leading link front end

[stevie]

hello. is there any experts in LL forks

:AGGHH: im having a little problem with my leading link end , ive built
for my trike, its bouncing a bit down the road, it works well on bumps, speed ramp and even going over small animals , but when im on a motorway about 50mph and over it bounces like the shocks where iron bars,
shocks are out off a kawaski vulcan 1600 which must be far to heavy but
are needed just to keep the end up and the swing arm straight
she weighs about 25 stone (350lb) on the wheel i have the and trail down to about 3" which is not bad i moved the shocks to the on temporary brackets but that didn't work,
i think the shocks are far to hard but i dont no what way to move the
shock brackets so i can put lighter ones in ,
i was also thinking the fork pivot is to far back and i mite need to
be moved closer to the bottom of the shocks,
so its closer over the axel ,which i was thinking it would put the
weight more on the axel
than the back of the swing arm,so i could put lighter shocks and
springs in
i would like to be sure before i chop it
up .
i have more pictures and sizes if needed

cheers! stevie

 

[Rsw]

So is it the tire bouncing on a smooth road or is it the shocks not working when you get over 50 mph?

 

[chromedome1964]

Before you try moving the shocks, try lowering the air pressure in your front tire. Drop it down to about 15lbs and see how it does. If you do have to move them, move the lower attachment point away from the axle and toward the pivot point. From looking at your pictures, this will probably require moving the upper mount point higher on the forks. This will give the rockers more leverage and make for a smoother ride.

That's a beautiful trike by the way!

 

[jtilmon]

You might check the fork tubes- they may have some flex in them, they look pretty long for their size and you have quiite a bit of rake on them.

Suggest if possible get some one to ride or drive along side you and take of video of what is happening on the front end. Be careful and safe if you choose my suggestion.

 

[Rsw]

You might check the fork tubes- they may have some flex in them, they look pretty long for their size and you have quiite a bit of rake on them.

Suggest if possible get some one to ride or drive along side you and take of video of what is happening on the front end. Be careful and safe if you choose my suggestion.

I thought that to but the bail would act as a fork brace. Kind of need to know more about the bounce to see if it is a bounce or a shimmy or a shake and so on.

 

[jtilmon]

Possibility: some type of fork brace might help?
A fork brace certainly helped on my trike after raking it.

 

[Rsw]

Possibility: some type of fork brace might help?
A fork brace certainly helped on my trike after raking it.

But a bad tire even balanced will cause a bounce. I'v seen tires with zero runout shake. Spine them 180 degrees on the rim and they ride perfect. Dropping the air pressure down like chromedome said should tell you if it's a bad tire also.

 

[saab9k]

very nice job

 

[vwmaniac]

Your shocks are to hard, use some off a 550 or 750 bike, and also the end of the shock needs to be closer to the axle.<br /><br />
Your <span class="highlight">rake</span> is fine and you don't need no fork brace, at least not on your frontend, and by the way, very nicely done frontend.

 

[chromedome1964]

Coilovers are rated in pounds required to move the coil one inch. If it takes 400lbs to move the shock one inch, it may only take 200lbs to move it 1/2 inch depending on the progression of the spring. Moving the shock CLOSER to the pivot point and AWAY from the axle requires less compression of the spring, therefore less weight needed to compress it. It's all a matter of leverage.

Think about compressing the shock with a crowbar. Where you place your hand on the crowbar would relate to the axle attachment point, and the other end the pivot point. Moving the shock closer to the pivot point would make it easier to compress.

I can run Harley Fatboy shocks which are really heavy on my front end or Kawasaki 440 shocks just by moving the attachment points.

 

[caveman50]

Or you could use an air bag, want stiffer, add a few pounds of air, softer, let out a few. Works fine for me. Cheers, Cave

 

[jtilmon]

Stevie, Did you ever determine the problem with your trike?

 

[Pegasus1300]

As I remember from the old Earles Fork days on the 1960s R60 BMW the axel was much father away from the shock and the shocks were more verticale.More distance between lower shock mounting point and the axel will give you a longer fulcrum ( give me a long enough lever and I'll move the world)

 

[stevie]

sorry to all i havent been on for a wile:wave4:

but to answer every ones questions from the top down

ive tryed lots of things already moving shock forward at the bottom tire presure and my wheel dosnt need balanced and the front dosnt flex . ive made the front of all the right tuding. i was realy wondering was the pivot point in the right place or does it not mater:Shrug:
(i have looked at other LL front ends and the pivot was far closer to the axle)
shocks arent working at about 50mph causeing the front to bounce.
the shocks have to be this heavy or she wont stay up at the front , im thinking the problem mite be the damping is far to hard.

ThumbUpthank you all so far for all your help stevie

 

[vwmaniac]

Or you could use an air bag, want stiffer, add a few pounds of air, softer, let out a few. Works fine for me. Cheers, Cave

I tried the air bags and work great, great idea and thanks for the tip.

 

[stevie]

hello all , ThumbUp
well at the weekend i took the springs off the shocks to check how hard the damping was and it was very little so thats not the problem.
so i thinking ill go ahead and move the pivot point at the bottom of the fork legs forward to the bottom of the shocks.
i think if i do this it would put the weight over the axel more and not at the back of the swing arm,
so then i can put lighter springs in.
because as i have said earlyer i need the heavy springs to keep the swing arm up straight :gah
stevie

 

[Marty]

the bike looks great. the shocks are designed to work in a straight line so the top forward and up a bit,bottom back as well. the way it is it is probably binding before it reaches it travel limits..........Marty

 

[slick rick]

Marty,,, I'm sure you seen that was a older post but I hope he responds and lets us know ,,,that's a fine looking front end he built !! I do think your right the shocks looks as though they would bind in that position , almost as though their pulling instead of pushing ......ThumbUpThumbUp

 

[stacebg]

one thing that needs to be done here for sure... the pivot should be below the axle usually an inch or so.... and i think moving the lower shock mount back would help a lot .... maybe about 1/2 way back to the pivot..... with that long front end you dont need very heavy springs ... and changing the mount will change the leverage..

you can see here the pivot just a little below the axle... an with driver is a little more.... this setup was perfect... guessing the springs are lighter and the lower shock mount is back a tad
the the load on the front compared to yours is probably 3 or 4 times as heavy and ..... so in effect your springs are probably 5 or six times as heavy

 

[butchvoss]

I have a question guys . does this type of fork make steering on a heavy trike a little easier to turn. thanks.