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      02-01-2013, 05:57 AM   #1
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Coilovers - Front or Rear Higher?

I've been reading like crazy about ride heights recently and wanted to see if people biased their ride height or kept it square. People say you don't want a take because of nose dive on braking but isn't our brake system rear biased hence that's why our rear wear so much quicker?

So what's everyone's opinion I'm finding so many conflicting things online. Thanks
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      02-01-2013, 02:31 PM   #2
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You want about 3/4" positive rake.
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      02-01-2013, 05:08 PM   #3
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Originally Posted by TC Kline Racing View Post
You want about 3/4" positive rake.
Really, all the m3 guys seem to have the rear a half inch lower than the front. Being I'm an xi would that change anything?

Thanks
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      02-02-2013, 09:43 PM   #4
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Originally Posted by MassBimmer View Post
That's a lot of rake...no thanks

So mass what's your opninion.
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      02-02-2013, 09:57 PM   #5
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Originally Posted by TC Kline Racing View Post
You want about 3/4" positive rake.
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Originally Posted by MassBimmer View Post
That's a lot of rake...no thanks
Yea ignore the guy who has proven history building successful race cars lol. Perhaps we should survey the experts here with highest post counts.

OP if you're going to do this right and get a corner balance prior to alignment, the heights of all 4 corners will change anyway. Set it to what you like, looks good and is practical enough to get by. Racers will tell you rake, as long as not aggressive, won't make a huge impact. Getting it balanced is where it's at.
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      02-03-2013, 09:36 AM   #6
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Originally Posted by MassBimmer View Post
I don't track my car so what do I care if someone has built race cars? Ride height is all about what you use your car for. If I raced my daily driver, I would care about input from a company that successfully builds race cars. However, my application is all about getting the look I want so rake is not for me. Before you respond like that, think about where someone else might be coming from.
Nobody cares because nobody asked what looks good you fool. Read the original post.

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Originally Posted by pits200 View Post
I've been reading like crazy about ride heights recently and wanted to see if people biased their ride height or kept it square. People say you don't want a take because of nose dive on braking but isn't our brake system rear biased hence that's why our rear wear so much quicker?

OP asked about dynamic weight shifting and brake bias and TCK addressed just that. However your opinion of what looks cool is about as least technical as it can get and you answered a question nobody asked. Instead of advising others to consider where others are coming from, you should simply learn to read; the question was right there to begin with.
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Last edited by 3002 tii; 02-03-2013 at 09:43 AM.
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      02-03-2013, 11:02 AM   #7
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Originally Posted by DSC_OFF View Post
Nobody cares because nobody asked what looks good you fool. Read the original post.




OP asked about dynamic weight shifting and brake bias and TCK addressed just that. However your opinion of what looks cool is about as least technical as it can get and you answered a question nobody asked. Instead of advising others to consider where others are coming from, you should simply learn to read; the question was right there to begin with.
Well to be honest TCK didn't really address much. I was hoping for a slightly more detailed answer as to why we want a positive rake when it creates more understeer in this condition. Also, I'm an xi, wouldn't I benefit from a little more front turn in with a negative rake?
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      02-03-2013, 11:22 AM   #8
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From my personal experience on track with my xi I noticed that when I had front lower then rear the car didn't turn as well on those slow tight turns. But was great on higher speed turns. I then raised the front and turned much better. Im currently still experimenting but I have the front at 3/4" gap from fender to tire and rear at 1/2"

I'm considering raising the suspension about 1/4" more front and rear
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      02-03-2013, 11:48 AM   #9
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Nice, thanks Chris, so a slight negative rake, that's what I'm planning on going with. One thing us XI guys never talked bout was roll center correction.

