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Discussion Starter · #1 ·
Hi, I have a 4.56 gear in my 85 and want to swap out to the rear end of an 89 complete rear, rotor to rotor. Both are dana 44. I have read that there are problems with different mounting locations for some of the bolt on parts of the 89 rear end into the 85. I am doing this for two reasons. The 89 has taller gears,that is numberically smaller, and I believe the 89 has substantially lighter springs both items of which will be quite a relief for gas mileage and ride of car. I believe the rear of the 85 has a z51 spring so there should be quite a drifference. Also, will it require mods to the front springs stiffness wise if this is done. Thanks for any input.
 

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Discussion Starter · #2 ·
broken shock perch in 89 rear

Complicating the swap in the above referenced rear gear swap, is the fact that the shock perch has been broken in the 89. The seller says my part can be swapped to the 89 from the 85 alleviating this problem. Is this so? He also claims that I can have the alu shock mount welded back on, but it looks to be weak cast material, I dont think I can trust that a weld would hold at all even by a pro welder. What thinkest thou?
 

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You are better off just doing a differential swap. I forsee one problem wheel offset if you put the 89 rear in (if it even mounts up) you 85 wheels will stick out the fenders.

Didn't the 85 use separate drum type pads for the parking brake the 89 isn't like this.

Your just better off doing the differential swap and buying a a different spring.

I could be wrong and generally am though.
 

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Your just better off doing the differential swap and buying a a different spring.
:thumbsup3:
You will have to drill out the 2 holes for the inner camber arm mounts on your 85 brackets and use a larger bolt because the late diff have a slightly larger hole

Complicating the swap, is the fact that the shock perch has been broken in the 89. The seller says my part can be swapped to the 89 from the 85 alleviating this problem.
Is this so?
No
The spindles are completely different ;early vs late
Amongst other things , the 84 -87 has the shock mounted at a angle to a bracket on the side of frame ; 88+ has shock vertical into a hole in the frame so the angle of the shock bolt hole in the spindle is different
As noted to solve your problem all you need to do is swap over the batwing / diffhead assembly

http://www.digitalcorvettes.com/forums/showthread.php?t=66382
 

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I believe the 89 has substantially lighter springs which will be quite a relief for ride of car.
Also, will it require mods to the front springs stiffness wise if this is done.
If you want to soften the ride then you need to change the springs at both ends to maintain handling;
rear springs interchange cross all years but fronts are 84 - 87 or 88+ only
86 - 87 base (FE1 ) suspension is the softest front spring that fits your car ; nearly all base rear spring are the same rate
except for a very soft spring used in 94 - 96
Also you need to know what you are buying if parts are on the shelf. A '89 Z51 car has almost same suspension settings as your '85 Z51
You need to know the spring codes to identify what came out of what
FWIW
I found quiet a bit of difference just by swapping out the thick Z51 swaybars for base items ( and a lot easier than a front spring swap )
 
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