[Mr. 5]

So, I installed the dampers a while back and noticed a huge difference.
This was my review:
http://www.e90post.com/forums/showth...2909&highlight

When I ordered the performance suspension, it was somewhat understood that the performance springs were the same as the ZSP springs but just painted yellow, but thanks to Gesler, we found that there was a difference.
Gesler's review is here:
http://www.e90post.com/forums/showth...4603&highlight

I wanted to take full advantage of this suspension, and I wanted to see if there really was a difference between the two springs in terms of ride quality.
Thanks again to Evan at Tischer for hooking me up and getting these to me fast. For those who don't about Tischer, you can get the part from here www.getbmwparts.com

I borrowed one of the lifts over at MD Automotive (Thanks to Mark), and the installation took me about 3 hours. I'm sure I could have done it a bit quicker but Mark and I shot the shit talking.
This installation was a lot easier than the last time I did it because #1, there was no sway bar to install..Thank God! and #2, the struts didn't need to be changed out so the springs were changed with the strut still installed at the base.

I installed the rears first, and I was very surprised by how identical the rear springs were when comparing the ZSP springs to the Performance springs side by side. There was a slight difference in the overall diameter of the spring and also the thickness of the spring.
I used a dial caliper to take the measurements and here's what I found:

Rear ZSP spring:
Coil thickness--.556"
Overall Diameter--3.871"

Rear Performance spring:
Coil thickness--.581"
Overall Diameter--3.978"

What does this mean? Well, given the fact that the ZSP spring has a rate of 460 lb/in and assuming that the BMW Performance Spring is made from the same material as the ZSP spring, I could figure out the spring rate of the Performance spring.
So, given all of this, the rear spring rate is 505 lb/in.
That's not that big of a difference.

The front springs were surprising though.
They are much different than the ZSP springs, and you can easily tell just by glancing at them.

Here are the specs of the front springs:

Front ZSP spring:
Coil thickness--.476"
Overall Diameter--5.702"

Front Performance spring:
Coil thickness--.506"
Overall Diameter--6.172"

Since there is one less coil in the Performance springs then it would make sense that it should be stiffer and it is.
My calculations came up with 219 lb/in compared to the 145 lb/in of the ZSP spring. This is also assuming that the material is the same in both springs.
EDIT--There is actually 3/4 less of a coil with the Performance Springs and not 1 full coil, so my calculations indicate that the front springs have a rate of 195 lb/in.

I also noticed the "part numbers" on both the ZSP springs and the perfprmance springs. My rear ZSP spring had D4 written on it and the Performance spring had T4. You can see this in some of the pictures. The front ZSP spring has D7 and the Performance Spring has T3 on it.
These numbers make me curious. Would the Rear spring be shorter and stiffer if it was a different T model number?
Should I have gotten a T7 spring for the front since my ZSP spring was a D7?
I guess these are questions for Tischer, but I just thought I'd bring it up in this thread.

Driving Impressions

I drove about 40 miles afterwards taking it on the freeway to pick up my daughter, and side streets as well. It's obvious that the key ingredient of the performance suspension is the dampers. IMO, upgrading to the dampers with ZSP springs is perfectly fine, but I do notice that the car is a bit smoother over bumps.
It seems surprising that I could throw on these stiffer springs and make the car smoother but it's very obvious that the dampers and these springs were made for one another.

In conclusion, I never cared about the ride height, but I do care about the performance. I also care about how the car is going to feel when I take the family on a trip. I don't want the car bouncing all over the place. So, all in all, I believe I made the correct decision. The car is still pleasant to drive on the freeway, yet steps up to the plate when taking it to the track.

To those that really do care about the ride height, I did take some measurements before and after by measuring from the center of the center cap to the wheel well edge using a straight edged measuring level and another level to make sure I'm taking a horizontal measurement. (The reason for the levels is because a diagonal measurement could add 1/8th to the measurment)
I also think that the springs will settle a bit more but probably not any more than maybe a 1/16 of an inch.

Before:
Driver's Front: 14"-----------------Passenger's Front: 14 3/16"
Driver's Rear: 14 1/8"--------------Passenger's Rear: 13 15/16"

After:
Driver's Front: 13.5----------------Passenger's Front: 13 3/4"
Driver's Rear: 14"------------------Passenger's Rear: 13 3/4"

So, it's about a 1/2 inch shorter in the front and about an 1/8th in the rear.

I took a bunch of pics so enjoy!
The last picture is from one of the bolts that split from the M3 strut brace.
I thuoght it was interesting how it just split in half so I added it to the collection.

[scottmc129]

Glad you like them too! Are these springs the same as the ones that come in the "new" kit? I have the new kit from Tischer and will be put to the test at Laguna Seca on the 9th!

[Mr. 5]

Originally Posted by scottmc129

Glad you like them too! Are these springs the same as the ones that come in the "new" kit? I have the new kit from Tischer and will be put to the test at Laguna Seca on the 9th!

