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      10-13-2017, 12:03 AM   #23
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Then try rear m135i bar it?s 15mm vs 12 or 13mm stock, should make a significant difference without compromising suspension independence too much
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      10-19-2017, 08:25 AM   #24
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Hello BMW Experts!

Why do the front BMW bars have two numbers, ie: 25/22.5MM?

One person says replacing the back bar is easy. So how hard is replacing the front bar? Do you have to jack the engine or drop the subframe; does removing the struts help?

TIA! Murf
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      10-27-2017, 11:24 AM   #25
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Quote:
Originally Posted by Littlebear View Post
Hello BMW Experts!

Why do the front BMW bars have two numbers, ie: 25/22.5MM?

One person says replacing the back bar is easy. So how hard is replacing the front bar? Do you have to jack the engine or drop the subframe; does removing the struts help?

TIA! Murf
Hi,

There is a tapering in the middle which makes it 22,5mm there.

Both front and rear need lowering subframes. Rear is a little easier.
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      10-27-2017, 11:25 AM   #26
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Quote:
Originally Posted by Lancelot View Post
Then try rear m135i bar it?s 15mm vs 12 or 13mm stock, should make a significant difference without compromising suspension independence too much
I confirm- the ride quality is excellent with both M135i front and rear bars.
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      10-27-2017, 11:27 AM   #27
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Quote:
Originally Posted by Niart906 View Post
I'll second this, just installed a set of Megan Racing sway bars on my 335. The Dinan instructions are excellent, but make no mistake the install is a huge pain in the ass. The rear is relatively easy, but maneuvering the front bar into place took some time.
Yes it is. Better to do the front with a partner, who can see the bar moving from another side of the subframe to command where to turn it.
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      10-30-2017, 03:48 AM   #28
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Quote:
Originally Posted by Dmitry83 View Post
I confirm- the ride quality is excellent with both M135i front and rear bars.
Same here, I got the M135i bars on now, and very happy with the result; good compromise between firm and compliant.

By the way my H&R bars are for sale
(shipping to the EU - ridiculous shipping costs elsewhere)
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      10-30-2017, 10:53 PM   #29
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Quote:
Originally Posted by dotjonnL View Post
Already have Dinan springs and shockware, body roll still there.
what u got an xdrive?
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      10-30-2017, 11:03 PM   #30
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Quote:
Originally Posted by Lancelot View Post
Same here, I got the M135i bars on now, and very happy with the result; good compromise between firm and compliant.
front and rear M135?

Part numbers?

Are you planning to update chart in post #1?

Last edited by kabrichx; 10-31-2017 at 12:54 AM..
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      10-31-2017, 02:06 AM   #31
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Quote:
Originally Posted by kabrichx View Post
front and rear M135?

Part numbers?

Are you planning to update chart in post #1?
The M135i has the same as the 440i M Sport in the table, you can find the part numbers there.
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      10-31-2017, 02:33 AM   #32
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I normally spec rollbars based on dampers and spring rates. No point having stiffer spring and increased dampening and soft bars and vice versa.
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      10-31-2017, 04:07 AM   #33
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Quote:
Originally Posted by YR430D View Post
I normally spec rollbars based on dampers and spring rates. No point having stiffer spring and increased dampening and soft bars and vice versa.
Very good point, but how do you do that in real life?

Because indeed rollbars + springs should be considered as a spring system to be matched with dampers, but I have yet to see a vendor providing dampers *and* bars as a kit?

KW for instance sell coilovers and anti-roll bars, but nothing says they're designed to match, as the coilovers are designed with stock bars in mind per their own comment when I contacted them a few months ago.
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      11-01-2017, 12:32 AM   #34
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Quote:
Originally Posted by Lancelot View Post
Very good point, but how do you do that in real life?
Simple actually, adjustable coil-overs.

But apart from that, the stiffer tune of the shockware and simply going with a more aggressive shock/coil-over usually means higher damping rates and less chassis movement. Will it "match exactly"? Hard to say, but if that's what you are after, you either hope for random chance or get adjustables.
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      11-01-2017, 02:57 AM   #35
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Quote:
Originally Posted by JamesNoBrakes View Post
Simple actually, adjustable coil-overs.

