Moog spring confusion

[Robert Walton]

After much research I decided to buy some 5658 springs. I was re-reading this web site and now I'm confused. It appears that the 5606 may be a bit stiffer over the entire range of motion. Just have to cut off a coil or so to get the correct height. Is this right or stick with the 5658.

http://jeffd.50megs.com/Moog_Spring_Page.htm

[keyman]

The 5606(front) and 5379 (rear) are the Moog part #'s for their stock replacement springs. These should sit as close to factory as you're gonna get. I just put these on my car last week.

[Robert Walton]

I'm looking for stiffer and lower than stock. Go to the web site and read the chart. It appears that a 5606 is stiffer but not lower than stock.

[larobj63]

Then why get MOOG? Check out Eibach and Suspension Techniques...they actually make springs that are engineered for performance driving/look. MOOG is more in the business of OEM replacement, no?

Cutting coils, even if done properly, is a roll of the dice, (as far as final height) IMO...

[rastaz]

Originally posted by Robert Walton
I'm looking for stiffer and lower than stock. Go to the web site and read the chart. It appears that a 5606 is stiffer but not lower than stock.

I run the 5660's up front... they are stiffer and sit a little lower than stock... HTH

[87natty]

There's a huge difference in price between Moog and Eibach. Didn't someone post a while back about using 89(?) IROC convertible springs for stiffness and a lower ride height? I want to accuse Racer X of saying this or knowing about it, it was a thread about the $2004 challenge. My connection is too slow for a search, so you're SOL if you need me to do it. Good luck though, keep it low buck.

[Racer X]

Robert,

The Following quote is from the website you listed. Essentially, the 5606 and the 5658 are the same spring. What has changed is the height of the spring, which changes the spring rate. All things being equal and you SHORTEN the spring, you will INCREASE the spring rate. The Grand National came stock with a +/- 420 pound spring in the front. I have a 650 pound spring in the front of mine (which I bought from Hotchkis) and it's a good performer, but not good for the street. Too choppy for a comfortable ride.

Originally posted by Jeff Davidson
As you can see by the added numbers, there are numerous springs of the same spring rate available. This allows the spring to be matched to the weight of the vehicle since, depending on options, the ride height would vary if only one spring was available. If you know the weight of the front axle of your car, you could pick a spring that would give you the ride height you desire.
Example:
Let's say you want to use the 5658 S-10 spring in your Monte to gain some spring rate. Assume you already have 5606 springs in your Monte. Let's install a set of 5658 and see what happens. We know that we already have a front end weight of 2142 pounds (assumed) or, 1530 pounds at the spring, but if you look at the installed height weight capability of the 5658, you can see that it can't support that weight, at that height, so it compresses until it can. In this case, it compresses about .5" further than the 5660 does for the same weight vehicle.

The following chart shows the various spring forces generated by the different springs. As you can see, the stiffer springs lose much of their "push" at heights greater than their Installed Height. The 5606 produces almost twice the force at a 12.00" loaded length than the 5658 does. This should help handling as there will be less weight transferred when cornering. The stiffer spring will decrease body roll as well. One interesting comparison is the 5606 and the 5658. These two springs would have similar ride and produce the same force at around 9.00" height, but the 5658 force drops off rapidly under rebound conditions when the spring height gets above 10.75". This should prevent the vehicle from rising too far in the front in response to a rise in the road and get rid of the "floaty" feeling of excessive rebound. But, the 5660 will provide more spring rate if the spring is going to be shortened to attain a custom ride height. You already get around a .25" drop, but that really depends on the actual weight of the vehicle involved. If you want an even stiffer ride, the 5662 springs have been used with good success by several members of the Monte Carlo Mailing list. This spring will really resist the tendency to bottom the front suspension and is needed if you choose to lower the front end by two inches. If you only want to lower by one inch, trimming a quarter or half coil off of the 5660 would probably sufficient to give the ride height you desire and not bottom. The 5662 is strong enough to resist almost .75" of further travel compared to the 5658 and about .5" compared to the 5660.

[TTA89]

Originally posted by Racer X
Robert,

The Following quote is from the website you listed. Essentially, the 5606 and the 5658 are the same spring. What has changed is the height of the spring, which changes the spring rate. All things being equal and you SHORTEN the spring, you will INCREASE the spring rate. The Grand National came stock with a +/- 420 pound spring in the front. I have a 650 pound spring in the front of mine (which I bought from Hotchkis) and it's a good performer, but not good for the street. Too choppy for a comfortable ride.

I run 1000lb in my Lightning with QA1s. Its stiff but not bad, don't expect a Buick ride.

[Robert Walton]

Thanks Racer X as usual you have saved the day.