New Rear Springs Incorrect Wheelbase ???

[greenn50]

Ok so I new here and just wanted to run this by any one?

I bought some new rear springs from NPD the other day and installed them on my 1966 Mustang Fastback after installing them correctly I notice the rear tires seem to be real close to the front of the rear wheel opening not centered like the were with the old springs. So I looked up the spec. on the wheelbase for the mustang and found it is to measure 108 inches. I measured the wheelbase with the new springs measured 107 ½ inch. I checked to make sure the axle was seated in the bolt that bolts the spring together it was. Has new rear shackles. Any help and has any one run into this before. Oh ya the springs are the GT ones listed in the NPD catalog I guess the lower the car ½ inch.Thanks for the help!!

[Harleydave]

Do you still have the old springs? Measure them and compare.

[madstang78]

Loosen the I-bolts and rear shackle bolts. Put car on ground and bounce the rear end a few times by standing on bumper or something. That will get the springs and bushings to settle. If you have door jack up the rear with a floor jack and drop it to the ground a few times. Then measure and tighten the bolts With the suspension loaded

[greenn50]

I have the old spring and try to measure them the best i could but i will have to take the u bolts off to get a better measurement.

Good point didn't think about that i tighten everything hanging in the air.

[slotracer]

Originally Posted by greenn50

I have the old spring and try to measure them the best i could but i will have to take the u bolts off to get a better measurement.

Good point didn't think about that i tighten everything hanging in the air.

are they on the right way? if they are backwards, you would get a shorter wheel base. just a thought.

[cmefly]

Originally Posted by slotracer

are they on the right way? if they are backwards, you would get a shorter wheel base. just a thought.

That would not be possible.

[Maxum96]

Look at any vintage Mustang. The rear wheels sit closer to the front of the wheel well than the rear.

[cmefly]

Originally Posted by greenn50

Ok so I new here and just wanted to run this by any one?

I bought some new rear springs from NPD the other day and installed them on my 1966 Mustang Fastback after installing them correctly I notice the rear tires seem to be real close to the front of the rear wheel opening not centered like the were with the old springs. So I looked up the spec. on the wheelbase for the mustang and found it is to measure 108 inches. I measured the wheelbase with the new springs measured 107 ½ inch. I checked to make sure the axle was seated in the bolt that bolts the spring together it was. Has new rear shackles. Any help and has any one run into this before. Oh ya the springs are the GT ones listed in the NPD catalog I guess the lower the car ½ inch.Thanks for the help!!

The 65/66 mustang leaf springs should measure 22" from the center of both the front bushing and the center pin and 31" from center of the rear bushing to the pin. I do see a lot of venders that list leaf springs for 65-73 mustangs as the same and they are not. the 67-73 spring is the same 53" in length but the center pin is moved forward 1/8" to 21 7/8" and 31 1/8". Also make sure the housing is pushed back as far as it can go on the centering pin on the leaf. I just did a 9" housing with new mustang springs in a Falcon and I was able to pick up an extra 1/8" pushing the housing as far back as it would go. Not sure on a stock housing if there is much to gain, but on early falcons and comets that 1/8 is nice to have if trying to run a little taller tire.

[slotracer]

Originally Posted by cmefly

That would not be possible.

just a thought, I have seen some things you would think were not possible, like I tell my Carpenters, never say never!

[cmefly]

Originally Posted by slotracer

just a thought, I have seen some things you would think were not possible, like I tell my Carpenters, never say never!

I know what you are saying, It is crazy what people will do.

[blkfrd]

Don't get too hung up on the 108" wheelbase. Your current problem may be very real, but the wheelbase difference your seeing can be due to one or a combination of several things that are not a problem

[greenn50]

Ok problem solved I loosened the u bolts and took two ratchet straps on each side pulled the axle toward the back of the car and tightened the u-bolts. Now the wheel base measures 107 7/8 on both sides. I figuring that that is close enough for my liking. Thanks for the help!!