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bucketracer
25th June 2009, 21:43
Hi Folks I have been poking around on here looking to educate myself about suspension setup.

My problem is that my F4 race bike suffers from front wheel chatter when pressed moderately hard. I have tried changing things oil/preload, and cut the progressive bit off but made no real progress.

I was running 18" TT900 GP's 90/90F 120/80R and the chatter front and back was real bad. The bike would turn sideways, and slowed down like I had put the brakes on.

When I changed over to 17" 90/90F 115/70R slicks on the correct rims 2.5F and 3.5R the problem got better but is still a handycap.

Not only does it chatter in the dry on slicks, it will chatter on the front when running wets in the rain.

The fork springs are 28mm OD and the old damper rod type. Are there emulators or cartridges for these small forks?

Can someone point me to a thread that might help.

Thanks. BR

F5 Dave
25th June 2009, 22:30
Damper rod forks are tragic. But that sounds worse than they should be. Without springs I'd want to know if the forks are binding up. This will require two people to pump it up & down.

Further I would look at the rear for the same thing, I'm struggling with your description, but rear can upset the front esp if it packs down. You might be able to ride around some of it with less bar pressure & weighting other side peg to normal to see if that helps, my H counter intuitively liked the inside peg on some corners to make up for crap frame/suspension. Make sure weight is not too far back with radical rearset pegs forcing you there etc.

People often try crazy oil weights but will only lead to hydraulic lock, I'd stick with 10w for a ripply track like mt wgtn.

But yeah some emulators might be nice to try, I'd try to find if there are other reason first lest you spend a bit & only 1/2 fix the issue.

I'm assuming you aren't running silly amounts of preload & have some static sag.

Shaun
26th June 2009, 07:34
I am assuming of course, that you ballance all wheels correctly, also that you have cheched the wheels and discs for run out, as well as checking the axles for being true, play in the stearing head bearings can also cause chatter

bucketracer
26th June 2009, 10:12
Damper rod forks are tragic.

People often try crazy oil weights but will only lead to hydraulic lock, I'd stick with 10w for a ripply track like mt wgtn.

I'm assuming you aren't running silly amounts of preload & have some static sag.

Last time out, cut the soft part of the progressive spring off and ran 20wt, preload minimal sag 1/4 of travel F&R with rider aboard, weight distribution 45%F 55%R with rider in riding position.

Jacked the rear pre-load up and made things worse.

Will check for fork bind, last time someone bounced the bike up and down they said there was no/little rebound damping in the front?????

Will try again with two pairs of hands, then planing on removing the springs and seeing if the sliders go up/down OK.

The pistons on the rods dont have a piston ring like I have seen on other bikes, just relies on the close fit in fork tube I expect.

Thanks for the suggestions.

.

bucketracer
26th June 2009, 10:20
I am assuming of course, that you ballance all wheels correctly, also that you have cheched the wheels and discs for run out, as well as checking the axles for being true, play in the stearing head bearings can also cause chatter

Wheels ballanced by the shop when they fitted the tyres, runout OK but they are spoked wheels, axil runout? will have to check, stearing head?? will have to re-check that carefully too.

Swing arm and frame braced, swingarm rubber bushes replaced with bronze bushes. This bike has allways suffered from chatter whereas I know of other bikes like mine (without the bracing)???? have not had any problems.

Thanks for your ideas, I will check "all" the things you have suggested.

Shaun
26th June 2009, 10:31
Wheels ballanced by the shop when they fitted the tyres, runout OK but they are spoked wheels, axil runout? will have to check, stearing head?? will have to re-check that carefully too.

Swing arm and frame braced, swingarm rubber bushes replaced with bronze bushes. This bike has allways suffered from chatter whereas the other Suzuki GP125's in the team have not had any problems.

Thanks for your ideas, I will check "all" the things you have suggested.


