[850CSi]

Hi everyone,

I'm getting ready to refresh the suspension on my non-sport 325i at 173k miles. The ride feels pretty rough and I suspect my dampers have been fried for a while now.

I live in the city, drive on shit Midwestern roads, and the car does family duty. So I think I'm going to keep the stock ride height and go for Bilstein B4s, which I gather are the best option for a comfortable ride (unless someone can convince me B6s are worth the premium and don't sacrifice a lot comfort-wise).

I've never done any suspension work before, so I have a couple of dumb questions:

1) what are the chances I need new springs? What should I look for? It's a very minor expense but I'm not in the habit of replacing parts if it's not necessary.

2) a couple of years back, I dropped the subframe to take care of a leaky oil pan. Being even more ignorant than I am now, I did this on ramps, with the front wheels bearing the car's weight. By the time I was done, the wheels had slid forward in the wells substantially. We somehow managed to get everything back together, and the car has driven fine since, but does anyone have any thoughts on what I should closely examine for damage? (I gather strut towers, control arms... anything else?) I guess in some ways that was the equivalent of hitting a bad pothole?

[TGTIW]

It's very unlikely you will need new springs, unless yours are damaged or severely rusted, which obviously you'll see once you start working on the suspension.
I have no doubts that your shocks and struts are completely gone, mine were at 90k. You'll no doubt want to replace the strut mounts, bump stops, and rear upper and lower shock mounts.

Regarding any damage you should look for with the subframe issue, based on what you did the only area that really could have sustained any would be the strut towers, but it's not a bad idea to check the control arms anyway since they may be worn with your mileage.

One thing to keep in mind, and this may not be as big of an issue for you since you have the standard suspension, the Bilstein B4 strut shafts sit at half their length. Unlike many struts, they do not extend fully when unloaded. On sport suspensions this can make compressing the spring enough to get the top mount back on a pain in the ass. Again, may not be as big an issue with standard suspension.

[edycol]

Go B6. No particular hit in comfort department but big handling gains.
I drive kids to daycare and school every day in mine that has B6, M3 wishbones in the back, polyurethane subframe bushings in the back etc.
in front don't go regular bushings in thrust rod arm. Go polyurethane. If you go regular be aware there is specific methodology in tightening it. You have to load new arms to wheel height then torque it then do 90 degrees with wrench one more time. With polyurethane you don't need to do it.
If you are worried about comfort you can go LONI red special active dampers.
In the back get Monroe shock mounts. They are super cheap and big upgrade over OE spongy ones.
Did you ever refresh coolant hoses including reservoir? If not, do it.

[TGTIW]

Oh, totally second the cooling system refresh. Only BMW would design the plastics used in the cooling system to deteriorate when exposed to heat and coolant. Definitely replace the plastic inlet fitting going to the head with an aluminum piece.

[BSM n54iS]

Shocks/struts and all new rubber everywhere basically. So spring pads upper/lower, new bump stops and rear shock mount.

[edycol]

Originally Posted by TGTIW

Oh, totally second the cooling system refresh. Only BMW would design the plastics used in the cooling system to deteriorate when exposed to heat and coolant. Definitely replace the plastic inlet fitting going to the head with an aluminum piece.

Yep! Mickey Mouse flange. Absolutely aluminum!

[edycol]

Originally Posted by BdSM n54iS

Shocks/struts and all new rubber everywhere basically. So spring pads upper/lower, new bump stops and rear shock mount.

If he goes B6, struts have integrated bump stops. Rear shocks come with it.

[850CSi]

Originally Posted by TGTIW

It's very unlikely you will need new springs, unless yours are damaged or severely rusted, which obviously you'll see once you start working on the suspension.
I have no doubts that your shocks and struts are completely gone, mine were at 90k. You'll no doubt want to replace the strut mounts, bump stops, and rear upper and lower shock mounts.

That's what I figured, thanks for that.

Regarding any damage you should look for with the subframe issue, based on what you did the only area that really could have sustained any would be the strut towers, but it's not a bad idea to check the control arms anyway since they may be worn with your mileage.

