Front struts

Post Tue Dec 09, 2014 8:53 am

Hello everyone,

I'm currently replacing the front struts on my pre-facelift 318i to some I've sourced from a 51mm Tech 1 Sport.

I've disassembled the front struts and removed the springs. I have new Eibach springs to replace these with. My top mounts have deteriorated and I'll replace them.

My question is about the front shock absorbers. They are Bilstein, I have no clue how old they are or if they are OK. They seem to have lots of damping left as they rotate easy but don't compress easily and move back slowly.

How can I test them? Or, should I just replace them with new B4s?

Thanks all,

Post Tue Dec 09, 2014 3:18 pm

Hi Jona,

A good shock absorber should not compress easily and should move back slowly. I presume there are no leaks either, the seals are dry, etc so so far so good

I'm not sure either how can you test these without a special machine and having them off the car. I know of a few good indicating methods while having them installed.

However if you have sourced a 51mm strut and planning on reusing your old shocks, then they won't fit. You need to have shocks for the 51mm strut that you have now sourced.

Also, is the spring shortened? If so, then you will need B6 shocks, not B4s as these are too long and it would stress the spring too much, in my opinion,

Post Tue Dec 09, 2014 5:18 pm

That's interesting, I've got new B4s on the rear which is 30mm lower. The front, I dont know yet, but is quoted at 40mm lower. The shocks I have for the front are currently in the 51mm struts.

B4s won't fit? Anyone else confirm please?

Thanks,

Post Tue Dec 09, 2014 5:26 pm

with a 30/40mm drop you should be fine, anymore and you may struggle.

Post Wed Dec 10, 2014 4:20 pm

Any particular top mounts?
CP4L have Lemforder at £24 and OCP at £4 each.

Post Fri Dec 12, 2014 11:59 pm

Hi Jona,

If you are running your car with lowered springs you should be using B8's, good website below, just highlight heavy duty or sport for the year model of your car and it gives you a description of what bilstein intended how their shocks are to be used, always best to go with the makers recommendations.

http://www.eshocks.com/bil_veh.asp?Mode ... &SubChar=Q

If the 51mm sports shocks come with the housings as well your ok, if they are just the shocks, you will need to source 51mm housings, 318's run smaller shocks and housings.

testing older shocks, they can be machine tested on the car, a lot of work for you to find out they are no good, I have found bilstien recommend that the shocks be left in an upright position for 24 hrs prior to install, so do that, then grab one, put one end up against the wall and push like hell, being hydraulic it should have a smooth, steady progressive feel on the in push and you can feel it through your hands, then let it go back to its rest position and you can feel if its smooth in its operation, do so for both shocks, they should feel the same, do so a couple of times, if one feels different, buy new ones.

Used this check to test shocks when I bought a e28 m5, when I checked them, they weren't consistent with one another, so got new ones.
Bad shocks effect handling and braking distance.

am on my 3rd 318i suspension upgrade.

hope this info helps, cheers.

Post Sat Dec 13, 2014 6:56 am

If you're using the Eibach pro kit B4's will be fine. Many people on here have this setup including me.

Go for the Lemforder top mounts the cheap ones will be rubbish.

Post Sat Dec 13, 2014 8:54 am

Thanks motormanmick and capri-rob.
Yes, I have the Eibach pro kit springs. I'll test the shocks as described over the weekend.

One question: is there a special tool to undo the shock from the strut housing? Or, an easy DIY version. My attempt with an oil filter wrench failed badly.

Post Sat Dec 13, 2014 9:00 am

You need a stillson type pipe wrench to undo the circular screw fitting that holds the standard shocks in.

The collars that hold the bilstein shocks in are different and should come with the new inserts although a while ago lots of people were buying the inserts only to find the collars weren't in the box.
The standard round collars will NOT fit the Bilstein inserts

There is also a school of thought that says you need to put a bit of oil in the strut before fitting the new insert as this cools the shock.