combo/outfit question

[Zaphod]

just fitted a watsonian chair to a buddies bike (side by side child/adult wide body on fj1200) ...

watsonian gave us instructions how to fit (1/2" toe in, lead the bikes rear wheel by 20% of the wheelbase with the sidecar wheel and the bike leans away, no angle specified) ...

ok done all that, now the problem is we suffer serious headshake as the power is applied (not tried on the road yet so first gear only round my tarmacced yard), i'm wondering if it may be down to too much lean out or if the front suspension has compressed too much (looks very low now)...

i last fitted a chair 20 something years ago (watsonian tandem C/A on sohc750 Honda) which after lots of trimming rode reasonably well (90mph plus) with only a little shake under 15mph ....

any experienced chair users suggestions appreciated (i wanna minimise shake before considering a damper)....

already thought of the possibility of fitting external springs on the forks to assist the load carrying (good idea ? ), thought of slugs "inside" the forks to help extend old springs (bad idea ? )....

can't afford leading links at the moment, not sure how beneficial they'd be anyway....

gotta try and keep the costs down as this combo is for a disabled single dad who really wants to be able to take his son out with him without having to use the car all the time...

so all suggestions/hints appreciated

[Blackjack]

First thing I'd try is altering the pre load on the rear suspension.

Wind it up to maximum.

Cheap and easy. :D

Actually, if it's one of those chain driven shock adjusters and its seized, scratch the "easy".......

[Mr. Cool]

Don't have any experience in chairs, but i think if you put extra springs you'll need to do something about the hydraulic for the whole to work properly...
But then, what do i know about that?
Should be working or sleeping or drinking or... :D

[Mr. Cool]

http://www.cyclesidecar.com/Guides/document_downloads.html



Read Hal Kendal's stuff. He's probably the worlds leading authority on chairs.

You'll find the answer somewhere in the stuff he's written.

Tks a lot mate, 'not intending to build one myself at least for now, but there isn't such a thing as learning too much about all kinds of bikes. :cool: As i said before, should be working by the time i posted my "contribution", but this bloody forum is getting an adition for me. Did you noticed how many of us were online at that time? 2... :D :D
Again, tks for the link, this is probably the best i'm getting from the forum, excellent info on several matters and valid opinions about serious questions, the rest is just plain fun. :)

[Mr. Cool]

Did you noticed how many of us were online at that time? 2... :D :D


oops, sorry Happybiker, it wasn't you, it was Blackjack 'n i...

[TektroG]

I just sold a Watsonian Oxford K100 outfit. You need a damper but the good news is a VW Bettle one is ideal. Try GSF car parts for best prices - bout £20 when I had to replace mine.

[BigBod]

If you have done all the setting as per Watsonians instructions then I would suggest a damper will help, try it on the road first, I bet by the time you get into second gear the wobble is gone.

I know you can't consider leading links at the moment but questioned if they are worth it, trust me, they will make any outfit or trike an absolute joy to ride. The improvement in handling is huge. Another option is to rake the front end, this will help lighten the steering and eliminate some of the wobble on take off.

The lean out of my bike is only about 5 degrees if this is of any help. If the lady riding it is a novice, I would suggest hardly any lean out of the bike at all. Too much lean out and the chair will feel lighter on the left handers and feel like it's gonna lift off the road.

[Zaphod]

Thanks for all the replies so far (specially the Hal Kendal link, downloaded and saved), i knew i was getting things close to rideable and was on the correct path, H.K's instructions/explanations appear to be very clear and easy to understand (which will help my mate understand the way things need to be)...

hopefully as time progresses he will be able to afford l/links but as things stand we'll do the best we can with what we have...

one question tho ....
would it be worth putting extra springs round the stanchions below the bottom yoke to assist the forks ? (thinking of old Triumph/Bsa springs if they'll fit), i'll experiment with oil weight for the damping then if considered necessary....

