Hedingham damper unit

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DessieH
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Hedingham damper unit

Postby DessieH » Fri Apr 21, 2017 1:34 pm

Hi,
I have an R100RT with a Hedingham XL on it , but I think the damper unit may not be working as, when I hit a bump, the sidecar leaps into the air with a resounding bang .The unit is an unusual thing which seems to provide damping in both directions . Can anyone explain how it works and where can I buy a replacement ? Am i right that a non-working damper would do that ? Hedingham seem to have collapsed again ,so there is no help there.
DessieH

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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Fri Apr 21, 2017 1:42 pm

Does the same happen when the sidecar is loaded?
Keith
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Re: Hedingham damper unit

Postby DessieH » Sat Apr 22, 2017 11:39 am

HI,
I'll check how it behaves with a load.
Dessie Haughey

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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Sat Apr 22, 2017 11:51 am

I posted another reply to your post in the 'other place' (see below) before I saw this, but yes, try it loaded.

"With no load, the spring rate on the torsion bar may be too high to allow the bar to twist when a bump is encountered. Is the sidecar new to you? If it is, a previous owner may have set it up for a passenger and full load of camping gear. My EZS is set up for my 53kg wife and just maybe 20kg of luggage and even it bounces a bit when unloaded."
Keith
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Re: Hedingham damper unit

Postby DessieH » Sat Apr 22, 2017 3:17 pm

keith,
I've just tried it with a load (my wife ) and it is much better but she says it's very uncomfortable over bumps . When I bounce the sidecar at rest the damper unit only moves 1.5 to 2mm . It seems as if I have only got springing but no damping . The damper unit is really peculiar in that it seems to have damping in both directions , the question is who made them for Hedingham and can they still be bought ?

Dessie Haughey

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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Sat Apr 22, 2017 5:16 pm

It still sounds as if the torsion bar spring rate is too high and this is resulting in the suspension lifting the chair instead of twisting to absorb the bump. I don't think the damper is the problem as, from what I understand, there is no conventional coil spring associated with the damper unit unless the damper is seized.
Can you take the damper off and run it through its full stroke to check the range of movement and resistance in each direction. If the damper is too stiff or seized, maybe Hagons can help rebuild it. If it turns out to be that the torsion bar is too stiff, then I can't offer any advice I'm afraid.
Keith
PS. It would not be unusual for the damper to have resistance in both directions, usually more on the rebound stroke than compression
Last edited by keiththeoutfitter1 on Sat Apr 22, 2017 5:29 pm, edited 1 time in total.
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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Sat Apr 22, 2017 5:28 pm

Dessie, there is a Hedingham owners club and they have a technical officer who may be able to help. All contact details are at the bottom of this page:

http://hedinghamsidecars.co.uk/h.s.o.c..html
R1200RT
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Re: Hedingham damper unit

Postby DessieH » Sat Apr 22, 2017 6:31 pm

Keith,
I know there is and I e-mailed the technical officer about a week ago but there has been no reply . I have also phoned the guy I bought it from whose name is on their web-site and have left a message but,again , no reply . Maybe they only talk to you if you join the club . It's proving very difficult toget info about the damper .

Dessie

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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Sat Apr 22, 2017 7:10 pm

Firstly, make sure the damper is the problem and not the torsion bar.
If the damper is the problem, are there any markings stamped on the body? It is unlikely that Hedingham had units specially made, they are probably off-the-shelf units originally designed for another use and Googling the stamped name or part number may give a result.
I note that the person given as the technical officer for the club is Keith Walsh, who is the owner/director of Unit/ Hedingham sidecars and if his company has just gone under he may not be answering non-urgent mails at the moment.
Keith
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Re: Hedingham damper unit

Postby DessieH » Sun Apr 23, 2017 5:12 pm

Hi,
I'm pretty sure I have got a spring but your suggestion is worth trying .I reckon the way to try it would be to take off the damper completely and see how it behaves without it . There may be maker's marks that can't be seen until it's off . Does that seem a sensible way to go about it ?

Dessie

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keiththeoutfitter1
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Re: Hedingham damper unit

Postby keiththeoutfitter1 » Sun Apr 23, 2017 6:41 pm

That seems a good way to approach it. Check the damper action once it is off the chassis. I don't think there will be a spring incorporated in the damper unit as the torsion bar provides the spring medium and the damper is only to control unwanted oscillations, unless of course someone has added a coil over damper unit to add extra spring poundage to that provided by the torsion bar. If it still launches into the air with no damper on, then the torsion bar is too stiff.
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stevedowling1
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Re: Hedingham damper unit

Postby stevedowling1 » Fri Apr 28, 2017 5:06 pm

Any chance of a photo of the damper? Depending on how old your sidecar is it is possible it has been modified by a previous owner with a non standard damper being fitted. Very early Hedinghams didn't have dampers. The clanging may be the torsion bar lever that the wheel spindle is attached to hitting its return stop. I have an R100RT with a Watsonian Monza and on tight left bends if I hit a deep drain in the gutter the sidecar will easily bounce into the air if there is no one sitting in it. Don't forget, the air heads are quite tall bikes with a high C of G and sitting bolt upright as on the RT makes matters worse.
Regards
Steve

1994 R100RT with Monza Sidecar
1995 MZ 250cc Saxon Tour (nice little runabout)
1970 MZ 250cc Supa Five (in bits)

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Jaythro
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Re: Hedingham damper unit

Postby Jaythro » Sat Apr 29, 2017 8:20 am

Advice given in the answers above is sound. Isolate the defect (Diagnose and don't assume)

Dampers are "usually" single action, as in they prevent the rapid extension of the spring after it has compressed and I can't understand why a chair would have anything but a standard extension damper

I would take it off and try it to see how it responds, if you have a particularly stiff action both ways it may actually be seized or the adjustment if there is any set incorrectly

Chair suspension (Especially) has to be fairly supple and uniform or you end up with your scenario where the chair influences the bike geometry by taking flight and as any of us who have spent time piloting chairs know BIke -chair geometry is crucial or you get the most difficult ride imaginable!!
"Put your Ass on a motorcycle and ride with an attitude and the "Grim Reaper" will ride in your shadow!"

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Stitch
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Re: Hedingham damper unit

Postby Stitch » Sun Apr 30, 2017 11:08 pm

Hi Dessie,

Along with all the sound advice above, something else that can affect both handling and comfort is the age/condition of the tyre. I replaced the one on my XL a couple of years ago and J. says it absolutely transformed her ride. The one I replaced was ancient to say the least and there was virtually no give in the sidewalls. Along the same lines, what pressure do you run in it? Too high and there will some of the effects you've described.
Incidentally, Kieth Wash, as I understand it, has retired. That's not to say he won't give any advice but I don't think you'll find him at Unit Sidecars.
Cheers, Stitch.
'07 BMW G650 XCountry (black/silver)
'02 BMW R1100RS SE (red)
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'77 Honda CB400F Super Sport (red)
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Re: Hedingham damper unit

Postby PhilO » Tue Jun 20, 2017 12:28 am

Try reducing the tyre pressure in the chair wheel. Tyre pressure depends on the weight the tyre has to support and still maintain its designed profile.
Put some bathroom scales under the wheel and you will be surprised to see how little weight there is. I run both my Monza and ST2 with a mini 10" tyre at 10-12 psi. On the Mini it runs at 24-28 psi.


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