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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Are all the zsp spring the same between the 325/330/335i model??



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      09-24-2010, 01:43 AM   #1
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Are all the zsp spring the same between the 325/330/335i model??

Are they all the same? The lower height and spring rate??



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      09-24-2010, 02:20 AM   #2
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      09-24-2010, 08:15 AM   #3
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No they are different depending on model and transmission. The 335i has a stiffer spring to compensate for the weight. The auto trans uses D7 and the manual D6 usually. The 328i uses D4 springs, same as the 128i. The rear springs are the same depending on body style. Coupes have softer rear springs than the sedans. The wagon has stiffer springs than both. This is important for people to know when trying to put zsp springs in non zsp as they will not get an even drop unless they use the right springs. A lot of people on the forum seem ignorant to this....
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      09-24-2010, 09:07 AM   #4
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if you use the same springs its the same. dont mix springs from a 335/328.


i think hes more concerned if they fit.
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      09-24-2010, 12:33 PM   #5
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Originally Posted by mattsten View Post
No they are different depending on model and transmission. The 335i has a stiffer spring to compensate for the weight. The auto trans uses D7 and the manual D6 usually. The 328i uses D4 springs, same as the 128i. The rear springs are the same depending on body style. Coupes have softer rear springs than the sedans. The wagon has stiffer springs than both. This is important for people to know when trying to put zsp springs in non zsp as they will not get an even drop unless they use the right springs. A lot of people on the forum seem ignorant to this....
wowo so what good on the e90 lci 328i model? manual tran?
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      09-24-2010, 06:33 PM   #6
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wowo so what good on the e90 lci 328i model? manual tran?
Probably D4 front and D4 rear. Your current springs will have a number on them. The front is on a tag and the rear is painted on the spring. Just see what yours say and get those. Non zsp would be "C" then number. So C4 corresponds to D4. Then of course there are those random "T" springs that seem to be on one series. FWIW, you can get front springs from either a 1 series car or 3 series, just get the right number.
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      09-25-2010, 12:03 AM   #7
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Probably D4 front and D4 rear. Your current springs will have a number on them. The front is on a tag and the rear is painted on the spring. Just see what yours say and get those. Non zsp would be "C" then number. So C4 corresponds to D4. Then of course there are those random "T" springs that seem to be on one series. FWIW, you can get front springs from either a 1 series car or 3 series, just get the right number.
So I think the highest number mean stiffer spring rate?
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      09-14-2011, 02:10 AM   #8
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No they are different depending on model and transmission. The 335i has a stiffer spring to compensate for the weight. The auto trans uses D7 and the manual D6 usually. The 328i uses D4 springs, same as the 128i. The rear springs are the same depending on body style. Coupes have softer rear springs than the sedans. The wagon has stiffer springs than both. This is important for people to know when trying to put zsp springs in non zsp as they will not get an even drop unless they use the right springs. A lot of people on the forum seem ignorant to this....
How would you decide what spring code works for Xi Drive vehicles? Also is the Xi drivetrain sprung or unsprung weight? I would assume sprung weight?
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      09-14-2011, 10:32 AM   #9
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How would you decide what spring code works for Xi Drive vehicles? Also is the Xi drivetrain sprung or unsprung weight? I would assume sprung weight?
Yes all sprung except for a portion of the rear driveshafts leading to the wheels.
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      09-14-2011, 11:52 AM   #10
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Yes all sprung except for a portion of the rear driveshafts leading to the wheels.
Then that would also mean that the front driveshafts are unsprung too?

The reason I ask all these questions is that I have an e91 328xi that I am looking at installing ZSP springs. And based on BMW website for weight and weight distribution my vehicle (3,814 lbs and 51.2% frt) that would mean there is 1,953 lbs on the front. The 335i (auto) has 1,842 lbs on the front and uses a D7 ZSP spring. Can I assume that this would be the closest match? I have heard others saying that the 335i D7 springs actually raised their 328xi???? Is the difference in the unsprung versus sprung weight?
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      09-14-2011, 01:52 PM   #11
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Then that would also mean that the front driveshafts are unsprung too?

The reason I ask all these questions is that I have an e91 328xi that I am looking at installing ZSP springs. And based on BMW website for weight and weight distribution my vehicle (3,814 lbs and 51.2% frt) that would mean there is 1,953 lbs on the front. The 335i (auto) has 1,842 lbs on the front and uses a D7 ZSP spring. Can I assume that this would be the closest match? I have heard others saying that the 335i D7 springs actually raised their 328xi???? Is the difference in the unsprung versus sprung weight?
I have a 330xi sedan that I just installed springs from a 335i coupe. D6/D3 springs. Now you'd think (since the weight distribution of the coupe is 51/49 vs the xi 53/47) that the 'rake' would be reduced. In my case, while both ends dropped, the front drop was minimal increasing the rake. It's not bad (and the rear drop is perfect) but I wish I went with D5 or D4 springs on the front. According to the BMW website my vehicle would have 1922 lbs on the front and 1705 lbs on the rear vs your 1953/1861. If I were you, I'd look for D5/D4 (front/rear) or D6/D5.
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      09-14-2011, 01:59 PM   #12
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Then that would also mean that the front driveshafts are unsprung too?

