Shock Linkage Question

[Scotty]

Guys, forgive me if this has been answered before but i've looked and couldnt find a specific answer....
Does anybody know what effect I would get by moving the lowest linkage on the rear showck to the second hole provided on the mount under the engine?
I am thinking this would raise / lower the rear end?

I'm also looking at mounting wider bars but am hesitant about drilling the top yoke to fit the bar adaptors, is there any other option other than replacing it with a custom built job?

Any help appreciated...

[Triton]

Scotty,

My advice is don't even think about doing either one! The top yoke isn't overly strong, whether it's strong enough to accept the size of hole necessary for handlebar mounts is a question I personally wouldn't want to find out about. The shock and linkage will not work properly if you mount the knuckle in the second hole. Others may disagree about the handlebar mounts, but we have covered the second hole question before and it was generally accepted that trying this would not and could not work.

Triton.

[youngy]

From experience I can tell you that using that other hole to mount the shock lowers the rear to such an extent that the bike will not sit on the sidestand and you cannot get enough preload into the shock to make it work. It will make the bike unrideable due to no ground clearance.

[K9TRX850]

That 2nd hole (the rearward most one) appears to be the mount for the YZF750 linkage triangle. I read somewhere that a lot more research was carried out when they designed the YZF linkage triangle (from OW01/2 r&d i guess) and thus it appears the std TRX shock actuation is greatly improved when used with the YZF one!

I have just installed one from a yzf750 on my TRX, and I can tell you the settings on my std TRX shock are much more sensitive/better than before, also the rear end was lifted 10mm over the std linkage triangle/forward mount.

Note : I am also using the Dogbones from the YZF which alone gave the rear a 25-30mm increase in height.

I'm happier with the way trixfix handles now and won't go back, turn-in speed is improved and the shock actuation IS vastly improved over std!!

I highly recommend this mod!!

[fung]

Will you post a photo for us then?

[K9TRX850]

Sure!! when I figure out how to.....
trying now

[K9TRX850]

If you can tell me how to get the photo from my DSLR to the forum you can see the mod!

I usually read forums and rarely post anything let alone photos (never)

[fung]

Resize them for a direct upload or link to a photo hosting site.

[K9TRX850]

Link to original very large image http://iforce.co.nz/i/vdgrrkwc.z5a.jpg
mod-edit to fix image link

[cobbadiggabuddyblooo]

Here is a better comparision to the two linkages but before we even go there.
That looks pretty much like a tired old std TRX shock that may have never nbeen rebuilt and may be upto 18yrs old.
Next,
Does the std TRX spring rate suit your weight?? (around .9 is the std spring so suits a 75kg rider)


The std TRX Relay arm is the longer with the dogbones on in the photo.
You can see where the shock pivot point is so lets call that .... A
And lets call the dogbone pivot point .... B
And the frame pivot pint ..... C

So from point A _ B on the trx is 76mm compared to 56mm on the YZF750 relay arm so the yzf is 20mm shorter.
From point B _ C on the TRX is 96mm compared to 72mm on the YZF750 relay arm so the yzf is 24mm shorter.

Dont forget the yzf dogbones are 10mm shorter.
I can not measure your subframe pivot point as I no longer have a YZF frame to compare the difference.
There is also a 5mm difference in height with the TRX shocky (345mm) compared to the 340mm of the YZF shock.
So YZF dogbones on a TRX already pull the swingarm downwards being 10mm shorter raising the height changing the geometry of the TRX front end.
You also see that between point A_B on the trx that surface is a flat surface
But on the YZF this is slightly curved and shorter which pulls the dogbones even further from the swingarm raising the height even further..








So you can see there is a lot of geometry involved here and with the TRX being built from the parts bin, there must be a reason they just didn't use the +*itload of spare yzf relay arms they had left from yzf750 which are also used on the yzf1000r from 96-01 also.
Thing about rebuilding/revalving the std TRX shock and if neccessary spring rate on the std shock to start to your weight and use that as point 0 to start your comparision otherwise your chasing your tail to start..
It's always fun to trim and tune and experiment to suit you needs but you need a constant to start..

[K9TRX850]

@ cobbadiggabuddyblooo


Nice effort on the maths cobber not to mention your knowledge of the alphabet!

If i really cared that much about the maths I would go about it the way you have, but I don't really tbh.

I only put it on because I figured it would fit......and.......it does!

I figured it would feel different.......and.......it does, in a good way!

I wanted more height in the rear end and I got it.

Someone asked so I gave my two cents.

Oh by the way.....In all your photos you show the Linkages back to front

The TRX shock mounts on the 'knuckle' portion of the YZF linkage (where the left bolt is shown in all your photos).

Excellent photos too, nice job buddy!

Your post is like your currency.....back to front. $1 bigger than a $2?? WTF

[cobbadiggabuddyblooo]

that's the spirit .. You have every right to do as you see fit.. Rome wasn't built in a day...

[Con Rod]

Tis the season.

The point Cobba is making, and it is a good point is is that fiddling with the shock linkage on your bike is all well and good and should be encouraged but taking a tired shock to start with is possibly not the best way to get improvement to the stock set up.

By raising the rear you will get a better tip in. Dropping the forks through the yokes will also do do this.

But I am not clear on what improvement the swapping the linkage will give you other than raising the rear.

I have a yzf750 frame in the garage so I might pull it out and take some measurements for comparison

Also how far over do you need to go on the side stand

Not sure if this has been done before so thanks for posting. Could you post a picture of your bike side on. I am interested to see how the height increase looks.

[cobbadiggabuddyblooo]

All these changes as such impact on the damping factors and valving and squat in the shock being a rising rate linkage set up . Don't take things to heart mate, its not a criticism to your action as it may work for you and your bike set up , weight and all the other factors. The OW02 yzf 750 uses a different relay arm than a std yzf750 and Trx850 . The OW02 actually runs the same dogbones fitted to the trx tho .

Buy mounting the yzf relay arm in the rear pivot point in the frame this will offset the height gained using the YZF dogbones with this relay arm. (approx 5mm) and the extra 10mm gained through the shock height due to the mounting of the yzf relay.
So your prob sitting around the same ride height as fitting the yzf dogbones. This extra height and swingarm angle in itself helps in an antisquat nature when accelerating out of a corner but it's the rising rate nature of the suspension design itself and the shape of the relay arm that affect the damping characteristics and appropriate shimming to suit this ratio within the shock.

Even something as simple as using a larger rear sprocket will work in a pro-squatting nature as it's action pulls the swingarm up.

.

[alextrx850]

@ cobbadiggabuddyblooo


Nice effort on the maths cobber not to mention your knowledge of the alphabet!

If i really cared that much about the maths I would go about it the way you have, but I don't really tbh.

I only put it on because I figured it would fit......and.......it does!

I figured it would feel different.......and.......it does, in a good way!

I wanted more height in the rear end and I got it.

Someone asked so I gave my two cents.

Oh by the way.....In all your photos you show the Linkages back to front

The TRX shock mounts on the 'knuckle' portion of the YZF linkage (where the left bolt is shown in all your photos).

Excellent photos too, nice job buddy!

Your post is like your currency.....back to front. $1 bigger than a $2?? WTF

I am using a YZF set of dog bones , allows the TIp IN quite nicely, also my YZF front suspension is around 12 mm shorter in the front triples to sweeten the deal, feels great...up 12 mm to the rear and down some in the front.
We have often debated to the extra hole there for the pivot link, to no avail....interesting tohave come up with the most logical option that I've heard,...
K9 the forum here has a lot of experience and a wealth of knowledge, most of us enjoy and participate.
Would encourage you to follow.