up?

No need to change the studs... just buy some metric lug nuts. Lots less work

 

[dudeface]

4 speed crossmember goes almost 90 degrees to the frame, where the 3 speed crossmember is at an angle forward from passenger side to driver at about 30 degrees ( best guess)
looking at the crossmember out of the car.........if one end is cut at an angle, its a 3 speed x-member. if both ends are square.......4 speed


peace

 

[85 Cutlass Brougham]

You will need a TH 200 4R transmission mount and crossmember to swap it in place of a: TH-350, Powerglide or TH200. They all use the same driveshaft when used with a 7.5/7.625 axle assembly. If you use a 8.5, there is a 1 in difference. Most likely, you have a 7.5. If so, it should all just bolt right in, and the brakes will interchange also.

The biggest issue is the transmission crossmember. If you have a 1984 or newer car, the mounting position will exist. If not, you will need either a bolt in or weld on frame mount extension on one side.

 

[blackdogg442]

What is the web site that you can get the crossmember? and how do i tell if its a 7.5 or 8.5 count the bolts on the back?