Anybody got an idea as to costs to narrow a 8.5 rear. I've got one and from what I've read it's an inch wider than the old 8.2". Being as how it looks like the rear tires are very close to the fenders with the 8.2" I'm wondering if the 8.5" will rub with aftermarket rims. I'm looking at torque thrusts 17" with a 5" back spacing. Thanks for the input.
The 64-65 BOP rears are 5/8" narrower on each side,compared to the 66-72 BOP 8.2's,and the 71-72 8.5's. Chevy kept the narrower rear from 64-67,then went to the wider rear for 68-72. Since you haven't purchased the wheels yet,I would leave the 8.5" rear the way it is,get it installed,and do some mock-ups for proper wheel fitment. You can order the new wheels with the correct offset that you need. Also,if you are planning on installing rear discs,you will also need to take that into account. The disc rotors are thicker than the drums,so they will push your wheels outboard as well,about 1/4"-3/8",depending on the brand of rotor.
Hi Gary, I have a 1967 Skylark with fender skirts. I had my 8.2 narrowed an inch on each side so that I could fit aftermarket 17" x 7" wheels and keep the skirts. The cost to have that done was around $1200. The cost included new moser axles and the narrowing of the assembly (relocating brackets inward, welding, labor, etc). I think it's probable that it would rub if you ran the 8.5. It's pretty easy to measure these things. I would start by measuring your 8.2 and your 8.5 and go from there. Good luck, Dave
Brian brought up another good point about the disc brake swap. I also did the disc brake swap. One issue I ran into is the axle (hat?) had to be turned to accept the rotor...just something you may or may not run into if you do the disc swap.
There is enough room to go .5 on both sides without moving the shock bracket over. Cost is generally around $150/200 at most fab shops then however much the axles are , you can stock replacement Mosers for $285 or so
Well those prices may be the killer for this project. May do as suggested and install it to see how it fits and then special order rear wheels. Thanks for the input.
I've been able to order a variety of wheels,with custom offsets,for customers' cars. I would mock it all up and see where you're at.
I have a 71 Buick 8.5" rear end in my 65 Skylark and I just ordered the wheels with the correct backspacing. That is the best way to go and leaves the later rear stock for order parts etc. Also no additional money is involved and you can use that money elsewhere for your car.
Careful, there's a lot of conflicting information out there. for example, Oldsmobility.com says: >>>From 1964-67, the housing dimensions measure 56.5 inches, from flange to flange. Total measurements with the drums in place is 60.5 inches. 1968-72 rearend housings measure 58.5 inches from flange to flange, and with the brake drums in place, the total dimensions measure 62.5 inches. <<<< Personally, I have a '64 Ols and '66 Chev 12 bolt that are the 'narrow' rears, and 65,66, and 67 Buick rears that are about an inch wider. I never measured a 8.5 inch rear but have always read they are even wider. Would be nice if we could pool our resources, measure what we have, and post some real results.
I have made 10 bolt 8.5 one inch narrower and also have the 30 spline axles 1/2" narrower than stock to fit the 8.5 rears. (1 set on the shelf) THE price someone quoted for axles is WAY off. Moser axles and any axle manufacture that makes BOLT IN AXLES are in the 370.00 range. muscle car projects are NOT cheap. Nor are muscle cars cheap. Back in the day these cars were 500 -1000 for a good runner in the 80's NOT ANY MORE. custom rear stuff you will need to through at least 1000.00 with assembling narrowing and parts. rims seem like they will be a cheaper offset for you. what size tires are you running that your having a rub issue? Jim- J D
I have tried a set of GN wheels, fronts fit, rears with offset didn't. Tried a set of Torque thrusts with 8" rims and 4.5" back spacing, they didn't fit, and have a set of stock 15" buick rims that fit on 8.2 but don't know if they will fit on the 8.5" rear. Still haven't gotten the 8.5" rear here to try a test fit and see what I have. Back in the day we tubbed a roadrunner and that seems like it was cheaper (back then). Not cutting on the Buick!!
