05-19-2019, 03:25 AM | #2333 | |
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Some cars used in production car racing with live axles and watts links attached to the diff, raising the rear ride height lowers the roll centre and doesn't have the same effect as a watts link mounted on the chassis or independent rear suspension cars when altering ride heights to improve handling balance. A 1/4" change in watts link height (roll centre) is all it takes sometimes to alter the handling balance between oversteer and understeer. In racing categories where controlled springs/shocks and ride heights are implemented, massaging suspension pick up points to alter roll centres and achieve a particular handling balance a driver prefers is a common cheater the tech guys often look out for and roll centre changes can have a surprising effect. I'd be sure that roll centre is taken into account with BMW recommending a specific ride height when the car can be physically lowered a lot more. Last edited by RevNev; 05-19-2019 at 03:32 AM.. |
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05-31-2019, 07:23 PM | #2334 |
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Think I've decided to go for the MP-HAS option vs aftermarket coilover options
Question: Of those who have installed the MP-HAS suspension option, is anyone in northern NJ / NYC, where I might be able to see your car in person?......I'll also post in the NJ regional forum too FYI: Go to post #296 and you'll see my mineral white M4 at a recent NJ meet https://f80.bimmerpost.com/forums/sh...501627&page=14 Feel free to PM me...many thanks.... |
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06-01-2019, 07:00 AM | #2335 | |
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I don't disagree about the effects of adjusting roll centers to tune the handling characteristics of a car. But this is not really relevent in this discussion since the suspension attachement points are not altered with lowering springs.
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06-03-2019, 09:05 AM | #2336 | |
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Having never plotted the M4 suspension geometry to determine if this applies, however depending on the suspension geometry, lowing the ride height often lowers the roll centre more than it lowers the centre of gravity and the roll axis is the roll centre in relation to the centre of gravity. The closer the centre of gravity is to the roll centre, the less the car will roll at the same cornering force. As an aside, I'm fitting a carbon roof to my M4 and removing the sunroof in a couple of weeks which effectively lowers the centre of gravity closer to the roll centre from removing weight from the highest point of the car. I'm interested to see if I can determine a difference in the way the car handles particularly when they fitted CS rear springs to the sunroof ZCP cars. |
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07-03-2019, 07:27 PM | #2337 |
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I installed my suspension today but did not install the dust boot in the front. Thoughts of going without it? Or should I suck it up and put them in? The instructions did not say to put them in. But then I looked up photos - most people have it. Thoughts? |
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07-03-2019, 08:18 PM | #2338 | |
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Some tips: - Be sure to put some protection on the fender so your shock shaft doesn't nick it. - Undo the brake lines so they don't get stretched when you push down on the strut assembly. - Lower the spring perch all the way down before undoing the top hat nut just in case there is tension on the spring. Good luck! Like this picture, but leave the top hat on the car. |
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07-03-2019, 08:20 PM | #2339 | |
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Thank you. That’s what I thought. Gonna tackle it tonight. Silly mistake on my part. I did the install myself today. Was fairly easy. And yes I’ll be able to lower the strut and angle it away. Thanks again! |
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07-03-2019, 10:16 PM | #2340 |
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Just did it. 45 for both sides. Not bad!
Also lowered the front a bit. Took it for a drive - I like it!! |
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07-03-2019, 11:19 PM | #2342 | |
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If you did make a DIY video of the install, let me know. I'll edit it in on the first post of this thread and the Suspension Master List thread. |
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07-04-2019, 05:20 AM | #2343 | ||
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08-12-2019, 12:08 PM | #2346 |
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I'm sure this has been asked before but it's a 108 page thread. Anyway, what is BMWs recommended lowering height and how long did you guys wait till you got balancing and alignment done after installation?
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08-12-2019, 12:40 PM | #2347 | |
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It's a 25mm drop from stock I believe. Instructions are on getbmwparts |
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08-12-2019, 01:53 PM | #2349 | ||
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How long did you wait till balancing and alignment? |
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08-12-2019, 01:57 PM | #2350 | |
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08-12-2019, 02:49 PM | #2351 | |
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Mine arrives this week. Gonna have it aligned on install, then do a more aggressive track alignment a week later. |
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08-13-2019, 05:28 PM | #2352 |
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Well I had a chance to install the kit today....wow boys and girls, this is the kit to have! Well worth every penny. I told myself when I bought my car that I wasn't going to touch the suspension (knew that wouldn't last), but wanted to lower the kit with something engineered for the car. At least so far, boy did it deliver.
The install kicked my ass - not because it was hard, but just because I dragged it out due to my extreme caution. I've been wrenching on cars for 20 years and I've never been so careful with suspension work. Even knowing what to look out for, I accidentally banged the sensors a few times, but no codes. About the ride and handling - wow these things ride great. If the stock setup is a 5/10 in firmness, I would put these at a 6/10, but it is very controlled and compliant. I was really worried about the "lowered ride" of some spring setups, but this ain't it. Thrilled with the ride. Handling is obviously improved greatly, body roll diminished even in comfort mode. As a result, some of the numbness if the steering is gone too. As a bonus - my occasional strut clunk in the front end seems to be gone (I have this one stretch of road where I can make it clunk every time). I set the ride height arbitrarily based on Tommy's video. Might have gone too low - measures about 26" from ground to fender on all corners - did I slam it a little too much? Might raise it up a little. The only weird part is the left front had to be adjusted down further than the right front to achieve the same height. I'm going to drive it a few days to get the ride height dialed in, then send it in for alignment. |
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08-13-2019, 05:40 PM | #2353 | |
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08-15-2019, 06:35 AM | #2354 |
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The right way of doing this is, after setting the desired ride height, to put the car on scales and fine tune the height until both diagonal weight sums are the same. This is called corner balancing and ensures balanced cornering in both directions.
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