New springs ... or reset yours.

Why would you be yelled at? 

I discovered those today before reading this, seem like a good option!  I just don't know how to find them.

Here's the "rub" (pun intended): every 67-68 has a slightly offset rear axle. I've extensively restored 3 and fiddled with a 4th for vintage auto racing, so kinda been down this road A LOT, but wanted to wait for others to weigh in. The driver's rear is the flashpoint where this is exasperatingly dumbfounding.
   AFTER you have beat the hell out of the driver's rear fender lip (I ALWAYS cut this lip off with a grinder), several options remain: run an ever-so-slightly different offset wheel or 1/8" to 1/4" thinner spacer. This was an early Jerry Titus trick in vintage Trans-Am...PRIOR to banging out the driver rear fender with a sledge hammer. They actually shaved a 32nd or so off the mounting face of the specific rear wheel on the driver's side. The fronts were not specific side-to-side, only the rears. In my forum signature pic, I am running the absolute maximum width tire on the rear: 285/40/17. What you don't see is the driver's rear fender lip has been tightly curled/pinched up against the inside surface AND the aluminum wheel spacer is custom shaved with 1/32" taken off of it. No rub. No rub coming out of my drive way, no rub in tight corners of a road course, no rub on the ultimate test of all--the jouncy roads of Las Colinas (D/FW mid-cities area)
   Second, with the rear end u-bolts loose, shove the rear axle toward the passenger side as far as you can. Sometimes there's a very small amount of play in the spring saddles' locating pin that can produce a few thousandths of extra clearance (another Jerry Titus Trans Am trick).
    If you look up any of my old posts from the last 25 years on this forum, you will see where I try to fit as much tire as possible in the driver's side rear fender, because that's the side that is a tighter fit. I guess I had to speak up here before you start changing the suspension's dynamics with different springs, shackles, or spring eye-location (one standard (left rear) and one mid-eye (right rear), like you can order at Mustangs Plus). I tried panard bars but used watts link with some success.
  Even though folks here know I am currently throwing myself into a 70 Boss 302 Trans Am car, the 67-68 is my favorite Mustang. I hope you find a solution that you can live with...because something else will come along that needs attention. And you will love fixing that too.

Last edited by Prof (4/12/2020 8:47 AM)

Thanks for tip about the spring perch slot, side to side.

Considered that option, but wasn’t sure if it was a good idea. Never altered them.

Colour my neck red  
Here is my car with 1" longer  shackles on 15 year old rear springs.
All I remember about the springs is they were ordered for a 68 convertible, 289 engine, P/S, and no air.
 I put the long shackles on to gain tire clearance  because of all the extra weight of luggage and stuff needed for two weeks travel in the car.
 I'm OK with the way it looks now without the kitchen sink.
 If I ever get to doing the Arning drop I may revert to the O/E shackles, or not!

Knew a guy once (many-many-many years ago) who jacked up the back of his car(non Mustang) by putting muffler clamps around the rear shock absorbers! Just jack up the back where he wanted it and bolted the muffler clamp around the shocks
Looked wayyyyy cool and rode like $hit!
6sal6

Rudi, that's not stink bug stance, that's rake.  Looks just fine.This is stink bug stance:

WOW everyone, thank you so much, these have truly been amazing responses, especially you Bolted....

Funny thing, before reading most these last night I was really racking my brain on this knowing I couldnt change the lift, but also knowing when the shop restored the car he initially didnt like how high the car was sitting, then reduced it somehow???

now Im not a mechanic or restoration pro, but I have done lots, learned from people and youtube and have always had a knack with working with my hands/figuring things out........I started to think on "How do I know, and how does a shop Center the Diff???" 
after all it is just bolted and clamped down without anything really forcing it to be in a certain position.......then I read all these and Whammo, you confirmed my suspicion!   cause why else would 1 Side scrape, but not the other with all things created equal.....

No the question is, would an Alignment shop do this or do I have to (to save $$ and then go for an alignment???!!!???


