2003 Z4 Shock Replacement

So I just clocked 110,000 on my 2003 Z4 and it is time to replace the shocks. I've never done this on a BMW before.

Can anyone recommend a particular shock? Is OEM a good option? Is this a difficult job, or something that can be done in the driveway?

I've rebuilt MGA suspensions and BMW motorcycle /5 shocks and forks, but don't have any modern car experience.

Any advice would be most welcome.

Thanks,
Donovan

I have Koni Yellows and love them to death, much better ride than stock and reasonably priced. rears are cake, fronts are a PITA due to the spring clearance and rate.

Yikes, 110k miles and this is first replacement? The stockers were probably shot by 30k, maybe 40k tops. I'd go with Bilstein HD's, that's what's going on my Z4MC soon. I have Koni Yellows on my Mini Cooper, and I'm not crazy about them.. though that's a completely different application.

Originally Posted by KevinC

I have Koni Yellows on my Mini Cooper, and I'm not crazy about them.. though that's a completely different application.

What don't you like about the Koni's? I'm about to put a set on my Z4C (first replacement at 65K miles - and yes, it's high time).

Believe it or not but shocks can last a long time. The only way to tell if a shock needs replacement is to stand outside the car while someone drives over a bump. If the impacted tire rebounds more than once then the shock is worn. Even a little oil weeping from a shock is normal and not a sign that it needs replacement. I like mono tube shocks such as Bilstein.

Whatever shocks you get will be just fine, especially if you have not lowered the car. Koni, Bilstein, OEM.

The job is very easy for the rear. Just jack up the car, remove the shock bolt at base of shock and the two bolts on the shock mount. It isn't a bad idea to get aftermarket rear shock mounts such a the Rogue Engineering 10mm RSM (12mm for Koni). I have tinkered several times with shocks, and can do the whole rear in about 45 minutes.

The job is nearly as easy for the front struts with the exception of the fact that OEM springs need a spring compressor. This will slow and complicate things a little. In addition, I find it much easier to remove both wheels and both sway bar end links before you remove the first strut so that you don't have the sway bar resistance interfering with the job.

If you are familiar with spring compressors, the front should take less than two hours to do.

The total job for all four dampers would probably take under five hours if it is your first time with this car, but you have done similar maintenance before. If not, you could do it in under 3 hours. You can do this in a driveway without problem.

If you go Koni, you may want to consider the externally adjustable variant of their shocks. See TCKline. But, it is probably unnecessary if you are simply replacing OEM and not looking to adjust performance. Just set them at full soft and be off.

I am waiting for a replacement suspension, and can document the process as a DIY when I receive it... any day now... so it could be within the next two weeks that I post such guide if you are interested.

Good Luck

Originally Posted by nlink720

Whatever shocks you get will be just fine, especially if you have not lowered the car. Koni, Bilstein, OEM.

The job is very easy for the rear. Just jack up the car, remove the shock bolt at base of shock and the two bolts on the shock mount. It isn't a bad idea to get aftermarket rear shock mounts such a the Rogue Engineering 10mm RSM (12mm for Koni). I have tinkered several times with shocks, and can do the whole rear in about 45 minutes.

The job is nearly as easy for the front struts with the exception of the fact that OEM springs need a spring compressor. This will slow and complicate things a little. In addition, I find it much easier to remove both wheels and both sway bar end links before you remove the first strut so that you don't have the sway bar resistance interfering with the job.

If you are familiar with spring compressors, the front should take less than two hours to do.

The total job for all four dampers would probably take under five hours if it is your first time with this car, but you have done similar maintenance before. If not, you could do it in under 3 hours. You can do this in a driveway without problem.

If you go Koni, you may want to consider the externally adjustable variant of their shocks. See TCKline. But, it is probably unnecessary if you are simply replacing OEM and not looking to adjust performance. Just set them at full soft and be off.

I am waiting for a replacement suspension, and can document the process as a DIY when I receive it... any day now... so it could be within the next two weeks that I post such guide if you are interested.

Good Luck

Very clear and to the point. Not a lot of opinion injected, I love it. I wish we could see more of this. This is what coming to forums is all about.

Originally Posted by nlink720

I am waiting for a replacement suspension, and can document the process as a DIY when I receive it... any day now... so it could be within the next two weeks that I post such guide if you are interested.

Good Luck

Thank you all so much for the advice. I would be very interested in seeing a DIY on this if you have the time. I think it would be very helpful.

I will be tackling this early next month I believe.

Thanks again,
Donovan

Originally Posted by Donovan303

Thank you all so much for the advice. I would be very interested in seeing a DIY on this if you have the time. I think it would be very helpful.

I will be tackling this early next month I believe.

Thanks again,
Donovan

OK.

I will document and post the process within the next two weeks. I'm waiting for the dampers I ordered in the end of January to come in. The only part that will not be covered is the actual spring compression process since I use 6" springs and not the OEM springs, but it will be clear and understandable what you will need to do.

Here a question how do you get to the upper 2 shock mounting bolts in the rear trunk area ? I took out the bolt & star bolt that hold the base to the top support not luck and then decided to take the carpet out thinking that the bolts might be accessed under the top support - nope.
Any quick answer?
http://www.bimmerfest.com/forums/sho...d.php?t=247840 - found out what has to be done


Thanks,
Andy

Are you in a coupe of convertible?

Originally Posted by Donovan303

Thank you all so much for the advice. I would be very interested in seeing a DIY on this if you have the time. I think it would be very helpful.

