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Although being happy with the dinan stage III suspension i have had on my car for ages, i feel that they are too soft for the current status of my car. The car is alil bit jumpy on the road and shaky at top speed which makes me want to either harden them abit or change them. Any suggestions ? thx
 

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see drallen's and my comments on our GC coilovers with 430/315 and 550/425# springs respectively -- until replacing my Dinan 3 with the coilovers with stiff springs i never thought i could use more power - huge improvement in control under all circumstances
 

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I also found the Dinan Stage III too soft...... the Eibach coilover setup is a LOT better. The car feels smaller, tighter and flatter with the big eibach roll bars. But even though I haven't had experience of the Bilstein PSS9, that would be my choice.

Playing with ride heights did allow me to dial out 90+% of any understeer. The Eibach set up is more comfortable than the Dinan and much sportier and stiffer as you load the car up as well as being very well damped (progressive springs)

Bilstein would be my choice for your car and HP !
 

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stever said:
see drallen's and my comments on our GC coilovers with 430/315 and 550/425# springs respectively -- until replacing my Dinan 3 with the coilovers with stiff springs i never thought i could use more power - huge improvement in control under all circumstances
I am with stever on this one...for the speeds that you go and the power that your car has...I would go with stever's set up but get the 7" springs for the front instead of the 6.5" like stever has...you will need all the jounce travel that you can get on your front end....especially if you hit anything at 180mph+....

I may be one of the few that got to sit in both of the "twins"....

Mark
 

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the 7 inch springs won't really make any difference, with the 6.5 inch springs, the perches (sp?) are set in the middle of the adjustment range at 14 1/4 inches ride height -- i could still get another inch of jounce (which i don't think is necessary with the stiff springs) but only by raising the ride height

my only gripe about the GC setup is the geometry of the front struts make 14 inches (from wheel center to fender lip) the minimum acceptable ride height for adequate spring travel regardless of the springs you're using -- talked to Jay about cutting an inch off the bump stops, but i'm happy with the ride height (and not scraping the front plastic on my driveway) and i've exercised the spring travel pretty thoroughly and it seems to be just fine
 

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stever said:
the 7 inch springs won't really make any difference, with the 6.5 inch springs, the perches (sp?) are set in the middle of the adjustment range at 14 1/4 inches ride height -- i could still get another inch of jounce (which i don't think is necessary with the stiff springs) but only by raising the ride height

my only gripe about the GC setup is the geometry of the front struts make 14 inches (from wheel center to fender lip) the minimum acceptable ride height for adequate spring travel regardless of the springs you're using -- talked to Jay about cutting an inch off the bump stops, but i'm happy with the ride height (and not scraping the front plastic on my driveway) and i've exercised the spring travel pretty thoroughly and it seems to be just fine
stever,

that is interesting...I am one thread from the top (19 from the bottom) of my front shock to get 14 and 3/8" with my #430 springs...It is also true with the rear shocks...I am also one thread from the top on the rear...rear ride height is 13.7/8 " to 14"... I think that #375 would be more realistic in the rear...It would be THE ride for street...

I am soooo glad that those darn #350s are off my front end...It made for a horrible ride...Just looking at a square edge bump would make you bottom and loose confidence in your car...I have put another hundred miles on this set up, mainly on bad levy roads in the Central Valley of CA... and with the slightly firmer rear springs...this would be the ride of constant fun...I almost had my car airborn today with out any weird suspension effects...I can almost live with this set up with the softer rear springs...

HOWEVER, stever...I am with you...with this suspension set up...I am also looking for more power...I am still amazed at the speed at which that I am able to enter and to exit corners... This is so much fun... I really have to have the stereo cranked up high to drown out my hoots and hollers....

Mark
 

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Balck,

Two suggestions. Ground Control with customized spring rates, or PSS9s that you can tune for stiffness. Ideally, the DFC system, but it's no longer available.

Good luck.

CP
 

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drallen said:
I would go with stever's set up but get the 7" springs for the front instead of the 6.5" like stever...........

Mark
If you ask for 7" 550lb springs, the front of the car will likely sit too high. I am only making this statement after reading about Stever's adjustability range for the 6.5" version.

The 430lb springs with 7" free length compress a lot further compared to 550's, under chassis loading.