Our control arms are probably way off or will it be soemwhat similar to the i guys with the roll angle.
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      02-03-2013, 11:52 AM   #10
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I'm thinking of upgrading my front sway bar end links with the adjustable ones from HP autowerks. Cause with all that drop up front (especially on an xi= ~2.5inch drop) I'm sure something went wrong there....question is do they fit on xi ....Harold??
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      02-03-2013, 12:04 PM   #11
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Quote:
Originally Posted by Chrisred View Post
I'm thinking of upgrading my front sway bar end links with the adjustable ones from HP autowerks. Cause with all that drop up front (especially on an xi= ~2.5inch drop) I'm sure something went wrong there....question is do they fit on xi ....Harold??
No reason they shouldn't fit on the xi even with our bigger drop than say from the i guys with the sport suspension and probably only a half inch drop.

What I'm worried about now is the angle of the control arms since they're suppose to be parallel with the ground when the car is under load. But with lowering the car so much, I'm wondering if our control arms are aiming upwards which is a big no no in terms or body roll.
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      02-03-2013, 08:52 PM   #12
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Quote:
Originally Posted by pits200 View Post
Well to be honest TCK didn't really address much. I was hoping for a slightly more detailed answer as to why we want a positive rake when it creates more understeer in this condition. Also, I'm an xi, wouldn't I benefit from a little more front turn in with a negative rake?
While I can't speak for TCK, I think they assumed you wanted rake for the aggressive stance. So I'm guessing 3/4" would be the max you could go without feeling any negligible effects.

But I agree with your intuition on the more rake you have, the more the car would understeer as it would tend to nose dive more. I'll let the xi owners chime in but is the car's weight distribution any different than a non-xi model? If not, I would imagine whatever works on a rwd should work for xi. If the xi is more front heavy, then you probably want to go with less rake.

But like I said end of day, if you're willing to spend the $$$, a corner balance would yield the appropriate height for best handling (ie it'll take the guesswork out of how to set the rake). Set the overall height to what you like, and the corner balance would then tweak each corner separately (and you may see variances of up to 1/2" between corners).
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      02-04-2013, 09:37 AM   #13
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Quote:
Originally Posted by pits200 View Post
Really, all the m3 guys seem to have the rear a half inch lower than the front. Being I'm an xi would that change anything?

Thanks
Quote:
Originally Posted by DSC_OFF View Post
Yea ignore the guy who has proven history building successful race cars lol. Perhaps we should survey the experts here with highest post counts.

OP if you're going to do this right and get a corner balance prior to alignment, the heights of all 4 corners will change anyway. Set it to what you like, looks good and is practical enough to get by. Racers will tell you rake, as long as not aggressive, won't make a huge impact. Getting it balanced is where it's at.
Quote:
Originally Posted by DSC_OFF View Post
Nobody cares because nobody asked what looks good you fool. Read the original post.




OP asked about dynamic weight shifting and brake bias and TCK addressed just that. However your opinion of what looks cool is about as least technical as it can get and you answered a question nobody asked. Instead of advising others to consider where others are coming from, you should simply learn to read; the question was right there to begin with.
Quote:
Originally Posted by pits200 View Post
Well to be honest TCK didn't really address much. I was hoping for a slightly more detailed answer as to why we want a positive rake when it creates more understeer in this condition. Also, I'm an xi, wouldn't I benefit from a little more front turn in with a negative rake?
Quote:
Originally Posted by DSC_OFF View Post
While I can't speak for TCK, I think they assumed you wanted rake for the aggressive stance. So I'm guessing 3/4" would be the max you could go without feeling any negligible effects.

But I agree with your intuition on the more rake you have, the more the car would understeer as it would tend to nose dive more. I'll let the xi owners chime in but is the car's weight distribution any different than a non-xi model? If not, I would imagine whatever works on a rwd should work for xi. If the xi is more front heavy, then you probably want to go with less rake.

But like I said end of day, if you're willing to spend the $$$, a corner balance would yield the appropriate height for best handling (ie it'll take the guesswork out of how to set the rake). Set the overall height to what you like, and the corner balance would then tweak each corner separately (and you may see variances of up to 1/2" between corners).
Ok, a lot of information here so I will try and address everything.

First, let's determine where we are taking ride height measurements from. We measure from the rocker panel to the ground, not from the fender. So, at the very front of the rocker panel just where the front wheel well meets the rocker is where we take the front measurement. Then, we take the rear measurement where the rear wheel well and the rocker meet. This may add to the confusion, as we all may be picturing ride heights based on where we measure.