Do not trust the shop ballance mate, I have seen/re done many a wheel ballance from a shop, 1 in paticuallr in the Auckland area:jerry:

Wheel rim, discs RUN out check also mate, and the axles could be bent from prior crashes?

Robert Taylor
26th June 2009, 11:00
Beyond all the totally valid points that Shaun has made chatter is a ''frequency interaction''. It often happens on the racetrack because the spring rate and or preload is incorrect ( usually insufficient ) It can also happen because the low speed damping is weak and allows the suspension to blow through its stroke too readily to the compressed part of the stroke. Damper rod forks have this undesirable characteristic and emulators will certainly provide a major improvement in that and other areas, money well spent. You also need to establish exactly what the spring rate is.

bucketracer
26th June 2009, 21:35
RT thanks for the tips.

Before I got started looking on these threads I had purchased some YSS PD fork valves No 238. I would have liked Gold Valves but did not know where to get them, Sorry.

Are Gold Valves in this size available? Price?

I am begining to suspect that there is to much clearance around the piston for the rebound to work. There is no piston ring on the piston.

The piston measures 23.7mm are there emulators that small that will fit my forks?

.

Robert Taylor
27th June 2009, 09:53
RT thanks for the tips.

Before I got started looking on these threads I had purchased some YSS PD fork valves No 238. I would have liked Gold Valves but did not know where to get them, Sorry.

Are Gold Valves in this size available? Price?

I am begining to suspect that there is to much clearance around the piston for the rebound to work. There is no piston ring on the piston.

The piston measures 23.7mm are there emulators that small that will fit my forks?

.

Yes I think there are and will check.
The poppet springs on those valves you purchased sack out very quickly ( we have tested some ) and the bypass hole size is on many sizings too large leading to too little low speed compression control. Once the anodising wears through ( from spring rubbing ) it also gets ugly with alloy chards contaminating the oil and finding their way into the bushings, embedding into them. They are a very substandard product and a very poor copy, typical of so many mainland Asian products.
Race Tech emulators are more expensive but with good reason, they are a reliable product that also work properly and with full backup / tuning knowledge.
Yes the damper rods should seal properly and theres a lot of detail points for proper emulator installation and therefore function.

bucketracer
27th June 2009, 13:53
RT thank you for your reply. I would be interested to know if there are emulators and/or Gold Valves available.

The bike/rider combo weighs 190Kg all up with 45%F 55%R weight distribution with the rider on board and in the riding position.

I was planning on removing a fork leg, putting a cable tie on the stanchion to measure compression travel and using a set of bathroom scales measure how much weight I can apply to the fork leg.

From the weight and distance compressed I should be able to get an idea of the spring rate in Kg's a Cm.

Is this idea workable???

Are spring rates even measured in Kg's/Cm ???? this is how little I know.

I had better go and read up some.....

Many thanks for your help

.

Robert Taylor
27th June 2009, 18:35
RT thank you for your reply. I would be interested to know if there are emulators and/or Gold Valves available.

The bike/rider combo weighs 190Kg all up with 45%F 55%R weight distribution with the rider on board and in the riding position.

I was planning on removing a fork leg, putting a cable tie on the stanchion to measure compression travel and using a set of bathroom scales measure how much weight I can apply to the fork leg.

From the weight and distance compressed I should be able to get an idea of the spring rate in Kg's a Cm.

Is this idea workable???

Are spring rates even measured in Kg's/Cm ???? this is how little I know.

I had better go and read up some.....

Many thanks for your help

.

I will pm you on monday with sizing and pricing of emulators. We have a digital fork spring rating load cell set. If you purchase a pair of emulators we will test the fork springs foc.

cowpoos
27th June 2009, 18:52
RT thank you for your reply. I would be interested to know if there are emulators and/or Gold Valves available.

The bike/rider combo weighs 190Kg all up with 45%F 55%R weight distribution with the rider on board and in the riding position.

I was planning on removing a fork leg, putting a cable tie on the stanchion to measure compression travel and using a set of bathroom scales measure how much weight I can apply to the fork leg.