But apart from that, the stiffer tune of the shockware and simply going with a more aggressive shock/coil-over usually means higher damping rates and less chassis movement. Will it "match exactly"? Hard to say, but if that's what you are after, you either hope for random chance or get adjustables.
I take it that you mean adjustable preload, not just height? Ohlins do that IIRC, do you know of other brands?
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      11-01-2017, 09:16 AM   #36
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Quote:
Originally Posted by Lancelot View Post
I take it that you mean adjustable preload, not just height? Ohlins do that IIRC, do you know of other brands?
Um, no. If you increased the preload you are increasing the starting force, it's a poor substitute for the proper spring rate, but will allow small changes to adjust how high the chassis rides and starting force. Adjusting preload is not adjusting damping.

These are adjustable coil over shocks that can adjust the damping: https://www.tirerack.com/suspension/...171101140644:s

They have adjusters that can be turned to increase rebound/compression, etc. The more fancy the shocks, the more adjustments you can have. Typically, most adjusters adjust the low-speed effects, which means low shaft-speed. Low-speed shock performance deals with weight shift, chassis movement, chassis stability, etc. When you throw the car into a turn and it leans, it's a low-speed event for the shock shaft. When you hit a pothole at 30mph, it's a relatively fast shock shaft event, where the damping piston has to blow off and bypass a lot of oil very quickly. This can be important to be able to adjust for the proper roadholding for high end racing, but for most people, it's not necessary. This is either pre-set, can be re-valved, or can be adjusted, but it takes fairly complex damping circuits to allow true adjustment of high-speed damping via external adjusters. Low-speed is much more common and the perfect way to offset the effects of your stiffer swaybars. In general, a more aggressive coil-over will have higher damping rates because they assume stiffer springs and sway-bars, hence the terms "stage 1, stage 2 and stage 3 suspension". These usually assume stages of upgrading everything, including swaybars, bushings, links, springs, etc. This is one way to make sure you at least roughly match the shocks to the sways, but if you want to have a better chance of nailing it, get adjustable coil-overs.

A lot of this is suspension 101, not that everyone should be this in-tune with suspension, but if you go down this path, you should do some research on basic suspension theory. I do a lot of work with mountain bike shocks and forks, rebuilding, taking apart, servicing, in addition to custom-dampers. Some of these back in the 90s were just complete jokes, some of them though, from custom manufacturers or even the big manufacturers these days, are more high end than you'll find on 99.9% of performance road cars, with twin tube high and low damping circuits and adjustable high and low speed damping. The damping has to match the spring rates, to which the sways contribute.
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      11-01-2017, 10:11 AM   #37
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My mistake I thought you were talking about adjusting spring rate, not dampers, and got confused. Thanks for clarifying.
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      11-01-2017, 12:19 PM   #38
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Quote:
Originally Posted by Lancelot View Post
Same here, I got the M135i bars on now, and very happy with the result; good compromise between firm and compliant.
You did front and rear?
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      11-01-2017, 12:35 PM   #39
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Yes both front and rear, thought it best to keep a balanced combination
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      11-02-2017, 12:39 PM   #40
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Quote:
Originally Posted by Lancelot View Post
I take it that you mean adjustable preload, not just height? Ohlins do that IIRC, do you know of other brands?
Ohlins you can adjust ride height and preload independently and that is how it should be done. Most coil overs I would set about 2mm preload which works well for both street and track day use. Ride height I would set with some rake approx 10mm on a street car.

To match dampers to roll bars takes time and lot of track testing with suspension deflection and roll data logging. I loath slammed cars! It’s ridiculous and pointless.
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      11-17-2017, 07:19 PM   #41
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How involved is a rear sway bar upgrade on a 2014 328i ?
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      11-20-2017, 06:38 PM   #42
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...and if you have had a shop change your sway bars,
Que Quanto Coste??

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      11-25-2017, 04:13 AM   #43
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Four years on, and I can't shake my reality that a 2006 Subaru Legacy (albeit with Bilstein B6 and stiffer RSB) steers with much better agility than my 335i Touring. Can the OP cite the diameter of the RSB from the M235i, assuming they are interchangeable with an F31. If it's slightly stiffer than my OEM M-Sport RSB, then that could be worth trying out to sharpen the steering of my wagon.
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      11-25-2017, 05:21 AM   #44
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M235i is the same as 440i, 15mm rear bar so you can give it a try.
And yes, the e46 3 series of 20years ago was a reference, if you want the same sort of experience m140i or m240i is the way to go, 3 series of today is 5 series of yesterday and it’s not even spacious
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