Trike front end

[adriandiamond]

Hi Ya'll, got a problem. I'm building a trike using a Yamaha XS750 as a donor bike and have nearly finished the trike back end. Tonight I thought I'd run it down the road to see how it goes. At the moment I have not got the rear brakes fitted so am relying on the front brake only. My problem is when I brake and the forks go down, my front mudguard catches the exhausts. Is there a way I can stiffen up the forks? does this make any difference to handling? I know I can raise the forks through the trees by about 3/4" max but I don't think that will be enough.
Any thoughts guys.

If you want to see the photos of the rebuild go to www.adiessite.piczo.com and click on "Trike Things". there is also a second page that I have just started.


Adrian

[Manky Monkey]

"Trees"?. How very colonial!     You mean "yokes" Sir!
The forks would have to go DOWN through them to give you more clearance rather than up. Our Manky frames are very low. The forks are standard length but because the headstock's so much lower than standard, the front ends are pushed out at more of an angle, ("rake"). That gives us more clearance. It also means the forks don't travel as far as they would at the normal angle, effectively giving us stiffer front ends, (!!). Another useful side effect of more rake is greater stability at speed, though the down side is heavier steering at very low speeds.
None of which helps you does it!
Increasing the volume of damping oil in the forks will stiffen them a little. I also ran my last trike on normal engine oil in the fork legs cos it was thicker than fork oil, though I was never sure if it made a difference. Or you can preload the springs by fitting a solid metal slug on top of them. Some bikes have these as standard, (I think the XSs might), so you could experiment with longer ones.
Or remove the front mudguard!

[adriandiamond]

Where did I get "trees" from then? Or are you "Yoking"? yeh, I meant fork down.
God I'm tired tonight.

I'll start by pushing the forks DOWN through the YOKES and replacing the fork oil with some treacle or summat to stiffen it up. If this doesn't work I'll have a look at compressing the spring.

Cheers Andy

[longboarder]

Our Manky frames are very low. The forks are standard length but because the headstock's so much lower than standard, the front ends are pushed out at more of an angle, ("rake"). That gives us more clearance.
Another useful side effect of more rake is greater stability at speed, though the down side is heavier steering at very low speeds.

Out of interest Andy, what angle do you run your headstock's.
Cheers Dom.

[Manky Monkey]

Hiya.
45 degrees -ish. It's never actually measured. The rear wheels & tyres determine the height of the axle off the ground. The prop runs horizontally & connects to the gearbox so that sets the height of the engine from the ground, The tank has to sit above the engine & in a position that looks right & between all those set measurements the forks have to sit in a position that allows a decent amount of turn & not foul the radiator or anything else -so it sort of works itself out. 

[longboarder]

How heavy do you find the steering at that angle, i.e. around town & lane's etc.
Mines a bit more than 45 & it's pretty heavy have got to do some work on it at that end so might try dropping it back a bit.

Dom.

[Manky Monkey]

Wouldn't say it's unrideable but then I've always had chops & trikes so I guess I'm used to it. As I've just said in another thread, we use wide, big diameter bars to give plenty of leverage. Seems to work for us. Flap's orange trike's got a bit more than 45 degrees & the only real problem is he's got a turning circle in the super tanker class. 3 point turns everywhere you go. I'd say 45 is a good balance between looks & practicality.

[trikerpete]

Rake whats that 

just kick it out till its right 

this guys got the right idea 

[adriandiamond]

Over here in Lancashire..................pretty useless, as stupid drivers park on each corner of the road. So when you pull up at a "T" junction and nose out to look for traffic...............SMACK, BANG, CRASH
there goes the front end.

But me in my infinate wisdom have come up with a plan....................oscilating cctv camera mounted on the front mudguard and wired to a screen on the handlebars...............voila.

[Little Miss PMT]

Increasing the viscosity of the oil will only help on the rebound. If you need to change the compression I would first of all remove the springs and measure them against the spec in the book and replace them if any more than 10 mm shorter, make sure if they are progressive springs they have been fitted the correct way round.  If this is ok I have added spacers up to 1" to tighten up the front end.

Mark

[Manky Monkey]

Thanks Mark. We get very little fork travel anyway due to the amount of rake. More oil, rather than thicker, seems to make a difference to the nose diving Adrian was getting, but thicker seems to smooth the action a little.

[Little Miss PMT]

You get more travel than you know. I spent hours on the mill making an alloy bracket for the very "feature" chrome horn, only to find that when you hit the brakes hard it made a 1/4 indent in the from mudguard........................ Turn the bracket upside down, no horn on display, no problem :-)

Any day that is not a school day is the day you die.

Mark

[jt jock]

Ive been allowed my own account. 

Any day that is not a school day is the day you die.

[Manky Monkey]

Flap's got the most rake & the least ground clearance on his trike. I seriously think we're gonna have to fit a sump guard before he hits the streets -literally.

[Manky Monkey]

Woo hoo!
A born again newbie  Welcome back then Mark. Why JT?