Yeah I'll try to see if anything looks amiss with the strut towers. The car's done a couple of thousand miles since then without any issues so hopefully I didn't damage anything. I don't have any symptoms (I'm aware of) of control arm/bushing wear but I'll definitely be checking them closely.

One thing to keep in mind, and this may not be as big of an issue for you since you have the standard suspension, the Bilstein B4 strut shafts sit at half their length. Unlike many struts, they do not extend fully when unloaded. On sport suspensions this can make compressing the spring enough to get the top mount back on a pain in the ass. Again, may not be as big an issue with standard suspension.

Ah, interesting. I'll keep that in mind. My plan is to find a shop that's willing to handle the spring compression part of the job.

[850CSi]

Originally Posted by edycol

Go B6. No particular hit in comfort department but big handling gains.
I drive kids to daycare and school every day in mine that has B6, M3 wishbones in the back, polyurethane subframe bushings in the back etc.
in front don't go regular bushings in thrust rod arm. Go polyurethane. If you go regular be aware there is specific methodology in tightening it. You have to load new arms to wheel height then torque it then do 90 degrees with wrench one more time. With polyurethane you don't need to do it.
If you are worried about comfort you can go LONI red special active dampers.
In the back get Monroe shock mounts. They are super cheap and big upgrade over OE spongy ones.
Did you ever refresh coolant hoses including reservoir? If not, do it.

Thanks for the suggestions. I'm actually not sure how original my cooling system is, because I had a water pump failure ~7 years ago. Thankfully no issues.

I had read something about the Koni reds being potentially more comfy than the B4s but I'm a little worried about the anecdotes re durability/quick wear. I want to do this job only once.

[edycol]

Originally Posted by 850CSi

Thanks for the suggestions. I'm actually not sure how original my cooling system is, because I had a water pump failure ~7 years ago. Thankfully no issues.

I had read something about the Koni reds being potentially more comfy than the B4s but I'm a little worried about the anecdotes re durability/quick wear. I want to do this job only once.

Bilstein is more durable. But B4 is twin tube unlike B6 which is monotube and that is what you want. KONI will be more comfortable.
I highly doubt whoever changed water pump changed hoses. You really want at this point to change every single hose. Cheap, and you will sleep much better!

[Jaronbwall]

I love and hate reading posts like this. The OP was talking about suspension refresh and people just doubled his labor time with cooling lines, bushings, and mostly unrelated items.
Anyone want to replace my rear main seal?

[850CSi]

So the good news is I found a solid BMW indy near me that is willing to compress my springs and swap the hardware.

Does anyone have any advice re Sachs v Bilstein? They cost about the same. Again, ride quality is my main concern. Is it possible that the slightly stiffer Bilsteins are a better fit for non-RFTs? I run 235/40/18 BFGoodrich Comp 2s all around in a square set of 219Ms, so I'm down about .5" of sidewall from, for example, the RFT 17s that came stock on a 330i.

One of the shops I spoke to locally said he hasn't had good experience with Bilstein quality of late. Conversely there are a lot of posts on this board shitting on Sachs but seemingly without any supporting evidence.

[edycol]

Originally Posted by 850CSi

So the good news is I found a solid BMW indy near me that is willing to compress my springs and swap the hardware.

Does anyone have any advice re Sachs v Bilstein? They cost about the same. Again, ride quality is my main concern. Is it possible that the slightly stiffer Bilsteins are a better fit for non-RFTs? I run 235/40/18 BFGoodrich Comp 2s all around in a square set of 219Ms, so I'm down about .5" of sidewall from, for example, the RFT 17s that came stock on a 330i.

One of the shops I spoke to locally said he hasn't had good experience with Bilstein quality of late. Conversely there are a lot of posts on this board shitting on Sachs but seemingly without any supporting evidence.

Bilstein!
If you are that concerned with comfort, go KONI active special red.

[850CSi]

So, this is a pretty simple job so far, have the strut assemblies out.