Based upon your comments, Mark, it almost sounds like a 430lb spring of 7.5" length is a good choice for folks interested in running a 13.75" or higher ride height.

Could you possibly tell me your rear spring part number, so I can determine free length? I would like to guesstimate what rear spring might be optimal for the 430 front.

The stiffer the spring, the shorter it's free length must be to maintain proper ride height.
 

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Lscman said:
If you ask for 7" 550lb springs, the front of the car will likely sit too high. I am only making this statement after reading about Stever's adjustability range for the 6.5" version.

The 430lb springs with 7" free length compress a lot further compared to 550's, under chassis loading.

Based upon your comments, Mark, it almost sounds like a 430lb spring of 7.5" length is a good choice for folks interested in running a 13.75" or higher ride height.

Could you possibly tell me your rear spring part number, so I can determine free length? I would like to guesstimate what rear spring might be optimal for the 430 front.

The stiffer the spring, the shorter it's free length must be to maintain proper ride height.
Rick,

I wrote down the spring number just for this reason as I was moving the setting for my rear bar...I am hoping that we could reach a good solution for the rear with a reasonable, streetable, yet fun, rear spring....I am at my girlfriend's house and I cannot read the rear numbers...When I get home, I wil post the numbers...Again I can not express the amount of fun that I am having with this set up....

So then, you think by adding another .5 inch in free spring length ( I'm running 7" now) it would help in my ride height/jounce (compression travel)?...I am running 14 3/8" now with out any problems...with the #430/7" springs...

Mark
 

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drallen, changing the spring length won't make any difference as the travel is controlled by the front strut geometry (the GC struts have about 3 1/2 inch total travel which is nearly an inch shorter than OEM travel) and you don't really want to go higher than stock ride height anyhow -- if you really think you're bottoming with the 430# springs you might want to cut the bump-stop although i don't think this should be necessary.

i'm a little surprised that you're nearly at the top of the adjustment range as there should only be 1/2 in difference in static height between the 550 and 430 springs, although the tolerances on spring lengths aren't very tight -- you may want to keep the softer rear springs and go to a stiffer front bar

so 7 inch 350# springs would be very marginal -- in my opinion if you want a softer ride you'll be much better off with the Dinan 3 which retains stock spring travel -- the GC needs at least the 430# front springs to make a worthwile difference (and avoid bottoming resulting from reduced spring travel0
 

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Lscman said:
If you ask for 7" 550lb springs, the front of the car will likely sit too high. I am only making this statement after reading about Stever's adjustability range for the 6.5" version.

The 430lb springs with 7" free length compress a lot further compared to 550's, under chassis loading.

Based upon your comments, Mark, it almost sounds like a 430lb spring of 7.5" length is a good choice for folks interested in running a 13.75" or higher ride height.

Could you possibly tell me your rear spring part number, so I can determine free length? I would like to guesstimate what rear spring might be optimal for the 430 front.

The stiffer the spring, the shorter it's free length must be to maintain proper ride height.
Rick,

My rear spring is 230.64.29

I am at the top on the strut with my rear spring perch. Ride height on the rear is 13 7/8...I would like to get it back up the the stockish height of around 14 to 14.5 inches...with the softest spring that does that...I need to talk to GC but I figure that a spring around #375 (vs the #315 that I have on now)...The front is perfect for me now at #430 with a ride height of 14 3/8"....

I want to keep as much compression travel as possible (with in reason)

Mark
 

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check the Eibach web site - i found the rear springs but not fronts in their online catalog

i don't really think there is a spring travel problem in the rear and you're only 1/8 to 1/4 inch low in the rear

you may find that 350 in the rear is a better match for the 430 fronts (although you're probably not going to feel much change with 10% change on the M5) -- keeping the rears a little soft and stiffening the rear bar one more notch may give the same handling with a bit nicer ride
 

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stever said:
check the Eibach web site - i found the rear springs but not fronts in their online catalog

i don't really think there is a spring travel problem in the rear and you're only 1/8 to 1/4 inch low in the rear

you may find that 350 in the rear is a better match for the 430 fronts (although you're probably not going to feel much change with 10% change on the M5) -- keeping the rears a little soft and stiffening the rear bar one more notch may give the same handling with a bit nicer ride
Opps!...

