Hey, Looking to upgrade my rear end (stock 7.5" w/ mini spool) to a 8.5" Hard to find a g-body 8.5, and I want a little wider rear anyway. I have a '75 Malibu and a '76 GMC Sprint (haven't had a chance to climb under them... they are stored as parts cars about 6hrs away from me). Either of those have a chance of fitting with the swap upper control arms I've heard so much about? Possible work required to make the shock/spring mounts correct?? Any help is appreciated...
No, don't use the 73-77 rears. Find a 71-2 Skylark/Cutlass 8.5 corporate rear. They will bolt in the 78-87 G-body with different trailing arms available from Summit and Jegs.
Ck out my earlier post on this swap, been through it many times, & the complete Jegs kit is not needed. http://www.v8buick.com/showthread.php?t=101200 Got Posi? :3gears: Roger
Why not '73-'77?? I think it's an 8.5" in the malibu... oPh... thanks, I've read that thread before... doesnt say anything about the 73-77 though?? Something wrong with those years? I just want something I'll feel a little more safe with when running slicks on the track. I'm not sitting at very big HP... still got a warmed up 455 under the hood though.
the 73-77 rears dont line up well ,the lowers will need to be longer or redrill holes and the uppers will need to be shorter to get pinion angle is much wider also .it can work but when i did it i wasnt happy with it so i went with an a body 12bolt/southside lift bars
DLG, As Alec alluded to above, there are problem areas with using the 73-77 A-body rear for the G-body swap. Basically they are: -Upper mtg geometry problem... Too wide a spread on cast-in '73-77 upper control arm mounts... wider than on the G-body castings. -Width problem...'73-77 A-body rears are another 1" wider than previos generation A-body rears, so add another 1/2" per side to where one's wheel would be with the modded '71-72 8.5 A-body rear. -Shocks are inboard on '73-77 A-body & '77+ B series rears. Entire outer perchs will have to be swapped to get to outboard shock perchs -Every '73-77 Monte, Malibu, & Elco 8.5 rear I've ever had in a partscar, or ck'ed for a posi in a yard was c-clip axle variety. Personally don't like building off c-clip housings when there are same bodystyle bolt-in axle 8.5 rears avail as hsg & axle cores for relatively cheap. Bolt-in tapered bearing axles are just superior, no axles to pit in the bearing land, superior sideloading, better axle retention. Hope this helps, regret not getting back w/ you quicker. Got Posi? :3gears: Roger
Thanks a lot for all the help guys.. I'm trying to save some bucks here... which is why I am looking into the 73-77 rears. I have one, just ripped it out this last weekend... all it will need is different gears (the carrier is even the right size for the 3.42 I want) Don't want to beat a dead horse here... but bear with me... Upper swap adj. control arms will correct the problem on top? Adjustable lowers or redrilled g-body lowers should work on the bottom? The shock mounts look like they can be relocated to the back of the bracket the lower arms mount to... need to look into that more.. The spring perches are the same location (within fractions of an inch) I know c-clips are not the preferred..... but I'm not going high horsepower... and again, I HAVE this rear. $0 invested! any other comments? Thanks Devon
adjustable uppers will not bolt in you will have to offset them and you will need to shorten them also, you can use adjustables on lower but they need to be shorter also then most of all you need to get the pinoin angle set otherwise you will ruin u-joint/pinion bearings /driveshaft length can change springs will be off some so the bind will cause ride stiffness not to mention the custom offset on the rims will make them almost useless for any other application. i still have my prostars at 5 in backspace with the holes drilled for slicks i didnt like the ride afterward and at 106 mph 1/4 mile speeds i when to abody you can fit it in there ,i did ,but the best setup for that is still a coil over/ladderbar suspension(and safest as far as i thnk) for that rear
Sorry it took so long to explain that to me alec296... just really tempted to try and use the one I have. What wisdom can you offer about the ladder bar/coil over setup you speak of? If looking for the 'right' 8.5 for this swap... 71/72 Cutlass/Skylark? Any other models? Thanks again... Devon
i think jegs has a setup or maybe competition enginering, a universal kit if fine just some extra work a 68-72 abody rear works good with a traction bar kit,bolt in setup but 71-72 bop rears are 8.5 the early ones are 8.2,if you use an 8.2 use the chevy axle as there is some difference on the carrier(posi) and most posi are for the chevy style
Get a '71-72 8.5 A-body from a Cutlass or Skylark. Carefully follow the housing mod steps on my earlier post & ck the e-bay link on the link for the special canted adj upper arms, & you'll be set. As far as Chevy 8.2's go, there is no reason to plunk money into one... lack of pinion support & c-clip axles put them in with the 7.5's as a bad choice for anything other than what they were designed for. Got Posi? :3gears: Roger
