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Offline Dex

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Re: front end bounce
« Reply #10 on: June 18, 2011, 09:43:44 PM »
I'd be very keen to hear the results. The front springs on my 800 Road seem harder than needed - there's nearly 2" of suspension travel unused on my bike even with hard braking on a dry road
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Offline Raprides

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Re: front end bounce
« Reply #11 on: June 19, 2011, 12:41:33 AM »
Yeah i thought something felt funny! this is my first bike in years without a steering stabalizer so maybe thats what i was'nt feeling. but theres something fishie going on! while coasting at about 45mph thake yer hands off the bars ,then lay your fingers across the top of the grips and you should feel this hopping too! somethings not right!!! :164:

Offline dhula

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Re: front end bounce
« Reply #12 on: June 19, 2011, 04:39:21 AM »
I've spoken with both triumph dealers locally (and one that is 140 kms away) via phone and they all say that I will need to spend money on changing oil viscosity and/or springs. Poppycock in my book.

I've had both wheels checked by a local bike shop I have faith in (and I've checked myself again) for run out, poor fitment of tyres, balance, warping, tyres fitted in correct orientation etc etc and all seams fine at both ends.

The bike is in bits at the moment (see my other thread on springs specs) working out standard spring specs. At the same time I'll be looking at messing with oil viscosity and a couple of different springs I have in the shed (may fit but won't be perfect as they are street bike springs). I'll also be checking headstock bearing tightness and a few other things.

Offline dhula

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Re: front end bounce
« Reply #13 on: June 19, 2011, 04:52:51 AM »
Doing a rough calc and even using a few online calc tools I come up with an overall  spring rate of about 0.54kg/mm.

Some rough measurements I took a little while back showed that the bike weight (full tank of fuel) used 38mm of fork travel and then when I sat on it (I'm in the tonners club before gear) with rear preload set as standard it used a further 23mm of travel. This puts it at roughtly 1/3 of total travel for rider sag which is about right for a DS but it seams to me that the front end is over sprung beyond the initial compression of the spring and damping not the best either.

I'll be messing with it today/this week and see what transpires
« Last Edit: September 19, 2011, 10:00:46 AM by dhula »

Offline Drumster

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Re: front end bounce
« Reply #14 on: June 19, 2011, 06:59:27 AM »
*Originally Posted by dhula [+]
I've spoken with both triumph dealers locally (and one that is 140 kms away) via phone and they all say that I will need to spend money on changing oil viscosity and/or springs. ...

That's rich, it must be your fault cuz they built a lemon. :138: WTF? :027: Methinks you'd best be putting your foot down on this one.

Offline dhula

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Re: front end bounce
« Reply #15 on: June 21, 2011, 09:47:54 AM »
After a bunch of trying and seeing if things fit, I can use the springs I have in the shed if I want as they do fit. Thing is they may be to high a rate at 0.95kg/mm and 1.1kg/mm springs respectively but I think the calcs I did on the stock springs could be incorrect (as per my other thread). There are other things also like length (free and compressed) but these could be overcome or put up with to see if the rate is right for me.

Anyways, first change I have made is oil viscosity. I have changed the Showa SS08 (about a 10w oil) to a 15w oil set at a height of 105mm instead of the manuals 103mm (which is ~ 450mls. The difference is noticeably better but I still have the bounce however to a lesser degree. It rides better over bumps at the front having a slightly more controlled "bump", but is let down by the back which has a "crash". I do have the preload wound right up tight on the back tho so will change this and see what happens.

One thing I did notice was that the front now dives a bit more under hard braking (not sure why I get this feeling, more investigation needed) causing the rear to rise but the rear doesn't seam to fall back down at a speed I expect, like it gets stuck or has a damping rate that is too high holding it up.

Offline dhula

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Re: front end bounce
« Reply #16 on: July 04, 2011, 02:40:05 PM »
I've done couple more 100 kms with this set up at varying speeds and roads including a bit of dirt (these tyres suc arse on slick dirt BTW) and no change to the bounce I'm getting. I've mucked around with tyre pressure and rear preload to no avail so it's onto the next setup.
The next one will be 0.95 springs with the current oil in the forks set at 105mm as before.
By my rough reckoning these springs will give less bike sag but I'm hopeful it might come out pretty good for rider sag but we'll see once it's all done.
I'll either be doing the swap thru the week after work or on the weekend.

Offline dhula

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Re: front end bounce
« Reply #17 on: July 07, 2011, 02:22:42 PM »
Well I've tried the 0.95 springs and although they were good for on road I won't bee keeping them in as I feel they are over sprung for the bike and my intended use. If I was going to be using the bike 100% road, I recon they'd be a keeper but the damping would need a bit of improvement. With the 0.95 springs I ended up with a rider sag of 40mm and an unused 60mm of travel (as opposed to ~20mm unused with the stock springs). The other drama is that the bounce is still there.

I've now got the stock springs back in and used both a 7.5w for a bit and a 5w for a bit and while the damping was slightly different at each time (I am prefering the 5w ATM TBH) the bounce effect is still there. I'm begining to wonder on teh wheel runout or perhaps if it something to do with the rear suspension in any way.
I've called the dealer and will be delivering the bike to them tomorrow and they are guna keep it for the week (can't get back to pick it up for the week anyways, so no biggie) and try to sort it.

I'll get back to you with what ever they find.
« Last Edit: July 08, 2011, 11:12:03 AM by dhula »

Offline szach

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Re: front end bounce
« Reply #18 on: July 14, 2011, 09:01:53 AM »
Hello Everybody
I think I have the same in my bike. But in my case I can feel ( and see  :033:) bounceing when I release the bar. It heppend in speed between 60-90 km/h. When J release the bar it start moveing (more and more) until I hold it back. It looks like kind of shimmy. Interesting is that the bounceing is biger when I drive with w luggage (central case givi trakker 46).
Of course I visited service in my dealer they checked everything (front suspension) but nothing found. They said that will contact with factory in Hinckley and ask what to do.
If I find out something I will inform You.

Offline dhula

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Re: front end bounce
« Reply #19 on: July 14, 2011, 10:45:02 AM »
Called dealer yesterday to ask how they was going with my tiger and got some interesting news.
When I dropped off the bike I told them how, when, where, etc about it happening. I told them the steps I'd been thru so far trying to eliminate or diagnose the problem.
Anyways, the response I got from the dealer was less than satisfying for me ATM.
In a nut shell I got told that the demo bikes they have do it including the XC and it caused by the little waves in the road so my bike is normal and it's a characteristic of the bike.
I'm picking up my tiger tomorrow and now the fun begins on what to do next; live with it (as I lurve the rest of the bike) trying to solve the problem or trading it at a huge loss and buying something else
« Last Edit: July 26, 2011, 03:23:31 PM by dhula »

 


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