It seems like we hijacked Black's thread...

Any ways lscman, I miss read the numbers on my rear springs...They are

230.64.49 ( .29 springs would be like...150 pounds...)

Wow! that kind of sucks...that means that my rear springs are a hair less than #300s...

Mark
 

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drallen said:
Opps!...

It seems like we hijacked Black's thread...

Any ways lscman, I miss read the numbers on my rear springs...They are

230.64.49 ( .29 springs would be like...150 pounds...)

Mark
Your rear spring looks to be 280lb/in and 9" free length, assuming part# decoding of these newer metric rates is consistent.

It's no wonder you struggle to attain 14" ride height, since Stever's non-metric code rear spring seems to be 50% stiffer rate, in addition to being 1" LONGER free length too! No doubt you'd need to drop to a lower perch groove. The 10" rear barrel springs on Stever's car come in 25 lb rate increments, so rates of 350, 375 or 400 should be available. I have no doubt that any of these 10" springs would provide the ride height you want to match the front. The only unknown would be "which groove", but it'd be close to Stever's setup. Find "our" recent GC thread with calculations and part#'s.
 

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Lscman said:
Your rear spring looks to be 280lb/in and 9" free length, assuming part# decoding of these newer metric rates is consistent.

It's no wonder you struggle to attain 14" ride height, since Stever's non-metric code rear spring seems to be 50% stiffer rate, in addition to being 1" LONGER free length too! No doubt you'd need to drop to a lower perch groove. The 10" rear barrel springs on Stever's car come in 25 lb rate increments, so rates of 350, 375 or 400 should be available. I have no doubt that any of these 10" springs would provide the ride height you want to match the front. The only unknown would be "which groove", but it'd be close to Stever's setup. Find "our" recent GC thread with calculations and part#'s.
Thanks Rick...

I just caught the wimpiness of my rear springs...

So then are you suggesting that I go with the #375 springs in the 9 inch length or in the 10 inch length?

Thanks,

These are going to be a ***** to change...

Mark
 

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again figured out the Eibach site -- go to motorsports/request catalog/download complete catalog

i've got 1000.250.425 -- 10 inch length, 2 1/2 inch id, 425#/in

i'd recommend 1000.250.350 -- the 350# springs will be a better match to your 430# fronts than the 375s but still provide a noticeable difference to the 275 or 280# springs you have

although we've slightly hi-jacked Black's thread, i think there are a couple useful lessons here for everyone

a) if you're going for the GC coilovers, talk to Jay first and find out exactly what you're getting (it may take several phone calls- don't expect him to call you back - but when you talk to him it will be worthwhile0

b) with any coilovers, find out what the front suspension travel is as limited by the strut design and what the ride height will be with 50% jounce
 

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ps, if what GC says is true, changing the rear springs can be done from the outside without taking out the parcel shelf, etc.
 

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stever said:
again figured out the Eibach site -- go to motorsports/request catalog/download complete catalog

i've got 1000.250.425 -- 10 inch length, 2 1/2 inch id, 425#/in

i'd recommend 1000.250.350 -- the 350# springs will be a better match to your 430# fronts than the 375s but still provide a noticeable difference to the 275 or 280# springs you have

although we've slightly hi-jacked Black's thread, i think there are a couple useful lessons here for everyone

a) if you're going for the GC coilovers, talk to Jay first and find out exactly what you're getting (it may take several phone calls- don't expect him to call you back - but when you talk to him it will be worthwhile0

b) with any coilovers, find out what the front suspension travel is as limited by the strut design and what the ride height will be with 50% jounce
Thanks stever,

Is there any way to tell if I have the GC rear mounts so that I can service the springs with out removing the shocks ?

Is there any way that I can just slide the spring off the base of the shock and replace the spring with a new one or do I have to go through the whole thing of removing the rear deck?

Thanks,

Mark
 

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Who long have you had the stage III on your beast?
was it like this from the begining?
i am asking because i am thinking about getting the stage III myself.

emperor
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Black M5 said:
Although being happy with the dinan stage III suspension i have had on my car for ages, i feel that they are too soft for the current status of my car. The car is alil bit jumpy on the road and shaky at top speed which makes me want to either harden them abit or change them. Any suggestions ? thx
 
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