Yes, but from what I understand the springs that come in the kit all depend on the options that you have on your car.
In other words, My performance springs are T4 in the rear and T3 in the front but yours may be different depending on the options that you have installed.

[e90southfl]

How did the M3 Strut brace nut crack? Was it during your re-install or just a defective nut?

[scottmc129]

I have the T4 springs up front. I just measured and I am at 14 up front and 13.5 in the rear give or take a mil. I did not install so I dont know if this is possible but can the front be brought down like yours? Is there a reason why mine would be sitting a little higher then yours. the guys who did the install did say they thought it was actually higher in front with the performance!

maybe we should measure from the ground to the bottom of the front bumper and just behind the front wheels? would this help??

[crqflier]

Nice write up. One of the primary reasons I didn't do my suspension install myself was I didn't want to guess at the torque specs for all the different bolts. Since you've done this a couple times, mind share what specs you used and what that was based on? Thanks.

[Mr. 5]

Originally Posted by e90southfl

How did the M3 Strut brace nut crack? Was it during your re-install or just a defective nut?

I'm thinking that I may have torqued that nut a bit too tight a while back when I installed it and it just split down the side.
It may have been a defective nut though. When I was removing that nut this time, it was a little hard to get the socket over it, and I was wondering what was going on, but then I saw the crack.
Once I got the nut off, it just broke in half.

Originally Posted by scottmc129

I have the T4 springs up front. I just measured and I am at 14 up front and 13.5 in the rear give or take a mil. I did not install so I dont know if this is possible but can the front be brought down like yours? Is there a reason why mine would be sitting a little higher then yours. the guys who did the install did say they thought it was actually higher in front with the performance!

maybe we should measure from the ground to the bottom of the front bumper and just behind the front wheels? would this help??

It wouldn't be good to measure from the ground up because t he diameter of your wheels could be different that mine due to the size of wheels, tires, or even air pressure.
Measuring from the center cap to the fender is a great way to measure since it doesn't matter if you have 19" wheels compared to 16".
Also, hopefully your T4 springs are in the rear since they are rear springs.

Originally Posted by crqflier

Nice write up. One of the primary reasons I didn't do my suspension install myself was I didn't want to guess at the torque specs for all the different bolts. Since you've done this a couple times, mind share what specs you used and what that was based on? Thanks.

I used an impact wrench and just made sure that things were nice and tight.
I'm getting an alignment on Friday so I'll let them deal with anything that isn't tight enough, but I'm sure everything is fine. I didn't have any torque specs.

[scottmc129]

I just checked and the tags on my front springs say T4! i cant get a good look at the rears but the front are T4 for sure. maybe these were the compromise to include the E92?

So you think T3 front springs are different then T4 fronts?? Maybe Evan from Tischer can explain what this means.

[jah29]

I have some of the yellow performance springs too. I gave the vin number for my 135i and was sent T3 front and T2 rear. I counted coils and measured diameters and came up with 170 lbs/in front and 522 lbs/in rear. I plan to test the springs with my press and corner scales to get the actual rate, but probably won't get to it for a few days. I'll report back when I get the numbers.

these are going to be used with Koni FSD, but not anytime soon

justin

[LaYzEe]

great review as always Mr. 5!

when i finally decide to buy the bmw performance suspension and m3 parts i'll also do a before and after comparison of the height.

but i'll wait 3-4 weeks for the springs to really settle in and make the final measurements.

[Fraggy]

Without taking the wheels off, is there any good way to see the T number on the spring?

[Mr. 5]

Originally Posted by scottmc129

I just checked and the tags on my front springs say T4! i cant get a good look at the rears but the front are T4 for sure. maybe these were the compromise to include the E92?

So you think T3 front springs are different then T4 fronts?? Maybe Evan from Tischer can explain what this means.

You might be right. The e92 might get T4 springs and the e90 gets T3.
I sent Evan a message about this so hopefully he'll post about it.
It looks like jah29 had a 135 and he has T3 in the front and T2 in the rear.
I think I'm going to start questioning once I hear of an e90 with defferent part numbers than myself.

Originally Posted by jah29

I have some of the yellow performance springs too. I gave the vin number for my 135i and was sent T3 front and T2 rear. I counted coils and measured diameters and came up with 170 lbs/in front and 522 lbs/in rear. I plan to test the springs with my press and corner scales to get the actual rate, but probably won't get to it for a few days. I'll report back when I get the numbers.

these are going to be used with Koni FSD, but not anytime soon

justin

You also need to take into acount the coil thickness for the spring rates.
It's not just the number of coils.
I followed this spring rate calculator to figure out the newer spring rates:
http://www.engineersedge.com/calcula...ring_k_pop.htm

Originally Posted by Fraggy

Without taking the wheels off, is there any good way to see the T number on the spring?

