Greetings,

I'm in the middle of a complete front end rebuild on my non AC 75 coupe. I decided that while it was all apart and most everything else was being changed, might as well change the springs too. I ordered a set of Moog 5758 springs, the catalog part for a non-AC 75. When we removed the old ones, we discovered that they were approx 15" tall unloaded, while the Moogs were only about 12.5". So I then ordered a set of Moog 5762 springs, the w/AC version. These appear exactly the same as the 5758's, both in coil number and material diameter, and are also only approx 12.5" tall.

So next I figure what I have must be "big block" springs. However looking up springs for earlier year big blocks again calls for Moog 5762. So I'm trying to figure out what springs Bubba used and why?

The car did have a slight tire rub on the inner wheel well at full lock on one side only w/the tall springs in it. Now w/it sitting approx 1.5" lower (haven't driven it yet) I'm pretty sure I'm going to have clearance issues if left as is.

We did find a part number of 346939 AH on one of the "original" tall springs. Does anyone have any reference as to what these might be from? Or for that matter any input or thoughts on this matter. Any help would be much appreciated.

TIA.

 

in my experience...the new springs are shorter to make it easier to install...the spring rates are still the same...

RR

 

I know that the higher rate aftermarket springs are considerably shorter uncompressed than the stockers. I have mine out right now and am about to replace them with a set fom Zip's. They claim that there should be no change in ride height, although sitting side by side, the new springs are probably a good 2" shorter, but the diameter of the steel is much thicker, so it will not compress nearly as easily.

http://www.zip-products.com/Zip/prod...C9517C3CD4E62F

 

the after maket springs are shorter, but the compressed ride height will be the same. if you want to lower the front end, this is the time to do it. there's many threads on this topic. but if you cut the springs down, do it 1/4 coil at a time.
jeff

 

stock small block no AC springs were about 280 lbs/inch springs. Those aren't available anymore since the 70's.. All the so called replacement springs are shorter because they have a higher spring rate of about 500 lbs/inch. Stiffer springs are shorter with thicker coils. They will fit and give you the correct ride height (factory ride height and not ride height with worn out springs)
The replacement springs will give you better handling but worse traction as they reduce weight transfer on your front suspension. Weight transfer is important for good traction for straight line acceleration..

 

Well I understand the theory and explanations, but as of this moment the car is sitting on the ground w/the left side rebuilt w/a new "short" spring and the right side is awaiting disassembly and has all the old components including the old apparently factory spring. The left side is sitting approx 1 - 1.5" lower than the right at this moment. I know that the two different springs may be somewhat affecting the measurements, but it sure appears that the car is already going to sit lower w/the replacement springs even w/o cutting them.

 

I understand but that's not what I'm seeing so far. With the front end 1/2 rebuilt, the left side w/the aftermarket spring is sitting approx 1 - 1.5" lower than the yet to be rebuilt right side and I'm a bit concerned about tire clearance.

I'm curious what others have experienced using the shorter higher rate springs w/o cutting them. Has the ride height changed or stayed the same?

 

Well, I guess that it depends on who the manufactorer of the replacement springs is. The ones that I've seen restored factory ride height but there are several manufactorers. The spring rate is DEFINETELY much stiffer on all the replacement springs and therefore they are shorter. Unfortunately, nobody makes springs with the stock spring rate anymore..

 

As originally stated they are Moog springs but so far I haven't been able to find spring rate info on the 5758's or 5762's. No doubt they are higher than the originals but what rate, I don't know.

I guess I'll just have to wait and see where the car sits after I get the right side finished. If it doesn't work w/what I have, I can always swap them out then.

Thanks for you input!

 

I got Moog replacement springs for my 68 through Advance Auto Parts and they were a couple inches shorter but they were real easy putting back in and the ride height is a little bit higher than my old springs, which I needed because my stock springs were weak. The ride is a lot better.

 

Based upon all I've learned from yesterday I would agree and think that the ride height should be the same or higher than the worn out 34 year old originals. However that's not what I'm seeing so far. The rebuilt side w/the new spring is lower by over an inch from the yet to be rebuilt side. Now I'm sure the current mismatch of the two springs may be throwing off the measurements a bit, but it certainly appears that the front is going to be lower, not higher, with the new springs. This is what I'm concerned about as I already had a slight tire rub on the inner wheel well near full lock.

Thanks for your input.

 

check the suspension heights in the aim. i believe it's the "Z" number in the front. if thats ok, something else is making the nose low.
jeff

 

If you don't like the ride height, you could use spacers to get the ride height that you want.. Those aren't awfully expensive..

http://cgi.ebay.com/ebaymotors/New-R...spagenameZWDVW