Anstey Shimmy

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simon.holyfield
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Re: Anstey Shimmy

Postby simon.holyfield » Thu Jun 28, 2018 1:36 pm

Leejm wrote:So am I right in thinking there will always be some wayward movement on the rear due to the fact there is no dampening action on theses units without going to Davids method? The stronger springs help but then you lose some action?


I think so - plus the fact that the brake side seems to deflect first on braking, leading to some small lateral deflection at the wheel rim.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
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http://ariel-square-four.blogspot.com

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Leejm
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Re: Anstey Shimmy

Postby Leejm » Thu Jun 28, 2018 1:50 pm

How bad does it feel Simon? So I know what to expect
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rschurr
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Re: Anstey Shimmy

Postby rschurr » Thu Jun 28, 2018 1:58 pm

david.anderson wrote:My 4 was initially fitted with sidecar plunger springs and I found that I may as well ride a rigid frame.
A few years ago there was an article in Cheval on the use of a period friction damper on the Anstey plunger. Dimensions were given in the article.
DSCN1659.JPG


Hello David,


very fine solution! Exactly what I am looking for! Is it possible that you can give me / us the dimensions or drawings of the sheet metal components?
I would like to go to a laser cutter and get an offer for these parts. Maybe I can even get a small series for a reasonable price? Others who are interested can get that from me.
Rudy
1923 James Model 12 500ccm v-twin -- 1960 Chevrolet Corvette C1
1926 Douglas EW 350ccm flat-twin -- 1967 Chevrolet Corvette C2
1936 Motosacoche 500ccm single --- 1979 Chevrolet Corvette C3
1948 BSA A7 500ccm parallel twin -- 1955 Ariel Square Four MKII :!:

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simon.holyfield
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Re: Anstey Shimmy

Postby simon.holyfield » Thu Jun 28, 2018 3:31 pm

Leejm wrote:How bad does it feel Simon? So I know what to expect


Not too bad, if you are expecting it. It feels like your rear tyre has skidded sideways very slightly and then regained grip, but it only happens as the brake engages - once its engaged its fine. Then when you take the brake off, you get a similar feeling in the opposite direction, but again when the brake is off everything is normal.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
http://ariel-square-four.blogspot.com

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PeterW
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Re: Anstey Shimmy

Postby PeterW » Thu Jun 28, 2018 9:33 pm

Have you grabbed the wheel and tried to twist it in the frame? Might be able to see where the play is.

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alan.moore
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Re: Anstey Shimmy

Postby alan.moore » Thu Jun 28, 2018 11:36 pm

Simon,
A couple of ideas that may help track down where the play is:

If your local bike MOT testing station has a rolling brake tester maybe you could try it on that and you should be able to see where the play is.

Mount a Go-Pro / SJcam type camera and record the area around the suspension / drum.
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simon.holyfield
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Re: Anstey Shimmy

Postby simon.holyfield » Fri Jun 29, 2018 12:10 am

All good ideas, thanks guys. I'm away working at the moment, so I'll probably have a look at the weekend.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
http://ariel-square-four.blogspot.com

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Re: Anstey Shimmy

Postby david.anderson » Fri Jun 29, 2018 9:47 am

Rudy
The dampers were made based on the article by Roger Harris in Cheval August 2011. There is a copy in the members area.
http://www.arielownersmcc.co.uk/members ... lector.php

The damper uses the Ariel steering damper star washer and friction discs so the size of the damper is made to suit the friction discs (2 ½” dia). The 2 arms are a different length (4” and 5” c-c) and the width of the arms is 1”.
I used polyurethane trailer leaf spring bushes for the ends and cut the length to suit. The offset on the bushes is adjusted top and bottom of the damper arms to suit the alignment between the mounting points. I made my wheel spindles and they are a little longer than original so I made my offsets to suit. There is a sleeve within the bush that is a little longer than the bush to provide end clearance and allow the bush to pivot. The outer size of the sleeve is to suit the urethane bush and the inner to suit the fixing bolt. The top pivot is an extended mudguard mounting stud 3/8” at the bush however I only used a 5/16” high tensile bolt threaded into the axle.
I use a nylock nut to hold the tension on the damper, and it does not need much tension. The damper does of course work in both compression and rebound.
I will be out of internet contact for about a week but if you need anything further please PM me and I will reply when I get back.
David
the photo below shows how the end bushings are offset to one side and the other to give a good alignment.
DSCN1661.JPG

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rschurr
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Re: Anstey Shimmy

Postby rschurr » Fri Jun 29, 2018 12:40 pm

Thanks David,
that helps me a lot!
Cheers Rudy
1923 James Model 12 500ccm v-twin -- 1960 Chevrolet Corvette C1
1926 Douglas EW 350ccm flat-twin -- 1967 Chevrolet Corvette C2
1936 Motosacoche 500ccm single --- 1979 Chevrolet Corvette C3
1948 BSA A7 500ccm parallel twin -- 1955 Ariel Square Four MKII :!:

MARK.WALSH
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Re: Anstey Shimmy

Postby MARK.WALSH » Fri Jun 29, 2018 9:14 pm

Chaps
all good ideas with the damping and well needed with the Anstey set up.
I never just use the back brake due to the strange effect on grab - as described a bit like a loose wheel for a second or two. Front brake first followed by the rear for best results (and that's not great)
I also notice the shimmy feeling is more pronounced when braking at a junction down a hill where the weight is more on the front end.
I guess it is due to the plungers not moving simultaneously due to all the extra linkages and a bit of slack throughout the system , but I could be wrong. I have thought of adding modern dampers as used on modern bike steering systems but never explored this fully. The pictures shown look like an easier option and if it helps...why not.
Mark


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