I will be tackling this early next month I believe.

Thanks again,
Donovan

ooooh, awesome topic, i'm also interested in a DIY as i'm tired of a rear squeaky shock on my 2003 (only 44k miles on mine, however)...I swear I had the same squeak on my old 2001 E46

Originally Posted by nlink720

OK.

I will document and post the process within the next two weeks. I'm waiting for the dampers I ordered in the end of January to come in. The only part that will not be covered is the actual spring compression process since I use 6" springs and not the OEM springs, but it will be clear and understandable what you will need to do.

cool, ty!

If convertible:

The shock sits right under part #5 in the diagram, but there are a few layers of things to remove to get to it.

You have to take the torx bolt, then some other bolts as well. You need to access above the tray (part 1 in diagram). To do this, you have to separate the aft part of where the fabric (part 2) attaches to that tray. You don't need any tools for this. Then, remove the tray after removing the clips (part 4) from where they sit (part 16). Then you can remove the tray, but be careful not to hurt the sensor that sits in the center of the tray at the back f the trunk (part 10/11/12).

Once the tray is out, you can access the other screws to remove the plastic that sits above the rear shock access. Start by removing any bolt that is part of part 3, and remove part 3. Then you will be able to fold/bend back the plastic on part 14/15 that covers the access.

I'll see if I can take a picture.

Reply to this thread and I'll see if I can assist you here and there during the day.

Below is step one: move the cloth out of the way so you can see above and below the tray



This shows where one of the retaining rivets was located. Remove this, the torx, and there is a 10mm(approx) bolt at the back where part #5 goes. You will be able to access this better once the tray has been removed.


Below you can see the tray retaining clip recesses


Below you can see the top of my rear external adjuster. (I made a hole to access it)
At the center too you can see where the tray retaining clips are located. There are 2 or three on each side and spaced the length in the tray in recesses.
There is a thin plastic splash shield that can be folded out of the way (part 14) , but underneath that is the hard plastic part (3) that must be removed to access the shock.



This is why it is best to get externally adjustable shocks -- otherwise you would have to go through all of this every time you would want to make an adjustment. With rear external adjustment you can simply open the trunk and make the adjustment via knob and not have to remove the shock and compress it.

Well I got them replaced an am now running a TEIN SS setup.
One note when reinstalling the convertible trunk cover be careful of the micro switch - I mistakably pop off the lever - had the error light on and no power top. Just had to clip the lever back on to the micro switch and I was good. Thought the rears were going to be the easy ones - not I'm at 78k and the rears were about gone - fronts I'm not sure since I didn't take the strut assembles apart yet.

Originally Posted by Acz4

Well I got them replaced an am now running a TEIN SS setup.
One note when reinstalling the convertible trunk cover be careful of the micro switch - I mistakably pop off the lever - had the error light on and no power top. Just had to clip the lever back on to the micro switch and I was good. Thought the rears were going to be the easy ones - not I'm at 78k and the rears were about gone - fronts I'm not sure since I didn't take the strut assembles apart yet.

I was hoping to catch you before you got that far. See my post above

Common thing

so the difficulty to change 'em on the rears is high?

No. It is easy. Just frustrating because of the tight spots and poor visibility at times. It is not hard. I need to create a DIY on this, but have been busy. I threw my ASTs in less than 40 minutes per side, but had done it before.

just got word during an inspection while I was getting the oil changed that the right rear spring is busted...so this will definitely be a project for me

I read through the DIY in another thread (http://www.bimmerfest.com/forums/sho...d.php?t=247840). If i'm following right, I shouldn't need a spring compressor, just the jack to do the work, correct?

Anyone know the part number for the OEM spring? RealOEM isn't publishing it for some reason. EDIT- this is for a 2003 3.0 w/ sport suspension

http://www.trademotion.com/partlocat...layCatalogid=0

Looks like $122.68

Originally Posted by Acz4

http://www.trademotion.com/partlocat...layCatalogid=0

Looks like $122.68

2 springs, some pads, & shipping will probably run me sub-$300, alot less than the $778.96 the dealership quoted me

I don't understand the dealerships - I had gone to the one that I bought my car from to price a part - they were higher than the retail listed at Tisher. Nice - so much for them - haven't been back.

my local dealership listed the springs somewhere in the neighborhood of $180/each, the $779 figure I quoted included labor for the entire project (still trying to figure out their hourly rate on that one)

once I asked them to price match to Tischer, they said they'd lose money selling it so low...I laughed and said somehow Tischer is able to do it

swaped the springs out yesterday, not that bad of a project...

about 2.5 hours from start to the finish, I muscled in the spring myself, probably wouldn't hurt to have someone else help, didn't need a spring compressor as my jack worked great on the lower wishbone to compress the spring to put the shock bolt back in

my right rear spring was def busted

OEM shocks are speced based on cost. On the E46 M3, the stock shocks lose 50% of their dampening at about 10K miles (tested on a shock dyno by Ground Control). Older BMWs (E30) shocks would easliy last 80K, but current models, very unlikely.

FOr stock ride height:
Koni single adjustable
Bilstein HD

Botha re very good shocks. The Bilstein will ride a bit harsher and it not asjudatble, but should be good for at least 100K. The Konis are adjustable to add a bit of rebound control over time. I have run both and really don't have a preference of one over the other.

What ever you do, put in newa nd better rear shock mounts. Rogue Engineering, TC Kline, Ground Control are all good choices.