Rear End Lift

rsweld · Apr 27, 2010

Guy's,
I want to lift the rear end of my 65 Rag Top about 1 1/2" to install larger tires. I recently installed new leaf springs and really can not afford a new pair of 1 1/2" lift springs. My question is has anyone lifted the rear end of a 65 using longer lift shackles and will they clear the rear valance? Or would i be better off to bite the bullet and replace the rear spings, I would really prefer to use longer lift shackles as this is a daily driver. Any thoughts?

TeamEntity · Apr 27, 2010

I would do shackles for a daily.

tx65coupe · Apr 28, 2010

I know that most kinda frown on it, but I have extended shackles on mine. It works fine and will clear the valance. Just cut off the excess and paint them black. It looks tons better.

I have actually been considering going back to stock shackles and running 215 60 15 on all four. I'm running 235 60 15 rear currently.

The springs would be the best idea. Whatever you do do not get air shocks.

2+2GT · Apr 28, 2010

Just remember that the occasional pothole or RR crossing will jam your axle up to the stops. If the tire doesn't clear now, it won't clear then, either. Shackles alter the pinion angle, and if you don't compensate, it'll increase wear and stress on the drivetrain. Be careful of '4 1/2' or '5 leaf' springs, they'll make the car ride pretty harsh in the back. Not a good thing for daily use, and the ladies will not like it, either.

Oh, and +1 on the 'no air shock or coil over shock' thing, too. Kills handling and usually destroys the crossmember.

68RCodeConv · Apr 30, 2010

Air shocks are about the worst thing you can do. Shackles are not a lot better.

If you look at at a car with long shackles you will notice that the back half of the leaf spring is bent over backward. That is because in lifting the body higher a larger percentage of the car weight is being loaded onto the back of the spring. This (1) changes the center of gravity higher AND further back thus screwing up the handling, and (2) really puts a lot of load on the frame rails. Not unusual for the shackles to go right through the trunk floor when you hit a bump.

68EFIvert · Apr 30, 2010

Is there a place locally that can rearch your springs to give you the lift you need. If not buy the springs that will do what you want. I usually find out if I don't do it the right way the first time around I will regret it later. Good luck and post some pics when you get the new tires on. Before and after pics would be cool.

tx65coupe · May 1, 2010

68RCodeConv said:
Air shocks are about the worst thing you can do. Shackles are not a lot better.

If you look at at a car with long shackles you will notice that the back half of the leaf spring is bent over backward. That is because in lifting the body higher a larger percentage of the car weight is being loaded onto the back of the spring. This (1) changes the center of gravity higher AND further back thus screwing up the handling, and (2) really puts a lot of load on the frame rails. Not unusual for the shackles to go right through the trunk floor when you hit a bump.

I don't buy that. I have never heard that before. As the rear goes up, more weight is actually on the front of the car.

I don't think it stresses the rear of the car more though. I just don't see how that can be. I am curious to know if it is true though.

I will agree that it does screw with the handling and center of gravity. Thats why I was thinking about removing them.

2+2GT · May 1, 2010

As the rear goes up, more weight is actually on the front of the car.
Not enough to matter.

I don't think it stresses the rear of the car more though. I just don't see how that can be. I am curious to know if it is true though.
If the pinion angle does not match the engine/trans, the mis-match will start looking for the weakest point. Most likely the U-joints or differential.

I will agree that it does screw with the handling and center of gravity. Thats why I was thinking about removing them.
I'd be surprised if shackles move the center of gravity more than 1/8". What they do, though, is screw up the pinion angle, and cause the rear end of the car to wiggle from side to side like a cheap hooker, which screws up your handling.

Cobra ssc · May 1, 2010

What, I have air shocks on my car with a 347/Vortech combo! How can they be bad? j/k I am looking for a good rear suspension to handle the power and fit a good size tire though...

Has anyone done a mini-tub on a fastback and still kept the rear seat?

68stang351 · May 1, 2010

I'm interested in this also. I need the rear up just a tad for tire clearance, and absolutely will not run shackles because I HATE (and I mean HATE!) the way they look. Air shocks suck, and always blow out. Now I have these stupid bolt on coil springs around my shocks that I put on slightly compressed, and that's just temporary until I figure out what else to do.

I guess a set of new springs that are arched to raise it, or re-arching my springs are the best way to go for me?

tx65coupe · May 2, 2010

2+2GT said:
As the rear goes up, more weight is actually on the front of the car.
Not enough to matter.

I don't think it stresses the rear of the car more though. I just don't see how that can be. I am curious to know if it is true though.
If the pinion angle does not match the engine/trans, the mis-match will start looking for the weakest point. Most likely the U-joints or differential.

