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Old 09-22-2009, 06:26 AM
cn90 cn90 is offline
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Location: Omaha NE
Join Date: Mar 2006
Posts: 14,362
Mein Auto: 1998 528i 5-sp 140K+
Originally Posted by bluebee View Post
Wow! Hats off to you yet again!

This includes, potentially:
- front struts
- suspension springs
- strut guide

- control arm
- thrust arm
- tierod

Your DIY above seems to put it all together! Thank you! Let's START with this and add value where needed so we all benefit!
Hi bluebee,

I edit your questions a bit so I can answer the Front Suspension (I skip the Rear Susp questions for now). I have owned a quite a few cars and have wrenched for 25 years and here is my observations with E39 sharing many of these similarities. However, the E39 has its own problems:

- Struts deteriorates slowly so you hardly notice the gradual deterioration until it is really bad. So my guess is Strut lasts anywhere between: 60K (Boston and NYC potholes!) all the way to 150K (highway driving). So it is hard to judge a Strut by mileage alone.

- Springs seem to last well beyond 200K (I spoke to my cousin who is bmw indy guru!).

- Strut Guide. This part has the bearing in it. In contrast to the wheel bearing which lasts 150K miles because most of its load exerted on the outer race in a radial manner (along the axis of rotation), the Strut Guide Bearing has 100% of the load exerted in a lateral manner, i.e. the INNER race is constantly pushed UPWARD by the Strut Spring.
So even the Strut Guide barely turns much (compared with the wheel bearing), the lateral load kills the bearing.
At 80-120K, you will notice some play in the Bearing Guide. Those short of budget may re-grease the Guide and keep it until unbearable but since there is so much labor involved, replace it anyway.

- Control Arm: surprisingly, my CA was still good at 105K, the BJ has some looseness (compared with the new CA) but the bushing is OK.

- The thrust arm: the BJ has some looseness (compared with the new CA) but the bushing is long gone (all oil leaked out, rubber cracked).

- The tierods INNER BJ is still good, the OUTER BJ (this is where most of the wear and tear is) has some looseness but still good.

The BOTTOM LINE for those who are short of budget:

1- If you have shimmy at 50K, then switching to PowerFlex Bushing for the Thrust Arm is probably good enough. Read that post carefully and you may have to shave the bushing a bit to allow the washers to go in.
Best is:
- Using a micrometer and measure the existing Thrust Arm Busing width.
- Measure the PowerFlex Bushing + washers thickness
- Shave the PowerFlex Bushing a bit for ease of installation.

2- If you have more than 120K, do this DIY: Entire Suspension Overhaul.

Last edited by cn90; 10-01-2009 at 06:49 PM.
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