what the heck are these

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littlefeller
Joined: Sun 28 Apr, 2013 18:06
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what the heck are these

Post by littlefeller »

just seen these weights on a post on facebook, what are they for?
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
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  Z3 roadster 3.0i
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Re: what the heck are these

Post by Southernboy »

They are weights which apparently are there to keep the back of the car stable. Often responsible for an annoying rattle / clunk noise when their rubber mountings break... :wink:
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Brian H
Joined: Tue 16 Dec, 2008 19:55
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Re: what the heck are these

Post by Brian H »

littlefeller wrote:just seen these weights on a post on facebook, what are they for?
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I saw that post too, BMW did not just stick weights in a car for no reason, I am thinking they are there to achieve either the 50/50 weight distribution or as barry states for stability (weight over the backend)
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Southernboy
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  Z3 roadster 3.0i
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Re: what the heck are these

Post by Southernboy »

I read it was to reduce the butt lateral scuttle type movements and to keep the butt from being too bouncy in the vertical plane...
BMW originally called them "vibration dampers" in their brochures... Bottom line is they weigh around 65 lbs in total...like having an extra passenger on board... :shock:
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Parki
Joined: Sun 02 Feb, 2014 17:42
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  Z3 roadster 1.9

Re: what the heck are these

Post by Parki »

Hi all - has anyone tried removing these & what would be/was the effect on handling? Acceleration should be better?
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Southernboy
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Re: what the heck are these

Post by Southernboy »

Easy enough to find out...remove yours...you can always toss them in the boot corners if you felt they were needed, and toss them out when you go on a road trip and load the boot up anyhow... :D
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littlefeller
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Re: what the heck are these

Post by littlefeller »

:shock: :shock: 65lbs, that's 30kg, almost a full tank of fuel in weight :shock: so what kind of vibration are they designed to dampen? the coupe doesnt have them.
gookah
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  Z3 roadster 2.8

Re: what the heck are these

Post by gookah »

to reduce convertible scuttle shake which the Coupe doesn't suffer from due to having a roof.
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boustrophedon
Joined: Thu 01 Oct, 2015 20:29
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Re: what the heck are these

Post by boustrophedon »

I first saw these on the convertible Triumph TR7, their purpose was to tune resonances in the chassis to prevent scuttle shake. It is delightful to see BMW copying from such a paragon of engineering excellence. Lesser engineers might have put some of the weight into extra chassis members for strength and rigidity, rather than going for the elegantly simple solution of adding great lumps of metal to the rear of a sports car.
Last edited by boustrophedon on Fri 09 Oct, 2015 12:01, edited 1 time in total.
littlefeller
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Re: what the heck are these

Post by littlefeller »

surely adding dampers doesn't solve a problem, rather just masks it. never even knew they were there. some people are removing them, seems abit of a faf just to shed about 30kg, this is only equivalent to about 3 and a half ponies, but then free ponies is good, though bmw must have fitted them for a reason. could removing them lead to problems later down the line (not immediately noticeable but maybe fatigue due to the un-dampened frequency)
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Southernboy
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Re: what the heck are these

Post by Southernboy »

You'll probably notice the butt sticking up higher than normal, with extra clearance between the tyre and the wheel arch... might not look too pretty..
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boustrophedon
Joined: Thu 01 Oct, 2015 20:29
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Re: what the heck are these

Post by boustrophedon »

Southernboy wrote:I read it was to reduce the butt lateral scuttle type movements and to keep the butt from being too bouncy in the vertical plane...
BMW originally called them "vibration dampers" in their brochures... Bottom line is they weigh around 65 lbs in total...like having an extra passenger on board... :shock:
Where did the figure of 65 lbs come from? I have an old butchers' weight of 28lbs, it's huge and there is no way it would fit in the space behind the bumper.

Edited to add, a post here: http://www.bimmerforums.com/forum/showt ... er-Weights, reckons they weigh about 15lbs each, which is more realistic given their size.
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Southernboy
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Re: what the heck are these

Post by Southernboy »

Like you, I read it was a total of 65 lbs, but who knows, they may be half that. :shrug
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littlefeller
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Re: what the heck are these

Post by littlefeller »

had a looksie on google, total weight is 15kg, i figure some people have thought (like me) this was for each one. so 15kg isnt too bad, still 15 lt of fuel though :evil: to be honest i cant really see 7.5kg each side would really make much difference to scuttle :lol:
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