Wheel to spring clearance

-

Garys72Duster

Well-Known Member
Joined
Apr 23, 2017
Messages
558
Reaction score
323
Location
Golden, Co
Working on a 70 Dart 2 door with an A Body 8 3/4 rearend. Just wondering what is the maximum back space wheel a guy could use on this? I want to buy some 15" wheels when I get the axles re drilled to 5 on 4.5 pattern. Can I use an 8" wide rim on this ? Thinking about using Centerline wheels. Do these come with a 4" backspace? Thanks
 
What I have found was that 15" X 8" with a back spacing of 4.5" works. As for tires a 255/60
I had to make sure the axle was centered on the springs, so the tires would have clearance on both sides.
Good Luck
 
My 15x7's with a 4.50 backspace are real tight. I have 255-60/15's. I would say 1/2" or less clearance between the spring/tire and the same with the fender lip. You can gain a little by rolling the fender lip if you don't have wheel opening moldings.
001 50.jpg
010 (2)reduced.jpg
011 (2).jpg
040 (2).jpg
 
With the production tolerances that had back then, plus or minus 1/4" each car is a little different.
 
Just wondering what is the maximum back space wheel a guy could use on this?

straight edge from brake face to leafspring. deduct 1". There is your max wheel backspace.

That will require a tire that is no more than .5" section width wider than the wheel itself.

yes, you can use spacers for fine tuning the wheel fitment but realize that if you use a spacer you lose on the quarter panel side.
 
straight edge from brake face to leafspring. deduct 1". There is your max wheel backspace.

That will require a tire that is no more than .5" section width wider than the wheel itself.

yes, you can use spacers for fine tuning the wheel fitment but realize that if you use a spacer you lose on the quarter panel side.
OK, I'm going to go and measure it now. I'm getting 5.5" inches from the wheel mount on the brake drum, to the leaf spring. Wheel mount to tire edge is 4.5 " laying flat on the floor. But on the other side with the wheel on, still have 1.5 " inches to the spring. So it looks like I can do a max backspace on the wheel of 4.5 to 5".
 
OK, I'm going to go and measure it now. I'm getting 5.5" inches from the wheel mount on the brake drum, to the leaf spring. Wheel mount to tire edge is 4.5 " laying flat on the floor. But on the other side with the wheel on, still have 1.5 " inches to the spring. So it looks like I can do a max backspace on the wheel of 4.5 to 5".
Measure both sides. There is usually a difference between the two.
 
Measure both sides. There is usually a difference between the two.

YES!

That is why you always want to error on too much BS and then adjust as needed. YOu can always space, you can never move them further in
 
I had 15x8 American Racing Outlaw 1's with a backspace of 4 inches. They worked perfect with 275x60-15's on a 72 Demon.

Jack
 
4.5" backspacing it about the max on a Dart. Depending on what tire you're using it may or may not be hitting the spring. A thin spacer (1/8") might sometimes be needed. A 225 tire will fit, a 235 tire might fit, a 245 or bigger tire probably won't fit. But every car is unique. And a Duster/Demon has tons more room for tires than a Dart, so Coyote Jack's advice really doesn't apply here.
 
Just went through putting 9.5 with 5.5 backspacing rims on my 73 Swinger and had to move the springs in a half inch.
The Dart (mine anyway) has a 5.5 total distance from wheel mounting surface to the leaf springs.
I didn't touch the tubs and have one inch on each side of a 245/40 tire on that 9.5 rim.

after.jpg
 
Really it is worth it on any abody to install offset shackles. It's easy and gives you an additional 3/4 of an inch.
 
Working on a 70 Dart 2 door with an A Body 8 3/4 rearend. Just wondering what is the maximum back space wheel a guy could use on this? I want to buy some 15" wheels when I get the axles re drilled to 5 on 4.5 pattern. Can I use an 8" wide rim on this ? Thinking about using Centerline wheels. Do these come with a 4" backspace? Thanks

Remember as you read through these replies that you’re technically keeping a small bolt pattern offset by redrilling your axles. So, if you listen to someone that has BBP axles about backspace you’ll probably end up with too much backspace.

4” on a 15x8, even on a SBP axle, isn’t enough though. 4.5” is what you’ll probably need, although on some cars you may need to adjust that with a small spacer. Especially for a 245. Everything has to be pretty much perfect to fit a 245 on a lot of the Dart body cars. Some can get away with 255’s, a few have had trouble fitting 235’s.

Really it is worth it on any abody to install offset shackles. It's easy and gives you an additional 3/4 of an inch.

No it doesn’t. It gives you an extra 1/2”. The front spring hanger only has a 1/2” to the frame, so good luck moving it 3/4” inboard. The MP “3/4” offset kit has a 1/2” offset hanger and a 3/4” offset shackle. Puts a bind on the spring and still ends up giving you less than 3/4” additional clearance on the front half of the spring. That’s why drdiff calls his offset kit a 1/2” offset kit.
 
I've never actually measured. I was just going by the MPP claim.

I still think it's worth doing even to gain a 1/2"
 
4.5" backspacing it about the max on a Dart. Depending on what tire you're using it may or may not be hitting the spring. A thin spacer (1/8") might sometimes be needed. A 225 tire will fit, a 235 tire might fit, a 245 or bigger tire probably won't fit. But every car is unique. And a Duster/Demon has tons more room for tires than a Dart, so Coyote Jack's advice really doesn't apply here.

Yes sorry about the post. I know the Darts have much less room than a Duster or Demon.

Jack
 
Yes sorry about the post. I know the Darts have much less room than a Duster or Demon. ^^^^^^^^^^^^^^^^^^^^^^^^^

thread jack here; how does a 67-8-9 barracuda fastback compare w/ the duster and dart ?
 
tread width on 225/70's is only 6". A 8" rim would be a stretch. Literally.

yep... it's real close. The section width is just even with the outside of the wheel on a 8.5" wheel. On an 8" wheel it might be ever so slightly past it.
 
Just picked up my slicks mounted on 15" Cragar wheels. Brake drum face to spring measures 6" on the car. These wheels show 5 1/4 inches, from mount side of wheel to edge of sidewall when I measure. So I should have 3/4" to spare, right? Looks good on paper, anyway. LOL
 
-
Back
Top