Suspension (beating the dead horse)

Oddball option - KSport 1G TEL coilovers but have KSport swap out the rear shock lower tube for one from a 2000 Eclipse otherwise they will be too short.

Downside - the GVR4 front strut mount will have to be redrilled to the TEL pattern; not as good as HotBits.

Upside - height adjustable ~ +1/2" to -2.5" from stock; compression + rebound adjustable together; standard sized coilover springs easily changed to taste; ~$800.

 

[s_firestone]

Quote:
Steven, Someone can correct me if I am wrong, but none of the stock springs being discussed are progressive. The VR4, 1g and Evo springs are all considered linear. Of course, they do behave somewhat differently based on installation length. Mitsu rates the springs through the center range of their normal travel. At full extension or compression they may not exhibit their stated rate, but in normal installation height and range of travel they are considered linear.

The aftermarket 2.5" spring normally used with coilovers are very linear (usually, there are exceptions). You can see this in the construction.



Thanks for clarifyting that!

 

[s_firestone]

Quote:
Quote:
I plan to use neither high rate springs, nor extremely shortened springs (linear or progressive).



You're basically desribing the stock springs. Other than a custom made spring, I don't know how many options you're really going to have on the spring rates and lengths unless you go with coilovers. I may be wrong, though.

In a nutshell, then, I think you should be fine with AGXs. After 2+ years running stock GVR4 springs with AGXs set on 2 front and rear, I don't perceive the ride quality (and or rebound control) to be a big issue, even on Vermont's crappy roads. If you keep them set on 1s, you should be fine.

My suspension stiffened up much more due to installation of WL poly bushings. Less compliance means harsher ride, even with reasonable spring rates and shock settings. If ride quality is the overriding concern, I'd stick with replacement OEM bushings, new OEM springs (springs certainly fatigue after 15 years), AGXs, a stiffer rear sway bar, and ditching the rear steer.

-Jim B.



Hey I may reverse the rear steering lines for in-phase steering. Oversteer city. /ubbthreads/images/graemlins/devil.gif

 

Quote:
Oddball option - KSport 1G TEL coilovers but have KSport swap out the rear shock lower tube for one from a 2000 Eclipse otherwise they will be too short.

Downside - the GVR4 front strut mount will have to be redrilled to the TEL pattern; not as good as HotBits.

Upside - height adjustable ~ +1/2" to -2.5" from stock; compression + rebound adjustable together; standard sized coilover springs easily changed to taste; ~$800.



I saw these on ebay, so you are saying they are worth the $?

Are they good for autocross?

thanks for any info

 

With regards to KYB AGX rebound damping and spring rates:

225Lb/In Rear and 275Lb/In is doubling the stock spring rates. Without doubling the sprung weight of the car, you are changing the basic natural frequency of the suspension by about a factor of 1.4 (square root of 2). That is quite significant when talking about a stock replacement type strut.

If the car was critically or slightly under-damped in stock form, it is now going to be well under-damped. Picking spring rates for AGXs is just a matter of choosing how under-damped you want it.

Watch this car go through a sustained corner at the track accompanied by 25 or 30 cars with good stock suspension or expensive coil-over packages or any matched spring/dampers. From the driver's seat, it might not be as obvious as from the spectator's but this car is going to bob up and down like it were a basketball being dribbled through the corner. This doesn't do much to promote tire adhesion.

I watched a 400Lb/In AWD DSM on AGXs do this recently among 25 or 30 Audis, BMWs and Porsches. I haven't had the chance to watch my VR4 on 250Lb/In springs and AGXs do this yet but, the vr4 on the lighter springs probably has higher cornering limits due to greater suspension control. It feels more "right" than that DSM does in the corners.

My point, I'm not that unhappy with 250lb springs on AGXs on my VR4 but I know that it isn't perfect and any more spring is asking for trouble.

 

Now, progressive springs. I'm mostly interested in sustained cornering as I've mentioned above, so I'm sticking to that.

For a given corner, progressive and linear springs will be storing the same energy according to weight transfer. A linear spring will do that, uh, linearly and supposedly, will have the same spring rate with the spring compressed and that same linear, constant spring rate will deal with corner imperfections and mid-corner bumps.

On the other hand, a progressive spring will have stored the same energy when the car rolls over in the corner but will have have a higher rate at this point (it's compressed, right?) to deal with corner disturbances. For the same damper, a single KYB AGX, this means that the progressively sprung car has less mid-corner disturbance damping ---> more underdamped for what it's worth.

The issue with AGX rebound damping isn't one of system response to linear vs. non-linear springs, it is simply a matter of controling higher spring rates in general. As I said before, the 200-300lb spring region is doubling stock rates. There are implications to this.

 

[s_firestone]

I have a set of uncut EVO 8 springs. The only problem I see is that the springs are 11.5" vs the free length of the stock GVR4 springs. I will likely pair these with AGX stuts/shocks.

