Modest suspension upgrade: Dinan kit or Eibach?

[///BMW Junkie]

I am looking into upgrading suspension on my M4. I wish to retain EDC functionality, lower the car slightly without offsetting shock tuning and travel too much. My summer setup is 275/305, so not interested lowering much and scraping/rubbing.

So far I have found that Eibach springs offer minimal drop and slightly higher spring rate.

Other option I am considering is Dinan. I've read that Steve Dinan thought F8X was too stiff from factory and that his system softened the car to improve grip.

So my question is why are the spring rates stiffer than stock? Dinan states the spring rates are nearly 50% stiffer in front and 10% stiffer in the rear.

[M 4 FUN]

Hi. In your case i would suggest a height adjustable spring kit. Then you can set it up just how you want it and keep the EDC-function. Many springkits are stiffer because the car is lower so that is necessary to not make the car bottom out in suspension travel and also for ground clearance.
I have used the H&R VTF-kit which is height adjustable. A good thing with that is that it is 28% stiffer up front but 13% softer in the rear. That makes the car not to bottom out at the front but not too hard at the rear. it also builds in slightly more understeer in the car which i like on these tail happy cars, especially when they are tuned.

[DavidStr]

Does anyone can confirm rates of Dinan springs?

[///BMW Junkie]

Originally Posted by DavidStr

Does anyone can confirm rates of Dinan springs?

Dinan states the spring rates are nearly 50% stiffer in front and 10% stiffer in the rear. So again, if Dinan wanted to soften the car, why are his springs stiffer?

Now I have basic understanding of suspension. Is it perhaps with the entire suspension offering (coils, roll bar, ball joint, link kit) it results in a "softer car" he talked about?

[DavidStr]

I don't want softer, and I need numbers...50% stiffer....from CP or regular ?

[///BMW Junkie]

Originally Posted by DavidStr

I don't want softer, and I need numbers...50% stiffer....from CP or regular ?

Man have you read my thread and what I asked?

I have twice quoted what Dinan states in terms of spring rates, not sure what you mean by "I want numbers". I would assume it's compared to stock springs since Dinan came out with the product before ZCP became available.

[DavidStr]

i have seen the % increase, but compared to stock or competition pack rates?Competition rates are already higher, would be good to have real data
If Dinan states the car is too stiff and they increased the spring rates, it is contradicting...

[Luc@Speed&Tech]

Originally Posted by ///FastEuro

Dinan states the spring rates are nearly 50% stiffer in front and 10% stiffer in the rear. So again, if Dinan wanted to soften the car, why are his springs stiffer?

Now I have basic understanding of suspension. Is it perhaps with the entire suspension offering (coils, roll bar, ball joint, link kit) it results in a "softer car" he talked about?

Probably because the springs need to be stiffer to account for less preload when lowering the car (to prevent it from hitting the bumpstops at full compression). I've been in a few F8X and E9X with Dinan suspension and while it isn't drastic, they were definitely stiffer than stock so not exactly sure about them being "softer". Plus when you go softer you def improve grip but take away from chassis response...which I'd imagine Dinan doesn't want to do (could be wrong).

[///BMW Junkie]

Originally Posted by LucBroDude

Probably because the springs need to be stiffer to account for less preload when lowering the car (to prevent it from hitting the bumpstops at full compression). I've been in a few F8X and E9X with Dinan suspension and while it isn't drastic, they were definitely stiffer than stock so not exactly sure about them being "softer". Plus when you go softer you def improve grip but take away from chassis response...which I'd imagine Dinan doesn't want to do (could be wrong).

Thanks Luc, how's the Tesla treating you?!

[reprod]

I've had the Dinan for almost 3 years now. I would pick the Dinan because it is height adjustable and doesn't feel too much stiffer compared to ZCP.

Handling fast sweepers and tight back to back turns is definitely improved over stock but I think the F80 still needs retuned dampers to bring it all together.

[AlterZgo]

Originally Posted by DavidStr

i have seen the % increase, but compared to stock or competition pack rates?Competition rates are already higher, would be good to have real data
If Dinan states the car is too stiff and they increased the spring rates, it is contradicting...

Sometimes increasing spring rate actually improves ride quality when a car is lowered. Why? Because increased spring rate keeps the lowered car from bottoming out.

It may seem contradictory but some of the harshest crappiest spring only kits I've used were ones that lowered the car AND had soft spring rates. The ride quality would feel pretty good on ripples and small bumps... then you go over railroad tracks or a moderate bump or drive on some undulating highways and the ride quality turns to utter crap b/c your car hits the bump stops and your spring rate basically goes from very compliant to infinitely high because you've run out of suspension travel.