Rear axle alignment

[Swamp Donkey]

I’m doing some test fitting for some 305/35r18 tires.  My rear axle seems to be off by about 1/4 of an inch toward the passenger side.  So when I made my mockup tire, these are the measurements for clearance I get.  On the passenger outside fender lip I have about 7/16 or 11mm of room. Passenger side by the leaf spring 1/2 or 13mm of room.  Drivers side top fender clearance is 5/8 or 16mm.  Drivers side leaf spring clearance is about 1/4 inch or 5mm.  I’ve tried loosening my whole suspension and shifting everything towards the drives side, but there is really no wiggle room. So I’m wondering if I should just bite the bullet and weld on new spring perches. Or is there something I’m missing to get this rear end aligned.  Don’t really want to go to 295’s on a 10 inch rim.  I have the Dr Diff 1” relocation kit and also have new Mopar performance leaf springs P4452985 and P4452984. Car was never in an accident, and was super solid to start with.

Linkback: https://forum.e-bodies.org/wheels-tires-brakes-suspension-and-steering/12/rear-axle-alignment/27381/

[dodj]

That's within the tolerances of the day.
I have a 5mm spacer behind one of my rear wheels.....so....our cars are similar.

[Swamp Donkey]

Interesting.  I wonder, because I might have my rims made with a custom offset, if it would be insane to have each one built specifically to fit each wheel well evenly rather than use spacers. 

[gzig5]

Not in lover with the idea, but a single thin spacer would be the Easy Button fix. 

I like your low-buck mock up tool.  Definitely stealing that idea.  I had considered cutting a disk out of 1/4" plexiglass but the wood is even easier.

[Brads70]

Normal, mine was not mirror image either. Not likely but how is it fore and aft? If it's out some you could shim the hanger and gain a little tighter clearances maybe?  Plum bob, string and a tape measure are easy enough to use?
Instead of cutting off and welding on new perches, what about making the hole bigger in the perch and use offset bushings , then weld them in when your happy?

[Swamp Donkey]

Saw it on YouTube.  Can adjust dowel easily for test fitting.

[Dmod1974]

I had the exact same thing as well; it's normal.  One side rubbed with 275/60/15's back in the day when I ran them, and the other side had plenty of clearance.  I corrected that when I replaced 80% of the car during resto, and any remaining offset in any direction was easily adjusted out via the 4 link I have not.

[Bpret]

Both of my cars are like that 70 Cuda and 70 Dart not sure if it was on purpose or just within spec’s

[Swamp Donkey]

Both of my cars are like that 70 Cuda and 70 Dart not sure if it was on purpose or just within spec’s

Ok. I am not super meticulous, but it has been driving my insane with everything being just that 1/4 inch out from side to side.  But I think I will order rims and backspacing to fit the passenger side perfectly and use a small thin spacer on the drivers side. Won’t be more that 1/4” thick by my measurements. 

[gzig5]

1/4" isn't much difference, but make sure your bolts or studs on that side have full thread engagement.

[HP2]

For a street car, .25 isn't that much and is within the original build specifications. I'd also add that this .25" is only measured against the fender lips by your rig. You would need to drop a plumb bob down and plot all the suspension pick up points to verify if the suspension is off or if the body is off. Its entirely possible one of the quarters is off one direction and the other is the opposite. Assembly tolerance of the era were very lax by comparison to today.

I'd  open up the holes in the spring perch to allow it to slide over the .25", then weld up the gap. Then no worrying about spacers and thread engagement.

No way would I ever consider getting a custom offset in the wheels on one side to center the track width.