OzVMX Forum

Clubroom => VMX Sidecars => Topic started by: asasin on October 16, 2013, 12:15:04 pm

Title: What Did I get wrong
Post by: asasin on October 16, 2013, 12:15:04 pm
I hope I wont get too shot to bits on this one , I am after some usefull input.
 I built a sidecar for my girls to ride from a KT250 trials sidecar unit. I looked at the mX pictures etc and redid the measurements to suit and built a new wider chair etc.
 The problem I have is that it wont turn with any power on at all. I have used forks on the front insted of swing arm set up and I think this is the problem as the frunt can lift up when power is applied . NOT wheelstand but lift up approx 50mm on the fork travel.
 It is downright bloody dangerous as it is and before I gas axe it up I was hoping some of you could clue me in to sort it out. WE dont have any chairs here in NZ so it is not possible for me to go and look at one in the flesh
 Cheers
Title: Re: What Did I get wrong
Post by: shelpi on October 16, 2013, 12:41:38 pm
need pictures and mesurements just for starters ;)
Title: Re: What Did I get wrong
Post by: bazza on October 16, 2013, 12:44:10 pm
Photo of montesa cota side car on nett and 3 shots of auzie KT250 side car riding over a vw. photo from wrong side but you may be able to contact him?
Mike
Title: Re: What Did I get wrong
Post by: EML on October 16, 2013, 12:55:17 pm
Two things.
1/ passenger is in the wrong spot......look at the starts of races and watch what happens when the passenger moves...sometimes the outfit will lurtch one way or other...depending on the drive.
2/ your entry into the black arts begins (wohahaha) There is more about front ends on sidecars than you will ever know.
Basically though...and others will agree(or not) that it is alot to do with the patch that the front wheel/tyre puts on the ground. Remember it is a sideCAR. Therefore the steering is not a solo anymore and the steering reacts like the front wheel of a car...it rolls over as it turns...and looses contact with the ground. Picture in you mind a solo tyre as you turn...its patch becomes narrower but the length of it stays roughly the same, because as it rolls over the whole wheel goes too. Now picture as sidecar wheel, it doesn't roll over but rather turns up so that the patch actually shortens AND becomes narrower...ooops, no grip!! Very similar to the front of a car hence the wear on the inside front and the need for several wheel alignment methods on the one car.
Therfore and hence, one must drive a sidecar and avoid front end slippage by climbing over the front end and/or sliding through turns much like a quad(which over comes the problem with dual wishbones etc... Is That CLEAR !!
Very good thread on ADV site under Hacks....but you my use up much of your life reading it and the other threads on there :o
Title: Re: What Did I get wrong
Post by: Davey Crocket on October 16, 2013, 01:06:51 pm
Maybe it's the limp wristed Kati Kati KT Killer gone soft in his old age.....put the black pom on it....he'll tell you whats what.
Title: Re: What Did I get wrong
Post by: shelpi on October 16, 2013, 01:14:32 pm
 ;) onya EML ,please listen to what this man has to say and you will luv the black art in no time :o 8) :)
Title: Re: What Did I get wrong
Post by: asasin on October 16, 2013, 01:20:32 pm
Maybe it's the limp wristed Kati Kati KT Killer gone soft in his old age.....put the black pom on it....he'll tell you whats what.
Yea I forgot he was a copilot in the past . There aint nothing limp about my Wrist , Ive seen your Hawaiian shirt dearey ;)
 Thanks for the input guys. Being a car racer I understand what you are saying . what seems to happen is the weight transfers suddenly to the back and the front goes away.
 I will try to get a photo up for you .
 Cheers
Title: Re: What Did I get wrong
Post by: EML on October 16, 2013, 05:10:10 pm
Remember also that the trials solo is already set up to loft the front easily so maybe look at moving the pegs forward and lowering the front end up through the triple clamps.
Title: Re: What Did I get wrong
Post by: shelpi on October 17, 2013, 12:35:05 pm
we had a young chap saying his kit wont steer :o so we took it for a spin and relised the power was lifting the front, so we detuned it, problem solved then as he needed (wanted) more power we gave it to him ;) he just got 3rd Aussie Nats ;D we never did do anything to the front end :o
Title: Re: What Did I get wrong
Post by: Tim754 on October 17, 2013, 08:06:20 pm
1/ passenger is in the wrong spot.... Thank you EML for the most logical first up answer to the apparently dubious handling of sidecars. Asasin my friend practice different rider/ passenger operational positioning, on a quiet afternoon on some easy turf.
 Before metallic surgery. Cheers Tim754
Title: Re: What Did I get wrong
Post by: shelpi on October 19, 2013, 10:30:53 am
1/ passenger is in the wrong spot.... Thank you EML for the most logical first up answer to the apparently dubious handling of sidecars. Asasin my friend practice different rider/ passenger operational positioning, on a quiet afternoon on some easy turf.
 Before metallic surgery. Cheers Tim754
;) :) :D ;D 8)