Thanks for stopping in guys...

I'm planning on changing the springs in my Sunday driver because the 22 year old springs blow straight through their travel and I hit my custom Y-pipe (3" clearance)

I've removed the A/C, Stock Manifolds and A.I.R. were changed to Headers, Iron Heads swapped for Aluminums....

Right now the front sits @ 27" to the centre of the fender
and the rear @ 26.5" to the same reference...
with 245/45/16 tires...

I was planning on the Moog 5664 on the front (to prevent Blowthrough...)
and either Moog 5665 or 6377 on the back...

First off,
Would the 5664 have the same "ride height" as the weaker 5660 (748 vs 598) and just more resistance to compression?
I'm wondering about this because if the fender gap is too large with the 245/45/16's I'd have to cut the coils and would go with the 5660's as the spring rate will go up as I cut them.....

Secondly,
I found that the Moog 6377 has 141 lbs/in spring rate and slightly larger Bar Diameter @ .504" with the same inside diameter and install height as the 5665, but the "load" was different...
The 5665 had a load of 580 while the 6377 had a load of 485... can anyone explain this "Load #"

Any help would be appreciated... Thanx

 

It's late and my math may be wrong. But here it goes.

The difference between 245/45 and 245/50 should be aprox 0.5 inches in height, measuring from ground to fender lip. There is a 12.25 mm difference in the series multiplication. That converts to 0.5 inches.

So your car with same everything but 245/50 would be 27.0 inches in height.

My car is the same year/style as yours. I have the 245/50 tires. With Moog 5665, I have a height of 28.5 inches. I too compared the specs between various springs. But went with the tried and true 5665 springs. The 107 lb spring rate on them sounds low. But the springs are quite a good setup for our cars. Granted, I changed rear shocks at the same time.

So from the sounds of things, you're about 1.5 inches below stock at the moment in the rear. I'd say your springs are shot.

Getting to the front, have you considered the 5662 springs instead? They're in the middle of the 5660 and 5664 springs. (A 707 lb rate)

 

A quick search and lots of reading for my own sake seems to show that most people on here prefer the 5662 springs for the front for a stock spring. The rear springs seem to be choice.
As for the load rating of the springs they are a function of the bar diameter and number of coils per height. The lower number of coils the higher the load rating. Therefore I would assume that the lower load rated coil might have one or two extra coils.

 

Well after some more research and some quick # crunching I think that I may have more answers....
I used these resources
http://www.hotrodbuick.com/springs.html
https://www.thirdgen.org/forums/susp...og-5660-a.html
http://www.moog-suspension-parts.com...il_Springs.asp
http://www.eatonsprings.com/coil.htm

The load # that I was referring to seems to be the load that the particular spring was designed for...

Therefore the 5665 was designed for a "Load Weight" of 580 lbs static, where the 6377 was designed for 485 lbs.
So even though the 6377 was designed to have an installed height of 10.25" I can assume that it would sit about 3/4" lower due to the lower designed Load Weight, but with the slightly higher spring rate it will have more "resistance" to compression... (Help me if I'm wrong here...!)

Looks like I'll probably go with the 5662 (with 1/2 coil cut it'll drop 1" and have a spring rate of approx 780 Lbs/in and 5665 in the rear? and trim them to a desired height.

I'm afraid that the car will sit like a 4x4 though!!! My fender gap already seems too large.... 3.75" up front right now and with new springs it'll be 5" or more!!!
Anyone else with insight that may help a brother out?

 

Would Moog's 5659 fit the rear spring perch?
I ask because it has different ends...It has a square end and a pigtail end...
It has a spring rate of 162 Lbs/in
Load rating of 576 Lbs and a 4.3" inside diameter .500 Bar dia
Installed height of 10"

Looks like it could fit the bill...?
But couldn't cut it down...

 

DO not get those moog springs i had the 5662 and 5665 and i had indexed them correctly and my car sat like a truck...my fender gap was like 4.5 inches in the front and about 5 in the back.. i even took off the isolators in the back and i still had waaaay too much fender gap.... you will not like the look trust me... after about a month i switched to the prokit...... MUCH better and they are stiffer too... now my fender gap is about 1.5 inches up front and about two in the back... love the look...if i were you i would get the pro kit....

 

I'm not sure how you lost 3" of height by going from the 5662/5665 springs to the Pro Kit springs. But I will agree that if GTA Sammy is going to cut an inch off a new set of Moog springs, it would be much easier to just get the Pro Kit springs and not deal with cutting.

Putting the Pro Kit in would probably raise the height of the car, since the stock springs are compressed so low right now.

 

I think that the Eibach Pro-Kit springs are progressive, correct me if I'm wrong...
I don't want a progressive suspension till I smash my undercarriage... I have limited ground clearance because of the exhaust system...approx 3" and our roads are crap!!!

I was gonna go with the 5664 springs for their stiffness and resistance to nose drop, but I don't want the 5+ inches of fender gap... and if I cut them down my spring rate will be ridiculous!!!

So that being said, think that I'll go middle of the road with the 5662 springs cause I'll cut them down an inch or so (therefore increasing their effective spring rate to around 780 Lbs/in, which is stronger than the original rate of the 5664's)

I think that if the car sat flat and resisted the squat I'd be OK...?
Hopefully changing the springs to heavier spring rates will limit the car from sagging in the "dips" of the road. Smashing into the highway @ 60 Mph sucks a**

The next set of tires I buy will be 50 series sidewalls (to fill out the fender better) and the transmission crossmember gets arched for clearance this year with a higher exhaust routing. Uggghhh.

Any other insight would be greatly appreciated....

 

Are you changing shocks/struts at the same time? What ones do you have in there and how old are they?

 

I did shocks and struts 2 years ago which was only 200 miles ago

I went with Munroe sensa-trac's which were the best I could get off the shelf at the time... I know everyone says they suck but they are brand new and did help with the ride, as it was very harsh before...

The more I think about it, the springs were probably just blowing through their travel and I was thinking shocks instead of springs...

 

Possible, but probably not. My car has 80,000 kms. And when my struts came out this year, I could "easily" compress them by hand. Shocks weren't much better.

 

Just a little plug or Koni here... I have all 4 KONI YELLOW shocks installed and I just got the car back today. I adjusted the rebound to half way firm in the rear and one more click firmer in the front. The car rides 10 times better over bumps than my Tokico Blues (which had MAX 2000 miles on them since 2008!)

Really, I cannot fathom how stupid I was for not investing in these earlier.. The car is also much more predictable in the rear and it's just an overall smoother ride.. I have MOOG 5662/5665 springs with the KONI's and it's really a firm but comfortable ride now.

I really recommend this setup (comparing this from stock springs/struts, and 5662/5665 springs with tokico blues.. The KONI's greatly outperform the other two combos I've had by far and the car isn't even aligned yet).

Also, the front's are on car adjustable with that adjuster piece that came with the YELLOWs. The rear you have to pull out since you have to twist the shock shaft to adjust it.

REID you were right about the shocks being seriously amazing! Have you installed the fronts yet?