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      06-05-2017, 07:14 PM   #1
HOT M
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replacing stock suspension

I have a 06 Z4M, started AutoX and wants to hit the track. I believe that my suspension needs to be upgraded or at least replaced. I don't want to lower the car, my exhaust barely hits exiting my garage. Don't want coilovers, because I will have to run modified.
for my previous BMWs and VWs I went with Koni or Bilstein and Eibach or H&R. But both these springs will lower the car.
What do you guys suggest?
I already checked out the forum and google, called ECS and TcKline and can't seem to find any springs that will keep the factory height.
Should I go with factory springs (they are awful) and Bilsteins or Konis?
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      06-06-2017, 03:39 PM   #2
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Quote:
Originally Posted by Z M ROAD View Post
Don't want coilovers, because I will have to run modified. for my previous BMWs and VWs I went with Koni or Bilstein and Eibach or H&R. But both these springs will lower the car.
Bilstein B12 package lowers the car mildly (10mm in the back), so that might be a reasonably priced starting point.
When I looked into my suspension build, every non-stock spring package advertised some amount of ride height drop.

Separately, are camber plates within your mod point & dollar budgets?
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      06-06-2017, 10:40 PM   #3
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Quote:
Originally Posted by CTMP4me View Post
Bilstein B12 package lowers the car mildly (10mm in the back), so that might be a reasonably priced starting point.
When I looked into my suspension build, every non-stock spring package advertised some amount of ride height drop.

Separately, are camber plates within your mod point & dollar budgets?
Thanks for the bilstein b12 suggestion, I haven't checked into camber plates, what is the gain other than severe camber?
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      06-07-2017, 09:50 AM   #4
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Originally Posted by Z M ROAD View Post
What is the gain other than severe camber?
More grip and more optimal and even tire wear at the track. All-stock suspension using every adjustment trick maxes out around 1.8-2.0 degrees in the front and 2.0 in the back.
Regularly tracked Z4Ms typically run 2.5+ degrees.

An alternative for more camber without going to adjustable camber plates in front by using a camber bolt/shim kit (plus the kit is <$25 vs $400-500 for camber plates). I don't know how these would be classed for AutoX though.
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      06-07-2017, 09:12 PM   #5
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Quote:
Originally Posted by CTMP4me View Post

An alternative for more camber without going to adjustable camber plates in front by using a camber bolt/shim kit (plus the kit is <$25 vs $400-500 for camber plates). I don't know how these would be classed for AutoX though.
The camber plates and shims are treated the same by just about every classing guide. With the BMWCCA points system the shims add the same points as the camber plates. For SCCA, which is the classes most groups use, installing either moves a Z4M from Street to Street Prepared.
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      06-07-2017, 09:30 PM   #6
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I maxed out front camber at -1.5 left and right, rear -1.8 left and -1.9 right.
I did order the camber bolt shim kit. Should I try to use them and get -2.5 camber in the font? Will that affect the handling since the back will stay at -1.8 and -1.9?
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      06-08-2017, 09:44 PM   #7
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Quote:
Originally Posted by Z M ROAD View Post
I maxed out front camber at -1.5 left and right, rear -1.8 left and -1.9 right.
I did order the camber bolt shim kit. Should I try to use them and get -2.5 camber in the font? Will that affect the handling since the back will stay at -1.8 and -1.9?