From the weight and distance compressed I should be able to get an idea of the spring rate in Kg's a Cm.

Is this idea workable???

Are spring rates even measured in Kg's/Cm ???? this is how little I know.

I had better go and read up some.....

Many thanks for your help

.
take a fork leg off...and see how much forward and backward play there is in it.

bucketracer
27th June 2009, 20:56
Thanks CowPoo's

Very Good Idea. Will do that.

bucketracer
27th June 2009, 20:57
I will pm you on monday with sizing and pricing of emulators. We have a digital fork spring rating load cell set. If you purchase a pair of emulators we will test the fork springs foc.

The best discription I heard was "it was like the springs bouncing the wheel up and down like a Yo Yo".

Thanks RT, I am looking forward to getting the price, testing the springs, that will be great many thanks.

.

bucketracer
1st July 2009, 12:04
I will pm you on monday with sizing and pricing of emulators. We have a digital fork spring rating load cell set. If you purchase a pair of emulators we will test the fork springs foc.

Thanks RT, got your PM, I have replied with Visa details etc.

.

bucketracer
10th July 2009, 21:29
.

Front Shocks

Pulled the fork legs from the bike, and tried compressing them by hand. They pushed in Ok but bounced right back, just as RT predicted blowing through the rebound damping (20wt oil) as if it wasn’t there.

Stripping them down, I found the style of damper rod was the kind that has a piston ring with the damper shaft passing down through a washer trapped in the end of the fork tube. At the top were two small (2.5mm?) rebound damping holes and at the bottom two larger (5.5mm) compression holes and a small rebound cushion spring.

The piston rings did not touch the fork tubes, I guessed they had collapsed or worn down to the point that they were no longer sealing and I figured this was the problem with the fork legs blowing back up through the rebound damping.

I made new rings from glass filled Teflon that sealed the piston rod and fork tube without dragging. I drilled another pair of 6mm compression damping holes in the bottom of the damper rod and blocked with weld the lower of the two rebound holes at the top of the damper rod.

I was very happy with the new Gold Valves from RT, and they were a very close fit in the fork tubes. I was happy because I know that some damper rods just rely on a close fitting piston without any piston ring to seal the rebound damper. The fork springs will hold the Gold Valves firmly in place on top of the damper rod and they would act like pistons. I was happy because I now had a piston and a good piston ring on each damper rod to seal the rebound damping.

I assembled the whole shebang and filled each forkleg with a 130ml of 10wt and gave them the hand compression test. And wouldn’t you know it, apart from the last 20mm there was no discernable rebound damping. They just bounced right back up and then slowed for the last 20mm.

I don’t understand it! I expected to see more visible rebound damping in the mid stroke. I am sure the Gold Valves are doing a good job of the compression damping but I can’t see that I have made any real improvement to the rebound damping.

.

cowpoos
10th July 2009, 21:46
.

Front Shocks

Pulled the fork legs from the bike, and tried compressing them by hand. They pushed in Ok but bounced right back, just as RT predicted blowing through the rebound damping (20wt oil) as if it wasn’t there.

Stripping them down, I found the style of damper rod was the kind that has a piston ring with the damper shaft passing down through a washer trapped in the end of the fork tube. At the top were two small (2.5mm?) rebound damping holes and at the bottom two larger (5.5mm) compression holes and a small rebound cushion spring.

The piston rings did not touch the fork tubes, I guessed they had collapsed or worn down to the point that they were no longer sealing and I figured this was the problem with the fork legs blowing back up through the rebound damping.

I made new rings from glass filled Teflon that sealed the piston rod and fork tube without dragging. I drilled another pair of 6mm compression damping holes in the bottom of the damper rod and blocked with weld the lower of the two rebound holes at the top of the damper rod.