If you stick your head under the rear bumper and look towards the springs, hopefully the springs will be twisted enought for you to see what is imprinted on them.
Jack up the front just a bit and you will see a tag on the spring.
You should be able to see it in between the tire and the fender when the car is jacked up a little.

[scottmc129]

Originally Posted by Fraggy

Without taking the wheels off, is there any good way to see the T number on the spring?

I was able to get a look at the front springs just by looking at the springs with a flash light. look at the white tag that should still be on the springs. The rears are not so easy. i think that would require a jack. i have the part numbers from my order.

I have the part numbers from my order? would that help?

[Mr. 5]

Originally Posted by scottmc129

I was able to get a look at the front springs just by looking at the springs with a flash light. look at the white tag that should still be on the springs. The rears are not so easy. i think that would require a jack. i have the part numbers from my order.

I have the part numbers from my order? would that help?

Let's stick with what's on the spring for now.
It's obvious that there's a difference between T4 front and T4 rear, but I'm 99% sure that a T4 rear is the same exact thing as a T4 rear if you know what I'm trying to say.

[mikeokimster]

I really do appreciate the detail and the depth you went to in creating a very documented write up for all your posts regarding suspension upgrades on your car.

[jah29]

Originally Posted by Mr. 5

You also need to take into acount the coil thickness for the spring rates.
It's not just the number of coils.
I followed this spring rate calculator to figure out the newer spring rates:
http://www.engineersedge.com/calcula...ring_k_pop.htm

that's what I meant by diameter'S'. Anyway, I didn't write down my measurements, but your measured numbers seemed different from what I recall. I doubt either of us was perfectly accurate with our measurements. I just wanted to add to the data.

that being said I think your front number is way too high. the front rate increase was way out of proportion to the rear, and the rear has a much lower motion ratio making the difference even greater.

If I had to guess, I'd say both of us got numbers too high for the front. I think it will turn out the main difference changing to the yellow springs is the slight drop. And there might be a 10% rate increase. Personally I was hoping for 20% stiffer and no drop.

[Mr. 5]

Originally Posted by jah29

that's what I meant by diameter'S'. Anyway, I didn't write down my measurements, but your measured numbers seemed different from what I recall. I doubt either of us was perfectly accurate with our measurements. I just wanted to add to the data.

that being said I think your front number is way too high. the front rate increase was way out of proportion to the rear, and the rear has a much lower motion ratio making the difference even greater.

If I had to guess, I'd say both of us got numbers too high for the front. I think it will turn out the main difference changing to the yellow springs is the slight drop. And there might be a 10% rate increase. Personally I was hoping for 20% stiffer and no drop.

I disagree.
I understand that it is way out of proportion, but that doesn't mean that BMW didn't intend for it to be that way.
This is also why I was perplexed at how the rear springs were in comparison.
I don't understand how surprised you are with the difference in the numbers when you compare the comparison of the rear springs and the front.

Again, I used a dial caliper to acurately measure to the thousanths of an inch, so I am confident in my findings.
This doesn't mean to say that I am not surprised by why BMW would change the front so dramaticaly and not the rear.

Then again though, we have to remember that you have a 135 and not an e90 335. There could be a difference. Well obviously since you have the T2 in the rear.
Since we're at it, will you please give us the numbers that are on your sport springs so we could compare with the Performance springs?

Look at these pictures again--

[mwahlert]

any pics of how the car sits?

i'm looking for a suspension that will retain suspension travel and decent ride quality but i hate the "reverse" rake - where the rear sits lower than the front..

[Mr. 5]

Originally Posted by mwahlert

any pics of how the car sits?

i'm looking for a suspension that will retain suspension travel and decent ride quality but i hate the "reverse" rake - where the rear sits lower than the front..

I can tell you that the front is much MUCH lower now.
I went out to my car at lunch and my front bumper was pretty much sitting on the parking stall.
It wasn't even close before.
The rear ride height is about the same.

I'll take pictures when I get the time.

[scottmc129]

Mr. 5, did Evan get back to you on the T3 T4 front springs? Would your car be lower because of the shocks you have? I am wondering if I had the T3s would the front sit a little lower?

[Mr. 5]

Hey jah29,
I believe you're correct with my front spring rate calculation.
I still think that 170 lb/in is still too soft, but I just looked at it again, and it looks like the front performance spring has a quarter more of a turn than the ZSP spring.

Based on finding this, I calculated the spring rate again.
By adding a 1/4 inch of length to the spring changed the front spring rate to 195 lb/in so I will edit my initial post.

[Mr. 5]

Originally Posted by scottmc129

Mr. 5, did Evan get back to you on the T3 T4 front springs? Would your car be lower because of the shocks you have? I am wondering if I had the T3s would the front sit a little lower?

It's a great question.
He did get back to me but he said that there are so many possibilities that he doesn't know how many springs there are.
It seems like he could state how many types of springs there are but then again, we don't know how hard it is to do that.

It would be great to know your options.
I have the following:

Manual Transmission
Performance Package
Cold Weather Package