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  1. #1
    Join Date
    May 2007
    Location
    vancouver wa.
    Posts
    38

    Default narrowing a 12 bolt

    I found a 65 chevelle 12 bolt with 308 gears, swapped out my 8.2.

    Im going to do disk brakes and the ford ends on it when I install new gears and posi unit. My question is how far can I narrow it by means of the ford ends? I know I will need custom axles (or just cut then down??) I will be installing aftermarket axles anyways.

    My goal is to get as big of tire in my fender as I can without tubbing it. I have already rolled the fender lip, Im looking at how I can clearance the inner fender too. I want the nice backspacing that a musclecar should have in the rear,

    There is a lot of room in the inside of the tire to frame side, one of my concerns is the shock mount to wheel clearance. Id like to run a set of 255-275's with a 17" wheel.

    I have searched but cant find the info i want from people who have already done this.
    65 skylark 2 door hardtop '71 455, T400, 12 bolt. T/A headers, MSD 6al ignition. HEI,

  2. #2
    Join Date
    Jun 2013
    Location
    Everett, WA
    Posts
    72

    Default Re: narrowing a 12 bolt

    I 'just' had my 8.2 narrowed to accommodate the aftermarket 17x7 wheels I purchased for my '67 (wanted to keep my fender skirts and have aftermarket wheels).

    I see you are in WA. One of the best guys in the business is in Kent (Scribner Welding). I would suggest talking to him to get an idea of what you are looking at. You'll probably need to do some measuring and what not. He (Bill) narrowed my stock housings (an inch on each side) and put custom length Moser axles (made to order) in. The quality of his work was outstanding. His shop is spotless and well organized. My paint guy has been using him for years. My hot rod buddies have had several rear ends built by him in the past. I could go on and on.

    Give him a call at 253-852-6088.

  3. #3
    Join Date
    Nov 2003
    Location
    Richfield , Ohio
    Posts
    2,235

    Default Re: narrowing a 12 bolt

    The rear end narrowness has NOTHING to do with the size tire you can fit in the fender well. The fender well is the accommodating factor.
    If you have 9" width of fender well THAT IS ALL YOU CAN FIT. Period.

    You need to watch your shock mount if you are narrowing the rear it will hit the inner rim on 15-16" wheels. You need at least 17" to go another inch narrower with out rubbing.

    Unless you need the outer part of the rim to look very deep you can just buy the correct offset to center the wheel in the fender well using the back spacing of the rim offset.

    Normally 4.5 -5" is about the right backspacing for the max tire size and center of the tire and rim with STOCK axle 65-72 GM

    Jim
    J D Race

  4. #4

    Default Re: narrowing a 12 bolt

    I would like to trade you my 70 12 bolt for your 65 since I will use it for a G body and it would fit better than mine but you are too far away.

  5. #5
    Join Date
    Jun 2013
    Location
    Everett, WA
    Posts
    72

    Default Re: narrowing a 12 bolt

    I agree with monzaz' statment...

    Mine being narrowed was a last resort. I explored all options before going this route.

    In my case, I searched high and low for different set of wheels with the correct lug pattern and a different offset other than 0. It's a very limited selection out there. The more prudent route for me was to spend the money narrowing the rear end to accommodate my wheels rather than having a custom set of wheels made (for thousands of dollars).

    Definitely explore your options before going this way

  6. #6
    Join Date
    May 2007
    Location
    vancouver wa.
    Posts
    38

    Default Re: narrowing a 12 bolt

    The point to all this is since I will be installing the ford outers and cutting it down anyways, then why not cut an additional inch(maybe more maybe less) off of it to gain that much more clearance ON THE OUTSIDE OF TIRE TO FENDER. . As stated I will be running a 17" wheel. I am aware of the shock mount interference.

    I have MUCH more room for a bigger tire on the frame side of the tire then the fender side.

    There is things that can be done to the fender to allow a bigger tire. THERE ARE OPTIONS!

    Yes I can run a different offset wheel to gain the clearance but personally I think it looks bad, it looks like your running a 6" wide wheel in the rear. I want to stick with the nice deep dish muscle car look.
    65 skylark 2 door hardtop '71 455, T400, 12 bolt. T/A headers, MSD 6al ignition. HEI,

  7. #7
    Join Date
    Nov 2003
    Location
    Richfield , Ohio
    Posts
    2,235

    Default Re: narrowing a 12 bolt

    Quote Originally Posted by B-rock View Post
    The point to all this is since I will be installing the ford outers and cutting it down anyways, then why not cut an additional inch(maybe more maybe less) off of it to gain that much more clearance ON THE OUTSIDE OF TIRE TO FENDER. . As stated I will be running a 17" wheel. I am aware of the shock mount interference.

    I have MUCH more room for a bigger tire on the frame side of the tire then the fender side.

    There is things that can be done to the fender to allow a bigger tire. THERE ARE OPTIONS!

    Yes I can run a different offset wheel to gain the clearance but personally I think it looks bad, it looks like your running a 6" wide wheel in the rear. I want to stick with the nice deep dish muscle car look.
    ---------------------------------------------------------------------------------------------------------------------------------------------------------------------

    iT IS FUNNY YOU SAY mUSCLE CAR LOOK. wHEN all STOCK mUSCLE CARS IN THE DAY WERE 6-7" wheels...lol.

    You mean Nostalgic Drag race look or NEW touring look. Jim

    I certainly understand the WANT... once anyone says 'I just want it that way', I CAN NOT ARGUE one bit after that. This is the reason WE restore cars to suit our wants: to look cool on OUR cars. What one guy thinks is cool does not work for another.

    Final note- Just be sure you do a lot of measuring before you cut and or order your parts. Have fun, that is what it is all about anyway. Take care, Jim Mitschke

    J D Race

  8. #8
    Join Date
    Aug 2003
    Location
    Southern NJ
    Posts
    279

    Default Re: narrowing a 12 bolt

    Before I narrowed my 12 bolt I purchased my tire & wheel combination,
    placed the tires mounted on the wheels under the vehicle locating
    them exactly where I wanted them & took the necessary measurements.
    I allowed 1" from the inside lip of the fender to the edge of the tire,
    which is the look I was going for.
    I also allowed for a larger tire, if I were to change my mind later on....
    I did however narrow the frame rails.
    I went with the late model big bearing ford ends & drum brakes....

    Tom
    Tom
    1965 Lesabre (455ci/ST-400/3.73gears)
    1968 Skylark (gone)
    1986 Century (gone)
    1994 Lesabre (140,000 miles)

  9. #9
    Join Date
    May 2007
    Location
    vancouver wa.
    Posts
    38

    Default Re: narrowing a 12 bolt

    Thats a great idea, How did you go about narrowing the frame? Do you remember how much you narrowed the axle? Any pics by chance? cutting and welding is no problem for me. I own all the equipment.
    65 skylark 2 door hardtop '71 455, T400, 12 bolt. T/A headers, MSD 6al ignition. HEI,

 

 

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