Someone mentioned in the EVO suspension threads that the EVO rear mount is proffered to the Galant mount correct? Does anyone know what part in particular creates the offset for the spring length? Is it the upper mount, the spring hat, or on the actual lower strut/shock collar? I'm trying to plan out how much the stock weight of the car is going to compress these springs.

I understand that higher spring rates of the EVO springs will sag less, but I'm unsure if its just a linear calculation of the lbs/inch rating of the spring times the corner weight exerted subtracted from the free length of the spring.

I searched several sites but was unable to find a satisfactory answer to the compressed length. Anyone know it right off hand? I want to check the numbers from what I have calculated using the above logic.

I'm using corner weights from Harry's #3 and averaging them since his car ended up very close to the stock weight.

Spring compression under corner weight:


Galant (stock springs)
7.09" (950/134)
6.34" (710/112)

Evo8
5.28" (950/180)
3.16" (710/225)

Spring travel remaining (compression minus free length)

Galant
14.2-7.09=7.11"
15.3-6.34=8.96"

Evo8
11.5-5.28=6.22"
11.5-3.16=8.34"

Difference in offset from stock with load:

7.11-6.22= -0.89"
8.96-8.34= -0.62"

Am I in the ballpark here?

Since I'm dealing with a larger variance of 2.8" and 3.8" in overall free length but ending up with a variance of less than 1" on both springs, I'm assuming that either I'm calculating incorrectly and in reality its too low to work or I need to get struts/socks with a smaller offset on where the collar rests. PERSONAL RULE #1: I always assume I'm wrong unless I can verify it.

These are the figures I used: (The EVO length is measured)

Model Fr Spring Length (in) Fr Spring Rate (lb/in) Rear Spring Length (in) Rear Spring Rate (lb/in)
Galant AWD 2.0T 14.2 134 15.3 112
Evo 8&9 11.5 approx 180lbs 11.5 approx 225lbs


I would also love to get some comparison numbers of any offset the different upper mounts/seats have(GVR4, 1G, 2G, 3G, Evo) as well as known offsets of different strut/shock collars. The more we document, the less we have to guess. Have not purchased the rear mounts yet due to the questions posed here. I have a brand new pair of OEM GVR4 front upper mounts.

 

Your calculation is correct, compressed Evo springs and compressed Galant springs will be very close to the same length, given stock Galant corner weights.

Top hat thickness, and upper and lower spring perch can all affect ride height. So when you use Evo rear hats, you can just compare the thickness with the stock rear hats. I believe that they are almost the same though.

 

[s_firestone]

Thankyou thankyou thankyou!!! /ubbthreads/images/graemlins/worthy.gif

Now on to determining the offset differences of the EVO upper rear mount and spring hat since thats the one that differs from the GVR4 mount.

Has anybody got this data before I go digging?

 

[joec]

Quote:
I just bought a pair of QA1 progressive coilover springs from Summit for $100/pair. Cheaper than a set of linear AFCO springs, they are 10" free length & 2.5" ID. They are 225-475 lbs/inch. Part Number HAL-10-225-475. I've got my fingers crossed that they'll cure my overly stiff front end caused by the 300lbs/inchers.



bob in chicago , any review on the progressive springs yet?

 

225-450 springs turned out to be way tooo stiff, esp. with my very tired GAB struts. I've ordered QA1's 140-250 lb/in springs, a new pair of front AGX struts and a kit of coil-over sleeves, all from Summit. I'll grind off the bottom spring perch and turn the AGX's into coilovers. I'll post a review with photos of making coilovers, perhaps in early Sept.

 

[joec]

Quote:
I've got that set up in now, as I was the one that picked up the GC set that Rice Killer sold. Al Grabau's installed them in the car now, so once I pick it up and drive it back to VT I'll post on my DD impressions of those spring rates.
-Jim B.
1432/2000



Jim, did you ever post a review of that GC spring combo?

And "bob in chicago", I'm eagerly awaiting the review of the progressive springs in September!

Now that my commute involves some winding roads again I'm suddenly thinking about my suspension again -- much more fun than the 5 mile straight road commute to the train station.

 

[skivittlerjimb]

Hey Joe,

I posted on the track results of the set up back in the "GVR4 Mods Quantified" post, but not on daily driver impressions. Unfortunately 1432 hasn't been much of a DD since May as the dead inspection sticker and seeping fuel pump gasket kept me from driving it much.

Overall though, I'm happy with these spring rates as a compromise between competent track car and livable daily driver, even on the crappy roads in VT. It's not overly harsh, IMO, and I have plenty of suspension travel. I don't think I've been on the bump stops yet. If anything I would go up on the rear spring rate a bit to make the car's handling a bit more neutral, but front camber plates will help me there. Higher rear rate might be too much for the much-maligned AGXs, though, which I'm perfectly happy with. To sum up, if you don't have $1100-$1500 for Tein or Hot Bits, a $300-$400 an E39A-specific GC coilover set up to go with your existing AGXs (if you have them) is a good compromise.

