Stabilus 0728pb 800Nm (special tool required)

[B21]

Just a follow up -- I felt like I needed to replace the hood/bonnet struts to renew them all after hitting the folding top and trunk struts. Again, I chose Stabilus (3B-611845) instead of the BMW parts. Glad that I decided to do so. When I snipped the zip tie holding the plastic washer tube bracket onto the strut, the hood dropped about a foot slowly. Apparently, it was creating some rigidity that the old struts were too worn to do without.

They were quick and easy to replace using a pick to pull the clips free. And now my hood wants to be up. After opening it a little less than 2 feet, it wants to lift it to the maximum on its own. So, it needed to be done, and I didn't have to get a headache to prove it. Total cost on Amazon was $44 USD for the set w/free shipping -- very acceptable.

Good to know I’ve got a couple of these babies..did the rears earlier this year..I’ll pop them on over the winter

 

[Christopher72]

How do you know that these struts need replacing ? What is the sign that they are weak? My bootlid struts are definitely weak and I will replace those shortly.

Robbi may have some diagnostic expertise to share on that. I replaced my folding top struts to reduce the "clunk" when the shells move into the boot. I did the boot struts because they were weak—the trunk would easily slam closed without care. The hood/bonnet struts were just an assumption that if all others were bad or going bad, these should also be replaced. All of mine were original from the 10/2010 factory.

Unfortunately, I can't tell you if the folding top "clunk" has gone away yet. My top's rear shell (2) is still disassembled until our upcoming Thanksgiving holiday when I'll have time to finish my wiring/hydraulic line replacement. Since we have snow on Thursday, it does not need to be driven until March! It's time to borrow a heater for my garage.

 

[RobbiZ4]

Robbi may have some diagnostic expertise to share on that. I replaced my folding top struts to reduce the "clunk" when the shells move into the boot. I did the boot struts because they were weak—the trunk would easily slam closed without care. The hood/bonnet struts were just an assumption that if all others were bad or going bad, these should also be replaced. All of mine were original from the 10/2010 factory.

Absolutely correct.

I've been struggeling in the past with a general recommendation to replace the roof struts only for noise reduction, as that can't be always achieved. There is a wider acoustic spread between the different E89s.

But, based on the increasing age of our cars, it's a clear recommendation to get it replaced after 10-15 years, as they do have an active job in the roof moving process! See my recommendations in the HowTo section:
https://z4-forum.com/forum/viewtopic.php?p=1861524#p1861524

Weakened struts will bring more load onto the hydraulic pump over the years, which should be avoided. Unfortunately it's not that simple DIY task as replacing the other 2 pairs.

Regarding the bonnet, it's a bit more tricky:
Replacing those struts depends on your hobbies. If you open the bonnet only once a year, who cares about the newer ones?

Here in Germany (EU, US?) the younger models as of 2012/2013 have an active impact protection for pedestrians. These struts have a production date printed in bigger letters on it, which have to be renewed after 5 years. If not, you'll fail the biannual technical check.

 

[Christopher72]

Replacing those struts depends on your hobbies. If you open the bonnet only once a year, who cares about the newer ones?

lol, well I may be a little bit more proactive than most on that. My daughter's 2004 Lexus RX and its steel hood grazed me when the single gas strut failed. A small laceration and changing my shorts... I'll just replace them when they get old. :lol:

 

[RobbiZ4]

Replacing those struts depends on your hobbies. If you open the bonnet only once a year, who cares about the newer ones?

lol, well I may be a little bit more proactive than most on that. My daughter's 2004 Lexus RX and its steel hood grazed me when the single gas strut failed. A small laceration and changing my shorts... I'll just replace them when they get old. :lol:

Absolutely ok.
But for this pair of struts I personally will not post a recommendation. That should stay an individual decision of each car owner.

 

[simnew]

So the struts support the hydraulic load on the motor when the the roof sections fold into the boot. But it seems like the hydraulics are still the main ‘effort’. I wonder how much a BMW dealer would charge to do this…. Although then there’s the electrics and the hydraulic lines themselves to consider! Discovered this afternoon that the garage that replaced my pump, didn’t replace the salmon relays, so I had a new pump with 15 year old relays…. Needless to say I changed them immediately

 

[RobbiZ4]

So the struts support the hydraulic load on the motor when the the roof sections fold into the boot. But it seems like the hydraulics are still the main ‘effort’.

Correct.
Both gas springs support the lifting of the main pillar with a force of 1,600 N/160 kg/352 lbs, that's a lot.
This lifts the roof package (or dampens it when lowering) and the hydraulics only have to push it back or forward "a little bit". This will change when the struts leave their force after a decade.

As we can “feel” on the trunk lid, the same aging effect will also occur on this pair of roof struts. Remember that all struts in our cars came from the same supplier: same quality, same aging effects.

 

[Christopher72]

I wonder how much a BMW dealer would charge to do this….

If you already have the boot trim removed, it's a super easy <8-minute job with the correct tool. IMHO, just buy the tool -- it's cheaper than what BMW will charge you to do it with BMW branded parts.

Recover the cost by being "that bloke with the clamp" in the UK that will let ya stop by and use the tool for a small fee or free. I haven't had anyone ask me from Ohio here, but I'm happy to do that.

 

[RobbiZ4]

I haven't had anyone ask me from Ohio here, but I'm happy to do that.

Keep an eye on the E93 scene in your region as well.

On these models, your tool is much more required than on our E89s.

The E93 convertibles currently are between 11 and 17 years old. Their roof struts (1.300N) are very weak in between and tend to jam when lifting up the roof package out of the trunk.
On these models it's a 200% recommendition to get this pair removed asap.

Roof struts E93 (BMW 54377128764)
Stabilus 459851 1300 N (!) (tool required !)

Trunk lid E93 (BMW 51247129215):
Stabilus 032963 230 N

 

[simnew]

Interesting - well I think I will definitely do this in the new year. Too much spending on the credit card to do it right now, but certainly in Feb / March time - when I start to fit the PDS and rear reverse camera, I will get the tool and replace the struts. Can't face another motor dying or perhaps the sensor in the motor going wrong through over heating ? I guess I will never know other than the original error code A6A3. Thanks a lot for your advice and input.