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      05-06-2017, 12:28 AM   #1
Todd
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i3 REX H&R spring ride quality

I just had H&R springs installed in my i3 Rex, and am very surprised by the bouncy ride on the front suspension. I have confirmed everything is correctly installed, and am wondering if there is supposed to be any trimming of the bump stops, or anything else that may affect ride quality. Any input is appreciated.
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      05-06-2017, 08:28 AM   #2
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H&R Bouncy ride

Hello Todd

I wonder about your tire inflation. Could you try more or less front tire inflation? Those who track their cars probably know about what tire pressures do exactly. I just know your can do some tuning that way. Perhaps the rears are too high?

Sounds like you need more damping in front. How many miles on the front shocks? Just a thought?

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      05-06-2017, 08:35 PM   #3
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H&R springs are tend to be bouncy if it paired with regular shock.
I have it on my i3 also, and yes it is bouncy. But the stock is not even that good either. Very stiff and it causes the car to hop and skip traction.
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      05-08-2017, 07:05 PM   #4
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I am thinking about the Bilstein shocks offered for the i3's. They are an OEM replacement shock, so dont know how much better they are than the OEM. In talking to Bilstein tech support, they said their shock is only marginally firmer than the BMW OE. I am also debating on using a shorter bump stop to re-gain some travel lost in lowering the car. The same bump stop used in the i3, is also used in many of the newer F chassis cars, and spring kits for those cars come with new shorter bump stops.



Quote:
Originally Posted by r33_RGSport View Post
H&R springs are tend to be bouncy if it paired with regular shock.
I have it on my i3 also, and yes it is bouncy. But the stock is not even that good either. Very stiff and it causes the car to hop and skip traction.

Last edited by Todd; 05-08-2017 at 07:11 PM..
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      05-09-2017, 08:30 AM   #5
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Quote:
Originally Posted by Todd View Post
I just had H&R springs installed in my i3 Rex, and am very surprised by the bouncy ride on the front suspension. I have confirmed everything is correctly installed, and am wondering if there is supposed to be any trimming of the bump stops, or anything else that may affect ride quality. Any input is appreciated.
Springs and shocks need to be matched together very carefully, otherwise, you get unpredictable, and frequently undesirable results.

Most aftermarket springs are not linear (with few coil-over exceptions that don't apply here). The compression/rebound rate of all shocks is not linear either.
What that means is that shock's rebound/compression rates usually start lower around stock ride height, and get stronger as you go further beyond the stock ride height equilibrium to more aggressively dampen the isolation.

The more you lower the car, the more you move ride height equilibrium further away from shocks initial engagement zone. The worst part is that now they will compress with much higher force than rebound. Thus you get bouncy castle ride where shocks no longer evenly dampen spring isolation back to equilibrium. Now overlay stiffer springs, and the OEM shocks struggle even more.

Most competent aftermarket tuners sell lower (and stiffer) springs packaged together with shorter (and stiffer, or adjustable) shocks.

If you buy just the springs, you frequently get what you got...



Quote:
Originally Posted by bailyhill View Post
I wonder about your tire inflation. Could you try more or less front tire inflation? Those who track their cars probably know about what tire pressures do exactly. I just know your can do some tuning that way. Perhaps the rears are too high?
i3 is very sensitive to tire inflation, and given funky tire sizes and varying sidewalls, you need to stay close to the BMW recommended 35 front and 41 rear:
https://cache.bmwusa.com/PDF_9752ed5...2-6cd02d8b5b74


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      08-07-2017, 03:50 PM   #6
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just recently installed the H&R on my '17Rex. ride has definitely changed, but as other have mentioned, that's the nature of the beast.

on the flip side, my Rex is much more fun thru the canyons and twisty-bits as this is what the lowering effort is really meant for. hugging the ground better and reduced body roll in the turns. it also looks a hell of a lot better.
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      12-18-2017, 06:06 PM   #7
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I'm ok with mine but def bouncier than stock. My wife hates it but I didn't tell her I lowered it. She thinks it's stock that way LOL.

There's that certain look I had vision on this car so I had to lower it & put new wheels on. Now it's time for me to get into an new i3 (lease swap) I'm not sure I'm going to lower it again. We'll see.
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