GN front coil springs

shifty6

Member
Joined
May 11, 2004
Can someone tell me if Moog #5598 fronts are a good option for street/strip usage. Any info on them would be greatly appreciated. TIA
 
Are you trying to go back to stock or???
Was wandering if they were a stock replacement but I also thought the #5606 was the stock replacement....I am actually looking for sum lift/stance and good weight transfer and don't know what these (#5598) springs specs are or what they are even for. Thanx for ur input...I was hoping u would reply with ur expertise.
 
5598, 5600, 5608, and 5604 are all the same rate but different installed heights. The 5598 would be the correct spring for the factory replacement. Originally the rate was 355 lbs per inch and the replacement is 340 lbs per inch so you're loosing just a small amount. The 5606 spring is a higher rate spring at 420 lbs per inch and will let the car sit slightly lower than original. Lift and weight transfer aren't synonymous so you might want to scale the car and check the ride height as it sits now. You may need to do some suspension work other than springs to get where you want. I can tel you that if you replace the front or rear springs, you need to do the other end as well since the car will not sit the way you expect in most cases.
 
5598, 5600, 5608, and 5604 are all the same rate but different installed heights. The 5598 would be the correct spring for the factory replacement. Originally the rate was 355 lbs per inch and the replacement is 340 lbs per inch so you're loosing just a small amount. The 5606 spring is a higher rate spring at 420 lbs per inch and will let the car sit slightly lower than original. Lift and weight transfer aren't synonymous so you might want to scale the car and check the ride height as it sits now. You may need to do some suspension work other than springs to get where you want. I can tel you that if you replace the front or rear springs, you need to do the other end as well since the car will not sit the way you expect in most cases.

Thanx for your response and helpful info, as always!! Sent u a PM.
 
5598, 5600, 5608, and 5604 are all the same rate but different installed heights. The 5598 would be the correct spring for the factory replacement. Originally the rate was 355 lbs per inch and the replacement is 340 lbs per inch so you're loosing just a small amount. The 5606 spring is a higher rate spring at 420 lbs per inch and will let the car sit slightly lower than original. Lift and weight transfer aren't synonymous so you might want to scale the car and check the ride height as it sits now. You may need to do some suspension work other than springs to get where you want. I can tel you that if you replace the front or rear springs, you need to do the other end as well since the car will not sit the way you expect in most cases.
I don't mean to hijack the thread, but you seem to know a bit about these springs... I'm working on my uncles car and I could really use some input. When he got the car a few years ago, it sat normal. It was a full weight car with a stretched stock location IC, oil and trans coolers with iron heads. This is how it sat back then... Note the red line and the bumper level vs the T-Type with stock springs and shocks... The line starts at the tip of the air dam and goes straight across just to give you a better visual of the height difference before and after its diet.
IMAG1116.jpg
and this is pretty much how it currently sits... Note the red line again.
IMAG0478.jpg
We've since put aluminum heads, fiberglass front bumper, aluminum bumper shock delete, removed the oil cooler, put the battery in the trunk, mini starter, front mount IC and a light weight radiator. I'd really like to have it scaled to know just how much weight is off the nose of the car. I have no idea what springs are on the front and was wondering what I should do to bring it back to stock height but still have a good 60'. Right now, it's able to leave with about 5psi on the street without blowing off the tires. Since he's had it, it hasn't been to the track, just been getting a lot of work done to it, working out bugs and what not. Getting the final bugs worked out now and we're trying to get to the track on the 9th.

I'm not sure what springs are on the car, it came with them. It has kyb gas-a-just shocks on the front right now and the car seems kinda stiff. I'm trying to get it to at least stock height and still 60' at least as good as it's doing now. I have no clue what spring rate or spring height is needed to achieve this since the front is likely over 100 pounds lighter than stock (between the heads and bumper alone is 83lbs off). I'm thinking about going with the Qa1 dual adjustable front shocks.

If you're wondering about the rear, yes, those are 17" rims with a 295 M/T ET street radial II. I'm expecting the car to run high 9's/low 10's. The rear springs have been replaced, just don't know with what. Has air shocks, air bags, HR swaybar, Hotchkis upper and lower control arms (not adjustable) and a Moser 12 bolt.
 
First things first. The pics of the car is in 2 different locations and you can't tell if the camera's level or not. You need to measure the height of the tires and make sure they're the same as the original ones, then check the ride height. Ride height is measured from the center of the wheel to the rocker panel 24 1/2" from the front and 21" from the rear. If the body bushings haven't been replaced then you at least need to check them to see if they're in good condition. Ride height should be 9 & 1/8 to 10 & 5/8" front and rear.

Getting 17's to hook is a major problem and the G body doesn't lend itself to good traction with a tire that doesn't have a sidewall that can be soft enough to flex and give you the traction you need. There are lots of reasons for lack of traction so start a new thread and let's see if we can help you figure things out. It will also help if you can get the car on a set of scales (all 4 corners) so you can see where the weight is sitting on =each wheel.
 
First things first. The pics of the car is in 2 different locations and you can't tell if the camera's level or not. You need to measure the height of the tires and make sure they're the same as the original ones, then check the ride height. Ride height is measured from the center of the wheel to the rocker panel 24 1/2" from the front and 21" from the rear. If the body bushings haven't been replaced then you at least need to check them to see if they're in good condition. Ride height should be 9 & 1/8 to 10 & 5/8" front and rear.

Getting 17's to hook is a major problem and the G body doesn't lend itself to good traction with a tire that doesn't have a sidewall that can be soft enough to flex and give you the traction you need. There are lots of reasons for lack of traction so start a new thread and let's see if we can help you figure things out. It will also help if you can get the car on a set of scales (all 4 corners) so you can see where the weight is sitting on =each wheel.
There is another set of Moog springs for the front of the GN that you didn't mention; the 5596 and that's the set I've decided to go with. This site is very big and filled with all kinds of information, it's just a matter of having the time and patience to find what exactly you're looking for. 9 times out of 10, someone else has been there and done that so to speak when it comes to these cars... Thanks for the info mate! Now since the car has FINALLY run out of excuses, it will most likely rain on the 9th (track day) lol.
 
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