More Findings & Discussions About Lowering the M3

[!Xoible]

Originally Posted by TXM32B

How long to install? What can I expect to pay for alignment afterwards?

at the dealer it's about 200-300 unless they pull the "this is an M3" and charge you more

[rzm3]

my dealer charges ~$140 for alignment

[32]

really? that much? does the dealer use something better than for example a Good Year Dealer? I had mine done and they charged my $60.
however, i live in the suburbs

[rzm3]

Originally Posted by 32

really? that much? does the dealer use something better than for example a Good Year Dealer? I had mine done and they charged my $60.
however, i live in the suburbs

well, they have the official bmw recommended specs (some shops don't), and put weights in the car while aligning.

As for whether this makes a difference, I dont know...

[lucid]

Rldzhao, what one really needs to know is the effective spring stiffness vs. displacement. As I've said earlier, if you plot the force vs displacement curve for the H&R springs+stock bumpstops, you'll see that you will run into the really steep part of the curve sooner (the bumpstop curve will probably look like two straight lines with distinct slopes; the slope of the second line at larger displacement will be significantly higher than the slope of the line at smaller displacement). I appreciate you documenting H&R's answer, but I still think messing with the force vs. displacement curve in a significant way, especially during the initial displacement interval, without retuning the dampers is not sound. Nothing in their answer suggests they are doing the right thing here.

The other thing is that the H&R guy is making claims about how the Dinan bumpstops behave. Has he actually seen/tested one of them? How does he know how they behave exactly? I sure don't know, and would like to find out, but I suspect that he doesn't know either.

[rzm3]

Originally Posted by lucid

Rldzhao, what one really needs to know is the effective spring stiffness vs. displacement. As I've said earlier, if you plot the force vs displacement curve for the H&R springs+stock bumpstops, you'll see that you will run into the really steep part of the curve sooner (the bumpstop curve will probably look like two straight lines with distinct slopes; the slope of the second line at larger displacement will be significantly higher than the slope of the line at smaller displacement). I appreciate you documenting H&R's answer, but I still think messing with the force vs. displacement curve in a significant way, especially during the initial displacement interval, without retuning the dampers is not sound. Nothing in their answer suggests they are doing the right thing here.

The other thing is that the H&R guy is making claims about how the Dinan bumpstops behave. Has he actually seen/tested one of them? How does he know how they behave exactly? I sure don't know, and would like to find out, but I suspect that he doesn't know either.

Lucid, like you said, all I have done here is documenting H&R's words and some facts from my measurements of my car. I am not making any conclusions or personal judgements. I don't see what's wrong with that?

I have the H&R installed and I am monitoring it closely. I think this is the best way to review a product instead of just listening to both company's marketing. Until I have more miles on the car, do a track session, and conduct a side-by-side comparison, I am not making any conclusions.

[gthirtyfizle]

Hey rldzhao, I c ur in NY. Where did u install ur springs? I am either gonna go with rd sport or dinan springs but need someone to install and wouldnt mind going to someone who has already worked on our cars.

[lucid]

Originally Posted by rldzhao

Lucid, like you said, all I have done here is documenting H&R's words and some facts from my measurements of my car. I am not making any conclusions or personal judgements. I don't see what's wrong with that?

I have the H&R installed and I am monitoring it closely. I think this is the best way to review a product instead of just listening to both company's marketing. Until I have more miles on the car, do a track session, and conduct a side-by-side comparison, I am not making any conclusions.

Not saying there is anything wrong with the thread. I appericiate you documenting what you can. I was somewhat reacting to you saying, "Dinan's and H&R's stories make sense". As you know by now, H&R's story doesn't make sense to me. Anyway, you are doing all of us a great favor by sharing what you are finding out.

Do you still have your stock springs? Maybe we can get force vs. displacement data from them. If I can find someone local who has purchased H&R or Dinan springs (and bumpstops), I'll try to convince them to let me take data on them before installation. It would be great to have that all documented.

[rzm3]

Originally Posted by gthirtyfizle

Hey rldzhao, I c ur in NY. Where did u install ur springs? I am either gonna go with rd sport or dinan springs but need someone to install and wouldnt mind going to someone who has already worked on our cars.

Hey. I actually installed the springs myself. ICS performance in Stamford, CT has a mechanic who used to work for Ferrari, and he seems to be quite knowledgeable and quite a gentleman.