I was very happy with the new Gold Valves from RT as they were a very close fit in the fork tubes. I was happy because I know that some damper rods just rely on a close fitting piston without any piston ring to seal the rebound damper. The fork springs will hold the Gold Valves firmly in place on top of the damper rod and they would act like pistons. I was happy because I now had a piston and a good piston ring on each damper rod to seal the rebound damping.

I assembled the whole shebang and filled each forkleg with a 130ml of 10wt and gave them the hand compression test. And wouldn’t you know it, apart from the last 20mm there was no discernable rebound damping. They just bounced right back up and then slowed for the last 20mm.

I don’t understand it! I expected to see more visible rebound damping in the mid stroke. I am sure the Gold Valves are doing a good job of the compression damping but I can’t see if I have made any real improvement to the rebound damping or not.

.
mid and higher stroke movements [high speed damping] should be ALOT faster...and your last 20mm you speak of is resemabling low speed damping...

Robert Taylor
11th July 2009, 09:29
.

Front Shocks

Pulled the fork legs from the bike, and tried compressing them by hand. They pushed in Ok but bounced right back, just as RT predicted blowing through the rebound damping (20wt oil) as if it wasn’t there.

Stripping them down, I found the style of damper rod was the kind that has a piston ring with the damper shaft passing down through a washer trapped in the end of the fork tube. At the top were two small (2.5mm?) rebound damping holes and at the bottom two larger (5.5mm) compression holes and a small rebound cushion spring.

The piston rings did not touch the fork tubes, I guessed they had collapsed or worn down to the point that they were no longer sealing and I figured this was the problem with the fork legs blowing back up through the rebound damping.

I made new rings from glass filled Teflon that sealed the piston rod and fork tube without dragging. I drilled another pair of 6mm compression damping holes in the bottom of the damper rod and blocked with weld the lower of the two rebound holes at the top of the damper rod.

I was very happy with the new Gold Valves from RT, and they were a very close fit in the fork tubes. I was happy because I know that some damper rods just rely on a close fitting piston without any piston ring to seal the rebound damper. The fork springs will hold the Gold Valves firmly in place on top of the damper rod and they would act like pistons. I was happy because I now had a piston and a good piston ring on each damper rod to seal the rebound damping.

I assembled the whole shebang and filled each forkleg with a 130ml of 10wt and gave them the hand compression test. And wouldn’t you know it, apart from the last 20mm there was no discernable rebound damping. They just bounced right back up and then slowed for the last 20mm.

I don’t understand it! I expected to see more visible rebound damping in the mid stroke. I am sure the Gold Valves are doing a good job of the compression damping but I can’t see that I have made any real improvement to the rebound damping.

.

The emulator controls compression only. I will post later on what you will need to do to sort out the rebound issue you have.

bucketracer
11th July 2009, 10:07
The emulator controls compression only. I will post later on what you will need to do to sort out the rebound issue you have.

Thanks RT, yes I knew the emulator was compression only, I thought I had the rebound sorted too, but no, and now need help with the rebound side. Many thanks RT for taking an interest in this.

.

Robert Taylor
11th July 2009, 17:03
Thanks RT, yes I knew the emulator was compression only, I thought I had the rebound sorted too, but no, and now need help with the rebound side. Many thanks RT for taking an interest in this.

.

Ok here goes. With damper rod forks rebound is controlled ( or not controlled so well! ) by;

1) One or two tiny holes drilled underneath the ''hat'' of the damper rod. Very often we have to bronze up those holes and drill one only smaller hole or none at all.

2) Look down inside the fork once you have installed and tightened the lockbolt for the damper rod. All too often you will find that it is not concentric with the centreline of the fork tube, it will be skewed to one side. That means that the piston ring will not seal around its entire circumference ( even though youve made some lovely new ones! ) and will create a lot of uncontrolled spillage that will negate any rebound damping.
What you have to do is to lightly machine the bottom of the damper rod to true it up, but that itself is no guarantee. You need to clock and reclock until you can get the rod sitting as concentrically as possible. Very often the rods themselves are not straight and if you do have to end up bronzing up the stock rebound holes be very very mindful of heat disortion!

