E46Fanatics

E46Fanatics (http://forum.e46fanatics.com/index.php)
-   Suspension & Braking (http://forum.e46fanatics.com/forumdisplay.php?f=97)
-   -   Bilstein struts cause car to ride higher than spec (http://forum.e46fanatics.com/showthread.php?t=916794)

Nroussakov 04-19-2012 07:24 PM

Bilstein struts cause car to ride higher than spec
 
Hi all,
I have an '03 e46 325 iT. I just got my factory front struts replaced with Bilstein struts (non sport). The ride height of the car increased quite a bit from before. I went back to the mechanic, they measured the height and compared against BMW factory spec. The result was indeed higher.

The spec says from bottom of wheel rim to wheel well should be 589 mm with a +/- 10mm tolerance. However the measured height with the Bilsteins is 605mm. This is 15 mm off spec and 5 mm off from the top tolerance level.

We checked the part number with Bilstein to make sure they didn't send me the rough road package struts, and they confirmed they are the normal ones. The mechanics also verified the installation to make sure the strut is all the way in steering knuckle. All looks good with the install. Btw, it's been 3 months now since the install, so there was time for the struts to settle.

My question is whether this increased height is normal of non-factory struts? If I had the option to replace them with BMW factory struts, would there be a risk of ending up with the same issue?

Thanks,
Nick

Weste46 04-19-2012 07:29 PM

I have Koni STR.T shocks and one of them had been replaced right before I bought it, and that shock held it higher than the others. It has almost settled now to where the others are, and it's been around 10k. They might settle in after a while.

peytonracer4 04-19-2012 07:44 PM

That makes absolutely no sense. Shocks determine 0% of the ride height.
Is this happening in front or rear? More often than not the person doing the install will put the spring in a different location on the spring pad instead of the mark that's already worn in and it will make the car sit higher.
I can guarantee its not because of the shock though

6spd330i 04-19-2012 09:05 PM

Struts are not made to carry the weight of the car, they are designed to reduce the oscillation of the spring.

jasonbimmer 04-19-2012 09:16 PM

another problem could be you altered the alignment.
when my control arms were bad, the alignment was way off the front sit wayyy low compare to new control arms.
also make sure the springs are installed correctly cuz they can be not seated right. someone was asking same issue when he didnt install the springs correctly. 1 inch difference before and after.

Scooby24 04-19-2012 09:26 PM

Yup it did it on mine too. I have a feeling bilstein puts a little extra "oomph" in the shocks compared to factory. While the travel is the same, the shock itself has a bit more pressure loaded in which relieves a bit of compression on the spring and it causes the car to ride a touch higher.

If you were like me and were playing around with the bilsteins before installing, put some pressure on the shock to compress it and you find it has quite a bit of push back...put two down and push on each one and you can practically lift yourself up on them before they start to compress.

It's true struts are not meant to carry the weight of the car, but they have internal pressure which want to push the strut out and it takes pressure to compress it. Compare a worn out shock that has no pressure anymore and won't even push out unless you pull on the shaft to one that has enough force that you have to lift yourself off the ground to get it to compress, and you can see while that little bit of extra oomph is enough to make the car ride higher.

jasonbimmer 04-19-2012 09:36 PM

Quote:

Originally Posted by Scooby24 (Post 14311356)
Yup it did it on mine too. I have a feeling bilstein puts a little extra "oomph" in the shocks compared to factory. While the travel is the same, the shock itself has a bit more pressure loaded in which relieves a bit of compression on the spring and it causes the car to ride a touch higher.

If you were like me and were playing around with the bilsteins before installing, put some pressure on the shock to compress it and you find it has quite a bit of push back...put two down and push on each one and you can practically lift yourself up on them before they start to compress.

It's true struts are not meant to carry the weight of the car, but they have internal pressure which want to push the strut out and it takes pressure to compress it. Compare a worn out shock that has no pressure anymore and won't even push out unless you pull on the shaft to one that has enough force that you have to lift yourself off the ground to get it to compress, and you can see while that little bit of extra oomph is enough to make the car ride higher.

internal pressure is true however its not that strong. I installed my Bilstein rear shocks. they were kinda easy to compress. not like one finger but they were compressible.
but a normal person only weights 180 lbs and one shock can be pressed easily with 90lbs but your car weights 3600lbs, thats 900 lbs per wheel.
also idk what kind of springs you have on your touring. also the spec is for loaded, not empty car.
http://i1015.photobucket.com/albums/...ghtSpecs-1.jpg

Scooby24 04-19-2012 09:40 PM

Quote:

Originally Posted by jasonbimmer (Post 14311391)
internal pressure is true however its not that strong. I installed my Bilstein rear shocks. they were kinda easy to compress. not like one finger but they were compressible.
but a normal person only weights 180 lbs and one shock can be pressed easily with 100lbs but your car weights 3600lbs, thats 900 lbs per wheel.


Figure 100 lbs can compress one shock, multiply that by two and that's 200 lbs of pressure.

Go grab the underside of your rear fender and lift with your legs with the same amount of strength as you'd exert lifting a 200 lb person. You're going to lift the car a bit.

See what I mean?

Compare that 200 lb of pressure in new shocks to the old shocks which don't even have enough pressure to push the shaft all the way to the end of its travel.

The reality is this: The bilsteins have the ability to lift the rear of the car. That's fact. I'm just trying to explain why in laymen's terms. There is simply no other explanation other than the internal shock pressure. It's a tube, with a shaft, and some pressure. There's nothing more to it. Pressure is what does it.

always-there 11-22-2012 07:34 PM

Time to lower it.