Does anyone have any advice for a noob like me on how to tell if any of my thrust/control arms (or the tie rod ends or sway bar end links) need replacing? I see some hairline cracks in the rubber but they seem fine otherwise.

[edycol]

Originally Posted by 850CSi

So, this is a pretty simple job so far, have the strut assemblies out.

Does anyone have any advice for a noob like me on how to tell if any of my thrust/control arms (or the tie rod ends or sway bar end links) need replacing? I see some hairline cracks in the rubber but they seem fine otherwise.

At 173k you do need replacement! There is no guessing and checking at that mileage.

[bmw_solid]

Originally Posted by 850CSi

So, this is a pretty simple job so far, have the strut assemblies out.

Does anyone have any advice for a noob like me on how to tell if any of my thrust/control arms (or the tie rod ends or sway bar end links) need replacing? I see some hairline cracks in the rubber but they seem fine otherwise.

As for tie rod ends and sway bar links - check that the ball/swivel joints are not free or loose, i.e they should be hard to move/rotate. - Also, if they come back to the middle position after moving that means they are shot. Also, if the rubber boot that surrounds the ball/swivel joint is cracked or missing then you should change them as dust gets in there and damages the ball joint.

For thrust and control arms - check for any fluid leaks coming out of the control arm bushing ( arm nearest to the front of the car - the wonky/bendy arm) if your car is a SE. If M-Sport then check for cracks/tears (M-Sport has no fluid in the bushing) and you could also check for play in the arms but you have your suspension overhauled so cannot do this! If there are cracks then surely worth changing them. Same rule applies for the ball joints on the arms as mentioned above.

As for comfort - I have had a few threads on here complaining about comfort in my E92 SE Pre-LCI. I have new OEM SE-Spec control and thrust arms, SACHS shocks at front and B4s at rear and Lemforder/Sachs mounts and bump stops. BUT... I realised the fruit of changing all these parts after discovering a CRITICAL fact of BMW tyre pressures!

Do one thing after you have fitted your suspension back - Check the tyre pressures on your door card and fill your tyres to the exact pressure WHEN COLD. I have a 12v Air pump at home as you don't want to drive your car to a gas station / superstore and then fill your tyre pressures because they are warmed up by that time!

You will realise, that when you fill the correct tyre pressures as stated by BMW, the car will handle great and comfort should improve a lot!

In BMWs even a 1 PSI drop in pressure can make the car drive bad and comfort drop to poor levels! If you don't believe me check this below thread as I don't think many people realise the importance of pressure in BMWs
https://www.bimmerfest.com/threads/r...tivity.393911/

This problem appears even in F-generations BMWs as well. There are even more threads on this same topic!

My car is on 19" rims 225/35 and 255/30 and we have some poor roads in UK but when the pressure is right, the car does handle the bumps well and handles great! I have budget tyres but I am confident if I put on some premium tyres, the ride will be even better!

Also, remember that whether or not you replace your arms, you must replace the bolts as they are TTY (stretch) bolts and should not be used again ideally. They only cost like $10 per bolt set. Only hand tighten the bolts first, then raise the wheel hub to ride height, torque at specified value (note 8.8 grade bolt or 10.9 grade bolt have different torque values) then do the 90 degrees turn then you can lower car.

Note, when raising the wheel hub to ride height, I disconnect the sway bar link as this allow the wheel hub to raise fully to normal ride height. Most people just raise the wheel hub until the car starts to lift but you will notice that the wheel hub is not at the normal ride height as the car starts to lift.

[KhaosKid]

I recently changed my springs and dampers on my car. If your car sits lower than the standard ride height that it should be at, then you need new springs. I find that over long period of time, the non-sport springs tend to sag which lowers your ride height and changes alignment angles. Mine were all sagging by about 20mm - 30mm in the front and 10mm - 20mm in the rear. I changed them mainly so that the car would hold alignment better and not wear out the inside of the wheel.

