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E85 Front suspension/shock absorbers- How To

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bigwinn
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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Sat Jul 10, 2021 12:27 pm

E85 Front suspension/shock absorbers- How To

I did this on my last Z4 and noticed that the write up on here from Shipkiller was missing the photos. Decided to document my change on the current car.

Symptoms were a knock from nearside front, which when I investigated it was clear from visible cracking that the rubber in the top mount was failing.

Order list:

2x shock absorbers
2x top mounts
2x 18mm knuckle bolts (a must do according to Patriot66)
I decided to renew the rubber top and bottom pads being 18 years old, so two of each
Dust cover kit (2x plastic sleeves and 2x bump stops)
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All in all this came in at around £200 using Autodoc and selective buying!

Optional if showing signs of mushrooming, you can purchase reinforcing plates for the top of the suspension towers. As my top mounts showed no sign of the pins moving outwards I didn’t purchase.

Anyone looking to do this as DIY I’ll state the obvious: this is fairly high on the danger scale IF things go wrong, so judge for yourself if you can do this without risk. Biggest risks are jacking/supporting the car safely while working on it and the inherent risk when using spring compressors.

What follows is what I did- your call if you follow it or disagree.

Remove struts from car:

Loosen front wheel bolts
Jack the car up and support well, chock rears etc
Take wheels off

Some guides suggest unclipping the ABS, brake sensor and brake pipes from the seated positions on the strut, I didn’t need to do this as all came away from the bracket secured by the 18mm knuckle joint.

Loosen and remove the upper anti roll bar drop link- 16 or 17mm. If it spins pop a same size spanner behind it to stop the ball joint from spinning. Once off- move out of the way.
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For cars with Xenons, on the offside wishbone, unbolt the headlamp level mechanism. Again stow safely out of the way. 13mm under the wishbone.
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Loosen but don’t remove the 3x 13mm at the top of the suspension towers. At this point I also removed the top dust cap from the centre of the strut and took the tension off the bolt (21mm) with the strut in place. Needless to say DON’T undo this bolt as the resulting carnage wont be worth enduring!
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Then onto the knuckle. I soaked the bolt and the whole area in WD40 liberally- you can see from the pictures what 18 years of road crud has done. Undoing the 18mm knuckle bolt without an impact gun I wouldn’t want to try, but out they came. At this point there was no movement (unsurprisingly) of the strut.

I readied the following before trying to get the strut out of the joint:

A jack to place under the hub to control the downward movement of that area
A method of securing the hub once the strut is removed, to prevent any stress of the hub pulling on the cables/pipes
Something to support the hub from beneath

Then I started to free the strut from the knuckle joint. I found the best way (as I was replacing the strut) to use a hammer and gently tap the strut itself. I didn’t want to use any force on the hub (in case of damage to bearings) or by doing what Haynes manual says to open the knuckle by putting a screwdriver in the gap- for fear of cracking the metal.

Both sides slid down with a little encouragement, once lower freed up the 3 bolts per side were removed. Using the jack the assembly was lowered until the strut could be removed. Then, using the jack the hub was raised, an axle stand popped under to prevent strain, and the rope/webbing threaded and tied to support the hub. If it helps- I used the anti roll bar to tie the webbing around.
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Struts out!
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Strut strip down:

Restating the obvious- this is the dangerous part, so only attempt in a safe manner. Alternatives are take the struts to a garage for them to use their hydraulic compressors etc.

Apply spring compressors to the spring. Once the tension is off the top and bottom, remove the 21mm bolt from the top of the strut. I found that this was very easy to achieve.

Taking the unit apart-

Remove the bolt, remove the top mount. Set aside all components and decide what you will be keeping or renewing from:

Top bolt
Top mount
Holding shim
Thick washer
Top rubber
Bottom rubber
Bump stop
Bellows/ sleeve
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Reassembling the strut:

Definitely the hardest and most complex part for me- what I describe is the way I did it. That doesn’t mean it’s the RIGHT way or the BEST way, it’s the way that worked for me.

I used 3 spring compressors in the following order- again if you choose to do this and cause damage or injury I accept no blame/responsibility; what I did in my back yard is only for info. The challenge with shorter springs is there is little coil to attach to. You can see the different types of compressor used- I call them type 1 and 2.

Reassembling the strut in the correct way: strut, bottom rubber, bump stop and tube, spring and top cap/rubber, I attached type 1 spring compressor as this:
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Then type 1 compressor like this:
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Once this was compressed it enabled me to as a priority get the TOP BOLT only on and secured.

From that point, I attached a type 2 spring compressor here, and then continued to compress all in the relative safety of the top being bolted. Once I was happy that I had the suitable length on the top of the strut to attach the top mount, I popped the thick washer, shim and top mount on, bolted and torqued up as best as possible. Then backing off the spring compressors gently- a completed strut!
IMG_0354.jpeg
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Reattaching to car- done in reverse- step by step.

Then- back on the car!

Retorquing:

Upper 3x13mm 24 Nm
Upper ARB drop link 65 Nm
Main strut bolt 64 Nm
Main knuckle bolt 81 Nm

After all done and you are happy with the set up, its advisable to get the steering alignment redone.