///Miles 11-22-2012 09:03 PM

Yep, it's normal. Bilsteins HD and Sport dampers are high pressure monotube and will add very slightly to the spring rate. It makes almost no difference on aftermarket springs, but it will on long, soft, heavily pre-loaded springs like what BMW uses stock.

always-there 11-24-2012 07:24 PM

Bilstein sucks
 
So how do you guys suggest we cure this (1-2 inch lift) problem ??? last night i took the struts apart again to inspect the strut mounts and the seat where the coil sits and i noticed it was off- so i corrected the problem, re-tightened the mounts and the horrible lift still existed. I did notice one of the springs lower coil to be somewhat bent or not seating correctly without me spending alot of time to adjust it on the seat of the strut. I'm not so sure what's going on with the Bilstein struts having this horrific lift, but i want out. Really, i hate it. I don't even feel like it's a Bimmer anymore, at least, not with that crappy handling. It has since them affected the 'stable' feel it used to have. I have lowering springs arriving on the 29th so i hope they were just bad coils or it lowers it back to my liking. If anyone else on this forum has had experience on this dilemma, please chime in, thanks. :help::(

always-there 11-24-2012 08:07 PM

Okay so I looked more into this and now I understand why. You guys might've pointed it out already, so I apologize- it seems that the stock Sachs struts have less travel and do not allow the shaft to extend any further, like the Bilsteins, so that's what's causing the huge lift. It's actually the springs causing this "lift", and that's because the new Bilstein struts offer more travel, thus allowing the stock spring that was designed to work with the Sachs "shorter travel" strut expand more and raise the car. The only solution I see is installing shorter springs to make up for the huge gap. You might say it'll ruin the struts in the long run but, I really don't want that wheel gap. Interestingly, I'm positive you'll have better handling with the lower springs than the set up you would have with Bilsteins and stock springs. It's just such a horrible combination. Our cars weren't designed to work that way, with a huge ass lift, they're supposed to have a low center of gravity, not have a monster truck lift. It's what makes a Bimmer a Bimmer..low, with awesome handling. Once I get the springs here I'll let you guys know how it went, and I'll take pics.

tks 11-24-2012 08:14 PM

didn't read the essays of everyone else above, it's seated incorrectly.

always-there 11-24-2012 08:16 PM

Quote:

Originally Posted by ruskisky (Post 14924062)
didn't read the essays of everyone else above, it's seated incorrectly.

Have you purchased these struts before?

ac_2007 11-25-2012 11:49 AM

Quote:

Originally Posted by peytonracer4 (Post 14311083)
That makes absolutely no sense. Shocks determine 0% of the ride height.
Is this happening in front or rear? More often than not the person doing the install will put the spring in a different location on the spring pad instead of the mark that's already worn in and it will make the car sit higher.
I can guarantee its not because of the shock though

Struts can absolutely alter the car's height.
The bottom plate which holds the coil spring can be higher up compared to the OE strut.

If you took the same old coil spring mounted it in the new strut, it would sit more compressed since it has less room to travel. That equals increased ride height.

dkrab 01-10-2013 10:55 PM

I just posted a new thread about this, my search did not turn this thread up at first.

The Bilstein strut and the Sachs OE strut are dimensionally the same. The spring perch is the same. It is not the spring perch. It is not the dimensions of the strut itself.

I compared the OE strut to the Bilstein strut side by side at the BMW dealership. The only significant difference I can see is that the rod on the Bilstein extends out 1-1/2 inches farther than the OE strut. And it takes more force, quite a bit more, to compress it fully. This is on an "OE equivalent" Bilstein, not a performance upgrade unit.

The only explanation I can come up with is similar to what UDM said; the higher internal pressure and the naturally higher at rest position of the Bilstein strut lifts the front of the car. I see someone arguing that the additional upward force is not enough to make the car ride higher, but I disagree. You do not have to lift upward very hard to move the car up. Same goes for the strut.

UDM, let me know how shorter springs work out. I don't want to lower the car below the factory ride height, I just want it back down where it was. 3/8" or so lower would be right.

always-there 01-10-2013 11:44 PM

1 Attachment(s)
Attachment 485554

I ended up installing Megan coils and so far so good. If you want a stock suspension stick with the Sach's. If it's still high you can buy a set of perches to lower it a bit; or buy zhp coils, I hear they're just a tad bit lower than the regular 330i.

Grande D 01-11-2013 06:48 AM

Quote:

Originally Posted by peytonracer4 (Post 14311083)
That makes absolutely no sense. Shocks determine 0% of the ride height.
Is this happening in front or rear? More often than not the person doing the install will put the spring in a different location on the spring pad instead of the mark that's already worn in and it will make the car sit higher.
I can guarantee its not because of the shock though

Not 0. They can change it a bit- for example on a car with a totally collapsed shock, the ride height may end up a little bit lower.

dkrab 01-11-2013 05:47 PM

Quote:

Originally Posted by UDM-E46 Enthusiast (Post 15050672)
Attachment 485554

I ended up installing Megan coils and so far so good. If you want a stock suspension stick with the Sach's. If it's still high you can buy a set of perches to lower it a bit; or buy zhp coils, I hear they're just a tad bit lower than the regular 330i.

Too late to stick with the Sachs, the Bilsteins are already on the car (that's how I discovered that they raise the ride height a little). I would rather not have to replace otherwise serviceable struts. If I can put different springs on it to bring it down just a tad (technical term), that's what I would rather do. Okay, I am too cheap to just eat the cost of these struts.


All times are GMT -5. The time now is 11:16 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use