[bmw_solid]

Hi All

As above, I got new Febi Bilstein front upper and lower control arms installed alongside my new SACHS shocks back in August by my local mechanic and I am doing some work down there so might as well take the opportunity to Torque both arms up on both sides (with the wheel hub loaded to normal ride height). The reason being because it is a local mechanic and not a BMW specialist and therefore I don't think they would have torqued them up because I even asked them about this and they didn't really know what I was on about!

My question is, would the control arm bushings be pre-maturely damaged/worn due to them not being torqued up and being used un-torqued for the last 4 months, mainly city driving?

I'm hoping the answer is No because I have got the tools to correctly torque them up in order to preserve them for long-term and avoid any more wear on them.

Thanks.

Edit:

Forgot to mention, car is a Pre-LCI E92 330d SE and the new Febi arms that I got installed were the standard chassis (SE OEM spec) parts, not the M3 ones.

[Vivek.]

Did you get M3 or standard ones? One pair on the M3 arms has a bearing, so (from what I understand) torquing under load doesn't matter. The other one is a pretty stout solid rubber bushing, so it's more likely to be okay than the standard set.

On the standard ones, they're fluid-filled, so you'll be able to see the leak if its damaged. 4 months is plenty of time to ruin them if they were indeed improperly installed. Shop may have some warranty for this.

[MrFrizzzz]

I changed my front arms with standard ones about four months ago and did them up to the same torque I do everything up to, nipped and a bit. I’ve had no issues and no damage to the bushings.

[bmw_solid]

Originally Posted by Vivek.

Did you get M3 or standard ones? One pair on the M3 arms has a bearing, so (from what I understand) torquing under load doesn't matter. The other one is a pretty stout solid rubber bushing, so it's more likely to be okay than the standard set.

On the standard ones, they're fluid-filled, so you'll be able to see the leak if its damaged. 4 months is plenty of time to ruin them if they were indeed improperly installed. Shop may have some warranty for this.

Its the standard chassis (SE suspension) ones, so meaning its the fluid-filled ones.

Yes, I will check for any visible leaks...if there are no leaks, I will assume they are ok but still won't be at full peace of mind as I don't know if any pre-mature wear has been put on the rubber which may result in leaks in the near future. I wish I had cleared this out with the mechanic much before rather than asking the second after giving the keys to the mechanic!

How important is it to torque up the bolts/nuts? Assuming they are still tight enough, when under load what sort of play will be present in the bushing if not torqued? The lower control arm (the wonky one) fits very tight into the chassis opening so how would the bolt not being torqued up on load make the bushing not work properly or sit loose in the opening? I'm just wondering whether I should consider replacing them as I still have the 1 year warranty...

[bmw_solid]

Originally Posted by MrFrizzzz

I changed my front arms with standard ones about four months ago and did them up to the same torque I do everything up to, nipped and a bit. I’ve had no issues and no damage to the bushings.

Please clarify what you mean by same torque I do everything up to?

[mweisdorfer]

Originally Posted by bmw_solid

Its the standard chassis (SE suspension) ones, so meaning its the fluid-filled ones.

Yes, I will check for any visible leaks...if there are no leaks, I will assume they are ok but still won't be at full peace of mind as I don't know if any pre-mature wear has been put on the rubber which may result in leaks in the near future. I wish I had cleared this out with the mechanic much before rather than asking the second after giving the keys to the mechanic!

How important is it to torque up the bolts/nuts? Assuming they are still tight enough, when under load what sort of play will be present in the bushing if not torqued? The lower control arm (the wonky one) fits very tight into the chassis opening so how would the bolt not being torqued up on load make the bushing not work properly or sit loose in the opening? I'm just wondering whether I should consider replacing them as I still have the 1 year warranty...

Typically, they are torqued at 75-80# at the subframe & 120# at the hub.

It's always a good idea to torque under load at ride height.

It's always a good idea to go back in there, after 30 days, and re-torque

[Tambohamilton]

So, you've been driving with loose control arms for 4 months?

Or you think they've just been torqued at full droop instead of ride height? If that, just loosen and torque at ride height. Any damage is done already. Youcan prove whether it was done properly by loosening the bushing for the first time with the suspension at ride height; if the bushing rotates to a relaxed position as clamping force is released, you know they were torqued with the suspension in the wrong position.

