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Re: 275/60/15 on a Cuda (long)
[Re: Gavin]
#889017
12/27/10 04:43 PM
12/27/10 04:43 PM
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Joined: Jan 2003
Posts: 5,394
Pikes Peak Country
TC@HP2
master
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master
Joined: Jan 2003
Posts: 5,394
Pikes Peak Country
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That certainly is a new approach to fitting rubber. It seemed to be a bit intensive time wise and now with a custom backspace wheel, may not have been the cheapest, nor quickest, method to achive a bolt in fit, but I'm glad it worked for you.
The simpler bolt in method is to move the springs inboard 3/4 to 1 inch, then bolt in the B body rear. While the B body housing does not offer any more wheel well room than the E body housing, their ready availability does make it easier for most guys than cutting and rewelding the perches off the E body rear. However, either of these changes will alter the required backspace to fit the rims, especially since there is a difference in B body housing widths pre/post 67.
For my Challenger, the 3/4" spring move combined with a '67 B body housing allow a 15x10 with 5" backspace install that resulted in a 12" wide tire fitting with room to spare on both the spring and fender side. Entirely bolt in, using off the shelf parts.
BTW, the splayed spring design is a handling benefit that is designed in to all E bodies, post 72 B bodies, and all FJM bodies. E bodies are narrower at the front, while all other are narrower in the rear. What the splayed mount does is put the spring in a position that provides additional torsional resistance to the leaf, hence more roll resistance to the body, and minimizes roll steer by the rear housing moving and altering wheelbase length. The extra tread width doesn't contribute to either of these attributes.
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Re: 275/60/15 on a Cuda (long)
[Re: TC@HP2]
#889018
12/27/10 05:38 PM
12/27/10 05:38 PM
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Joined: May 2005
Posts: 598
NC, USA
davenc
OP
mopar
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OP
mopar
Joined: May 2005
Posts: 598
NC, USA
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I think the approach I took was an "intermediate cost" route. I considered using a B-body rear but if I went that route I didn't want to put an 8 3/4 back in. The cost of stepping up to a Dana was significant. Even if using an 8 3/4, you still need the housing and axles from a B-body plus the front and rear hangers. The AR TT2 15 X 10 rims are actually more expensive (around $270) versus the custom offset 15 X 8 (around $250). From what I investigated, going to a B-body rear was going to be more expensive than what I did. Of course the extra expense would allow the fitment of even larger tires but for my car, 275/60 will be plenty. I do agree that it took a good bit of time and labor to work this out. And I did end up with a set of rims which I didn't use. I can still recover some of that cost if I choose to sell them. It would have been easier if I had the idea in advance. I thought I would share this idea, since it might help someone else facing a similar situation. I agree that it is not for everyone, but it may be worth considering. For me, it provided the "right" look for the car. Thanks for the insights on the handling. I'll have to wait until the weather improves to see if I can notice any change in the roll stiffness of the car. 
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Re: 275/60/15 on a Cuda (long)
[Re: TC@HP2]
#889019
12/27/10 06:15 PM
12/27/10 06:15 PM
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Joined: Jan 2003
Posts: 1,756
London, England
Gavin
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,756
London, England
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Quote:
BTW, the splayed spring design is a handling benefit that is designed in to all E bodies, post 72 B bodies, and all FJM bodies. E bodies are narrower at the front, while all other are narrower in the rear. What the splayed mount does is put the spring in a position that provides additional torsional resistance to the leaf, hence more roll resistance to the body, and minimizes roll steer by the rear housing moving and altering wheelbase length. The extra tread width doesn't contribute to either of these attributes.
Thanks, that explains it, useful info. FWIW my point about the extra tread width was not that I expected it to directly compensate for the loss of splayed spring benefit (whatever it was) but just that usually one of the most significant 'handling' improvements is better tires. Therefore I was suggesting that even though a benefit may have been lost, the one that was gained is also significant - probably more so than what was lost!
Or to put it the other way around - if it isn't then there is not much point in doing this unless you don't care about cornering.
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Re: 275/60/15 on a Cuda (long)
[Re: Gavin]
#889020
12/27/10 07:10 PM
12/27/10 07:10 PM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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I just stuffed 325 50R 15 NITTO 555R's under my '70 'Cuda with 10 inch wide 5.5" backspaced Ralleys, a b-body rearend, Dr Diff's 1 inch inset hanger kit and Caltrac Monoleafs. It's tight, but nothing rubs through the whole range of travel,and I didn't have to roll the fenders. It fills the wheel well nicely.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: 275/60/15 on a Cuda (long)
[Re: davenc]
#889025
12/28/10 01:57 AM
12/28/10 01:57 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
Wow! That sure is stuffed. Is this a street car? How much tire sidewall to inner fender lip clearance do you have on rear suspension compression?
