If you're looking for a low buck way to get a narrower rear under your ride, you can take one out of a 78-87 Monte carlo/ Cutlass/ Regal. It's 4 inches narrower, allowing 2 extra inches on each side for fatter treads. The only mods you have to do is swap coil spring perches and re-route the rear brake hose so it atteches on the top of the differential. Small potatoes for a little more room to fit more common backspaced wheels. I personally have a 67 Skylark, and as most of you know, mine came with pizza cutter 14 x 6 wheels. I've stuffed 15 x 7 Buick rally's with 245/60/r15 in there WITH my fender skirts on!!! Without the skirts, I can run a 15 x 8 with 275/60/r15's. On some wheels, you might need a spacer on the back to prevent rubbing the frame. I hope I could shed a little insight for my fellow Skylarker's. Keep the rubber side down, -Josh:3gears:
I don't yet have pictures, but I'm in the process of doing a swap on my girlfriend's '65 Camino, so I'll be sure to get before, during, and after shots. As for the width of the rearends, the stock a-body rearend, from mounting point to mounting point is 61 inches. The 78 - 87 G-body rearend is 57 inches, which gives you 2 inches off either side. If you plan on doing anything like this before I get my pictures up, just double check everything, take lots of measurements, and let me know how it comes out for you. -Josh
How about the trailing arms? Seems like I recall hearing somewhere that the angles are a bit different for the three versions (64-67, 68-77, and 77 & up)?
Not to bring a dark cloud onto this "swap"... but am very welll aquainted with the differences in the '78+ A-G series rears & their differences with the narrow (early) A-body rears & the slightly wider A-body rears like the '71-72 8.5 A-body rear. A few fallacies in the info I read in above posts.. (1) The '78+ A-G series rears are not 2" narrower on each side than any of the '64-72 A-body rears. Narrow A-body rears like the '65-67 12 bolt & 10 bolt Chevelle rears, one would be looking at 3/4" narrower on each side w/ a '78+ A-G body rear installed. In cars with the later A-body rears, like the '71-72 A-body rear, looking at 1 1/4-1 5/16" narrower on each side with a '78+ A_G series rear. (2) The spread & positioning of the cast upper perchs on a '78+ A-G series rear is different than all of the different '64-72 A-body rears. This wider positioning causes a major bind with upper control arms when trying to manhandle either an earlier rear into a '78+ A-G body, or the opposite. (3) Pinion inclination: when swapping an earlier A-body rear into a '78+ A-G body, the pinion will be angled up 10-12 degrees from where. Installing a '78+ A-G rear into a '64-72 A-body will cause the pinion to be down from optimal 10-12 degrees. (4) The shock mounts on the '78+ A-G body rear angle outwards towards the section width of wide tires. '64-72 A-body rears, on the other hand, also have outboard mounted shock mounts, but they point straight back, providing more inner clearance. By swapping to a '78+ A-G series rear with shock mounts that angle toward a wide tire's section width, one gives up inner tire clearance. (5) Coil spring mounts... -'78+ A-G body rears mount the coil springs directly on top of their 2.6" diam axle tubes. -'64-72 A-bodys rears mount the coil springs in front of their 3.0" diam axle tubes. This difference has proven enough to warrant moving the spring perchs on 8.5 A-body conversion rears I've built for '78+ A-G body mounting. While (2) & (3) can be remedied with special aftermarket upper control arms for those swapping earlier A-body rears into '78+ A-G series cars, have yet to un across upper arms to mount a '78+ A-G series rear into a '64-72 A-body. The '78+ A-G series 7.5 rears are quite weak, so swapping them in anything earlier is quite rare. Got Posi? :3gears: Roger
I was wondering why a swap to 7.5" would be worth it. I suppose if it was strictly a stock driver it would be ok, but if that was the case tire clearance would not be a huge concern. But there is 8.5" units out there, but I bet they are pretty expensive and highly sought after by the "G" crowd.
i have heard of the turbo guys changing axle tubes as the 7.5 and 8.5 are the same. have anyone heard this? but a 7.5 swap into a older car still not worth it as far as i think
Cut your Buick ralley wheels behind the hub and add a 1" spacer.This gives you an 8"wheel and pulls the outer sidewall in 1/2". Install a 71-72 Skylark 8.5" rear unit which is narrower. Trim or roll the fender lip,(careful here). This will give you the clearance you need for 11 1/2 to 12" wall to wall tire. This will also give you a stock 8" Buick ralley wheel. I would say a 11" tire would fit even with fender skirts on. I have done this and now have 28x12.5-15 MT Street drag tires. Their actually 12 1/4" wall to wall on my "stock" 8 inch wheels. My car is a 1967 GS and they are a tight fit until you take steps to gain clearance. Tf body is offset, you may have to loosen body bolts and shake the body into a center position since most are off center from the factory.