One more thing on my 1965 Skylark. We pushed out the wheel well on the rear maybe a 1/2" to gain more room. You cannot tell it was done. Also curled up the "lip" to increase the clearance. And last but not least we reworked the inner wheel well to be even with the frame. I did not want to cut or rework the frame to go even larger. I am running 285/40ZR17's on the rear. I have enough room to go 295's if I can get the right tire.
From the 1,000+ rears that I have done,my info seems to be accurate. The 73-77 A-body rears are a hair wider than the 71-72,but that is a completely different chassis altogether. Why Chevy kept the narrower rear for two more years,who knows. There could also be a time frame in 65,where they started making the wider BOP 8.2's. Hard to say when they exactly started doing that,and if certain plants got them before others. When I did a customer's car with the wider rear,and discs,we ordered a set of 18 X 10 Torque Thrusts with 6 1/4" back spacing.That might not be what you need,but just an example. Get the rear that will end up in the car installed,and mock your wheels up from there.
Gary, What size tires? 255's should fit with 15x7 Buick wheels, 4-3/8" backspacing. It may be tight on one side if rear isn't centered. Brian, are the >'71 8.5 rears the same width as the wider 65-67 rears? I had thought (roughly): 64-67 Chev and some others= narrowest 65-67 Buick, Pontiac, 68-72 Chevy = 1" wider 68-72 Buick & ? = another inch wider than the Chev and 65-67 BOP. Anyone have actual measurements of an 8.5?
"we ordered a set of 18 X 10 Torque Thrusts with 6 1/4" back spacing." I have a 1971 Buick 8,5" rear in my car 65 Skylark and we used 6 3/8" backspacing. These are American Racing 17" x 9.5" VN500 wheels. So our cars are right in the ball park with each other.
We also had to go with a deeper backspace on the front,due to the suspension & disc brake kit installed.It pushes the track width outboard another 1/2",so we had to go another 1/2" deeper on the fronts.
Some where in 1966 the BOP rears got wider to the 61" over all width. I have Buick and Pontiac rears that have flat spring perches and are 60" over all and 55.25 flange to flange width. Pontiac start the WIDE TRACK commercials and that is why they got popular and was most likely a selling gimmick as i doubt a 1/2" on each side will make a hill of beans difference in handling...LOL. Being that all the mounting points are identical for all the arms and springs. So you have Pontiac 1964-1966 1/2 earlier 54.25 wide flange to flange 60" over all Buick 1964-1966 1/2 earlier 54.25 wide flange to flange 60" over all Oldsmobile 1964-1966 1/2 earlier 54.25 wide flange to flange 60" over all Chevy 1964-1967 54.25 wide flange to flange 60" over all Pontiac 1966 1/2 later to 1972 55.25 wide flange to flange 61" over all Buick 1966 1/2 later to 1972 55.25 wide flange to flange 61" over all Oldsmobile 1966 1/2 later to 1972 55.25 wide flange to flange 61" over all Chevy 1968-1972 55.25 wide flange to flange 61" over all ALL Gm 73-77 were 56.25 62' over all (these rears and chassis' were TOTALLY different than the 64-72 era and to try to fit them into the 64-72 era is a PAIN IN THE BUTT... do not try...not worth the headache. ) Please.... 1973-1975 many 76 BOP cars had bolt in axles and all Chevys had c-clip axles. AGAIN... I am sure there were some plants that installed a bolt in axle rear in a El Camino or other Chevy from time to time. Jim J D
Info You all need to remember that most of the old muscle cars are not original anymore...So it is possible to find anything under any year these days. Since most of the 64-72 rears were fairly interchangeable most did not fix the rear they went to a yard bought a rear and slapped it in ASAP... I know in 1970 there was a GM strike for some of the older guys that were working there.... Tempest rears ended up in Chevy all the time...12 bolt olds also ...this is why we find Monte Carlo with a Pontiac rear under it and 12 bolt olds under El Camino, Pontiacs etc. The line just did not stop...
