suspension Mods

[Redog1]

G'Day all. I am new here. Just purchased a 99 TRX and am looking to sharpen up the steering.
Have read many of your comments, but was concerned about head shakes. A friend raised the forks so far through that the bars would shake violently if you let them go!!
So how much through at the front and up at the back before this happens?

Thanks
John.

[idl1975]

I know some people are running very extreme changes to the ride heights at each end on R1 front end conversions with no problems at all (later R1 forks are very much shorter in total length than the old skool TRX forks).

Stating the obvious, but remember that there are other elements to steering stability than head angle, which is why manufacturers don't rely on super-long wheelbases and 25+o head angles any more.

You are certainly safe to start with 10mm through the yokes and work from there. It will not become slap-tastic without a lot more than that.

Be aware that you may be best advised, unless you are very light, to start off by rebuilding the forks with rider-specific springs (almost inevitably a much higher rate) and "fettled" damping. Dumping a lot of weight onto the stock front end can have negative implications, because the stock springs really aren't up to it. Especially if you throw in a set of blue spots as well.

The forks can basically end up folding up like you're on a stock VTR1000, and as the damping is harsh in any event, it's not a recipe for a great front end. Wallowing, crashing, pitching and diving all over the place...

G'Day all. I am new here. Just purchased a 99 TRX and am looking to sharpen up the steering.
Have read many of your comments, but was concerned about head shakes. A friend raised the forks so far through that the bars would shake violently if you let them go!!
So how much through at the front and up at the back before this happens?

Thanks
John.

[Corners R Us]

I have 25mm of fork leg showing above the clip ons and 30mm shortened dog bones on the rear and weigh 11 stone dripping wet. Despite pressing on a bit at times I've yet to suffer any head shakes and these mods have noticeably sharpened up the steering. Suspension settings front and rear are stock at the mo although I plan to have a tinker to see if I can stop the forks diving as much under heavy braking - I have gold spot R1 calipers with EBC HH pads. I also have a set of Ohlins springs that came with the bike that will be fitted IDC along with different weight oil/air gap once I've research this subjecta little more! Tyres are Avon Storms run at stock pressures, which always strike me as a bit low?

Spookily I had a VTR 1000 a few bikes back and whilst the front forks were ok on the road their shortcomings were very apparent on the track! Wish I'd spent time and money throwing some Blade forks at it or having the stock items revalved as it was a good bike, albeit the tank range poor (100 miles - race cans and brisk riding!). I was always worried about binning it and having to fork out for those side rads too! Think my 2 TRXs have been more all round fun on road and track mind.

Corners...the clues in the userid and avatar!!

[idl1975]

I have 25mm of fork leg showing above the clip ons and 30mm shortened dog bones on the rear and weigh 11 stone dripping wet. Despite pressing on a bit at times I've yet to suffer any head shakes and these mods have noticeably sharpened up the steering. Suspension settings front and rear are stock at the mo although I plan to have a tinker to see if I can stop the forks diving as much under heavy braking - I have gold spot R1 calipers with EBC HH pads. I also have a set of Ohlins springs that came with the bike that will be fitted IDC along with different weight oil/air gap once I've research this subjecta little more! Tyres are Avon Storms run at stock pressures, which always strike me as a bit low?

Spookily I had a VTR 1000 a few bikes back and whilst the front forks were ok on the road their shortcomings were very apparent on the track! Wish I'd spent time and money throwing some Blade forks at it or having the stock items revalved as it was a good bike, albeit the tank range poor (100 miles - race cans and brisk riding!). I was always worried about binning it and having to fork out for those side rads too! Think my 2 TRXs have been more all round fun on road and track mind.

Corners...the clues in the userid and avatar!!

I rode a VTR demo bike when it first came out. I went from full throttle to shut throttle in second going into a roundabout and I swear the forks actually bottomed. But perhaps they'd forgotten the fork oil? Lovely engine, although the ~20mpg advantage to the TRX makes the power difference easy to ignore when you're commuting on it...