3) At the very bottom of the chrome fork tubes should be some encapsulated nylon rings or shim steel check plates whose id is slightly larger than the od of the lower reaches of the damper rods. These provide a form of sealing, if they are damaged in any way again your rebound control will be non existent

4) Oil viscosity selection will then be dependent on how much uncontrolled bleed you have minimised and the size of the rebound holes. If you have done a good job with this you will be able to run a relatively light viscosity, that pays a further dividend in that lighter viscosity oils are less variable in performance according to ambient temperature shift.

On another thread I was bagged by a customer for not being totally specific about oil viscosity to go with the emulators we sent him. The reality is that given the variables above every job is different. I can safely say we fit way more emulators than anyone else in the country and with a model we havent done before we do one fork first and try our best guess with oil viscosity. If it hasnt got the rebound feel we want we either change the viscosity or we pull the rod out again and tune the size of the return hole. Thats a pain in the butt but the only way of ensuring a good job.

Hope this all helps!

If you can forward a fax number on Monday I can send you some flow path diagrams that will help you understand damper rod function a little better.

Robert Taylor
11th July 2009, 17:11
mid and higher stroke movements [high speed damping] should be ALOT faster...and your last 20mm you speak of is resemabling low speed damping...

Further, bronze up those 2 x 2.5mm rebound holes and drill one new one starting at 1.5mm, allied with all of the other things to sort in my previous post. Start with 10 weight as you have it to hand. Rebound return speed should be relatively fast BUT CONTROLLED with no aftercycle or solid thud back up to full re-extension. Hard to describe in words!
Its arguably worse having too much rebound, that is more likely to cause crashing as the forks wont follow depressions as readily, allowing the tyre to stay interlocked with the pavement.
Please do let me know how you get on.

bucketracer
11th July 2009, 18:37
Further, bronze up those 2 x 2.5mm rebound holes and drill one new one starting at 1.5mm, allied with all of the other things to sort in my previous post. Start with 10 weight as you have it to hand. Rebound return speed should be relatively fast BUT CONTROLLED with no aftercycle or solid thud back up to full re-extension. Hard to describe in words!
Its arguably worse having too much rebound, that is more likely to cause crashing as the forks wont follow depressions as readily, allowing the tyre to stay interlocked with the pavement.
Please do let me know how you get on.

Thanks RT, I will forward the fax number Monday. Your last two posts make sense and give me plenty to work on. I feel sure the problem is in there somewhere amongst the things you describe.

Today I have been looking at a friends older Honda RS125 and can see the rebound of those forks is much more controlled, so now I have an idea of what I am looking for.

You have given me plenty to go on with, and will start by looking at the sealing of the check plates and the concentricity of the damper rods, many thanks for your input.

.

bucketracer
12th July 2009, 21:17
.

Pic-1 is pretty much what my setup looks like now, I suspect there is a problem with sealing of the damper rod.

I am thinking of converting the damper rod check plate thats in the bottom of the fork tube to the better looking foot valve assembly you see on some damper rods.

.

Robert Taylor
13th July 2009, 10:04
.

Pic-1 is pretty much what my setup looks like now, I suspect there is a problem with sealing of the damper rod.

I am thinking of converting the damper rod check plate thats in the bottom of the fork tube to the better looking foot valve assembly you see on some damper rods.

.

Yes you are on the right track!

bucketracer
5th August 2009, 23:06
An update of where I am at with my suspension problem. I fitted the Gold Valves and took the bike for a spin they worked a treat. I could attack rippled sections much more aggressively and the front end of the bike no longer jarred on the bumps. And I expect more improvement of the ride is possible with tuning of the spring adjustment on the valve.