I managed to get -2.5 camber in the fronts with shims and pins removed. The rears are at -1.5. I'm no expert so I can't speak to what ratio rear camber should be relative to fronts only that it should be more negative at the front. I'm on stock suspension and stock wheels wrapped with 235/40 and 265/35 PSS tires.
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      06-09-2017, 07:26 AM   #8
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Quote:
Originally Posted by Z M ROAD View Post
I maxed out front camber at -1.5 left and right, rear -1.8 left and -1.9 right.
I did order the camber bolt shim kit. Should I try to use them and get -2.5 camber in the font? Will that affect the handling since the back will stay at -1.8 and -1.9?
That's not a bad starting point for an autoX setup as it helps get the car to rotate a bit easier. You can adjust rear toe a bit more toe'd out also which also improves rotation. You might find it the more toe'd out, less rear camber a bit loose for track use though. For either use you'll want zero toe in the front to improve turn in while you're getting the alignment done after you install the shim kit.
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Last edited by dc_wright; 06-09-2017 at 08:35 AM..
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      06-09-2017, 05:06 PM   #9
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Quote:
Originally Posted by dc_wright View Post
That's not a bad starting point for an autoX setup as it helps get the car to rotate a bit easier. You can adjust rear toe a bit more toe'd out also which also improves rotation. You might find it the more toe'd out, less rear camber a bit loose for track use though. For either use you'll want zero toe in the front to improve turn in while you're getting the alignment done after you install the shim kit.
Thank you all, I just got new tires and will be running it tomorrow. I will see how I like it and where it needs improvement keeping your words in mind.
I may try the shims and more camber upfront and toe out in the back, and run it for another event next week.
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      06-12-2017, 10:01 PM   #10
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Just tried my 1st autocross last month,did ok. I need seat time more then anything :-)
I'm in the same boat, i can't justify lowering the car for 3-4 track events a year.

I did install these,and the rear is more planted now,haven't tracked with them yet:http://www.bimmerworld.com/Powerflex...treet-Kit.html
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      06-13-2017, 12:32 AM   #11
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Quote:
Originally Posted by kaybat View Post
Just tried my 1st autocross last month,did ok. I need seat time more then anything :-)
I'm in the same boat, i can't justify lowering the car for 3-4 track events a year.

I did install these,and the rear is more planted now,haven't tracked with them yet:http://www.bimmerworld.com/Powerflex...treet-Kit.html
I need to change my front struts they are very bad, the rears a little better. I am starting to believe that eibach/bilstein will be fine, I just need to change the factory exhaust. That way I can justify the exhaust. Lol.
Did you install them yourself? What was the cost?
I think that could be a good thing to do with RE struts mounts, while replacing the springs and struts.
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      06-13-2017, 08:41 AM   #12
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The subframe mounts i had an indie install,was around $160.
I installed bilsteins,definitely use RE mounts,you won't want to to that job again!
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      06-14-2017, 06:34 PM   #13
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Quote:
Originally Posted by kaybat View Post
The subframe mounts i had an indie install,was around $160.
I installed bilsteins,definitely use RE mounts,you won't want to to that job again!
thx, any thing else you recommend replacing when doing this job?
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      06-14-2017, 07:11 PM   #14
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some of the more experienced guys on here can help you on that(i'm only at 26k,so i haven't had to lean too far in yet.)

if you need any help getting to the rear struts,i've done it twice,post it here.
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Last edited by kaybat; 06-18-2017 at 10:11 PM..
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      06-17-2017, 11:28 AM   #15
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Quote:
Originally Posted by Z M ROAD View Post
thx, any thing else you recommend replacing when doing this job?
When you replace the rear shocks in addition to the shock mounts, you'll probably need new bump stops. The original ones deteriorate over time and they're cheap so might as well replace them while you've got everything apart.
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      06-19-2017, 12:11 AM   #16
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Quote:
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When you replace the rear shocks in addition to the shock mounts, you'll probably need new bump stops. The original ones deteriorate over time and they're cheap so might as well replace them while you've got everything apart.
Thank you
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      06-27-2017, 06:49 PM   #17
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Bilstein B12 Pro-Kit & Eibach Pro-Kit Springs Installed....
Replaced OEM front control arms with BMW ZHP performance control arms, OEM front control arm bushings, all new spring pads, strut support guides and bearings....front lowered 3/4 inch & rear 3/8 inch....4 wheel alignment....performed by Eastside Bavarian - Eric the Tech's acumen, detail, thoroughness and precision is awesome....

First impressions....the visual change is freaking awesome....the seat time reveals it feels like it's on rails....freaking awesome.
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