**** Note, I have a second topic going on Wheel Height and how to increase the Gap between the Tire and Wheel well.......*****
I neglected to mention because I had forgot about this detail ------ When I go over a mild-greater size bump or dip in the road that either hits a bit harder, or causes some bounce, It feels like when the REAR hit after, the car want to Side Strafe typically LEFT, I believe;  Either way left or right i feel this movement like it wants to shift perpendicular to the way shes facing......Obviously Alignment but Could Very Well Be An Indication of the Diff Positioning?
 

TKOPerformance wrote:

........ some jig was way out of spec at the factory 

 
Ohhhhhhhhhhhhhhhh..."Mom!.....he said jig!"
6sal6

M1Mustang69 wrote:

WOW everyone, thank you so much, these have truly been amazing responses, especially you Bolted....

Funny thing, before reading most these last night I was really racking my brain on this knowing I couldnt change the lift, but also knowing when the shop restored the car he initially didnt like how high the car was sitting, then reduced it somehow???

now Im not a mechanic or restoration pro, but I have done lots, learned from people and youtube and have always had a knack with working with my hands/figuring things out........I started to think on "How do I know, and how does a shop Center the Diff???" 
after all it is just bolted and clamped down without anything really forcing it to be in a certain position.......then I read all these and Whammo, you confirmed my suspicion!   cause why else would 1 Side scrape, but not the other with all things created equal.....

No the question is, would an Alignment shop do this or do I have to (to save $$ and then go for an alignment???!!!???

It doubtful an alignment shop would do this. You don't have to be a good welder to do this, I'm not. After removing the housing, I used a piece of aluminum flat bar shoved up in the spring perch to provide a back to my hole. Then proceeded to fill in the hole with my little mig welder. The weld did not stick to the aluminum. It won't stick to the copper either. Just make sure you have good measurements on the holes of where they are and where you need them to be. On a side note, I didn't notice a change in the alignment after I center the rear end. It still tracked straight and the steering wheel was still centered. 

M1Mustang69 wrote:

**** Note, I have a second topic going on Wheel Height and how to increase the Gap between the Tire and Wheel well.......*****
I neglected to mention because I had forgot about this detail ------ When I go over a mild-greater size bump or dip in the road that either hits a bit harder, or causes some bounce, It feels like when the REAR hit after, the car want to Side Strafe typically LEFT, I believe;  Either way left or right i feel this movement like it wants to shift perpendicular to the way shes facing......Obviously Alignment but Could Very Well Be An Indication of the Diff Positioning?
 

Look at the front eye on the leaf springs. You can buy reverse eye, mid eye, and standard eye springs. I think the mid and reverse eyes get you a 1/2" and 1" lower stance.

I know that feeling. My back end went right it seems like. Think of the tire rub as hitting the brake in one tire. It'll be obvious where the the tire rubbed the first time cause you will see the on the wheel well lip. After you make some changes, it's not so easy to tell. I use blue painters tape to see where the next rub comes in at. If you find you have reverse or mid eye springs and want new springs to raise it up, then I would suggest at least a 4-1/2 or 5 leaf spring to help with the wheel hop. 
 

Prof wrote:

It would help to know exactly WHERE the rub is occurring...actually different solutions.  Just curious: is it the fender lip at 10 o'clock and 2 o'clock? The lip at 9 o'clock and 3 o'clock? Or up inside the fender at 12 o'clock?  My headaches really increased when the rub on mine was at 9 o'clock/3 o'clock AND inside at 12 o'clock. That's when I began shaving spacers til it went away.

TKO has yet to write the usual dissertation on this. Wait for it, he's never wrong.
 

Oh, if I had a surefire solution to this I'd have posted it already.  It wouldn't take 40 pages though.

MS wrote:

On my 68 coupe, I installed a 65 rear end which is 2” narrower. Used 17x8 wheels with 4.5” backspacing a and 245x45/17 tires. Fit like it should have fit from the factory.

I wish I could fit this Tire.......On my 69 FB I had 245/45R16's modifying Nothing!