Best PS Gearbox for Saginaw

F

FJKen

Joined
Jan 12, 2003
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31
I'm prepping for a PS conversion on my '76 FJ40. Got a gearbox from a 1986 Blazer, but I'm hearing that it's better to use the gearbox from a GM car due to the superior number of rotations. The Blazer box gives me 3.5 turns, which should be ok. Anybody got any experience with using a GM box from a truck v. a car? How many rotations from a GM car gearbox?

Thanks fellas!! :D
 
W

wheelie

Joined
Apr 22, 2002
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64
not sure, but i think the reason ya use the ps out of a car is because it mounts to the inside of the frame. where most conversions mount to, guess ya coud do it on the outside but why?
 
hammerhead

hammerhead

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Wheelie is right. The truck box mounts on the outside of the frame and unless you are using full size axles you dont have room. The 4x4 truck box has the additional problem of the arm working in the wrong direction. GM 4x4s have a strange arrangement where the steering box accuates front to back. The car style sag box mounts inside frame thus not interfering with front wheel clearance. It also has the arm pointing rearward for left and right steering travel. Also, if you look hard enough, you can find the big brother to the 3 1/8" piston car sag. It is a 3 1/2 " piston sag in the same casting.
 
F

FJKen

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Jan 12, 2003
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Thanks Wheelie..the ps box from a truck looks the same and mounts just as the ps box from a car. I believe it's just the internals that are different in that a truck box doesn't have the same number of rotations. I'm just wondering if anyone has used the box from a GM truck or SUV and had success.
 
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FJKen

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Jan 12, 2003
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Thanks Hammerhead! I'll go check out the box from the Blazer but from what I remember it doesn't look much different from a GM car box. It mates up nicely to the scab plate that's part of the Downey kit that gets welded to the inside of the frame rail.
 
hammerhead

hammerhead

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Look again dude. I just finished a cross over steering on a blazer and they dont use the same box as a car. It is a mirror image. The mounting points are on the opposite side.
 
F

FJKen

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Jan 12, 2003
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Hammer.. I looked again. The 1986 Blazer box looks good. The spline facing the frame rail with the pitman arm on the bottom and the flat mounting side mating up with my scab plate that mounts on the inside frame rail on the driver's side. Is it possible that the '86 Blazer used a different box?
 
F

FJKen

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Jan 12, 2003
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or... I've got a mislabled ps box from the junkyard!
 
T
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Feb 19, 2002
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[quote author=FJKen link=board=1;threadid=4657;start=msg35216#msg35216 date=1061918178]
or... I've got a mislabled ps box from the junkyard!
[/quote]

Which way does the pitman shaft turn when you turn the input shaft? If that is correct you should be OK. But some GM boxes were mounted behind the front axle and have "reverse" rotation (i.e. pitman arm mounted pointing forward instead of back.)
 
F

FJKen

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Jan 12, 2003
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Looks like the box is ok. I think Hammer is right about the Blazer box..at least from what I'm hearing. The box I have is marked "4 x 4", Blazer 1986. I have no idea if that is correct, but it looks like every other auto GM box I have seen. The conversion starts tomorrow, so I guess I'll figure it out real soon...
 

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