Heck, I'm still hanging close to an '04 M3 with sticky tires on a "handling" track with a decent driver, and I'm still on the stock intercooler! That tells me the handling of my GVR4 is pretty darn good. /ubbthreads/images/graemlins/grin.gif

Good luck with your set up, and post your impressions of whatever you end up with.

-Jim B.
1432/2000
166k

 

My new front setup with QA1 progressive 140-250 lb/inch spring on coilover'ed AGX struts is too soft. They'll nearly bottom out on buckled pavement bumps which grow like dandelions after this hot summer.



Next experiment: replace springs with the previous ones (progressive 225-450 lb/inch).

 

[toybreaker]

Bob, do you have any bumpstops installed on your struts?

When I finally got a good compromise on my Z-car lite duty rally/dd, it was the koni silasto bumpstops that got it perfect~ish. Soft spring rates for dd, and dirt traction, and custom cut silastos for jumps /ubbthreads/images/graemlins/devil.gif . Without the silastos, it would bottom on frost heaves, with them I don't think I ever bottomed things out. You can tune the width/taper thickness and gain a somewhat tunable final progression.

I'm following this thread with great interest, as I don't know what works on these cars. Sounds like there's some very knowledgable people playing with spring rates and shock dampening. /ubbthreads/images/graemlins/worthy.gif Please continue

 

[joec]

I see Summit Racing has a set of HAL QA1's in 250-350lbs/in, in 10 or 11 inch free length. Maybe that would be a closer match?

 

[s_firestone]

Update: Evo springs/AGX/Galant mounts (front) - Evo Springs/AGX/Evo mounts (rear)

My AGX struts and shocks arrived day before yesterday. I still think these were an excellent deal for the lowest price listed on Ebay plus shipping. I was able to buy all the boots, bumpstops and rear mount kits with the left over money.

The following parts have been purchased over time to be installed all at once. I'm going to meticulously measure all relevant distances and dimensions against the stock suspension for future reference. I will also measure any differences in my calculated offsets vs. actual results. Hopefully this will take out some of the guesswork. When finished I'm hoping there will be enough information for a FAQ about our stock suspension components that will add to what is already documented.

FRONT:
EVO springs uncut front
KYB 734005 AGX Struts front
KYB SB101 boots/bumper

MB518670 Upper Mounts front

1G lower front control arms with new ball joints, end links, and poly bushings (already assembled)

MB910859 Outer Tie Rod Ends front
MB753385 Sway Bar bushings front (will likely substitute for poly bushings)




REAR:

Evo springs rear
KYB 741014 AGX shocks rear
KYB SB107 boots/bumper

EVO upper mounts rear (ordering for comparison, measurement)
-or-
KYB SM5091 upper mount kit rear (minus bearing housing)
KYB or MOOG mount bearing housing (ordering for testing)



Ordered OEM GVR4 and Evo rear upper mounts and Evo spring perches from JNZ Tuning today. I did find out that very little OEM rubber is available for the rear.

 

[s_firestone]

Someone has an answer to this question.

Ok I ordered all the necessary parts to assemble a quasi-Evo/AGX suspension. This question applies to the rear. The original Galant Spring are 15.3" in length. The Evo springs are 11.5" in length. When I assembled the shock, mount housing, mount, spring pad, and spring together there is about 1/2" to 1" of travel left in the shock. I simply did not take into the account that the AGX piston would have a longer travel than the Evo spring. The 1G DSM AWD spring is only .6" longer. If I compress the shock by this amount it all seats perfectly.

Question one: Is the shock's maximum extended length(stop) what determines how far the suspension can travel? Is the shock the lower stop for when the wheel drops downward, in the way that the bumpstop determines the upper limit?

Question two: What is the best way to go about fixing this? Can I shim the lower spring seat of the AGX shock? Shim between the upper mount housing/spring pad?

I know the suspension when loaded will be compressing the whole assembly. It has always been my understanding that the shock/spring assembly must be tight to keep the spring from dislodging. Although I don't plan on going airborne (intentionally).

Thanks in advance,
Stephen Firestone

 

[atc250r]

My Evo8 rear springs on DSM AGX's are a couple of inches too short but they haven't given me any problems yet. Shimming it will increase ride height which you may not want. Maybe some limiting straps like some of the drag race guys use on the front of their RWD cars?

John

 

[s_firestone]

Thats good to know John, thanks for the reply. I may attempt to shim it anyway since the calculated right height will be -0.62" anyway. I am using the EVO rear mounts so that may alter it a bit.