Once and for all time......67 B Body wheel backspacing.

33 IMP

FBBO Gold Member
FBBO Gold Member
Local time
8:18 AM
Joined
Dec 21, 2017
Messages
7,666
Reaction score
10,753
Location
taxifornia,soon 2b Arizona.
To add to my comment above, if I were ordering a new rear end I would be assuming the measurement in question would be outside axle face to outside axle face, not housing flange to flange. For the very simple reason that I have no idea how far the axle protrudes from the housing and all I care about is the face my wheel is going to bolt to.
The 54 1/4 measurement is the housing flange to flange, where the backing plate bolts to. Drum to drum would be where the wheel bolts on. That would be axle flange to axle flange, PLUS the thickness of the drums, if so equiped.
But i agree, if ordering a custom rear, i would specify the TOTAL width i wanted, whether drum or disc (gotta remember to add the thickness of the disc hat too!)
 

33 IMP

FBBO Gold Member
FBBO Gold Member
Local time
8:18 AM
Joined
Dec 21, 2017
Messages
7,666
Reaction score
10,753
Location
taxifornia,soon 2b Arizona.
Can you attach a link? I'm not a member of a-bodies. Thanks,
I would, but i dont know how. You dont have to be a member, just to lurk. There are lots of lurkers.
The chart you posted is very close to what i see at a-bodies. Probably fine for our use.
 

Ghostrider 67

Power corrupts.....lol.....
FBBO Gold Member
Local time
11:18 AM
Joined
Oct 16, 2014
Messages
26,234
Reaction score
53,567
Location
Salisbury, Vermont
So, to recap.....

I have 39" from outer edge of leaf to the outer edge of the other one. I have 59 1/2" from wheel mounting surface to the other one. I have 15 3/4" of wheel well to work inside and want to use a 10" rim for a M/T tire that's 29 tall and has a section width of 15"with 13 " of tread. As I understand it I need a 10" rim with 7 1/2" backspacing to center up that tire while leaving an extra 1/2 or so on the lip side to accommodate the roll in of the tub wall.
Does that sound right?
 
Last edited:

33 IMP

FBBO Gold Member
FBBO Gold Member
Local time
8:18 AM
Joined
Dec 21, 2017
Messages
7,666
Reaction score
10,753
Location
taxifornia,soon 2b Arizona.
Ghost, i would go with the 7 1/2 backspace. I am almost positive it will work, as is, but IF (i dont think so) it is too close to the frame, spacers can make it perfect. (I have spacers on an eleven second car, and a nine, and a former eight second car)
There is a limit,in a lot of cases, as to how much backspace, or offset, deep backspace or shallow, that can be done. You will need to consult your custom wheel maker if they can give you the bs you want. It depends on the shape of the hoop, where they can weld in the center.
My bottom line... yes, 7 1/2 bs., if you can get it.
 

Ghostrider 67

Power corrupts.....lol.....
FBBO Gold Member
Local time
11:18 AM
Joined
Oct 16, 2014
Messages
26,234
Reaction score
53,567
Location
Salisbury, Vermont
Ghost, i would go with the 7 1/2 backspace. I am almost positive it will work, as is, but IF (i dont think so) it is too close to the frame, spacers can make it perfect. (I have spacers on an eleven second car, and a nine, and a former eight second car)
There is a limit,in a lot of cases, as to how much backspace, or offset, deep backspace or shallow, that can be done. You will need to consult your custom wheel maker if they can give you the bs you want. It depends on the shape of the hoop, where they can weld in the center.
My bottom line... yes, 7 1/2 bs., if you can get it.
Summit has a couple hundred choices with 15x10 w/7.50 BS...& 5/4.50 pattern. This is the tire,,,...

mtt-6620_xl.jpg
 

33 IMP

FBBO Gold Member
FBBO Gold Member
Local time
8:18 AM
Joined
Dec 21, 2017
Messages
7,666
Reaction score
10,753
Location
taxifornia,soon 2b Arizona.
Also checking for 17,18" rims....
You just might be able to find the larger diameter wheel in the bs you want, without having to go to custom. The larger wbeels from late model typically have lots of backspace for their wide wheels.
I would look at something (not necessarily oem) intended for a late model mustang, same bolt pattern as a mopar.
 

65wgn440

Well-Known Member
Local time
11:18 AM
Joined
Aug 16, 2016
Messages
628
Reaction score
752
Location
Toledo, Ohio
Still think this is the shit ! Can check clearance through full suspension travel or steering arc, if for front. I was going to go in on a similar one with a couple buddies, to keep our costs down. I've collected singles of various size big tires over the years, in anticipation of using this style tool. Takes ALL the guesswork out.
images (3).jpeg
 

Stanton

Well-Known Member
Local time
11:18 AM
Joined
Aug 8, 2012
Messages
3,986
Reaction score
4,296
Location
Ontario, Canada
I have M/T 28 x 12.5 15LTs on Weld Pro Stars. These have a 13" cross section. The ProStars are 10" wide (11" outside) The BS is 5-1/2" outside. They came off a '69 Charger which had 1/2" spacers to bring them out a bit - probably just for looks. On my 69 RR they cleared everything comfortably. However, its a different story if you just crunch numbers.

One way to do it would be to draw up a scale cross section of the wheel/tire combo and cut it out of a piece of plywood. Set it against the hub and run it around to see what the clearance will be.
 

Rat.klr69

New Member
Local time
10:18 AM
Joined
Dec 9, 2019
Messages
3
Reaction score
2
Location
Montgomery, Ala.
I have a 66 Coronet with a BBD 4-link rear suspension system which uses the factory leaf and spring perches for lower control arm location. Its ALL about the backspacing on Mopars. I tried some American Racing Torq-thrusts, 17 x 8 with 4.81, but had too much gap so I ordered a wider width, 17 x 9.5 with 5.56 backspacing. The rims fit really well with 255x55x17 tires with 10.4 tread width. So i used the 17 x 8 with 4.81 on the front.

1419.jpg 1418.jpg
 
Top