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GM G-body triangulated 4 link rear swap options

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11K views 16 replies 9 participants last post by  64nailhead  
#1 ·
My son just picked up an 80 Cutlass and we will be needy of a different rear axle as it currently has a 26 spline axle 7.5" 10 bolt that I'm sure won't make it with 5-600HP with sticky tires. From what I've found a g-body rear from an Olds Hurst or HO 442 or Buick GN are direct bolt ins, but they seem to be relatively hard to find (I consider hard to find as being more than $1K for used stuff.)

Is there a triangulated 8.5" that uses the same geometry for the links? Or are there one that the upper links' geometry is the same? If needed I'm more than willing to change the tube lengths and/or relocate the lower links, but I would prefer not to have to mess with the upper links.

Thanks in advance - Jim
 
#6 ·
Welding the upper eyes on a cast iron housing is NOT a good idea. You need to start with a 9 inch Ford or a 8 3/4 Chrysler rear end so that you can weld the ears on the housing safely.

Another problem with the G body cars is that the rear end is only 58 inches wide. This is much narrower than almost any other rear end, so narrowing a rear end is probably going to be required.

There are many places where you can buy a bolt in 9 inch, 12 bolt or Dana 60 for the G body cars. Any of these would be a better way to go. Even the GN and Olds 8.5 rear ends had 28 spline axles, so you still would need to upgrade one of them if you went that way.
 
#9 ·
big gear head said:
Welding the upper eyes on a cast iron housing is NOT a good idea.
Noted - and that was my concern also.

There are many places where you can buy a bolt in 9 inch, 12 bolt or Dana 60 for the G body cars. Any of these would be a better way to go. Even the GN and Olds 8.5 rear ends had 28 spline axles, so you still would need to upgrade one of them if you went that way.
Click to expand...
I'm asking, you don't think a 30 spline 8.5 is enough? I'm aware that I'll have to buy axles, Moser or Strange, but I was making the assumption that an 8.5 with 30 spline axles should be adequate. Please advise if you think I'm outta whack.

Thanks - Jim
 
T
#7 ·
#13 ·
Yes, I completely forgot about the Mustang 8.8. There is a company that makes control arms to adapt the FOX body 8.8 to the G body. I would recommend upgrading it to 31 spline axles. They were all 4 lug, so an axle upgrade would take care of that too. They are 59 1/2 inches wide, so you will be gaining a little bit of width. That can be taken care of with the correct offset wheels.
 
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