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      11-15-2009, 01:10 PM   #13
Lieutenant Colonel

Drives: 335
Join Date: Jun 2006
Location: Canada

iTrader: (1)

Impressive that you got this done with the resource you have. It is a big job and usually takes over 20-30 hours to do a full swap out.

I wouldn’t use all what I have done and expect the same results. There a lot things I did that I never mentioned.

A few notes:

• The springs I am using are 400 lb/in front and 800 lb/in rear with the M3 roll bars but it for 335i and the 1 series needs some so modification to get the same results. This works for me because it is car and setup specific and it not something you can buy right now. I have done a few extra things to increase mechanical grip in the rear and it something I am not sharing at this point. It is possible for 450 lb/in front spring maybe better for higher speed tracks or if you having trouble with mechanical grip in the rear. It is going to be what you like in the end.
• I’m really not sure if there a single person selling suspension components understands how to calculate proper spring lengths for this car. For a 400 lb/in front spring it needs to be 8” long to keep in the linear range. You can get away with a 7” front spring but it the rate will spike as approach 1.5” of shaft compression. The rear spring at 800 lb/in needs to be 8” long which still a bit short but acceptable. Any rate lower than 800 lb/in spring in the rear needs to be 9” long.
• The front struts need to be adjusted for height so that there is very little preload on the spring. It took me two revisions on my camber plated adapters to get this right but it was worth the effort. The front end of my car is considerably more compliant than the KW v3 kit especially on big bumps.
• How much you drop this car is dependant on your spring rate. For the spring rates I need 2.5” on wheel travel front and rear. Dropping the car more than optimal creates a lot of problems. The roll center changes really work against you verses any advantages in CG. It truly a lose situation so if want to drop more then stiffen up the spring but this creates new problems as well. Nothing is easy as you really have to account for all the small details.
• You rear low speed compression is something you want to pay attention to during setting up the dampers.
• The roll bar end links need to be optimized for both front and rear geometry changes. It can make a significant difference.
• I would sugest your rear toe in be set at a minimum of 0.15 to 0.20 degrees. The sub frame still gives a lot even with the M3 bushing upgrade. Anything less and you not going to like late exit rear grip. If you don’t put enough toe in up front your daily drive it will not pleasant….every rut in the road will keep you occupied.

The prototype rear toe links is something I don’t plan to sell or market the links at this time. The next revision of the toe link uses fewer parts and is easier to assemble. I will also increase the stiffness by 20% while retaining the M3 design intent for looks but more importantly function. The testing validation of the links was completed a along time ago and there was significant amount of upfront analysis done before hand. The problem with selling these to the average person is the cost is too high for a small production run. The link is designed to outlast the car under any condition and truly is a no compromise design. If a group of 25 people wanted these then it maybe something I consider and cost could be reasonable. Honestly, it is not on my priority list as I'm working on other things.


Originally Posted by Justin(OKC) View Post
Hey guys, thanks for all the comments. Here are some answers to some questions:

Blacky, the dampers and springs cost me about $4500.

Primo135, it is so dumped it looks stupid. I'm going to try to fix that today but I'm so sore that I have sensation in parts I didn't know were on my body

Snertz, they are AST 5200's.

arrutled, I wish it was a screwdriver. If you look at the pics I posted, there is a shot of the special tool on the passenger rear subframe bushing so that you guys could see it. Without it, I'm not sure how you would get it out (and I have cut bushings out on my E36 M3 before)

vitig, In addition to the swaybar and subframe bushings I've got the rear upper link kit, rear guide rod kit, and the rear lower camber link from the M3. With the rear camber link I have to use M3 shocks

larryn, you got it man. I might have some other pics of the tool if you need some. The hardest part of the install had to do with the front subframe bushings. The M3 bushing install from the top instead of the bottom. What makes it harder is that the subframe is tapered opposite of how the M3 bushings install. To help with the installation we used a hose clamp around the new bushing to compress it and make it easier to go in without stripping/shaving rubber off the bushing. The stock bushing you can twist in your hand, the M3 bushing are solid rubber. HUGE difference. I will definitely post my thoughts when I get it all sorted out. It was too much to do a DIY, but I thought I would post something for those that have some mechanical ability (like yourself). Looking at some of the things you have done and talked about on the forum, larryn, I think you have the ability to do the rear problem. The bushings are cake if you can borrow the tool from someone.

Yes, I do have the front M3 bits as well. I think I have converted almost everything possible on the car. I used a lot of info from orb to help make my decision. Hopefully there will be some sort of toe link available for the rear like orb has on his car. When that occurs, I will buy it. As far as the alignment. I'm trying to get suggestions and ideas. If you have any, please share I'm thinking for the street -1.5 camber front and rear (I may have to do more on the back to fit the forgelines under there....totally different topic that I will go into once I try to test fit them). These are the guidelines that I got from Harold at HP: 1/16" total toe-in for the front with -1 to -1.5 of camber. For the rear, 3/16" total toe-in with -1.5 to -2.0 of camber.

I'll be back under the car a bit today. If anyone has anything they want photographed, just let me know!! Thanks again for all your comments, guys.

Oh, if you were wondering....I think the hardest part of the install was getting the rear muffler hanger (rubber) disconnected to drop the exhaust and getting the rear swaybar bushing mounted up. As I told my friend, Bryan that took the lead on the install.....I've never seen a swaybar bushing that was easy to install.

Last edited by Orb; 11-15-2009 at 08:38 PM..