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FFCobra Craftsman
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Discussion Starter · #1 ·
I've read the manual and searched and searched but it seems I can not find a consistent answer. I need to know what backspacing I need to run 15x7 for the front and 15x10 on the rear of a Mark II. I'm very concerned about ordering the correct backspacing since custom backspaced wheels cannot be returned. Thanks.

Mark

[ June 07, 2004, 09:29 AM: Message edited by: mgibson ]
 

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Assumptions:
1. Fox width rear axle
2. Fox front spindles
3. Stock brakes, not Cobra
4. Your selected rims do not have excessive lip thickness.
5. Standard tire widths 275/50 rear, 235/60 fronts.

Goals:
We want to center the rims
and
"fill the wheel well"
and
have some "dish" if possible.

Standard:
9" rims get 6" backspace

Rear:
10" rim wants to move inboard 1/2" to maintain center.
So, 6.5" backspace

Front:
7" rim wants to move 1" outboard to maintain center
so, 5" backspace
However, the tire will not "fill the wheel well" so one could go with 4" to move the tire closer to the fender and give a deeper dish appearance.
 

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Larry,
If Pin Drive narrows the rear arms by 2 1/2" per side and the fronts by 1 1/2" per side, can your example still be used? Put another way, can the 2 1/2" and 1 1/2" be subtracted from the backspace to enhance the deep dish look?

Assume 15" wheels, SN95 hubs, standard tire widths and stock (t-bird and non cobra) brakes.

Many thanks.
regards,
 

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Larry

I have wanted to ask this question myself -- thanks for the response. However, as a Mopar guy (sorry, that's what I have worked on most in my life) "Fox" length means ?? 1987-93 Mustang standard front and rear donor parts?? I'm trying to learn the terms (like SN95, too!) Thanks!

Mike
 

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Mark
Ok you are good.

wickershaw
Yes, the narrowing simply subtracts the exact amount from backspace, i.e., 6" backspace becomes 3 1/2" with a 2 1/2" narrower setup. That way rim sits in exact same place on the car relative to fenders and frame clearances.

The "gotcha" is that if one has true "pin drive" rims, they have an adapter that is 3/8" thick, which is like a "spacer" or exactly like less backspace.

Same goes for big Cobra brakes. Unless one has Team III rims, then spacers are needed to clear thes big calipers. The spacer wants to be accounted for. For example a 3/8" spacer used on a 6" backspace creates effectively a 5 5/8" BS net.

Mike Kilian
"Fox" Mustang means 87-93
"SN95" Mustang means 94-95
Regarding spindles, the Fox has a 4-cylinder and 8 cylinder ones, so specify V8 parts. Not sure the same is true for SN95.

John
Yours is a 2000 rear end. I responded on thgat thread so we don't get too mixed up.

Hope this helps.
 

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Con Man
Here is the car:

Here is the setup:
Rear FFR IRS pin drive width, 54.5" wide flange-to-flange
Rear T-Bird SuperCoupe stock disk brakes
Rear 9 1/2x15 Halibrand Cobra II rims (Magnesium), 4" backspace
Rear Goodyear Eagle GTII 295/50x15 tires
(4) 3/8" Trigo adapters 3 5/8" effective backspace
Front 7 1/2x15 Halibrand Cobra II rims (Magnesium), 4" backspace
Front Goodyear Eagle GTII 235/60x15 tires
Front spindles Fox
Front lower arms FFR pin drive tubular
Front brakes Mustang Fox
Front rotors/hub Lincoln Mark VII 5-lug
 

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FFCobra Craftsman
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716 Posts
Discussion Starter · #20 ·
For not exhausting all my resources before asking a question. Most of the time the answer is right there in front of you but you have to look for it. It's the same as not reading the manual or using the search function in this forum.
 
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