my dangling weights are very harmonic ..improve the ride experience and are maintenance free...about the old thing on a d3/4 that is
How often do you gat them "felt" ?BREXIT - done properly.
Right now ...We need Government - not Politics
Save the Dipstick Flagbearer-keep it simple, less likely to fail campaign-agenda items:Starting Handles, Acetylene Lamps.
Founder: Dipsticks-R-Us Inc
D3 HSE-perfectly formed, passenger friendly...has real DIPSTICK
Jag XK-but sadly no DIPSTICK...HUGE design fault
FL2 has DIPSTICK..."real comfort in rear seats"
VW Golf wondermobile (?)..has real DIPSTICK
Morris Minor..original DIPSTICK technology..and a real KEY.
6th Aug 2014 7:16 am
Dickbrowne
Member Since: 23 Apr 2014
Location: Newport Pagnell
Posts: 144
Holy thread resurrection, Batman
Anyway, as a keen physicist I have an interest in tmd's and would love to see the graphs showing the effectiveness of the weights. I knew about the two big ones at the back, but apparently there are smaller ones all over the Discovery.
It would actually be very interesting to drive a Discovery without the dampers attached, just to experience the difference.
From a physics perspective, the easiest way to think of the effect the dampers give is to visualise the holy trinity of car comfort - Noise, vibration and harshness (commonly referred to as NVH) as nothing more than energy waves. The damper can be thought of as a big rechargeable battery or capacitor - the energy is stored in the weights and (this is the clever bit, and why they are "tuned") it is released back into the car in a way which counteracts broadly similar NVH traits which are subsequently generated by the car, and all but eliminated by the opposing wave - it's a bit like burning speakers in by connecting them out of phase and pointing the cones toward each other. One wave pushes whilst the other pulls.
From an engineering perspective, the free swinging weights are almost a definition of Occams Law - it's a simple solution which works (imperfectly, we still feel some vibration). It could be better and there are undoubtedly solutions which use mammoth amounts of oil damping and electronics to give a better ride, but the improvements are marginal and to my mind the increase in cost, complexity and, yes, weight, is unjustified, and that's before looking at failure rates.
But what do I know? I'm just a techy
7th Aug 2014 8:40 am
DG Site Moderator
Member Since: 12 Dec 2005
Location: The Gaff
Posts: 50934
Harmonic damping requirements can make for some interesting requests
Member Since: 30 Oct 2011
Location: plymouth
Posts: 6525
interesting dickbrowne ..thanks
7th Aug 2014 9:45 pm
Ben4
Member Since: 28 Apr 2017
Location: Buckinghamshire
Posts: 934
How are the dampeners fitted in place?
Wondering if the fixings might be the source of a long searched for rattle?!formerly Disco3Ben
2016 D4, Santorini Black
2007 D3, Black - sold
16th Oct 2018 8:36 pm
charlietortoise
Member Since: 29 Oct 2011
Location: Staffordshire
Posts: 502
Shakes
You will be suprised at the effect of harmonics. I towed a light boat trailer on my disco 2. Not more than 100kg all in.
The effect was traumatic, at 56mph it was just managable, at 58 the steering wheel was vibrating so much I could just hold it. I thought it was the wheels as I often towed boat trailers and never had a problem before.
I swapped the spare on, no effect. Swapped the fronts to rear, no effect. Stopped at a garage, had all the wheels balenced. Still no good, I really couldnt imagine what was causing the problem, prop shafts maybe?
In the end I got to my destination, took off the trailer and drove the car. No problem at all, it was a hamonic issue with the trailer. I never sorted it, new wheels on the trailer made no difference at all.
It stunned me how such a small light trailer could have such an impact on a 2ton discovery.Discovery 4 3.0 HSE 2010 year. I like it a lot. Now with winch 😂
16th Oct 2018 11:39 pm
Hot Tub
Member Since: 15 Aug 2017
Location: Milton Keynes
Posts: 1071
KISS engineering solution Keep It Simple Stupid nothing to go wrong with them glad someone asked as I had seen them but didn't know what they did.' Every Day Is A School Day'
17th Oct 2018 5:37 am
Browny90
Member Since: 19 Jul 2016
Location: Ashbourne
Posts: 687
Quote:
i was merely comparing what is a simple low tech solution
I work for Rolls-Royce Civil Aerospace, developing the Trent 1000 & 7000, I can assure you that even the most high tech machines sometimes can only (cost effectively) be fixed by low tech solutions, and in actual fact it is a very complex problem..
We work within a very tight vibration envelope with different resonant frequencies for Taxi, Take Off, Climb, Cruise and Decent, then another for Thrust reversers.
We use simple weight dampers and literally steel cable (Like winch cable) to damp the frequencies that fall into the envelope. If they do sit in the envelope, it means that particular part if resonating at its worst case and is highly likely to substantially reduce it's life..
People seem to think you need the thing to be shaking itself to bits to cause a problem, it's quite the opposite, we have had some very high frequency vibrations causing cracking and other issues over the years..Disco4 MY16 SDV6 Landmark Black
Disco4 MY12 SDV6 XS Orkney Grey (Gone)
Defender 90 200tdi Completely rebuilt.
Ive decided to make my life miserable and attempt some sort of corrosion inhibition on the chassis. Ive stripped away most components at the rear to make access easier. Can the harmonic dampers be removed with the body on? There are 2 13mm bolts on the inside and outside of each damper which seem to be the mounts to the chassis. On the outside, there is a 17mm bolt which seems to hold the two halves of the damper together. i could only get a ratchet spanner on and couldnt get it moving. Decided to stop and have a think before breaking something. so 2 questions:
1. Can they be removed with the body on? and
2. Is the 17mm bolt normal thread or for some reason is it left hand thread?
Thanks
PS: Has anyone worked out a way to coat the top of the chassis with the body on?
27th May 2020 10:52 pm
waterbuoy
Member Since: 26 Oct 2013
Location: Argyll
Posts: 2861
With regard to your PS:
Having done the top of my chassis with the body off I cannot for the life of me see how it could be done with the body on!Currently 2009 Disco 3 SE, 2013 MY D4 HSE and 2016 D4 SE
Previously:
TD5 Defender 110 CSW (230k miles)
300TDi Disco 1 (289k)
4 RR Classics (300-350k each, 2 manual, 2 auto)
110 V8 CSW (220k)
S3 109 hi cap pickup (ex RN)
S2A 88 Safari SW with lpg conversion (bloody lethal)
Still looking OK almost three years later!Currently 2009 Disco 3 SE, 2013 MY D4 HSE and 2016 D4 SE
Previously:
TD5 Defender 110 CSW (230k miles)
300TDi Disco 1 (289k)
4 RR Classics (300-350k each, 2 manual, 2 auto)
110 V8 CSW (220k)
S3 109 hi cap pickup (ex RN)
S2A 88 Safari SW with lpg conversion (bloody lethal)
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makes sense.