[bmw_solid]

Originally Posted by mweisdorfer

Typically, they are torqued at 75-80# at the subframe & 120# at the hub.

It's always a good idea to torque under load at ride height.

It's always a good idea to go back in there, after 30 days, and re-torque

Point noted. I didn't know they require a second re-torque process. Will keep this in mind.

[bmw_solid]

Originally Posted by Tambohamilton

So, you've been driving with loose control arms for 4 months?

Or you think they've just been torqued at full droop instead of ride height? If that, just loosen and torque at ride height. Any damage is done already. Youcan prove whether it was done properly by loosening the bushing for the first time with the suspension at ride height; if the bushing rotates to a relaxed position as clamping force is released, you know they were torqued with the suspension in the wrong position.

I wouldn't say loose, but more rather I've been driving around with un-torqued front arms for 4 months. I actually just realised this just a couple of days back when I was discussing about the E9x suspension with my brother.

Spot on - I think they have been torqued/tightened at full drop because their car ramp leaves the wheels completely relaxed as opposed to loaded.

Point noted. I will keep an eye for the bushing rotating when loosening the nut (wheel hub loaded to ride height) and if it does rotate, I will then know that they weren't torqued at ride height. Thanks for sharing this phenomenon!

If there are any visible leaks, I could be able to replace them within my 1 year warranty. If there are no leaks around the bushing that would be good, provide the bushing does not rotate when the nut is loosened. If it does rotate, then that would leave me in the middle knowing that those 4 months could have caused pre-mature wear on the bushings, which will be very annoying.

[Emilime75]

I wouldn't say it is "required", but good practice to do so.

Originally Posted by bmw_solid

Point noted. I didn't know they require a second re-torque process. Will keep this in mind.

[bmw_solid]

Originally Posted by Emilime75

I wouldn't say it is "required", but good practice to do so.

Point noted.

[matteblue3er]

I think you are confusing two different things here; torque and pre-load.

Personally for most a suspension components, I don't care about torque specs. Just make them tight...

Pre-load however is necessary for factory bushings. Pre-load is when you tighten the bushing mounts when the bushings are in their natural resting position....which as you stated is when the wheel hub raised. Otherwise, they WILL fail pre-maturely as when you lower the car, the bushing is pinched in the mount and does not allow it to rotate freely. So when you lower the car, the bushing will twist in a way that causes it to fail much sooner than intended.

If you can drive up on some ramps, you can get under the car, loosen the mounts to allow the bushing to twist back into its resting position, then re-tighten. However if you've already driven some distance, the damage is likely already done. Factory tension strut inner bushings are hydro filled so if you see oil leaking, they are damaged/done.

[mweisdorfer]

You just need to figure out ride height.

Measure from the center of the hub to the bottom of the fender, while the tires are still on. Remember the measure 2x before cutting once principal even though your not cutting anything.

Once you get the car on 4 jack stands, use a jack & place it under the rotor. Jack up the rotor & measure from the center of the hub to the bottom of the fender, until you reach your original measurement.

Then & only then do you torque the various bolts etc down to spec.

It's always a good idea to use new bolts; especially if you are over 100k or you are upgrading to M3 parts etc.

[bmw_solid]

Originally Posted by matteblue3er

I think you are confusing two different things here; torque and pre-load.

Personally for most a suspension components, I don't care about torque specs. Just make them tight...

Pre-load however is necessary for factory bushings. Pre-load is when you tighten the bushing mounts when the bushings are in their natural resting position....which as you stated is when the wheel hub raised. Otherwise, they WILL fail pre-maturely as when you lower the car, the bushing is pinched in the mount and does not allow it to rotate freely. So when you lower the car, the bushing will twist in a way that causes it to fail much sooner than intended.

If you can drive up on some ramps, you can get under the car, loosen the mounts to allow the bushing to twist back into its resting position, then re-tighten. However if you've already driven some distance, the damage is likely already done. Factory tension strut inner bushings are hydro filled so if you see oil leaking, they are damaged/done.

That's my plan, to raise the front on axle stands, then raise the wheel hub to ride height and loosen the bushing whilst observing and stored twisted energy and then re-tighten and torque. I will look for any oil/fluid visible.

