Advice on springs to pair with Bilstein dampers

[850tgul]

Awesome thx

[850tgul]

Thanks to all who contributed to this thread, especially ShocknAwe & Houtan for replying to my many PMs, it was all extremely helpful.

Over the past few days I was able install the Bilstein HD dampers, Swift springs, Dinan camber plates, Dinan rear shock mounts, and Meyle HD tension struts onto the car. PITA but well worth it.

Biggest shock is not how much sharper the car is, and it is, but how much more compliant and composed it is. It's 10x more driveable and, dare I say, more comfortable than before. Didn't expect that at all. I was fully expecting, and willing, to put up with an increase in nvh in order to get some sharpness but I was pleasantly surprised with the improvement in ride quality.

Turn in is much better now, the added neg camber from the Dinan plates no doubt playing a big part here. Handling is much more neutral now that the front end bites into the corners and allows the rear to step out a bit. Whereas before the front would just wash away never allowing the rear to rotate. Feels like a RWD sports car now.

Still need an alignment but giving it a week to settle.

As for the drop from the swift springs, I think it's still settling but after 2 days on the car, it's perhaps only a 1/4" lower than my stock sport suspension was. Hoping it settles maybe another .5" tops. So far no rubbing and I clear the strut up front.

With the front end and 4 corners all tightened up, the subframe wabble does stand out now, so that will be my next, and hopefully, final suspension mod. I already have the inserts but am not 100% satisfied with them. Will be going full replacement. Eyeing the Whiteline two piece design given the ease of the install.

[ShocknAwe]

Glad it worked out well for you man.

[850tgul]

Wanted to give a visual for anyone thinking about the Bilstein HD/Swift Spring combo. Great setup for those looking to tighten things up without slamming the car as it's a very mild drop vs stock sport suspension. I would guess it's a similar drop to the BMWP coils but a few bucks cheaper and with stiffer rates.

[lowbudgethero]

is it possible to get the swifts at a stock ride height, there are a number of places I frequent that the car simply won't clear if lowered even a 1/4 inch

[houtan]

Looking good. What size tires are you running up front?

Originally Posted by 850tgul

Wanted to give a visual for anyone thinking about the Bilstein HD/Swift Spring combo. Great setup for those looking to tighten things up without slamming the car as it's a very mild drop vs stock sport suspension. I would guess it's a similar drop to the BMWP coils but a few bucks cheaper and with stiffer rates.

[850tgul]

235/40/18 all around. No rubbing thus far. I do have dinan plates up front running -1.5 camber.

[850tgul]

Originally Posted by lowbudgethero

is it possible to get the swifts at a stock ride height, there are a number of places I frequent that the car simply won't clear if lowered even a 1/4 inch

Doubtful. I think the only reason I didn't see more of a drop was because I'm using the hd dampers, which may increase ride height a bit. The dinan plates also increase it a bit up front. I also have the dinan mount kit out back.

[houtan]

Originally Posted by 850tgul

235/40/18 all around. No rubbing thus far. I do have dinan plates up front running -1.5 camber.

Thanks. Reason why I asked is I have the same tire size up front but my front sits a little lower. Tire is basically even with the fender. I have dinan camber plates as well. Shocks are b8.

[850tgul]

Originally Posted by houtan

Thanks. Reason why I asked is I have the same tire size up front but my front sits a little lower. Tire is basically even with the fender. I have dinan camber plates as well. Shocks are b8.

Yeah, I used your car as a template for mine when I was putting my setup together. You have arc-8s as well too right?

I honestly think there may be something to the thought that the B6 HD dampers slightly raise the ride height. That's the only thing I can think of as others, like yourself, have run the B8 sports with the swift springs and gone a bit lower. I'm not complaining as the drop was exactly what I was looking for. I was fretting about rubbing before it went on but it has been rub free so far.

[houtan]

Yup. Arc8's.

[swagon]

Originally Posted by houtan

Thanks. Reason why I asked is I have the same tire size up front but my front sits a little lower. Tire is basically even with the fender. I have dinan camber plates as well. Shocks are b8.

The reason I think is that you have a 135 (heavier) and B8's (shorter).

[dojk]

How much of a height increase did the B6 give over stock?
Also what is the cause of the increase? Isn't the spring that determines ride height?