Cheers for the tip about the steering damper from GSF

Virtual beers all round :D

[johnr]

its all down to the geometry, a combo is an unstable mix of bike and chair and handling is always going to be compromised, and if you are running telescopic forks then im afraid that some degree of head shake is innevitable. get a vw beetle car steering damper(the old aircooled beetle, not the modern golf in a bodykit one) theyre cheap and robust, forget bike steering dampers, they arent man enough for an outfit, no matter how much you spend on one. make sure you have a rose joint on the end and fit it to the bottom of the l/h fork leg, spacers above the springs might help with the weight as will a fork brace, best thing though is leading link forks, however they dont come up often and arent cheap new either. make sure that your sidecar is sat level with the ground both side to side and back to front. , make sure that your sidecar mounts are completely rigid, no flex at all. as for lean out, it only needs a tiny bit to help it turn, if the rh bar is a half inch closer to the ground than the l/h one, then thats enough, make sure your tyre pressures are ok, run them a bit higher than for solo use, to try and eliminate some of the flex in the sidewalls of the tyres, that you will get. 25mm tow in is a good start, and sidecar wheel lead should bebetween 9 and 12 inches, doesnt need much more than that.
however, the shake isnt going to go away till you fit a damper, thats just the nature of the beast im afraid. and dependant on the width of the outfit (wider is better) and the weight of the chair (heavy is good) then you might also need to put some ballast in the chair to help the guy to ride it without the chair popping skywards on every left hander.
if you have any questions or other probs, drop me a pm (as you may be able to tell, ive done this more than a few times, and all my outfits have handled ok)

[Mr. Cool]

make sure you have a rose joint on the end

'sorry to get in to this chat, but i'm soaking every bit of info i can get here.
As i'm not THAT familiar with the english language, what's a "rose joint"? I'm sure it isn't a joint rolled with rose paper :D

[Jus1]

here ya go fella .... one rose joint

http://users.bigpond.net.au/lachlan/tech/img/rosejoint.jpg

[Mr. Cool]

here ya go fella .... one rose joint

http://users.bigpond.net.au/lachlan/tech/img/rosejoint.jpg

tks a lot, mate.
So a "rose joint" is a "rótula"(portuguese), got to give you something back... :D :cool:

[johnr]

rose joint will allow the up and down movement of the forks to hapen without adding any friction to it, and will also allow the steering to pivot, meaning that the damper will only offer resistance as it slides in and out.

[John Hopkins]

The last time I rode a combi was in the 60s..an old Matchless 600 twin...if I took the sidecar off the steering was all over the place, and I had to adjust the damper..If I put the sidecar back on without adjusting the damper the bike would only go in a straight line...all the old British bikes that I rode had a big damper adjustment wheel in the center of the forks...However that is no help at all in your case other than to suggest that the damping is probably preset for solo riding at the factory and maybe you should contact the manufacturer...John

Just read up on my Kwack GT750 manual and they are set at the factory but if the steering head bearings are shot that could cause your wobble..if the bearings are ok..ride it very slowly down to your bike shop and let them adjust it...from what I've read it is just a matter of tightening the top nut...BY THE CORRECT AMOUNT..

[johnr]

ive a friction damper on my 53 bsa, trouble with them is they arent consistent, when they get warm they lose damping ability, same as when theyre wet, so you tighten them up, then it cools down, or dries out, and suiddenly the steerings awfully tight!! :D

[Zaphod]

ok folks, a little update.....

think we've eliminated the worst of the shake :D although it's not been fully roadtested yet, ridden it without and with passenger around the yard and just the tiniest shake under power so it's looking like it can be ridden thru :D

obviously there's gotta be more testing at greater speeds, but thanks to the descriptions/directions given in the link earlier it's simplified the job hugely...

the only bit i found difficult was getting the toe-in correctly, i ended up disconnecting all but the centre two fittings and looping a thin rope round the one fork leg and the front of the chassis and then twisting it till the measurements were correct then re-attached the other three fittings carefully and making sure everything was rock solid before removing the rope...

unfortunately i feel rather crap at the moment so further testing and the wiring isn't going to happen for a day or two ....

anyway, thanks to all for your help :D