Well after slamming my tremec into parts of the road a few too many times and having to actually slow down while racing to save the underside of my car as well as not being able to get my car into my driveway. I have decided to return my car to a more stock ride height for the winter. Presently i am running an eibach pro-kit. I would like to get a stiffer set of springs as what ever rate these are they are not stiff enough. I went to the parts store today to check the Moog catalog and i found something interesting. they list 2 different springs for V8 cars with A/C one for up to around 84-85 that is listed at about 450 lbs inch and another for the later cars that specs out at 750 lbs per inch. I would like to use the 750's but i find it hard to believe moog lists these as stock replacement. Do they raise the ride height over stock? the PN is 5662 has anybody used these? Heres the intesting part. I looked up the rears and they only list one PN for all years of 3rd gens it is 5665 and the rate is 107 lbs/inch. this is considerably softer than the aftermarket replacements i believe the eibach's are at least 150 lbs/inch. Does this make any sense? to go way stiffer in front and softer in back?? I don't see how the car could handle right. So does anybody have any input on these sets? do the 750 fronts raise the car over stock??

Yep...I've got a set of 5662's in my car right now. Work just fine and not overly stiff. The 5662's spec out at 649lb\in at load height. Stock IROC BZW\X\Y\Z springs spec out around 550lb\in at load height.

Spring setup is all a matter of balance. Depends on your front and rear spring rates and rollbar settings. I Autocross and prefer the car to turn in right now. Therefore I tend not to go too high on the front spring rate. The 5664's are not out of line but I would use them for Road Racing only.

Try installing the 5662's with 1\4 coil cut of the top. Do not cut anymore and do not cut the bottom spring. Let them settle in and see how your ride height is. If necessary trim another 1\8th coil off...but be carefull.

Don't trust the load rating on the 5665 rear springs. It is out of whack somehow. Much stiffer than what the book says. They should be fine as well. Try 1\4 coil of the top with the OEM 3rd Gen isolators. If necessary trim another 1\4 coil off but no more.

The variable springs RCS635V also works well. Again the load specs for the rear springs are way low in the book for some reason. Maybe a misprint.

Sounds familiar. I used to have Eibach Sportlines on my 91 Z and my car bottomed out alot (good struts and shocks, just the springs were too soft). I know Eibachs are Progressive rate and all (meaning the spring rate changes as load changes) but they felt waaaay soft. Definately too soft for the ammount of drop, and combined with the bad roads round here it just sucked. So I switched up from Eibach progressive rate springs to a set of custom length linear rate springs and some adjustable spring pertches. My car now sits 1" lower than it did with the Sportlines (my choice of course), and I have not had ANY bottoming out issues. These new linear rate springs are the perfect spring rate for this drop (2.75" drop front and rear and thinking of going lower). Rates are 700# front and 150# rear. Of course the ride suffers (35 series tires too), but I'm completely happy with the setup. I just wouldnt recommend it if you want a smooth ride.

so the 5662 is a stock ride height but stiffer spring? the book says 750 but who really knows? I think i will get them if i can get a matching set of rears.

what are the 5664's, what rate are they?

do you know the actuall rate of the 5665 rears? is there another moog PN that is stiffer but a useable ride height?

i can't believe i spent over 200 bucks on eibach's when i can get the moog's for 100!!!

I've got a Spicer, TRW and McQuay Norris book. All list the 5662's as 649 lb\in. Moog " might" be different. I'll get a new catalog tomorrow and double check. Whatever brand you get the 649 lb\in is more than adequate. It is designed for Stock height IROC's with A\C.... so you might have to trim a bit. NOT TOO MUCH!!

The 5665's are at least as stiff, if not stiffer than stock. I would suspect around 170 to 180lb\in.

I've used Moog and TRW springs for years. Much cheaper than the alternatives.

If you want some really neat deals on front and rear springs check out this site. Note the " Stock" appearing springs....including front ( 5.5" x 12 " ) and and rear "pigtail" springs ( 5.5" x 11" ) . All guaranteed rates.....all marked and dirt cheap!!!

http://www.lefthanderchassis.com/pdf/Ch4.pdf

Also check out the spring section at :

http://www.pitstopusa.com/default.htm

Give you any ideas?



I'm getting some 5.5" x 9" front HyperCoils and some Custom 5.5" x 9" rear spring from Suspension Spring Specialists. I have Ground Control rear height adjusters in my car now and will be making a set of Custom Weight jackers for the front.

BTW...if you get the Suspension Springs Specialists 5.5" x 9" Pigtail rear springs ( you will need height adjusters) or the 5.5" x 13 " rear coils ( no isolator required ) I would recommend around 200lb\in or 225lb\in. I have a set of 175's and they are too soft. The 5665's are stiffer...so that gives you an idea how wacky the 5665's rate is in the books.

Thanks for the help. The rates i quoted were from a Moog catalog i looked at saturday. I'm trying to get a newer one for myself. Is it safe to assume you think the 5665's will work well with the 5662 fronts?

i'm going to do some more research with other brands to see what i can find. the spicer, trw etc all use the same Pn's??

oops, should have read the rest of your post.

The 5665's should work fine with the 5662's . Just triple check the rate on the fronts. You want the 649lb\in rate spring. ( Moog 5660?? Everyone else 5662 ) NOT the 707lb\in ( Moog 5662?? Everyone else 5664 ).

