PSA: Beware of TRW tension struts and other suspension arms

[gkgsvensson]

Earlier this year I did a complete front suspension restoration: Tie rods, wishbones, wheel bearings, struts, etc. All of done by the book with new hardware and torqued at ride height. However, I had been chasing a maddening knock that would occur only at slow speeds (10-20mph) over small bumps from what seemed to be the passenger side.

This knock drove me crazy and had me doubting my ability to perform any mechanical service to my car. I looked at everything to try and determine the knock and came up short until I eventually removed the passenger tension strut.

In less than 2000 miles, the outer balljoint stud had gone completely floppy and was registering a loud signal on the chassis ears. Sure enough, I discovered that TRW has changed their manufacturing from Germany to Malaysia, and others have reported QC issues.

I wanted to shed light on this because it was such a subtle fault that wasnt easy to determine but drove me absolutely crazy. So dont make the same mistake as me and stick to Genuine BMW (which are still the nice German made ones)

[drwankel]

0% surprised. I was one of the first to report the manufacturing change.

This seemed like a cost cutting measure through and through. If they had just changed the manufacturing location that would be one thing. But to change the location to a cheaper country, and completely change the design? Had zero faith that was going to work out long term.

Fought like hell to get some of the few remaining German arms and was successful. Glad I did.

[For3]

Exact same thing happened to me. I refreshed my control arms in Winter of 2022 with TRW (non German) arms and by Spring of 2023 I had diagnosed a low speed knock. Unfortunately I thought it couldn't possibly be the 6 month old arms so I replaced suspension struts and shocks, steering rack, and teering shaft in that order all in effort to figure out what it was. On a whim I put my old thrust arms back in and problem solved. So frustrating. Luckily I diy'd everything but it was still expensive and time consuming.

The silver lining was I upgraded to Ohlins R/T when I thought the front strut might be the issue and love them.

Stick with the OEM arms in this case.

[S65Hunter]

Did yall torque the bolts to spec? I had a similar issue on my e93 328i with TRW. I won't if their torque specs are different than oem? I can't remember what they were off the topnof my head, but maybe the oem torque spec is too high for the TRW?

[drwankel]

Originally Posted by S65Hunter

Did yall torque the bolts to spec? I had a similar issue on my e93 328i with TRW. I won't if their torque specs are different than oem? I can't remember what they were off the topnof my head, but maybe the oem torque spec is too high for the TRW?

TRW IS the OEM supplier on the e9x m3. Lemforder is the OEM supplier for the regular e9x.

The best option at this point would be to get the lemforder arms and have monoballs installed in them. There is no difference in length between the non M arms and the M arms. Really the difference is in the bushing, which is a moot point if you upgrade to monoballs at the same time. GAS claims that the ball joint in the lemforder arms is superior to the TRW arms.

[amrazM]

balljoint failing that quickly is alarming. I recently redid my rear arms and ended up with all oem in the back because I was concerned about the "new" trw quality.

[Dr Ed]

I really wish you can just change the ball joints out on these arms. For example, on the E36 M3s, you can press out the ball joints and use E30 ball joints.

[kolopn]

Actually on e90post I have created solution to this problem https://www.e90post.com/forums/showt...php?p=30479366

[Ali-E90]

Originally Posted by drwankel

TRW IS the OEM supplier on the e9x m3. Lemforder is the OEM supplier for the regular e9x.

The best option at this point would be to get the lemforder arms and have monoballs installed in them. There is no difference in length between the non M arms and the M arms. Really the difference is in the bushing, which is a moot point if you upgrade to monoballs at the same time. GAS claims that the ball joint in the lemforder arms is superior to the TRW arms.

so just to confirm... if someone is looking to replace their control arms, with no intention of doing the monoball upgrade (not a track/performance setup), then Lemf is still ok to use, even with the softer bushings?

based on thsi comment "GAS claims that the ball joint in the lemforder arms is superior to the TRW arms"

Any other recomendations for street car with comfort kept as a priority? I have Ohlin RT waiting to be installed in the Spring too.

Thanks!!

[kolosy]

Originally Posted by Ali-E90

so just to confirm... if someone is looking to replace their control arms, with no intention of doing the monoball upgrade (not a track/performance setup), then Lemf is still ok to use, even with the softer bushings?

based on thsi comment "GAS claims that the ball joint in the lemforder arms is superior to the TRW arms"

Any other recomendations for street car with comfort kept as a priority? I have Ohlin RT waiting to be installed in the Spring too.

Thanks!!

softer bushings will make the steering more vague. there is no downside to a front monoball upgrade. no incremental NVH, just better steering feel.

[Trinh_7]

I got the GAS pre-installed monoball Lemforder arms + TRW lower wishbones installed last summer, and they made a big improvement, even though my oem arms only had 70k miles on them. New arms got rid of some small issues like understeer, mild vibration over 80mph, clicking during low speed parking. They do add some stiffness in the front though.

