TRX850 FORK LENGTH

[cobbadiggabuddyblooo]

780mm springs to mind on the length of the std TRX850 forks from the top of the fork leg to the centre of the axle.
Can anyone confirm this for me please as I no longer have any std fork legs and can't find where I wrote that info down.
measure including the cap if possible..

[Stu99]

780mm is correct Cobba, from top of fork tube to centre axle.
783mm measuring from top of fork cap, or do you need total height to top of adjuster?

[devlin]

I'll ask here so Cobba will see when he checks back.

What was the drop you used for the top yoke on your set up? Just looking at geeting something machined up and can't seem to settle on a drop. At the moment I am looking at 20mm center thickness with a 30mm drop and 30mm deep leg clamps. Almost mimicks the lower yoke in shape.

[cobbadiggabuddyblooo]

Cheers thanks Stu. That length is perfect as I make further notes to recall on the rebuild.

Devlin, look at the length of the forks you are choosing to use.
This is how I broke it down.
750mm is the length of the 98/01 model R1 forks from the top to the centre of the axle.
But remember on the TRX 18mm is fork length is set through the clip ons and they themselves are ressessed a little into the top yoke.
So I've placed a 10mm step down on the top tree and the added 20mm fork length through the yoke and clip on the std TRX forks/yoke gets me to the same distance with the 98/01 R1 forks sitting level on the billett trees.
With the 750mm r1 forks +
10mm step yoke +
20mm length through the top yoke =

780mm being the same length as std TRX forks

The 15mm of extra travel on the R1 forks (std trx 120mm, 98/01 R1 135mm) also deals with the running a 70 series front tyre which is absorbed in the sag figure.
14mm of the R1 forks through the top tree and 5mm shorter dogbones gives me a rake of 23.5*

Why they added the extra travel on the 98/99 R1's was there inherrant habit of lifting the front wheel in their early design, so with this little bit more length on the sag figure it gave you a little more front wheel traction before the front wheel became airborne out of the corners.
The R1 castor/frame angle on the head stock is 24*(TRX 25*) ,be aware of the different offsets on the trees from 35mm 98/01
from 02-03 which had 25mm offset being the same as the trx trees.
2004 onwards 30mm offset 15mm shorter fork length with only 120mm travell, 43mm forks and radial brakes.
Offset being a parrallell measurement from the centre of the stem to the to the centre of the fork tubes not to be confused with the castor angle in degrees.

http://www.totalmotorcycle.com/modelhis ... -Page1.htm

a wealth of R1 chassis/suspension info.

[Rich]

just measured the old 96 ones and I get 797 mm from top of stanchion to centre of axle, free length not compressed.

[cobbadiggabuddyblooo]

cheers Rich,
797mm is that including the cap??
Stu gave me a measurement of 780 but as he said that's a static sag measurement.

I'm just working out the R1 set up but I feel the extra mm's you have mentioned may be factored into the thickness of the trees as the billet trees are a lot thicker than the std ones.
But the dome nut on top of the trees I've had to space with 2 washers so I need to do a few maths again .
(it may just be the way the stem is pressed into the bottom too.)
Over at Rods place today he pulled out a couple of protractor/guage devices to measure the angle of the front end so I'll get a few measurements next week on the TRX.

If only I can find the notes I made when I first worked this out ...
I have an idea the 780mm may be centre of axle to level of the top face of the tree where the stem nut locks down onto and I'm sure I originally did my measurements with the complete front end taken off the bike so no sag factor with it leaning against the wall.
Allow the 10mm step,the 12mm extra tyre height and a couple of mm stem difference I'm in the ball park..
The bottom ball race sits flat on my bottom tree and I thing the std trx bottom tree may have a couple of mm raised face it sits on.

[Rich]

No sag, to the top of the stanchion, nut adds 10mm extra to the top of the nut, pre-load adjuster not included in measurement.

If you want measurements including yokes let me know what measurements you want and I'll set the old ones up to measure.

[cobbadiggabuddyblooo]

Thanks Rich,
The measurement I need for a reference is the thickness where the stem enters through the top yoke.
If I have the thickness there from the bottom of the yoke to the top yoke face i'll be happy.
Would you mind taking the depth of the reassess where the nut sits too please??
Just looking at a few links online with photos of trx trees but I can't see if the bottom face where it sits on the stem lock washer is flush with the bottom of the tree or has a slight raised flat face?

[devlin]

Mine is all apart at the moment and looking at all of this at the moment. I'll measure and do a sketch for you.

Also, if you look on http://thetrxproject.blogspot.com.au/?m=1 he's done a heap of sketches with the info. Also remeber the std bearings are about 2mm wider then the bearing seats in the head tube when you're adding it all up.

[cobbadiggabuddyblooo]

thanks maaaate,

[Rich]

IMG_2726.JPG

top recess 2.13mm

IMG_2727.JPG

bottom recess is just for clearance on the non threaded part of the stem

IMG_2725.JPG

[cobbadiggabuddyblooo]

excellent thanks Rich