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Tymono / Rushton Chair (Twinshock Conversion)


slogger
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Having had a try in the chair last year I am putting an outfit together to move from solo into sidecar next year. I have managed to get a very nice rushton clair off of a club member and am planning to pair it to TYMono I have in the garage. The rear shock is shot to pieces and once the outfit was paired with two riders the bike pitched right over to the right with the inside of the mudguard on the tyre! As the replacement mono shocks for this are getting scarce I have planned to do a twinshock conversion on the TY and would appreciate advice on shocks? The main thing I assume is spring weight? I am about 76Kg in kit as will be the passenger.

The main reason for the TY is it is my spare bike to get me going (I am sure if I really enjoy it, it may be changed at some point for another bike) and I am not worried about entering a twinshock converted mono as it is only at my local club who are trying to get a sidecar class going so are encouraging people to "have a go".

Any help or advice would be appreciated

Rob

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Hi Rob

Glad to here about some one else coming into sidecar trials.

My son and I built our own chair for our Bultaco. At this time we are using SM pro trials rear shocks with 50 Lbs per inch springs. they do seam a bit soft in the first inch or so of travel. So we have the prload wound up a bit. I'm 15 stone and my monkey's range in size from my 12 year old daughter through to my wife who's about 10 stone I think. I also changed the fork oil for two stops heavier I.E from 15 wt to 25 wt. this made the hole outfit less like a rocking horse and the front end much less likely to dive under braking.

Going back to the rear suspension the spring and damping rates you need will very much be influenced by the angle and how far along the swing arm you mount them. I.E the further away they are from the wheel center the more leverage there is and so the softer they seem.

Hope this helps

Paul

post-2720-0-70885400-1373370285_thumb.jpg

Edited by p@ul250
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Paul, thanks for that. I am talking to John Bull at RockShocks at the moment and they are advising 80lb springs.... Am also looking at stiffing up the front end as well. Cant wait to get is sorted and out on it!

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I was going to suggest Falcon shock absorbers Ltd to you as they also do a shock rebuild service and may be able to bring your TY Mono's old shock back to life.

http://www,falconshockabsorbers.co.uk

As I think I have posted before "Trials outfits are about as much fun as it's possible to have and still have clothes on"

I have attached a photo of a friends TYz outfit to inspire you and I hope you'll post photos of your outfit soon.

Paul.post-2720-0-47328100-1373387327_thumb.jpg

Edited by p@ul250
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  • 2 weeks later...

Falcon advised that they don't do TY mono rebuilds. Have ended up going for a pair of Rockshocks and doing a twinshock conversion of the rear which I am quite happy with. So another question re cambers, toe it etc???

Logic is telling me that with both the rider and passenger in place and the shocks loaded with their weight, the bike should be vertical and the chair flat (with a few degrees toe in). Did you get the bike vertical and chair flat with no load, bolt it up then adjust it or did you load both items, strap the bike suspension in position then bolt it up? Just wondering the best way to get the initial starting point???

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Hi Slogger

My son and I built our chair. So we started with the bike vertical and built out from there, then adjusted the sidecar's shock mounts to get the bike vertical when rider and passenger are aboard.

May be best to make the top front mount with a bit of adjustment in it at first, then fully weld up after you and your passenger have had a stand on it. Bear in mind that the bike will have about four inches of suspension movement and the chair only about two. So you do feel the outfit tilt now and then.

Some I have spoken to have the bike leaning in towards the chair when every thing is unloaded. So bike is upright when loaded.

( don't forget to have the tire pressure's set as it can make a big difference as to how the bike sit's ) We currently use 7 psi in the rear to counter the extra weight of the passenger and 25 psi in the sidecar's tire (any softer and you can feel the drag).

we have the sidecar wheel lead the bike's rear wheel by 9.5" But with my next one (a Beta Evo with a Rushton chair I will try 9") a track of 34.5" (to comply with ACU Reg's) and a toe in of 1.5" over the wheelbase of the bike.

I hope this helps and hasn't just confused thing's for you.

Paul

post-2720-0-94251200-1374177144_thumb.jpg

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  • 10 months later...

Very interesting, I'm reading through this and its giving me ideas!

I have one of these sidecars and think one day I would like to fit it to something a bit more user friendly as this time I will be on the bike rather than in the chair. So far its been on an HT/HS500 and a TriBSA.

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hi rob give norman at njb shocks a ring,, over the years he has supplied me with shocks for most of the outfits i have built and ridden he always seems to come up with the goods at a reasonable cost ,he used to be the top man at girlings so really does know how to set up suspension, good luck with the outfit . will.

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