[aggieshan]

I don’t think Lemforder (non m) is the same length as TRW (m) for thrust arms. I had e90 328i and upgraded the arms to TRM. Due to the length, it creates a bit more camber and toe out. Alignment needs to be redo. But that was positive for non M. It gives more neg camber for track driving.

For M3 to use lemforder, it would reduce camber which is not desirable. i think TRW is longer than lemforder.

[drwankel]

Originally Posted by Ali-E90

so just to confirm... if someone is looking to replace their control arms, with no intention of doing the monoball upgrade (not a track/performance setup), then Lemf is still ok to use, even with the softer bushings?

based on thsi comment "GAS claims that the ball joint in the lemforder arms is superior to the TRW arms"

Any other recomendations for street car with comfort kept as a priority? I have Ohlin RT waiting to be installed in the Spring too.

Thanks!!

Don't do it. If you are not upgrading to monoballs, you should be using OEM BMW branded arms. The car did not come from the factory with oil filled bushings, only the regular non-m 3 series did. That being said, lemforder arms with a monoball upgrade is absolutely the move on the M3. There is basically no downside.

[drwankel]

Originally Posted by aggieshan

I don’t think Lemforder (non m) is the same length as TRW (m) for thrust arms. I had e90 328i and upgraded the arms to TRM. Due to the length, it creates a bit more camber and toe out. Alignment needs to be redo. But that was positive for non M. It gives more neg camber for track driving.

For M3 to use lemforder, it would reduce camber which is not desirable. i think TRW is longer than lemforder.

This is completely wrong. Watch the video above. The TRW and Lemforder arms are identical dimension wise.

It's the M3 lower control arm that adds the additional camber in the non-m 3 series, not the thrust arm.

[aggieshan]

No, i didn’t change the lower control arms. In fact i wanted to change them but TRW is a bit thicker at the subframe side. So it doesn’t fit unless some force or cutting at subframe on non M cars.

For the laborer arm size, i don’t know the length but that was the result i got after swapping to TRW trust arms only.

[aggieshan]

Just watched the video. I see why people say they are the same length based on GAS’s measurement. Well, based on my experience, it is not the same. (That was based on TRW arm purchased in 2018. )

[Ci13Josh]

Exact same issue with Mine, ordered from autodoc and they replaced under warranty no questions asked. Genuine TRW arms, driver side failed approx 5k miles later with a very worn ball joint, almost as if there was no grease in it?

then approx 10k later the passenger side failed. This is on an F32. Deffo something up with it. Sorry to necro the thread but thought it was worth mentioning

[LKN624]

Good thing I read this thread...I was just about to order the TRW ones for my E82 125i. Looks like OE BMW from now on...a lot more expensive but at least I know the Quality will be top notch still.

[miser]

What about SPL?

[drwankel]

Originally Posted by Ci13Josh

Exact same issue with Mine, ordered from autodoc and they replaced under warranty no questions asked. Genuine TRW arms, driver side failed approx 5k miles later with a very worn ball joint, almost as if there was no grease in it?

then approx 10k later the passenger side failed. This is on an F32. Deffo something up with it. Sorry to necro the thread but thought it was worth mentioning

German made arms or Malaysia made arms?

I'm now dealing with a knocking sound over low speed bumps that also happens under low speed braking. It could be the ball joints on my TRW arms have gone out already. Mine are German arms, so it seems unlikely.

However, the fact that it occurs under braking would seem to implicate the tension struts, as so other suspension component would cause that.

[a5m]

Originally Posted by drwankel

German made arms or Malaysia made arms?

I'm now dealing with a knocking sound over low speed bumps that also happens under low speed braking. It could be the ball joints on my TRW arms have gone out already. Mine are German arms, so it seems unlikely.

However, the fact that it occurs under braking would seem to implicate the tension struts, as so other suspension component would cause that.

I'm getting the same thing with TRW German wishbones and Lemforder non-M German Tension Struts with GAS Monoballs preinstalled. Hard to imagine the ball joints are gone already. Could also be the tie rods, but the sound seemed to start shortly after I did those arms.

Funnily enough, it was dead quiet during my drive yesterday when it was below freezing out, then came back once the car was warm

[drwankel]

Originally Posted by a5m

I'm getting the same thing with TRW German wishbones and Lemforder non-M German Tension Struts with GAS Monoballs preinstalled. Hard to imagine the ball joints are gone already. Could also be the tie rods, but the sound seemed to start shortly after I did those arms.

Funnily enough, it was dead quiet during my drive yesterday when it was below freezing out, then came back once the car was warm

I would absolutely love to know if you figure out what it is.

I got the car up on a lift a couple of weeks ago, and both the sway bar end links had some grease accumulation outside the boot and possibly seemed a little loose. Going to replace them first and see if it helps anything. Parts are ready to go, just waiting on the weather to clear up so I can book some shop time.

I'm a bit skeptical, as sway bar end links might explain the knocking over low speed bumps, but it wouldn't explain the clunking with low speed braking. Either it has nothing to do with the problem, or I've got two separate problems.