All in all, if you don’t get stuck it’s a simple enough job. I wouldn’t have done it without an impact wrench. Note I also binned the replacement sleeves which were plastic, in favour of the original rubber ones- which were much more robust (even after 18 years)

If anyone gets stuck in future feel free to drop me a line!

Cheers

Stuart

Credit as always to the helpers on here- Partiot66 (Si) and Tony!
If the forum helped you, why not help the forum back. Thats the Z4 way! :thumbsup:

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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Sat Jul 10, 2021 12:28 pm

Completed Struts ready to go back in
IMG_0356.jpeg
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E85 Front suspension/shock absorbers- How To

Post by enuff_zed » Sun Jul 11, 2021 6:55 pm

Excellent write up! I knew if I hung back you'd make life easier for me. :wink:

Did your new top mounts have the camber pins?
If not, did their absence have any effect on the rebuild?
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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Sun Jul 11, 2021 7:00 pm

Hola

Yes they did- lemforders

Have seen a few write ups where top mounts haven’t had them and as far as I could tell it didn’t make a huge difference
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E85 Front suspension/shock absorbers- How To

Post by enuff_zed » Sun Jul 11, 2021 7:02 pm

Ah ok, I got Febi Bilstein, which don't have them.
Soon find out eh?
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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Sun Jul 11, 2021 7:09 pm

What’s the worst that can happen
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E85 Front suspension/shock absorbers- How To

Post by Reamesy » Mon Jul 12, 2021 11:13 am

Great write up. Are they M Sport springs and shocks or standard?
Currently; 2011 E89 23i SDrive M Sport Highline Titan Silver
Previously;
2014 SLK250CDI AMG Sport
2012 E89 SDrive 2.0 M Sport. White
2011 Audi TT Quattro
2006 Z4 2.5 Sport
2013 420D coupe
2002 Z3 2.2 Sport
1996 Z3 1.9

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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Mon Jul 12, 2021 11:25 am

Reamesy wrote: Mon Jul 12, 2021 11:13 am Great write up. Are they M Sport springs and shocks or standard?
Having done my 2.2 then this being a 3.0 I think these are the lower sport springs- but I’ll stand corrected!

All I know is the spring compression on the other springs was much easier as there was more spring to grab!!
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E85 Front suspension/shock absorbers- How To

Post by maxman » Mon Jul 12, 2021 2:22 pm

Good help guide with pics. :thumbsup:

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E85 Front suspension/shock absorbers- How To

Post by pilch » Wed Jul 14, 2021 11:16 am

Nice clear write-up :thumbsup: If anyone down my way needs this doing I have a two post lift and floor mounted hydraulic spring compressors you're welcome to use :thumbsup:

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E85 Front suspension/shock absorbers- How To

Post by True-Blue » Fri Dec 17, 2021 9:13 pm

bigwinn wrote: Mon Jul 12, 2021 11:25 am All I know is the spring compression on the other springs was much easier as there was more spring to grab!!
Had my local garage sort mine yesterday, new Sachs struts with Eibach Springs, so again not many coils. His approach was to compress the spring and attach the top plate, then release the tension so the spring pulled the rod out of the new strut.

He then clamped the rod and re-compressed the spring, undoing the spring plate and this made it much easier to attach the new top mount. Once done, removed the clamp and job done.

I googled strut insert clamp and they’re £20 upwards. This might be slightly more time consuming than your approach, but you only need two spring compressors and it looked like a fairly ‘safe’ way of doing it.

Thought it was worth posting as it might make life easier and safer for the sake of circa £20 ish.

To be fair he was only going to charge me £10, but t was still a a bit of a faff for him so I gave him £20 anyway… like to keep the locals on-side :rofl:
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Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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E85 Front suspension/shock absorbers- How To

Post by bigwinn » Fri Dec 17, 2021 9:15 pm

Cheers bud- appreciated

Ironically on the 9th or 10th time of it failing I did consider going to my local kwik-fit or similar and paying to use their compressors- then nailed it!

Now I’ve got the technique sorted I’ve done 4 since with no issues
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E85 Front suspension/shock absorbers- How To

Post by True-Blue » Sat Dec 18, 2021 11:08 am

Once you’ve got an approach that works, why change it…

After reading your thread I was in two minds, order some new spring compressors or pay to have it done. When the garage around the corner said £10 my mind was made up :rofl: :thumbsup:
Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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E85 Front suspension/shock absorbers- How To

Post by WouterZZZZ » Sat Dec 18, 2021 2:19 pm

Hello bigwinn, super clear instructions how to replace the shocks and belongings. I just ordered them for my 2006 Z4 3.0si. Please, what are the OEM part numbers for the rubber top and bottom pads? I will order them too. Many thanks in advance!!

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E85 Front suspension/shock absorbers- How To

Post by True-Blue » Sat Dec 18, 2021 2:29 pm

This is useful…..

Spring pad upper is no. 8 as you can see,

Spring pad lower is 11 and is 31331096664
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Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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