[dandywarhol]

I'm surprised that fitting shorter dogbones hasn't made the rear spring rate too hard therefore giving the damping a hard time on an already mediocre unit - especially if weights been lost with lighter exhausts etc. It must also feck up the rising rate progression.

[ekoja]

That head shaking could also be tyres.
I used to run Bridgestones which were ok, but after a little wear if you let go the bars the thing would go into violent shakes and very quickly too.

I now run Metzlers and the shakes have gone.
I know that it's not all that scientific but thats what use to happen, and thats what stopped it.

[cobbadiggabuddyblooo]

Yer I found changin rubber helps a lot too. I use to give the misses A nudge at nite n I'd get a violent headshake n I changed rubbers and now..mmmmm. no more head shakes

[devlin]

I thought you'd enjoy a violent head shake!

I adjusted my forks to 30mm showing last night. I can feel a slight change in response this morning but Brisbane peak hour isn't the place for it really. Worst drivers in the world.

Shorter dog bones won't necessarily change the forces on the shock. You would have to look at the geometry of the links in motion and see whether there is that much of a change. I am going to model the rear of the bike so I can design this trellis swingarm I am working on. Part of the job will be to do the linkage and will see how much it's affected when it's done.

[cobbadiggabuddyblooo]

MMMM well we won't go into the geometry of where the heads gotta be placed for that one... going into the down forces and all that stuff... be here all nite.. (lucky me) but I'll run thro it again tonite just to make sure I got it right tho

[idl1975]

I'm surprised that fitting shorter dogbones hasn't made the rear spring rate too hard therefore giving the damping a hard time on an already mediocre unit - especially if weights been lost with lighter exhausts etc. It must also feck up the rising rate progression.

I've been warned about that as well, and not by DW. That's why in the end I bit the bullet and went with the Ohlins shock (ride height adjustable to +10mm as well).

I actually think the OEM shock is "liveable-with", despite the characteristic harshness and excessive rebound damping, and I was quite happy with my former setup of modded TRX forks, standard linkage and shock. I guess I'm saying not only can the dogbones affect the shock's action, but the forks are more of a problem than the shock, IMO.

[Corners R Us]

I'm surprised that fitting shorter dogbones hasn't made the rear spring rate too hard therefore giving the damping a hard time on an already mediocre unit - especially if weights been lost with lighter exhausts etc. It must also feck up the rising rate progression.

Doesn't seem to from my experiences.....not had my bike on a trackday yet mind, just brisk road work thus far.

Corners

[Kayla]

My bike's got 25mm showing above the clip-ons and a +20mm lift at the rear using shorter dog bones. Much better than standard.

[devlin]

Hmmmm.... I tried a couple of corers on the way home today. The 12mm I dropped the yokes seems to have made the front want to run wide a little now. Might have to go another 10mm and see what that does. Also might make some new dog bones and see what difference that makes. I lucked onto a bit of aluminium stock today from Capral to make a fork brace as well, it was an off cut for the change in my pocket. About $6.50 from memory. Fun and games for not much expense.

[cobbadiggabuddyblooo]

Yer I tore through a few corners this arvo with me new front springs all set up proper like to my weight(.9KG/MM SPRING-76KG BLOKE) and correct static/loaded sags and wow made the front end a LOT MORE STABLE and TRACKING where you want. Can't wait to see the difference new oil makes now,then damping sett up...mmmm.. oh and santa can I have a new rear shock and some tyres and ahhh mmmm what else...

[slow codger]

You don't need a fork brace on the TRX as its not powerful enough to try and warp the forks, time is all you need. I have 25mm through, but due to knackered back have the bars still at the top, steers fine, and can be hustled through the sharper corners if need be. May try the YZF dogbones at some time to see if they help with the riding position, after adjustable clutch lever (war wound !!).

Dave E