99.99% street, and still about two months away from being back on the road since the early '80's.
It's going to be too fast for the track without a full cage, but at least I'll get one good lap in.
I can stick my hand, up to my palm knuckles, between the tire and the fender lip. On a hard bounce only fingers. I ground the sheet metal until it was even with the wheel moulding trim to get the maximun clearance.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: 275/60/15 on a Cuda (long)
[Re: 1974Cuda360]
#889026
12/28/10 02:02 AM
12/28/10 02:02 AM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
jbc426, I am also curious to know if your car is street driven often and how the Caltrac setup affects the feel of the car on the street as well as the track.
This is a very informative thread. I am looking into improving my rear suspension and this information really helps.
It's a street car. I've only done a few hotlaps around the block, but it rides smoother than it ever has before, and that's with no glass, interior, trim etc. Caltracs with the split monoleafs +1 inch ride height are sweet.
It hooked up hard with some little pinner tires I had on it for painting etc when I smoked 'em in the driveway. Haven't launched on these big tires yet, as I have my steering column and dash out right now.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: 275/60/15 on a Cuda (long)
[Re: jbc426]
#889028
12/28/10 11:09 AM
12/28/10 11:09 AM
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Joined: Jan 2003
Posts: 6,497
N.E. Ohio
KillerBee
master
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master
Joined: Jan 2003
Posts: 6,497
N.E. Ohio
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Quote:
I just stuffed 325 50R 15 NITTO 555R's under my '70 'Cuda with 10 inch wide 5.5" backspaced Ralleys, a b-body rearend, Dr Diff's 1 inch inset hanger kit and Caltrac Monoleafs. It's tight, but nothing rubs through the whole range of travel,and I didn't have to roll the fenders. It fills the wheel well nicely.
Looks good. 
I'm planning on doing a similar B body Dana/Dr. Diff offset hanger swap under my wife's 71 R/T Challenger with a 325/50-15 drag radial tire.
My rim is a 15x10 with a 5.75" back spacing which I'm hoping to adjust outward with wheel spacers.
How close is your tire/rim on the inside near the leaf spring?
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Re: 275/60/15 on a Cuda (long)
[Re: KillerBee]
#889029
12/28/10 12:50 PM
12/28/10 12:50 PM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Quote:
Looks good.
I'm planning on doing a similar B body Dana/Dr. Diff offset hanger swap under my wife's 71 R/T Challenger with a 325/50-15 drag radial tire.
My rim is a 15x10 with a 5.75" back spacing which I'm hoping to adjust outward with wheel spacers.
How close is your tire/rim on the inside near the leaf spring?
It just missed touching when I first bolted them on. Now, it's just past the minimum clearance, at about 1/3 of an inch without the use of a 1/4 inch spacer. Dr diff said 1/4 inch is the absolute minimum clearance from the spring.
To get that much on my car without the spacer, I had to grind a slight relief in the rear mono-leaf being careful to to get it hot and spreading it out over aproximately 8 inches, being careful to smooth it completely and re-radiusing the edge again. I wouldn't have done this to the front segment because it has to handle much more stress, but in this case I didn't have to because of the earlier mentioned angling of the rea springs in the e-body. I have over 3/4 of an inch clearence up there.
I felt the rear spring's mono-leaf segment is really over-designed, so I got my space that way instead of using the 1/4 inch spacer and giving up that same clearance at the sharper fender lip. Unless you look closely, it isn't noticable. Of course, I'll be keeping a close eye on it for any type of deflection, bending etc.
On a regular leaf spring car, I would roll the fender lip and use the 1/4 inch spacers with the 5 & 1/2 inch backspaced 10 inch rims, order 5 1/4 inch backspaced rims, or use the appropriate spacer for the ones you have with the earlier dana.
For a Challenger, I would use the 1 & 1/2 inch Dr Diff kit. I believe he said you'll have to relocate the spring perch, or use an earlier model Dana 60. Challengers don't have the interferance issue at the valance panel that 'Cudas have.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: 275/60/15 on a Cuda (long)
[Re: TC@HP2]
#889031
12/31/10 02:07 PM
12/31/10 02:07 PM
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Joined: Mar 2007
Posts: 3,285
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,285
West Coast, USA
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Love that stance and rake!
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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