How To Get Maximum Tire Fitment!

[StRoKeR]

I took the time a several years ago to get the biggest tire possible in an ebody without fully tubbing it using stock wheelwells!

I had the rear custom cut to 54 5/8(b body is 55" and 44" centers on the perches) and use the dr diff 1" relo kit! 15*10 rims with 5" backspace! I had no rubs whatsoever! I did roll the outter top part of the lip which is easy to do even with the car painted! believe my perches were centered at 44" or maybe a hair less like 43.75" ! I believe my setup was 3" drums on that...

I got 315/60/15 ET street radial in there (which is 13.5" total width) an no rubbing at all
the pic below is a 29.5/10.5 slick!

You need to factor in for what type of brakes used - discs/2" or 3" wide drums! basically just buy a set of wheels you like first in 15*10 with 5" backsapce and set them in the wheelwells! I dropped a plumbob on each side fromt he frame rails and moved the tires to where I felt comfortable it wouldnt rub which was about 1/2" on each side (make sure tires have full air pressure in them for measuring) Prop the tires up to ride height you like also using blocks of wood or whatever!

Once that is done take a tape measure and measure from rim mounting flange to the other rim mounting flange! THIS IS YOUR MAGIC NUMBER TO START BY! after that its math! You can buy new moser ends for about $85

example: your rim flange to rim flange was 60.5" your using drums that are 3" wide total!(*2) 60.5-6 is 54.5" have the machine shop or yourself cut tubes and weld on the moser ends to where the total housing flange to flange is 54.5" (outside edges) and tell them how to offset the tubes...

After that is all said and done and your ready put the rear in the with springs etc... Now dont weld your new perches just set them in and just snug up u bolts on to make sure you can roll the rear so you have proper pinion angle and will get your perches exactly where they need to be on the housing also! get the car on its suspsension ( I use car ramps to get under there easily and be careful cause you have no driveshaft in there to lock the car, I stagger the ramps in different directions)

PINON ANGLE! now that is all done measure off the back of your tranny and measure off the yoke on the rear! add these 2 numbers together and that is your pinion angle! example: tranny is -2 down roll the pinion down to -1* to -2* down which gives you -3/-4 total pinon angle which is good for a caltrac type setup! and then tack the perches in then fully weld but box the perches in with the caltracs for strength which is just a flat plate cut to the dimension of the perch and housing opening there! you also do not need to use a pinion snubber with caltracs Superstock / Stock type springs example: Do same as above but lets say tranny is -3* down so roll your rear down -2 to -4* and tack in ! most like -5* to -7* pinon angle for that spring setup!

Now if your using a TALL tire setup and like to go to the track the rear will roll forward some and I suggest atleast 5/8" clearance to the front of the wheel well lip! Cause when you launch the tire will grab and pull all the paint off or worse....  Here are a few ways to move the rear back!
1. Weld the holes shut on the perches and drill a hole further back some to where needed!
2. Offset lowering block which is just a block with a hole in it and a pin moved back!
3. Cut some plates the thickness you need and place them in front of the front spring hanger and body you may only need 1/8"...

you can do same as above for low profile type rim and tire setups also! Hope that all made sense and I didnt forget anything 





I used all the steps above for my dart also..

[ChallengerHK]

Thanks for the write-up.

This may not be your thing, and may require a lot more effort, but I'm interested in the same topic re: front tires.

[Challenger6pak]

Nice writeup Sledgehammer.  Thanks. 

[go-fish]

Here's the expensive way. 

1) Buy a Strange S-60 rear end in standard E-body width.

2) Mini-tub the car.

3) Buy a custom built set of New Gen "Lite" 3 piece wheels with the offset depending on how much wheel lip you want. I went with a 12" wheel with 6" b.s. for a real deep look.

4) Narrow rear end to the width needed to have the custom width wheel sit in the wheel well perfectly.

[dodj]

To get the transmission angle, would you measure off the face of the output shaft? 

[dodj]

Hmmm... the numbers I'm getting don't look good to me. Tranny 3* down, rear 1.5* up.

[go-fish]

Hmmm... the numbers I'm getting don't look good to me. Tranny 3* down, rear 1.5* up.

Edited: mis information on my part. I was thinking of something else. pinion needs to be pointing down to allow for axle wrap.

[brads70]

IMO you want the rear pinion pointing down 3 degree's.

[dodj]

It would seem I need to roll the pinion down some. Am I correct that a 2* shim would change the pinion angle more than 2*? I'm thinking the rear is rotated 2* but the yoke is rotating towards the ground which will change the angle of the driveshaft as well. Or is the change minimal?

[mr_340]

I'm not sure you are looking at this correctly, Pinion angle is the angle between the rear yoke and the driveshaft and for a leaf spring car  5* to 7* nose down is recommended. And a 2* shim will change the angle 2*.

http://www.moparts.org/Tech/Archive/axle/8.html

Gary.

[dodj]

pinion needs to be pointing down to allow for axle wrap.

IMO you want the rear pinion pointing down 3 degree's.

I'm not sure you are looking at this correctly, Pinion angle is the angle between the rear yoke and the driveshaft and for a leaf spring car  5* to 7* nose down is recommended. And a 2* shim will change the angle 2*.
Gary.

I hear ya. I'm just concerned about overshooting the angle change. When the yoke rotates down, the rear of the driveshaft does as well. So by rotating the rear 2*, I was thinking the yoke to driveshaft angle would change like 3*. Or something a little more than the shim rating. Or am I over thinking this? Add 6* shim, get 4.5* nose down and you're done.

Actually, with a stock 8 3/4 rear (Swapped from another Chall) and Mopar XHD's, I'm surprised my driveline angles are so poor. I'm hoping they are the source of the vibes I've had.

[mr_340]

I think you're over thinking....with 6* you might see an extra 1/2*.
With mine after installing the SS springs I had 4* up, I put in 4* and ended up with about 0* i then added 2* more and it measured 2 1/2* nose down.

[mr_340]

6* of shim! I'd think I would just cut the perches off put new ones in and roll the rear down to where needed then weld up.

with 6* of shim your locating pin will no longer be engaged. (there are ways around that) but at this point I would relocate the perches too.

[dodj]

use the back of the tranny and the front of the yoke on your 8 3/4 for measurement! the rearend and diveshaft will rise under acceleration. 6* of shim! I'd think I would just cut the perches off put new ones in and roll the rear down to where needed then weld up.

Will do. New perches in garage now. Just bought a new MIG this morning. 

[brads70]

Will do. New perches in garage now. Just bought a new MIG this morning. 

Too bad we didn't live closer, would be fun to come over and help as I plan on doing this at some point too. I might learn something.    I'm planning on 10" rims and a new Dana 60 maybe next winter?