Back Spacing

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wazoo64

wazoo64

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I have a 64 Valiant that is getting a front end overhaul. When finished I will have stock geometry with 73 spindles and disc upgrade. Does anyone know how wide I can go on the front tire? What is the max backspacing?
 
Your best bet would be to take measurements to see what you've got to work with. I think the first obstacle will be the tie-rod/steering knuckle end which (from memory) will be in the neighborhood of 5.5" - so 4.5" and less to be safe.
 
I ran 16 X 7, on a couple of A bodies, It had a 5 (actually 4.92 in brochure) inch back space with no rubbing any where. This rim had about 3/4 of an inch clearance to the upper ball joint. I had them on a 71 Scamp, 74 Duster and a 65 Cuda. I had 225 50 R 16's on them. I could of used a slightly taller tire on the later A's. like a 225 55 R 16 to fill out the wheel well but it looked ok.
 
Keith Mopar said:
I ran 16 X 7, on a couple of A bodies, It had a 5 (actually 4.92 in brochure) inch back space with no rubbing any where. This rim had about 3/4 of an inch clearance to the upper ball joint. I had them on a 71 Scamp, 74 Duster and a 65 Cuda. I had 225 50 R 16's on them. I could of used a slightly taller tire on the later A's. like a 225 55 R 16 to fill out the wheel well but it looked ok.
Click to expand...

I am running 18's on the front and would like to go as wide as possible. Do you think an 8 would fit? I don't mind loosing a little turn radius for a little more rubber.
 
70Duster440 said:
Your best bet would be to take measurements to see what you've got to work with. I think the first obstacle will be the tie-rod/steering knuckle end which (from memory) will be in the neighborhood of 5.5" - so 4.5" and less to be safe.
Click to expand...

I hear ya man. I just want to start looking at options so I can move quick once it is put together. Right now I run the Boyd smoothie II and would like to stick with them if possible. Boyd has many options so I should be OK.
 
fwaugh said:
I am running 18's on the front and would like to go as wide as possible. Do you think an 8 would fit? I don't mind loosing a little turn radius for a little more rubber.
Click to expand...
Yea it would fit, if you had an 5.5 backspace. IF you lower your car alot the tire would be close to the outter fender, but as long as you have the steering cranked just go slow and stay away from bumps.
I have a set of 16 X 7's that I can check fitment on for you. Thay have a 5.5 back space from the wifes Avenger
 
70Duster440 said:
Your best bet would be to take measurements to see what you've got to work with. I think the first obstacle will be the tie-rod/steering knuckle end which (from memory) will be in the neighborhood of 5.5" - so 4.5" and less to be safe.
Click to expand...

When I take the measurement from the hub to the inner fender well is there a standard contact point to measure from? It is hard to tell where to land the tape measure.
 
I don't know as though there's a standard contact point to measure from. Generally if you measure to what appears to be the nearest obstacle you'll be close enough. Front and rear have different obstacles. Subtract 1.5" to 2" for clearance, tire bulge, etc and you'll be safe. You could get away with less but your measurements have to be more accurate.

Unless you order a wheel with a custom offset, they're going to have common backspace dimensions: ex: 3.75", 4.0", 4.5", 5", etc.

Many late model wheels have high positive offset (a lot of backspace). Gotta be careful with these. Short of taking measurements, I'll bet you could run an 8" wheel - front or rear - with 4.5" of BS. A 7" wheel about 3.75"

Try putting a jack under the control arm so that the suspension is loaded and not hanging down all the way. Put a piece of tape on the floor. Then, use a plumb bob (or make one) - hang it from the fact of the hub to the floor and make a mark on the tape. Hang the plumb from the inner fender or spring or whatever and make another mark. That'll give you the distance. Or place a straight edge against the face of the hub and use a ruler to measure from the straight edge to inner fender.

Go to AmericanRacing.com and check out the tech pages or newstalgiawheel.com

Hope this makes some sense.
 
Well I took my wheels in for a retrofit. That's right .....you can have them altered. Greg Coddington was the guy that helped me figure it out. Pretty cool. The Smoothie II is a 2 piece wheel and can be easily altered to fit any application. He recommended dropping from an 8 inch to a 7 inch with 5 inch BS. He said that small cars like mine would actually ride and handle much better with a smaller wheel. This goes against what I was expecting to hear. With 2 inch drop spindles.air ride. firm feel gear box and sway bar I will let you know in a week or so how it rides.
 
Finally got the front end put together with some really nice results. I was able to get the 18 x 7 wheels with a 5 1/4 backspace in. 215/40 With two inch drop spindles and air ride it sits real low with no rubbing. It was a little loose and sloppy until I put the firm feel sway bar on and that made a world of difference. I never new a sway bar could fix so many problems. The stage 2 steering box was a nice add as well. Hope it doesn't leak. Just another FYI. I have the tubular K member from Cap Auto and was able to fab some custom brackets to get the sway bar mounted.
 
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