Gotcha, i'll be printing this and taking it to the parts store. I really appreciate your help! By the way, i just dumped my Tokico HP's for some illuminas last night. The left front was toasted. I can't tell about the rest. The difference is night and day. I can't wait to get the new springs in.

Went to my local supplier and looked at a 2003 Moog catalog. Believe the rate that is quoted for the Moog 5662 is a misprint. Rate at Load height should read 648...not 748.

Look at the wire diameter of of the 5662 vs 5664. 5662 wire dia = .750" . 5664 wire dia = .765". Wire dia increases the spring rate significantly. Note the actual " Load " of the 5662 is less than the the 5664's. 1690 (5662's ) vs 1863 (5664's ).

So the 5662's are what you want. Rate at load Height = 648.

i got your PM. Thanks again for all your leg work, i didn't expect anybody to go through that much trouble to help me. 5662's in front and the 5665's in the rear. I'll get them this weekend and probably spend all of sunday fitting them. I might just install them for the winter without cutting them and let them settle. Then in the "spring time " i'll adjust the ride height.

Just to give a quick update.

I installed the 5662's and 5665's today without modification. I am sad to say my car is now at stock ride height. But on the bright side it rides better even though its stiffer. I only drove a few miles but it feels like an SUV compared to the prokit (from the drivers seat). I also got my new KDWS's 245/50-16 i had yokohama AVS intemediates in 245/45-16. I needed a good allseason tire to get me through the dark months. Tommorow, weather permitting i will open her up some and see how it compares. I'm a little leary about the rear springs though. They seem stiffer than the progressive eibach's do initially but since they are strait rate i expect that. Time will tell. i'm looking at the moog catalog for a stiffer alternative. I measured the wire diameter of the guldstrands in my brothers camaro and i get .525 but the moog catalog doesn't list a single .525 wire diameter spring with the appropriate ends. I would love to know the moog PN that guldstrand uses for there rear springs. The fronts are .750 wire diameter same as my brothers guldstrands. Anyhow i'll report back after some miles and i promised my friend who helped me install them i would wait at least a month before i start cutting them!

By the way if anybody is interested in an eibach prokit just email me!

Give them a week to settle if you drive it every day. You don't need any more. Then cut them as instructed. Avoid the temptation to cut too much.

Cut the springs with a cut off whell if possible. With the front springs, do not heat the top spring and flatten it. Not nesessary if you cut only the amounts as mentioned. This will also give a slight progressive ride which makes the car much more comforable to drive over things like expansion joints and railway ties.

The rear coils, depending on how they are wound, may require the top coil to be heated slightly and flattened to fit the isolator. Take this into account if you when cutting coils.

I think that you will find the 5665 rear springs just fine. You don't need to go too stiff on the back end.

For Autocross use, 3rd Gen Hotshoes use a fairly soft rear spring. Some even use V6 springs but those I find too soft. Stock IROC springs cut work just fine. The 5665's should be a bit stiffer than stock IROC rears.

Don't know what drag racers like for rear springs though.

chickenman,

i know your in the HMS camp up there, and ya'll are kinda secretive, but about what spring rates are running. i assume you are using softer rears in auto-x, to try to curb the oversteer since you are racing at such low speeds.. am i correct? are you guys running those springs with 1le bars? or using a smaller sway bar also. i assume you are using a higher rate front combo than just a trimmed iroc, running with stiffer front springs, do you also run a smaller sway bar? i know a couplf of us have found that running a huge sway bar and stiff springs isn't a great combo, as you start to make the front end lose it's 'independentness' so to say. my guess here, is that running fairly stiff front springs, and a smaller sway bar, is probably the way to go, but i haven't had time to test this theory, but i am sure Karl has

any insite into this would be very apriciated.


BTW, next time you see mike (cheezx) give him a big noogy for me

I'll send you a PM. I cannot reveal any of the KarlMeister's setup secrets...as members of the HMS Team are sworn to secrecy :hail: :hail: :hail: .

But I can send you some info on my car..... Just please don't repeat it on a public board. I've worked long and hard on my setups.

thanks dude,

not looking for a parts list or anything, since our combo's are sure to be diffrent, but if i can cut a few rounds of trial out, i am all for it.

and i understand keeping some of your 'tricks' from being common knowledge, we all have them and we all have some little things we do to our cars to give them that little edge. and since karl's buisness is doing those things for money, i can understand why he doesn't share everything.

So, what do you think about the rear springs now? Are they too soft?

not to get off topic, but did you notice a difference with the wing on your car?

Well the wing definately works...no doubt about that. Reasonably efficient profile.

As to how well...well that's hard to quantify.

I went this route to improve the downforce vs drag equation over my old setup. My old setup, which worked very,very well, used a 9" total height Nascar " plate "type spoiler. This provided lots of downforce...but the drag figures were a bit high. Overall not bad though...I set the Hill record with the Nascar spoiler.

The wing was an attemp to equal the downforce of the "plate " spoiler and yet lower drag.

The results were hard to quantify as it was a late addition and we had no time for testing. Car just got out of the Body Shop a few days before our first major event...Knox Mountain Hillclimb. Weather conditions were horrible that Weekend. On and off rain all Weekend and a " green" track.

I'll be doing some more testing this spring. It's probably going to be raised a couple of more inches. It needs some stiffening in the upper element ( Bends at high speeds....so it's working!! ), some more elements ( Side flip ups and possibly a third element) and some more adjustability.