Steering issues.

[Nathan S]

Do these have cartridge forks?

Yes. Ballard and Jess Gardiner sometimes run TTR forks on their WRFs - no doubt the revalve and resping them like crazy, but they're pretty good.

[Canam370]

Old racer explained it in terms adjusted for me ...."Trouble with the front, more throttle. Trouble with the back, less throttle"

[pancho]

Old racer explained it in terms adjusted for me ...."Trouble with the front, more throttle. Trouble with the back, less throttle"

Back in the Moorebank days in the heavy sand section the criteria generally accepted was 'power on , get the front wheel up out of it'
pancho.

[JC]

Nathan, I'm not 100% sure whether yr describing the front end tucking under (falling in) or washing out, but I think you mean tucking under.

My maths/physics teacher always used to say, "work it out from 1st principles", so here's a go (as I understand it):

As you turn the bars, you lose trail till it becomes zero then goes negative (ie lead not trail).
When you lean, it also brings into play the effect of the bike's C of G & the mass of the forks etc in front of steering centre-line (pendulum effect). Both those gravity forces work to overcome the self-centring effect of trail when you turn & lean.

That's why the wheel flops to the side when you put the bike on the side stand. Its the same effect as tucking under in turns.

The usual fix is more trail, usually via more rake &  as you know there's several ways to do that - push the forks thro triples, softer rear, sit further back (a trade off w losing front grip tho of course), gas it more etc, mentioned above.  Even tyre pressures can make a diff.

However one of the 1st things I'd be checking is if you can mount the big lights closer to the steering axis. As is, that extra pendulum effect will be overcoming the self-centring effect sooner as you turn & lean, making the tucking-under worse (happen sooner). Be mindful of the centre of gravity too.


Why does it happen in soft ground/sand & not on hard track?  2 things: as the tire sinks more under weight transfer in cornering, the effective dia becomes smaller so trail is less, but also, the contact area is considerably longer having another (perhaps larger) effect on shortening trail & reducing the self-centring effect. (Too-low front tire pressure has similar effect.)

Thats why its usually a good policy to sit back further & keep the power on in sand

[John Orchard]

I'm think of another angle .... front tyre, what size is it?  3.00, 2.75, 80/90, 90/100, 90/90?  Is it trail or knobby?  Maybe a wider tyre might sit higher in the sand and not tuck?

[JC]

Yeh, good point - effectively increases trail in the sand

[Mick D]

I reckon JC and JO are on the money. I would be going for floatation and height with wide and high 90/100 on the front. Basically experiment. Drop the rear spring tension off a mic hair if there is any leeway available and up a click or two on the rear rebound too. Make sure your forks are as low as you can get them in your top triple. Definitely different riding technique for steering 2S's and 4S's in the situation you describe.

That’s how we used to set up our big bores for Stockton Dunes. We used to live on a 100 acres on the dune fringe. I could really notice the difference in my 465G on the sandy/loamy access tracks if I didn’t take the time to put my forks back down in the triples after trailing on clay based Terra fir-ma.

If you decide to try Stockton Dunes while you still can? You will need two really good rim locks on the rear. Fair dinkum, it is a blast that you will not forget

[Mick D]

Also rode a stripped down DR500s on the dunes for a while. Bloody hard work I remember, compared to the pleasure of blasting the 465G.

[Nathan S]

Thanks for all of the input gents.

Will take it out and experiment with fork heights next weekend. Another interesting discovery was the compression adjustment on the shock was actually two clicks out from full hard  , which is probably a significant part of the problem.

During the week, I made new headlight mounts to bring the lights back as far as I can - got them back about 30mm.


I also removed the speedo and idiot lights.

The new footpegs:



(This peg is a bit clunkier/uglier than intended, because I built it from memory and forgot that it sat inboard of the mount and then had to modify it).

The high seat - reusing original cover is ugly but also very cheap:


The new top triple. Its from an '89 CR125. Compared to the stock TTR triple with the bars in the foward-most position, it puts the bars foward another 5mm and up by 5mm. I'd prefer another 5mm further foward, but this is still a useful help. It went straight on, except for the centre hole needing to be 0.5mm larger.


The lights:

Obviously, they're pretty bright, but the back ground of this photo (which was taken seconds earlier) shows how much the camera has compensated for the lights :

[pancho]

 Re #23 The 1st pic titled 'the new footpegs'-- That is not a crack in the weld on the frame I hope?
pancho

[Nathan S]

No. Just the way the camera flash caught the slighly lumpy weld.

The bike has had a very easy life (until now...).

[Mick D]

Dakar?

[maico police]

Dakar?

Maybe oil the chain first....  :'(

 

[Slakewell]

I have found on my current model YZ 2 stroker that the forks come with far too much compression damping and way to much pre load.
I turn them to the softest setting used the lightest oil and cut the springs down. I can now feel the front and turn at will the bike is so much fun to ride.

[Nathan S]

Update, if anyone cares: MASSIVE improvment in the way the bike rides.
Previously, you could go respectably fast on it, but it took a LOT of effort (both brain and physical). Now you can go faster with less effort - its so easy to ride at a decent (not amazing) pace that I'm worried I'm going to have a big crash on it... I mean, up to the point where the average suspension is an issue, you can go pretty quick with no real effort - but it gets ugly very quickly and you mind starts to wander before it gets ugly
Had fun hunting down a KTM350 (among others) this morning - but then failed to catch an '83 KDX250 too...