[850tgul]

Tough to say as the net effect with the swift springs was .25" lower than my oem sport suspension. If I had to guess I would say the HD dampers might only increase by .25" by themselves if you keep stock springs.
You are correct in that generally springs impact ride height but some believe the HD dampers, because they are designed to work with the longer oem style springs actually raise the height by a small amount. Not sure of the specifics but I did read about this possibility when I was researching. Also there is circumstantial evidence. Look at houtan. He has the same exact setup as me but with the bilstein sport shocks and he is a bit lower.

[ShocknAwe]

Originally Posted by 850tgul

Tough to say as the net effect with the swift springs was .25" lower than my oem sport suspension. If I had to guess I would say the HD dampers might only increase by .25" by themselves if you keep stock springs.
You are correct in that generally springs impact ride height but some believe the HD dampers, because they are designed to work with the longer oem style springs actually raise the height by a small amount. Not sure of the specifics but I did read about this possibility when I was researching. Also there is circumstantial evidence. Look at houtan. He has the same exact setup as me but with the bilstein sport shocks and he is a bit lower.

You'll end up a little lower than where you are now as the dampers break in. Still not as low as with the B8 though, which is odd as the valving is the same. I compared ride heights from ground to skirt and ground to fender with someone, maybe houtan, was a good 0.25" higher.

[850tgul]

Originally Posted by ShocknAwe

You'll end up a little lower than where you are now as the dampers break in. Still not as low as with the B8 though, which is odd as the valving is the same. I compared ride heights from ground to skirt and ground to fender with someone, maybe houtan, was a good 0.25" higher.

True, I am only about 30 days in with the setup.

[MightyMouseTech]

Might be a gas pressure issue. The higher the pressure, the more the shock will add some spring stiffness, and raise the car up. This is why the ride height will also change a bit with weather. My car, with stock dampers rides much lower in the winter.

[ShocknAwe]

Originally Posted by MightyMouseTech

Might be a gas pressure issue. The higher the pressure, the more the shock will add some spring stiffness, and raise the car up. This is why the ride height will also change a bit with weather. My car, with stock dampers rides much lower in the winter.

No change in ride height per seasons for me, then again no sub zero temps. Also, stock dampers are oil filled.

[MightyMouseTech]

Originally Posted by ShocknAwe

No change in ride height per seasons for me, then again no sub zero temps. Also, stock dampers are oil filled.

Yes, they are oil filled, but there is also a high pressure gas charge to prevent the oil from foaming. Because there is a gas charge in there, it is applying pressure on the valve on both sides, but because the shock rod takes away a small portion of the surface area the pressure acts on, there is more force acting on the bottom of the valve compared to the top. That force difference pushes the valve, and rod, upwards. This is why dampers also extend fully when they are not installed.

[houtan]

i think the difference in ride height in the front between the 128i and 135i is a result of the additional weight of the 135i. Reason I say that is I believe there are other 135i's running the b6/swift and still ended up with a mild amount of rake.

Shocknawe and I compared measurements a while ago. I think mine had slightly more rake (1/4"?). But we measured from the ground to the fender and we are running different size wheels (me 18s, shock 19s) which means we weren't comparing apples to apples. I believe the better way to measure would be from the center of the wheel to the fender, that way tire height does not impact the measurement.

[brocklanders]

I have b6 on stock wheels and have a slight rake on my 135.

[ShocknAwe]

Originally Posted by MightyMouseTech

Yes, they are oil filled, but there is also a high pressure gas charge to prevent the oil from foaming. Because there is a gas charge in there, it is applying pressure on the valve on both sides, but because the shock rod takes away a small portion of the surface area the pressure acts on, there is more force acting on the bottom of the valve compared to the top. That force difference pushes the valve, and rod, upwards. This is why dampers also extend fully when they are not installed.

Awesome! Thanks for the additional info as always.

Originally Posted by houtan

i think the difference in ride height in the front between the 128i and 135i is a result of the additional weight of the 135i. Reason I say that is I believe there are other 135i's running the b6/swift and still ended up with a mild amount of rake.

Shocknawe and I compared measurements a while ago. I think mine had slightly more rake (1/4"?). But we measured from the ground to the fender and we are running different size wheels (me 18s, shock 19s) which means we weren't comparing apples to apples. I believe the better way to measure would be from the center of the wheel to the fender, that way tire height does not impact the measurement.

We should re-do the comparison measuring to the bottom of the skirts. Should also be able to account for the overall diameter of the wheels fairly easily. I know mine aren't that much off stock. Tenth of an inch maybe.