PurelyPMD

iTrader: (3)

subd

SOCAL-Z

Here's a pic of the back springs installed. I will be doing the fronts pretty soon.

69442DREAMCAR

Did the 5662's raise the front any? I think mine stock front springs are worn, and it lets my front tires rub. I was told that the 5662's would raise maybe one inch if the stock springs are worn out. I had to spend the money and it change nothing. Thanks for your advice in advance.

Mark51960

Hi,
Did you put the 5662/5665 in? What happened?
What engine/trans does the car have?
Thanks

QwkTrip

iTrader: (22)

If you look at the Moog website you'll see that the target for most their front springs is an 11.0 inch compressed height after install in the car, except for the 5664 (707 lb/in) and the 5662 (748 lb/in) with a target 10.75 inch compressed height. That is the distance measurement between the bottom and top spring pocket, and those numbers are what Moog thinks will result in a stock ride height. The 10.75" is probably the IROC.

Moog also tells you the intended Load (lbs) for the spring. This is the sprung weight for which the spring is designed to give the advertised compressed height. For example, the Moog 6486 spring has a 1935 lb load spec with a spring rate of 343 lb/inch and free length of 16.63 inch. Run the math and you'll see that load on that spring ends up with a compressed height of 11.0 inches!

Moog 6486 --> 11.0 inch = (16.63 inch) - [ (1935 lb) / (343 lb/in) ]

Another thing you'll notice is that all of the Moog springs fall into a few groupings of approximately 300 lb/in , 345 lb/in , 420 lb/in , and 700+ lb/inch. Each grouping has multiple spring choices with slight differences of spring rate and free height. Those differences are to account for the variations of vehicle sprung weight depending what options the car had from the factory. For example, air conditioning adds sprung weight which would require the springs to be a little taller and maybe a bit stiffer so that the spring lands at 11.0 inch compressed height. Same idea with ground effects, power seats, etc.

Now you know what all the numbers mean on the Moog website. Bottom line is Moog has a few groupings of spring rates depending on the performance or ride quality you want from the car. And if you want a stock ride height then you choose the spring with a Load spec that best matches your vehicle's sprung weight.

But what if you don't know the sprung weight of your car? Or what if you want a car that's lower or taller? Easy, you just have to take a few measurements....

1. Take your car to a truck stop with a weigh station and put only the front wheels on the scale to get the front weight. Then subtract about 350 lbs and that is the approximate sprung weight of the car on the front springs. That 350 lbs is wheels, tires, brakes, spindles, outboard part of the A-arms, and anything else that that the springs don't lift.

2. Then use a floor jack to set the wheel to the ride height you want and measure the distance between the bottom and top spring pocket. That measurement is the target compressed height of the spring with the sprung weight applied.

3. Do the math to figure out which Moog spring would result in that compressed height in your car. Buy the spring. Install it. Done.

For example, my car's front sprung weight is about 1650 pounds. If I installed a Moog 6486 on my car then the spring would end up with a 11.8" compressed height. Whereas a Moog 5596 with same spring rate would end up with 10.4 inch compressed height because of the differences in initial free length of the springs.

Compressed Height = (Free Height) - (Sprung Weight) / (Spring Rate)
Moog 6486 --> 11.8 inch = (16.63 inch) - (1650 lb) / (343 lb/in)
Moog 5596 --> 10.4 inch = (15.19) - (1650 lb) / (346 lb/in)

That in a nut shell is how you get it right the first try.

If you're wondering why I didn't cut the sprung weight in half for two springs, I actually did but the A-arm force ratio is 2:1 so the springs end up seeing twice the force as the wheels so you end up getting the same number you started with.