I will agree that it does screw with the handling and center of gravity. Thats why I was thinking about removing them.
I'd be surprised if shackles move the center of gravity more than 1/8". What they do, though, is screw up the pinion angle, and cause the rear end of the car to wiggle from side to side like a cheap hooker, which screws up your handling.

Thats true about the U joints. I was thinking he meant it stresses the actual rear frame of the car.

I was still considering the lift springs that Laurel Mountain Mustang sells. They are the only shop that I have seen that even lists them.

2+2GT · May 2, 2010

Cobra ssc said:
What, I have air shocks on my car with a 347/Vortech combo! How can they be bad? j/k I am looking for a good rear suspension to handle the power and fit a good size tire though...

Has anyone done a mini-tub on a fastback and still kept the rear seat?

You would have to narrow the seat, and seat panels. The assembly butts up against the quarter trim panels, which butt against the inner wheelhouse. There is simply no room to give.

2+2GT · May 2, 2010

I don't think it stresses the rear of the car more though. I just don't see how that can be. I am curious to know if it is true though.

tx65coupe said:
Thats true about the U joints. I was thinking he meant it stresses the actual rear frame of the car.

I was still considering the lift springs that Laurel Mountain Mustang sells. They are the only shop that I have seen that even lists them.

You are probably correct. To answer him, I can only say I have been working with these cars since the 70's, and what air or coilover shocks do to the shock crossmember can only be described as 'cruel'.

68stang351 said:
I'm interested in this also. I need the rear up just a tad for tire clearance, and absolutely will not run shackles because I HATE (and I mean HATE!) the way they look. Air shocks suck, and always blow out. Now I have these stupid bolt on coil springs around my shocks that I put on slightly compressed, and that's just temporary until I figure out what else to do.

I guess a set of new springs that are arched to raise it, or re-arching my springs are the best way to go for me?

I could probably find other sources for high-arch springs, but the real problem is the tires. Raising the rear is a poor answer to tire clearance problems, sooner or later you go through a badly crowned intersection, or pothole, and the tire slams into the wheelhouse or opening lip anyway. And meanwhile, you have to put up with the poor handling the higher rear end gives you.

Cold arching of springs is useless, since they are tempered, and will always go back down. The proper way to re-arch springs, is to anneal them, fix the arch, and re-temper them. This is very useful for cars with unusual springs, like 53-62 Corvettes, but on a Mustang will cost you more than new, show-correct replacements.

Az Pete · May 2, 2010

Not everyone likes the idea but I prefer the raised rear look of the '60s....maybe because I grew up then.

I have used these springs from JC Whitney, Extra-High-Lift Rear Leaf Springs for Cars - JCWhitney , for the last two '66 Coupes I have done. I use stock shackles and standard type shocks that are about 3" longer to get the proper travel range. There is about 5 inches difference in the wheel well to ground measurements.

With four adults in the car, I only have to watch the rolling type dips in the road. Not much problem really. The ride is a little bit rough but that comes with the look....

The rear does not wonder of lean odd. The car handles fine in every day driving and corning. I do not race the car so that type of handling is not a problem.

I believe this car has 235/60/15's on the rear but the PO's choice of wheels put the tire out a bit. I like the wheels so I keep them. Might even go to a wider tire sometime. He used air shocks....yuk. In 18 months of owning this car, I have put 10,000 miles on it like this.

Sparxx · May 2, 2010

Just wondering why everyone hates air shocks? I have them on my '78 and don't have any problems with them. Also my father is building a '67 and he is putting airshocks on that.

Also both have shackle extensions

j69302 · May 3, 2010

air shocks are ok as long as you dont try to use them to raise the rear end by increasing the pressure. increasing the pressure in a air shock to raise the rear end result in a lot of extra load on the upper shock mount and they can rip through the trunk floor.

tx65coupe · May 3, 2010

Air shocks belong in the trash can.

Sparxx · May 3, 2010

tx65coupe Why?

Even if they have close to max air pressure it is no differnt than regular shocks. The car still weights the same. Unless your mounts are rusted out it is no worse then your regular shocks.

horseballz · May 3, 2010

Sparxx & All,
Shock mounts are not designed to support the weight of the car! They are designed to support what shocks are supposed to do, dampen/attenuate/control suspension movement.

"Even if they have close to max air pressure it is no differnt than regular shocks." = WRONG!
Shock absorbers do NOT support weight (unless air or coil over). The springs support the weight.

"I have them on my '78 and don't have any problems with them." = You Will. I'm an old fart and I've seen time and again.
Gene

tx65coupe · May 4, 2010

Exactly what he said. It is much worse than regular shocks. The air shocks cause the shock mounts to support additional weight which they are not designed to do. The air shocks can bust through the trunk floor. I have seen a few cars, and heard of many that had that happen. Another issue with air shocks is sometimes they can make the back of the car bouncy.

Rear End Lift

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