OP, your question seemed more like a 'performance' or 'technical' question as opposed to aesthetics. DSC_OFF is correct (thanks for the backing, btw) that we have done extensive testing on the street and on the track, and this is how we recommend you set your ride height if you want your car to perform. We set our cars up for function, not form. If you are looking for a 'stance' look, I have nothing more to offer, but if you want the car to function and perform well, then set the front ride height where you want, and then raise the rear 3/4" higher than the front. That is your base setting, and then you can corner balance from there.

You mentioned you don't want your car to 'nose dive' under braking......how hard are you braking on the street? That question just seemed more like a track related question

Just so you are aware, the car will actually understeer more as you lower the rear end, until you hit the bump stops. Once you hit the bump stops in the rear the car will oversteer again. So as you raise the rear end, the car will want to oversteer more and understeer less.

This set-up will be the same between an xi and non-xi, it does not change.

If you want your car to 'perform' on the street and track, this is the race/street proven set-up (assuming your are running the proper suspension and spring rates) based on the hours and hours of testing that we have done with our E90 both on the track and off.

The simple answer was 3/4" rake, but hopefully this explanation helps.

If you have any more questions, please let me know
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      02-04-2013, 12:17 PM   #14
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Originally Posted by TC Kline Racing View Post
Ok, a lot of information here so I will try and address everything.

First, let's determine where we are taking ride height measurements from. We measure from the rocker panel to the ground, not from the fender. So, at the very front of the rocker panel just where the front wheel well meets the rocker is where we take the front measurement. Then, we take the rear measurement where the rear wheel well and the rocker meet. This may add to the confusion, as we all may be picturing ride heights based on where we measure.

OP, your question seemed more like a 'performance' or 'technical' question as opposed to aesthetics. DSC_OFF is correct (thanks for the backing, btw) that we have done extensive testing on the street and on the track, and this is how we recommend you set your ride height if you want your car to perform. We set our cars up for function, not form. If you are looking for a 'stance' look, I have nothing more to offer, but if you want the car to function and perform well, then set the front ride height where you want, and then raise the rear 3/4" higher than the front. That is your base setting, and then you can corner balance from there.

You mentioned you don't want your car to 'nose dive' under braking......how hard are you braking on the street? That question just seemed more like a track related question

Just so you are aware, the car will actually understeer more as you lower the rear end, until you hit the bump stops. Once you hit the bump stops in the rear the car will oversteer again. So as you raise the rear end, the car will want to oversteer more and understeer less.

This set-up will be the same between an xi and non-xi, it does not change.

If you want your car to 'perform' on the street and track, this is the race/street proven set-up (assuming your are running the proper suspension and spring rates) based on the hours and hours of testing that we have done with our E90 both on the track and off.

The simple answer was 3/4" rake, but hopefully this explanation helps.

If you have any more questions, please let me know
Thanks for the clarification. Btw off-topic but I'm thinking about building a cage in my Z4 coupe, and I'm sure you guys have experience with this after. If so maybe I'll shoot you a pm.

Btw I love how the kid deleted his posts. What's even more funny is he sent me a PM with a big F U
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      02-04-2013, 12:18 PM   #15
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Quote:
Originally Posted by TC Kline Racing View Post
Ok, a lot of information here so I will try and address everything.

First, let's determine where we are taking ride height measurements from. We measure from the rocker panel to the ground, not from the fender. So, at the very front of the rocker panel just where the front wheel well meets the rocker is where we take the front measurement. Then, we take the rear measurement where the rear wheel well and the rocker meet. This may add to the confusion, as we all may be picturing ride heights based on where we measure.

OP, your question seemed more like a 'performance' or 'technical' question as opposed to aesthetics. DSC_OFF is correct (thanks for the backing, btw) that we have done extensive testing on the street and on the track, and this is how we recommend you set your ride height if you want your car to perform. We set our cars up for function, not form. If you are looking for a 'stance' look, I have nothing more to offer, but if you want the car to function and perform well, then set the front ride height where you want, and then raise the rear 3/4" higher than the front. That is your base setting, and then you can corner balance from there.