The reason I ask all these questions is that I have an e91 328xi that I am looking at installing ZSP springs. And based on BMW website for weight and weight distribution my vehicle (3,814 lbs and 51.2% frt) that would mean there is 1,953 lbs on the front. The 335i (auto) has 1,842 lbs on the front and uses a D7 ZSP spring. Can I assume that this would be the closest match? I have heard others saying that the 335i D7 springs actually raised their 328xi???? Is the difference in the unsprung versus sprung weight?
Yes, sorry, fronts too, I didn't grok we were talking about an xi. All the differentials and central shafts and whatnot are sprung though. The guesses that I have (from JAJ??) for unsprung weight are 105lbs per side front, and 135lbs per side rear. It's for an M3 I think.

It does seem like you'd get maybe .8" (EDIT: wrong! sorry!) drop from what you're planning, but there are weird differences in equipment sometimes. Have you checked the ETK for the two models? Check that the exact same parts and part numbers are used in the strut.

Also, when you put more load on a spring you get closer to coil bind. You know about shock travel I assume. Are there any clearance issues in front caused by all that extra stuff you've got down there?
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Last edited by luckyu; 09-14-2011 at 02:55 PM.
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      09-14-2011, 03:07 PM   #13
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[...] Can I assume that this would be the closest match? I have heard others saying that the 335i D7 springs actually raised their 328xi???? Is the difference in the unsprung versus sprung weight?
Mav, the other concern I have is that you're lowering the car and moving to a softer spring.

Also, won't the drop you expect to get, be relative to the 335i's ZSP height, which is 14.25"? That is, it's not relative to your current height. Unless you've got different parts in your strut.
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      09-14-2011, 05:19 PM   #14
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Mav, the other concern I have is that you're lowering the car and moving to a softer spring.

Also, won't the drop you expect to get, be relative to the 335i's ZSP height, which is 14.25"? That is, it's not relative to your current height. Unless you've got different parts in your strut.
Now I'm confused. Are ZSP springs softer than Xi springs? I am not looking to drop my car by much. I was hoping for a 0.5" with a proper spring rate. That is why I am scared to use D4 or D5 springs because they are meant for a lighter vehicle.

Here are the ZSP springs that I was going to use for my E91xi:

Front: D7 - from a E90 335i Auto
Rear: D8 - from a E93 335i Auto

To give you some perspective of weight and weight distribution:
E91 328xi Auto - 3,814 lb, Frt 1,953, Rr 1,861
E90 335i Auto - 3,605 lb, Frt 1,842, Rr 1,763
E93 335i Auto - 4,001 lb, Frt 1,908, Rr 2,093
E90 328xi Auto - 3,649 lb, Frt 1,967, Rr 1,682
E90 328i Auto - 3,428 lb, Frt 1,752, Rr 1,676

I am trying to find the best balance that suits my vehicle. I can tell you that E93 335i ZSP rear springs (D8) are the same length as the E92 335i ZSP rear springs except the coils are larger in diameter.

The front ZSP springs whether a D4, D7 or D8 look identical in terms of coil diameter and length. Very Odd.

I should mention that I am mating these with Bilstein HDs.

Last edited by MaverickBMW; 09-14-2011 at 05:25 PM.
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      09-14-2011, 07:57 PM   #15
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Now I'm confused. Are ZSP springs softer than Xi springs? I am not looking to drop my car by much. I was hoping for a 0.5" with a proper spring rate. That is why I am scared to use D4 or D5 springs because they are meant for a lighter vehicle.

Here are the ZSP springs that I was going to use for my E91xi:

Front: D7 - from a E90 335i Auto
Rear: D8 - from a E93 335i Auto

To give you some perspective of weight and weight distribution:
E91 328xi Auto - 3,814 lb, Frt 1,953, Rr 1,861
E90 335i Auto - 3,605 lb, Frt 1,842, Rr 1,763
E93 335i Auto - 4,001 lb, Frt 1,908, Rr 2,093
E90 328xi Auto - 3,649 lb, Frt 1,967, Rr 1,682
E90 328i Auto - 3,428 lb, Frt 1,752, Rr 1,676

I am trying to find the best balance that suits my vehicle. I can tell you that E93 335i ZSP rear springs (D8) are the same length as the E92 335i ZSP rear springs except the coils are larger in diameter.

The front ZSP springs whether a D4, D7 or D8 look identical in terms of coil diameter and length. Very Odd.