I replaced the springs with Bilstein B3 coil springs front and rear. They are an OE Style of spring. For the fronts for my car, they made a "reinforced version. Or heavy duty version. I emailed Bilstein directly and asked what exactly the reinforced version MEANS. They responded that the ride height is unchanged, and that they simply are "a bit firmer" so I guess the spring rate is a little bit higher. I went with these as I always found the front springs slightly too soft.

The rear springs I never really had an issue with (other than the sagging after many years of course), but they don't make the reinforced version for the rears anymore for my car anyway. Maybe its because they aren't necessary since I never had a problem with the spring rate in the rear personally.

I also upgraded to Bilstein B6 dampers all around so I don't know how much of the difference is from the shocks and how much from the springs, but I really enjoy how much tighter the front feels, especially over imperfections. I used to experience too much downward movement of the nose of the car when going over a speed bump with the front tires, sometimes causing my plastic transmission cover plate to scrape. The new setup has gotten rid of this. I can go over speed bumps at 20-30 kmph now if I wanted to and I wont scrape. I know this because I didn't see some speed bumps the other day and did this and I didn't scrape anything. Phew. Actually the car felt rock solid. Also over this dip on the highway I am always used to going over, the front end was way less upset by it. It felt like the front tires recovered from it with much stronger force, which was controlled very well by the dampers. No po-go action.

Overall I am/was very pleased. I should have gotten these dampers and coil springs years ago, but my mechanic talked me out of it saying it would be too harsh. The thing is, I personally like a little firmer suspensions on my sport sedans. I probably should have gotten a sport package car to begin with, but since I never drove one with sport package (as far as i can remember) i cant be sure. All I know is the dampers control the shocks very well, and moving up to the H.D. Springs turned out very good for me because the stronger dampers can still control the coil spring movement and damp out the oscillations a little better than stock.

If I had to put a number on it, i would say the bilstein b6 with my spring setup FEEL approximately 15-20% firmer than stock springs with b4 dampers (my old setup). By the way after ~60k miles/95k km my bilstein b4 dampers felt pretty weak on compression damping, not sure what this had to do with it, but im mentioning it. My mechanic who installed the b4's improperly installed the front strut mounts so im not sure if this affected the front dampers more, but the rears were also weak on compression so idk. Make sure you install the front strut mounts properly so they don't bind when turning. I installed the new stuff by my self (if you want something done right do it yourself), and I could instantly feel the smoother steering. Steering is still bmw-heavy but noticeably smoother snd easier to turn. I didn't know any better back then so I believed my mechanic that the binding SOUND upon turning the wheel sometimes was normal SMH.

BTW, I realized Bilstein mentions that they design their dampers to exhibit the ratio of about 25% compression damping, to 75% rebound damping. So its normal for the compression damping (decreasing length of the chrome-plated damper rod) to feel softer than the rebound damping (returning back to normal aka increasing length of the damper rod).

You can tell they are a bit firmer from the sounds they make when going over bumps and whatnot in the road surface. But they are way softer than most people explain them to be. MY back can't tell the difference. And im loving the improved ride characteristics. Im running non RFT btw (225/45/r17 continental extreme-contact dws06). My winters are (205/55/r16 continental winter-contact Si) and the ride quality is plenty comfortable because of the increased sidewalls on the tires acting as springs. I made sure to match the outer diameter of the wheels when downsizing my winter tire rim, to avoid any issues with speedometer or whatever. It also makes my winter tires cheaper which zi am fine with.

Also make sure you get the sport package strut guide mounts/bearings because they are made of a stronger steel, dimensions look the exact same. Part number ends in 5098 i believe. People still sell the older aluminum part but BMW superseded it with the stronger version for whatever reason.

Pics:

[850CSi]

Thanks everyone for chiming in! Buttoned everything back up last night and then re-tightened the thrust/control arms on ramps. Everything seems pretty solid so I’m going to go ahead and get it aligned.

The car looks hilarious now, like it’s on a lift kit! I hadn’t realized that blown dampers could affect ride height to that degree. Feels nice and smooth over previously jarring bumps.

