Suspension - When to tell if worn
Printed From: Bavarian-Board.co.uk - BMW Owners Discussion Forum
Category: Technical & Model Specific Forums
Forum Name: BMW 3 Series
Forum Discription: This forum will deal with any issues on the BMW 3 Series (E21, E30, E36, E46, E90, E91 & E92)
URL: http://www.bavarian-board.co.uk/forum_posts.asp?TID=12364
Printed Date: 07-May-2024 at 13:18
Topic: Suspension - When to tell if worn
Posted By: Stay Alive
Subject: Suspension - When to tell if worn
Date Posted: 30-November-2004 at 13:46
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Does anyone know how you can tell if your suspension is worn to the point where the struts will need replacing. It just my E36 318Ti Compact appears to be rolling slightly around corners and the back end comes out a little to easy for me in the wet. In case it is just me I would like to know if there is a simple way of testing. Measurements between the wheels and arches are the same all round but that doesn't mean this is OK as they could have all worn the same? Couldn't they? Any help would be greatful. PB |
Replies:
Posted By: Peter Fenwick
Date Posted: 01-December-2004 at 04:49
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The E36 compact had the same rear suspension as the E30 so it will be a bit tail happy in the wet. You can tell if the struts need replacing by pushing down on each corner of the car. If the body comes back up and stops then the strut is Ok, if if bounces up and down a bit then the strut is knackered. One of my struts was shot and it was very noticable when driving the car, i.e it was very difficult to control when driving down a bumpy road. measurements between arches and tyres doesn't really tell you a great deal other than if you springs are starting to sag. ------------- Entering an age of Austerity and now driving a Focus Diesel. |
Posted By: Stay Alive
Date Posted: 01-December-2004 at 05:49
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Thanks for that Peter. I guess I need new struts because they do bounce a little when you press down on them. Don't supose you could recommend suitable replacements? Regards |
Posted By: Peter Fenwick
Date Posted: 01-December-2004 at 06:19
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Bilsteins are good. I have their sport dampers on the front of my car. ------------- Entering an age of Austerity and now driving a Focus Diesel. |
Posted By: Madrab
Date Posted: 01-December-2004 at 08:20
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Maybe also worth getting the roll bar and bushes checked, as they, as the name suggests, control the roll of the car. They can also get tired with loads of miles. The rule I follow for suspension is - The springs control the ride of the car and the shocks control the springs. If the suspension is getting softer then the springs may be getting tired. As Peter says though, if you are getting rebound when you press the car down and it doesn't stop after the first bounce then the shocks could be getting worn too. Rob ------------- 1990 E3o 325i Touring and she's definately a she! Pain in the ass sometimes but goes like a bunny :oD |
Posted By: Stay Alive
Date Posted: 01-December-2004 at 08:35
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I hear what you are saying despite the fact I am now confused. I presume the bushes are checked via visual inspection whereby I am looking for cracks in the rubber??? I think I will have a professional check out the whole suspension. |
Posted By: SkyRocketeer
Date Posted: 01-December-2004 at 18:38
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In my experience, anti-roll bars themselves rarely 'wear' in a sense
that they change their performance. The bushes may become slack and
sloppy through age, but the roll bar, if it's intact, won't adversely
affect performance as it ages. Usually replacing the bushes is
sufficient, a visual inspection is a good start, but a skilled mechanic
with a lever or pry-bar will tell you which bushes have too much play. Most likely candidates for age related poor performance are likely to be shocks. typical german shocks (Boge I think are OE suppliers) will last over 100k without leaking, but the damping ability drops off a lot sooner. The 'bounce test' as described earlier is a good and easy way to check on their performance. From release the car should complete one to one and a half oscillations (i.e up-down-up) on good shocks. More than that indicated they're getting tired.. mine bounces for about a week, but I'm guessing at 127k it's not seen new shocks at all [shrugs] New shocks may raise the ride-hight slightly, especially if the old ones were leaking, as they offer a slight sprung resistance as well as damping. |
Posted By: Rhys
Date Posted: 01-December-2004 at 19:42
Another ti owner  ------------- V reg Rustbucket Merc C220 Cdi estate J Reg Saab 900i 16v '63 Ford Anglia 105e deluxe R reg Honda PC50 moped.. No BMW as yet... |
Posted By: Stay Alive
Date Posted: 02-December-2004 at 05:45
| Thanks for that Skyrocketeer. A bit more clearer again. |
Posted By: M3AG
Date Posted: 02-December-2004 at 06:08
| Don't forget to have the rear top mounts checked, if worn they can lead to knocks from the boot area and some strange behaviour where handling is concerned. Same with trailing arm bushes (which make the arm move if damaged and therefore upsetting the geometry of the suspension). |
Posted By: Hans Freikit
Date Posted: 02-December-2004 at 06:22
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Ditto on the rear shock mounts - one of mine has started knocking at 80k miles. The E36 can use improved parts from the E46 as direct replacements, and Z3 reinforcement plates for extra longevity. http://www.uucmotorwerks.com/html_techtip/techtips/rear_shock_mounts.htm - http://www.uucmotorwerks.com/html_techtip/techtips/rear_shoc k_mounts.htm HF |
Posted By: Madrab
Date Posted: 03-December-2004 at 08:38
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I wouldn't necessarily agree with not checking the roll bar itself. If the car has had heavy use and done a lot of miles then bars can undergo straightening which, in effect, can 'flatten' the bar and reduces antiroll strength.This can increase roll as the bars 'push back' can be compromised to some degree. Usually seen as surface flaking of the metal of the bar. Ever replaced a stock roll bar on a car with 130k hard miles and placed the new and old side by side? Can be quite a difference in shape and performance. I would agree that replacing other components first can reduce the slackness due to tightening the overall suspension system and can negate a slightly tired bar's give. This can then transfer higher loads to the suspension increasing the wear rates. I suppose this could be the last part of the suspension replacement though and could rule this out last. ------------- 1990 E3o 325i Touring and she's definately a she! Pain in the ass sometimes but goes like a bunny :oD |