[bmw_solid]

Originally Posted by mweisdorfer

You just need to figure out ride height.

Measure from the center of the hub to the bottom of the fender, while the tires are still on. Remember the measure 2x before cutting once principal even though your not cutting anything.

Once you get the car on 4 jack stands, use a jack & place it under the rotor. Jack up the rotor & measure from the center of the hub to the bottom of the fender, until you reach your original measurement.

Then & only then do you torque the various bolts etc down to spec.

It's always a good idea to use new bolts; especially if you are over 100k or you are upgrading to M3 parts etc.

Thanks for the advice. I followed a similar method when I replaced the rear shocks when torquing the main nut. The bolts are new as Febi supplied new bolts with the arms - whether or not the garage used them, outer space knows...

[bmw_solid]

I take it the other arm (arm 1 in the screenshot) is not a hydro-bushing, just a normal rubber bushing?

If so, am I correct to say that if arm 1 was not torqued/tightened at pre-load (normal ride height) it wouldn't be anything to worry about, because its just rubber in that bushing? I hope I am wright here as the last thing I want to do is worry over these as well as the other arm....

[Tambohamilton]

Originally Posted by bmw_solid

I take it the other arm (arm 1 in the screenshot) is not a hydro-bushing, just a normal rubber bushing?

If so, am I correct to say that if arm 1 was not torqued/tightened at pre-load (normal ride height) it wouldn't be anything to worry about, because its just rubber in that bushing? I hope I am wright here as the last thing I want to do is worry over these as well as the other arm....

It is not good for either one to be torqued at full droop, because both will be (probably gradually) damaged by the excessive bushing wind-up that this causes. The front one (item 2) being fluid filled just makes it a notch easier to spot when it's damaged, because you can often see fluid leaking. That said, I have had one of those fail an MOT with no sign of leakage.

[bmw_solid]

Originally Posted by Tambohamilton

It is not good for either one to be torqued at full droop, because both will be (probably gradually) damaged by the excessive bushing wind-up that this causes. The front one (item 2) being fluid filled just makes it a notch easier to spot when it's damaged, because you can often see fluid leaking. That said, I have had one of those fail an MOT with no sign of leakage.

Understood.

Any idea what made the MOT tester think that it had failed, despite no leaks?

Also, what would be the best method to check for any play in these 2 arms at the subframe side? Moving the wheel side to side, or pushing the wheel in and out at N,S,E and W points? I've seen some putting a crowbar near the bushing and using a prying motion to check for play. Never really understood which check to do for which arm though....

[Tambohamilton]

It honestly didn't look bad, but I think it was just a bit perished.

Visual inspection will tell you more than checking for play. The front one can be flexed by hand, for example, even when new. Check for cracking in the rubber, deformation, fluid leakage (front only); those sort of things. Of course, if there is free play in either it's a sure sign that it's dead...but damage will be visible long before free play develops.

[bmw_solid]

Originally Posted by Tambohamilton

It honestly didn't look bad, but I think it was just a bit perished.

Visual inspection will tell you more than checking for play. The front one can be flexed by hand, for example, even when new. Check for cracking in the rubber, deformation, fluid leakage (front only); those sort of things. Of course, if there is free play in either it's a sure sign that it's dead...but damage will be visible long before free play develops.

OK, so basically there should be no movement in any direction when moving it by hand or with the aid of a flat screw driver/small crowbar? If there is movement, I take it those 4 months have caused undue wear on the bushings due to not being installed correctly...

I will keep an eye for the visual pointers you have mentioned.

[Tambohamilton]

No; the front one can be flexed by hand even when new. The rear one is much stiffer, but still it's just rubber and inherently will flex. There should be no free play (slack) in either one, though.

[bmw_solid]

Originally Posted by Tambohamilton

No; the front one can be flexed by hand even when new. The rear one is much stiffer, but still it's just rubber and inherently will flex. There should be no free play (slack) in either one, though.

Ok, I see what you mean. The arm will move due to the rubber flexing when pushed by hand but there should be no slack between the rubber and metal inside the arm..

Will be checking the arms this or next weekend hopefully and I will be keeping this thread updated with some videos or pictures if required.

Thanks.