[KhaosKid]

Originally Posted by 850CSi

Thanks everyone for chiming in! Buttoned everything back up last night and then re-tightened the thrust/control arms on ramps. Everything seems pretty solid so I'm going to go ahead and get it aligned.

The car looks hilarious now, like it's on a lift kit! I hadn't realized that blown dampers could affect ride height to that degree. Feels nice and smooth over previously jarring bumps.

Woops didn't realize I was a little late. I hope my comments could help someone in the future then. When I finished everything my front looked so high too like a monster truck
The rear looks okay to me though. Front has to steer which is why its higher. I do like the lowered look with barely any wheel gap. But I prefer this for the roads I have to deal with, as well as the winter. I don't want to avoid certain routes to avoid speed bumps or bad roads in general and what not. Or to be worried about damaging something from being too low.

Btw. My front is 2cm higher than the rear. The ride height did go up a little though for sure. By about 13mm/half an inch in the front. Which is in line with what i've read on these forums. I made sure to have springs fully seated in their perches and everything, so the lift is definitely from the shocks or the springs (I bet its the shocks like everyone else).

In the rear ride height barely changed, it definitely did increase by about 3-4mm thats it. This is definitely from the shocks as I changed the springs and left my old shocks for a week beforehand and measured ride height and then again after the bilstein b6 were installed.

I'm right around stock non-sport height though. 583mm in the rear. 601mm in the front. Measured from the bottom of the rim flange to the top of the wheel well where the fender line is. I wonder if the front will lower around up to 1cm, when the top hats rubber component compresses. Because the old top hats were clearly much more compressed than the old ones by about a cm.

[850CSi]

Ha, no worries. My front/rear rake looks fine, there’s just a lot more wheel gap in both than I expected. Sort of regretting not switching to a sport suspension tbh.

I dropped the car off for an alignment and my Indy says one of my track arms is seized, preventing toe adjustments out back. Under the circumstances probably just going to have to bite the bullet and pay them the $500 to take care of it.

[KhaosKid]

Originally Posted by 850CSi

Ha, no worries. My front/rear rake looks fine, there's just a lot more wheel gap in both than I expected. Sort of regretting not switching to a sport suspension tbh.

I dropped the car off for an alignment and my Indy says one of my track arms is seized, preventing toe adjustments out back. Under the circumstances probably just going to have to bite the bullet and pay them the $500 to take care of it.

This literally just happened to me. Had to replace my rear toe arms and the eccentric bolts/washer/nuts. Ended up replacing all 4 eccentric bolts in the rear, as well as the front tie rods so that my vehicle could be aligned easily. It was a b*ch getting one of the rusty bolts out because it fused to the inner metal sleeve of the toe arm bushing. I spent $121 CAD on the 4 rear alignment bolts/washers/nuts and the other 2 rear toe arm bolts while I was at it. They really sodomized me… in total I spent $330 just on parts. And had to buy a sawzall ( got a nice dewalt XR one for $200 on sale). So it was not cheap, and sucked because I just spent like 1250$ on the springs and dampers.

As for the ride height, I do kind of wish it was lower. Sometimes. But at the same time if it was any lower I would have issues in winter, which I was/am trying to avoid. Also, speed bumpe, curbs,etc would be more annoying to dodge. If I didn't drive my car in winter it would be an easier decision for sure. Also I don't worry about lending my car to my parents this way either, so for me personally I dont mind. But if it was any higher i'm not gonna lie I wouldn't like it.

Also for me, since my previous mechanic didn't instal the parts properly like the spring not being in the right position in the seat, my front ride height went down 1cm. My rear he didn't touch, and the ride height went up only 5mm after settling. So not too bad for me. I made sure to seat the springs all the way in the struts and rear spring pads. And to tighten rubber bushings at ride height, to remove any chance of bushing bind increasing the ride height.

[AtlanticE36]

I just had the same fun with a sawzall doing my rear arms. The eccentric bolts in the top arms were both seized beyond recognition, good ol Atlantic Canadian winter.