I should mention that I am mating these with Bilstein HDs.
I like the Bilstein HD choice... For the rear of the car, you do have the "nuke them from orbit" option, which is to buy height adjusters and race springs. This option is about $100 more expensive than buying new rear springs. Then you can buy exactly the rate you want, and set exactly the height you want.

So on the front. Let's see, you are going from non-sport e91 328xi to ZSP e90 335i (auto)? My calculations agree with yours, about 0.5" "drop". But drop from where?

If you had the same strut parts as an e90 335i auto -- that is, everything under there is the same, except for the spring -- then imagine adding 111 pounds to the front of a 335i. It sinks 0.5" lower. Is that where you want to be?

And if you don't have the same equipment, then it's impossible to know, because the 335i spring only makes the ride height it does in a 335i. In fact, the xi doesn't have the same guide support as 335i ZSP; the xi has 31 30 6 785 962. So, not only the springs are different, but other things such as the guide support are different too. The struts also appear to be different, even for non-zsp 335i. Your xi strut could be a different length.

The only way to know for sure is to start measuring the static heights of the front springs, which is sort of hard to do. I am playing the same game you are, but I don't have an xi so it's a little easier for me. I am actually considering having a custom front spring made.
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      09-15-2011, 03:25 PM   #16
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I like the Bilstein HD choice... For the rear of the car, you do have the "nuke them from orbit" option, which is to buy height adjusters and race springs. This option is about $100 more expensive than buying new rear springs. Then you can buy exactly the rate you want, and set exactly the height you want.

So on the front. Let's see, you are going from non-sport e91 328xi to ZSP e90 335i (auto)? My calculations agree with yours, about 0.5" "drop". But drop from where?

If you had the same strut parts as an e90 335i auto -- that is, everything under there is the same, except for the spring -- then imagine adding 111 pounds to the front of a 335i. It sinks 0.5" lower. Is that where you want to be?

And if you don't have the same equipment, then it's impossible to know, because the 335i spring only makes the ride height it does in a 335i. In fact, the xi doesn't have the same guide support as 335i ZSP; the xi has 31 30 6 785 962. So, not only the springs are different, but other things such as the guide support are different too. The struts also appear to be different, even for non-zsp 335i. Your xi strut could be a different length.

The only way to know for sure is to start measuring the static heights of the front springs, which is sort of hard to do. I am playing the same game you are, but I don't have an xi so it's a little easier for me. I am actually considering having a custom front spring made.
Wow. Great advice now with all this info I don't know what to do. I picked up my Bilstein HDs this morning and they guys at RPI Equipped suggested that I stay with regular OEM springs for my Xi Wagon and just put on the Bilsteins. He said just the shocks alone would make a huge difference.

That said, I still would like a very mild drop and hence all the trouble of trying to figure out the right combination with ZSP springs. I really don't want to put on H&R or Eibach since they lower the vehicle more than I want. I use my vehicle in the snow and don't want it dropping too much.
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      09-16-2011, 09:58 AM   #17
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I encourage you to go with the new springs. Even though my front is a little too high with the 'D6's the ride has improved significantly. While 'stiffer', it is much more controlled. The extra spring stiffness means that I no longer have to look for every pothole and worry about the 'bang' that you get when the standard Xi suspension hits the bump stops.
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      09-16-2011, 10:11 AM   #18
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I encourage you to go with the new springs. Even though my front is a little too high with the 'D6's the ride has improved significantly. While 'stiffer', it is much more controlled. The extra spring stiffness means that I no longer have to look for every pothole and worry about the 'bang' that you get when the standard Xi suspension hits the bump stops.
Which struts and shocks did you use when you changed your suspension?
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      09-16-2011, 06:32 PM   #19
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Which struts and shocks did you use when you changed your suspension?
I used the Bilstein ones made for the Xi.
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      09-17-2011, 10:52 AM   #20
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I encourage you to go with the new springs. Even though my front is a little too high with the 'D6's the ride has improved significantly. While 'stiffer', it is much more controlled. The extra spring stiffness means that I no longer have to look for every pothole and worry about the 'bang' that you get when the standard Xi suspension hits the bump stops.
Did your vehicle lower even a little? When you say a little too high are you referring to what you had expected from the drop or did the springs actually raise the front end from stock?

Also is your vehicle a standard or automatic?
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      09-17-2011, 10:57 AM   #21
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http://www.e90post.com/forums/showthread.php?t=583071
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      09-17-2011, 11:07 AM   #22
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I encourage you to go with the new springs. Even though my front is a little too high with the 'D6's the ride has improved significantly. While 'stiffer', it is much more controlled. The extra spring stiffness means that I no longer have to look for every pothole and worry about the 'bang' that you get when the standard Xi suspension hits the bump stops.
It might be the shocks. Unless you went from 330xi non-sport to 335 sport, the spring rate is likely only 10% different.
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