You mentioned you don't want your car to 'nose dive' under braking......how hard are you braking on the street? That question just seemed more like a track related question

Just so you are aware, the car will actually understeer more as you lower the rear end, until you hit the bump stops. Once you hit the bump stops in the rear the car will oversteer again. So as you raise the rear end, the car will want to oversteer more and understeer less.

This set-up will be the same between an xi and non-xi, it does not change.

If you want your car to 'perform' on the street and track, this is the race/street proven set-up (assuming your are running the proper suspension and spring rates) based on the hours and hours of testing that we have done with our E90 both on the track and off.

The simple answer was 3/4" rake, but hopefully this explanation helps.

If you have any more questions, please let me know
great post! I know this is the way for performance....could this possibly help with comfort to? I measured from the bottom of the rim to the top of the fender because I was aving a very hard time finding level ground lol!!
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      02-04-2013, 01:33 PM   #16
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Originally Posted by DSC_OFF View Post
Thanks for the clarification. Btw off-topic but I'm thinking about building a cage in my Z4 coupe, and I'm sure you guys have experience with this after. If so maybe I'll shoot you a pm.

Btw I love how the kid deleted his posts. What's even more funny is he sent me a PM with a big F U
Yes, we have experience with cage building. OP, I don't want you to get discouraged, and that was not the point of my post. Just want to make sure we are all 'on the same page' with our discussion and I am happy to help further if you wish. Feel free to shoot me a PM too.

Quote:
Originally Posted by robc1976 View Post
great post! I know this is the way for performance....could this possibly help with comfort to? I measured from the bottom of the rim to the top of the fender because I was aving a very hard time finding level ground lol!!
Usually its easiest to measure in your garage. This 'should' help with ride quality and make it so the car is not 'pitchy.'

What's nice is that some tape measures will list on the side how 'tall' they are so you can just set it up right and pull the tape out until it hits the rocker. Add the measurement of the tape to the 'height' of the tape measure tool and you are good to go
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      02-04-2013, 04:49 PM   #17
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Quote:
Originally Posted by TC Kline Racing View Post
Ok, a lot of information here so I will try and address everything.

First, let's determine where we are taking ride height measurements from. We measure from the rocker panel to the ground, not from the fender. So, at the very front of the rocker panel just where the front wheel well meets the rocker is where we take the front measurement. Then, we take the rear measurement where the rear wheel well and the rocker meet. This may add to the confusion, as we all may be picturing ride heights based on where we measure.

OP, your question seemed more like a 'performance' or 'technical' question as opposed to aesthetics. DSC_OFF is correct (thanks for the backing, btw) that we have done extensive testing on the street and on the track, and this is how we recommend you set your ride height if you want your car to perform. We set our cars up for function, not form. If you are looking for a 'stance' look, I have nothing more to offer, but if you want the car to function and perform well, then set the front ride height where you want, and then raise the rear 3/4" higher than the front. That is your base setting, and then you can corner balance from there.

You mentioned you don't want your car to 'nose dive' under braking......how hard are you braking on the street? That question just seemed more like a track related question

Just so you are aware, the car will actually understeer more as you lower the rear end, until you hit the bump stops. Once you hit the bump stops in the rear the car will oversteer again. So as you raise the rear end, the car will want to oversteer more and understeer less.

This set-up will be the same between an xi and non-xi, it does not change.

If you want your car to 'perform' on the street and track, this is the race/street proven set-up (assuming your are running the proper suspension and spring rates) based on the hours and hours of testing that we have done with our E90 both on the track and off.

The simple answer was 3/4" rake, but hopefully this explanation helps.

If you have any more questions, please let me know
Thanks for the detailed explanation. Try to learn more about the geometry of quality handling. Just baffled at the amount of conflicting information online.

Also, the weight differential is about 215lbs more upfront on the xi so about 53/47 weight distribution.
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