Steve69 wrote:

So what is the benefit of moving the Spring perch out 3/4 of an inch?   How does it improve the handeling?

Since this is a clarification of my earlier comment in this thread, I will answer this here.

Moving the spring perch farther out towards the ball joint increases the force the spring and shock place on the ball joint. This means that the shock will have more dampening force as well as the spring apperaring to be a bit stiffer. It will also raise the car back to stock height after the shelby drop. I moved mine out a full inch. If I ever decide to move back, all I need to do is move the perch back to the factory holes.

I have full roller everything on my 66 coupe with heim joints on the strut rods, KYB shocks, PM progressive springs, shelby drop and the brgesson power stering. It rode ok when I put it together, but there was still a lot of float for my preference.

It took about 1.5 hours to do both A-arms on the car...Including removing and reinstalling springs and shocks. It was an immediate difference in how the car drives and handles. It settles instantly with virtually no rebound. The drive is very smooth without adding any harshness. I can only speak for my combination with roller upper and lower a-arms and roller spring perches.

I hope this helps.
BobN

The reason I do not like theTaiwan reproductions is because the rubber they use in them does not last very long.  They are just not made like the originals in that regard.  Daze cuts the rubber part out of the equation when converting to roller bearings, so that is no longer a factor.

Another note on spring selection.  I do not base any comments on something I read.  I base it only on actual testing on my own car.  Ride quality is an opinion that can vary widely.

The original question is based on a 65/66 Mustang.  Springs that ride well on a 69-70 Mustang may not be the same as a 65/66 because the 69-70 uses a 1" longer spring than a 65/66.  I have owned many 70 Mustangs and played around with springs on those as well.  A 620# lowering spring installed with the Shelby drop on a 69-70 feels totally different than same type thing on a 65/66.  The shorter spring, even though the rate per inch is the same, has one less inch of length being compressed, plus the car is lighter, so it "feels" stiffer than a 620 on a 69-70.  Not all Mustang years are equal, although they are similar.

I do not race my 66, but I do drive it pretty aggressively on the local Farm-to-Market roads with lots of rural 90 degree turns.  I have not noticed any unpredictability with the progressive springs, although I do greatly prefer the track version for cornering as well as control under straight line acceleration.

I have always said you can not have a top notch race car and also use it on the street.  You can not have a top notch street car and try to run it on a track.  It will fail in both cases.  Suspension is always a compromise because we all think we want a race car but in actuality we drive on the freeway at normal speeds most of the time.  Like Daze said, built it for its intended purpose and enjoy driving it.