[rzm3]

Originally Posted by lucid

Not saying there is anything wrong with the thread. I appericiate you documenting what you can. I was somewhat reacting to you saying, "Dinan's and H&R's stories make sense". As you know by now, H&R's story doesn't make sense to me. Anyway, you are doing all of us a great favor by sharing what you are finding out.

Do you still have your stock springs? Maybe we can get force vs. displacement data from them. If I can find someone local who has purchased H&R or Dinan springs (and bumpstops), I'll try to convince them to let me take data on them before installation. It would be great to have that all documented.

Yes I am open to gaining more knowledge about our cars. If you can find a lab that can do the testing I'd be glad to contribute.

[lucid]

Originally Posted by rldzhao

Yes I am open to gaining more knowledge about our cars. If you can find a lab that can do the testing I'd be glad to contribute.

You can ship one of your front springs to me if you'd like, and I'll ship it back after I get the data. We can split the shipping costs. Shouldn't be much. Or we can meet up if you are ever in the area. I have access to equipment that will yield accurate force vs. displacement data. Just an offer.

[doba_s]

it would be great if you guys can do that test ... i just purchased h&r springs too ... would be good to know what kind of results lucid can get from that test ...

[rzm3]

Originally Posted by doba_s

it would be great if you guys can do that test ... i just purchased h&r springs too ... would be good to know what kind of results lucid can get from that test ...

well we only have the stock and dinan available... don't know where to get the h&r from

[lucid]

Originally Posted by rldzhao

well we only have the stock and dinan available... don't know where to get the h&r from

Just to clarify: I don't have Dinan springs or bumpstops.

[rzm3]

hey lucid, you want to create a thread and ask for people's help on this project? it probably makes the most sense to do all three (plus other springs) at once?

[lucid]

Originally Posted by rldzhao

hey lucid, you want to create a thread and ask for people's help on this project? it probably makes the most sense to do all three (plus other springs) at once?

Good idea. I'll check with my colleague who manages the test equipment to make sure it is available and up to spec first. If it is, it would take only a few minutes to run each test, so doing them together is not a major requirement. It sould be fine. He was demonstrating some titanium samples he pulled apart the other day. The only setup issue might be to build a rig to keep the spring stable under compression so that it doesn't fly out.

[rzm3]

Just to be clear, this will not be destructive testing right? We should probably define a range such that the normal operational range is not exceeded.

My idea is that we should start by applying up to 3700lb/4 on the front spring, and then compress another 3-4" max. This should give a pretty good idea of the behavier of the spring.

Also, we could probably do a little "fund raiser". We can accept small contributions like $5 to cover the logistics and testing costs. We would probably want to buy some bumpstops as well (they are cheap) . lol this sounds like fun.

[lucid]

Originally Posted by rldzhao

Just to be clear, this will not be destructive testing right? We should probably define a range such that the normal operational range is not exceeded.

My idea is that we should start by applying 3700lb/4 on the front spring, and then compress another 3-4" max. This should give a pretty good idea of the behavier of the spring.

Also, we could probably do a little "fund raiser". We can accept small contributions like $5 to cover the logistics and testing costs. We would probably want to buy some bumpstops as well (they are cheap) . lol this sounds like fun.

No, it wouldn't be tested to failure or anything. I guess there is some kind of chance that if you compress it too much, you might get some plastic deformation, but as you are saying, there is not need to go there. You have full control over the displacement with this equipment. It actually acts as a displacement source. It applies whatever force is necessary to achieve a specified displacement. You specificy a displacement range and increments, and it records the values as it goes along.

[doba_s]

i am willing to donate $5 ... just make a different thread , so other people can see it

[AutoTalent]

Lowering height is one thing but spring rates is another. Just because one is lower doesn't mean that it will ride worse if using a lower spring rate. Oddly, RD springs ride better with the lower stance than H&R. I have not installed Eibach springs yet so can't provide any real input.

The proper way is to have springs matched to shocks like the KW Coilovers

[lucid]

Hi guys. I just checked the specs on the machine and it can easily handle the forces and the displacements we are talking about. I just need the dimension of the stock springs to make sure I can mount them properly. Diameter and uncompressed length? Also, can someone post a pic of stock and aftermarket springs? Once I get this info and verify that we are good to go, I'll start another thread on this.

[spyderco10]

Originally Posted by gthirtyfizle

So in conclusion, what would u guys say is the best way to go? Dinan or H&R? I deff wanna buy something to lower this.

How about a 300lb woman in the passenger seat?