But the front-end chatter is still there, no surprises though as that is related to the rebound damping which was non-existent. So I pulled one fork leg off, took the Gold Valve out and started trying heavier grades of oil starting at 20w and working up. Even with 85wt. gearbox oil the fork behaved like a pogo stick with no discernible rebound damping.

So I striped it down and welded up (Tig) the two 2.5mm rebound holes in the damper rod. Straightened the damper rod, trimmed both ends up in the lathe and checked that the piston end of the damper rod was central in the fork leg when every thing was re-assembled. With a 1mm rebound hole and 10wt Oil the fork leg was no longer a pogo stick and the rebound was visible controlled. Modified the other leg and reassembled it all back in the bike.

Bounced the bike up and down a few times and realised I had made a mistake. What was visibly controlled before had now become slow and sluggish. I had not figured on the weight of the bike. The fork springs were now working against the damping and the bikes weight. I will have to use thinner oil or increase the rebound damper hole size. I think I will go with thinner oil first off and take it for another test ride as soon as I can.

Using an old set of bathroom scales and a bit of arithmatic I figured that I have a set of 54lb/inch and a set of 71lb/inch springs so will try them both in due course.

Its a lot of work but I think I am getting there.

CookMySock
6th August 2009, 07:42
Very interesting to read about your project. I'm tempted to fit emulators to our road bikes..

Just for interest, I purchased a GT250 Hyo for my daughter, and at speeds over 90k the front got twitchy and darty and there was obviously something scarily amiss. We replaced the rear tyre (it wasn't WOFable) and discovered it had no balance weights on it. New tyre and re-balance, and the rear wheel took 55 grams to balance it. Bike now rides mint. Dunno if theres anything relevant there for you.

Steve

Robert Taylor
6th August 2009, 09:04
An update of where I am at with my suspension problem. I fitted the Gold Valves and took the bike for a spin they worked a treat. I could attack rippled sections much more aggressively and the front end of the bike no longer jarred on the bumps. And I expect more improvement of the ride is possible with tuning of the spring adjustment on the valve.

But the front-end chatter is still there, no surprises though as that is related to the rebound damping which was non-existent. So I pulled one fork leg off, took the Gold Valve out and started trying heavier grades of oil starting at 20w and working up. Even with 85wt. gearbox oil the fork behaved like a pogo stick with no discernible rebound damping.

So I striped it down and welded up (Tig) the two 2.5mm rebound holes in the damper rod. Straightened the damper rod, trimmed both ends up in the lathe and checked that the piston end of the damper rod was central in the fork leg when every thing was re-assembled. With a 1mm rebound hole and 10wt Oil the fork leg was no longer a pogo stick and the rebound was visible controlled. Modified the other leg and reassembled it all back in the bike.

Bounced the bike up and down a few times and realised I had made a mistake. What was visibly controlled before had now become slow and sluggish. I had not figured on the weight of the bike. The fork springs were now working against the damping and the bikes weight. I will have to use thinner oil or increase the rebound damper hole size. I think I will go with thinner oil first off and take it for another test ride as soon as I can.

Using an old set of bathroom scales and a bit of arithmatic I figured that I have a set of 54lb/inch and a set of 71lb/inch springs so will try them both in due course.

Its a lot of work but I think I am getting there.

Its a real positive if you can go to a thinner viscosity oil as its less sensitive to changes in ambient temperature, which is essentially what forks run close to. I do suspect though that you may end up having to process at least one small rebound bleed hole.

bucketracer
6th August 2009, 12:27
Its a real positive if you can go to a thinner viscosity oil as its less sensitive to changes in ambient temperature, which is essentially what forks run close to. I do suspect though that you may end up having to process at least one small rebound bleed hole.

Thanks RT for the reply and all of your help with this.

The forks presently have a 1mm rebound hole and there will be a chance to run the bike again this weekend. I have an oil mixing chart and will take a range of oils with me so I can progresivly try thinner oils.

As it is I am expecting the forks to packdown over bumps and will thin the oil. If it still packs down I will open the 1mm rebound hole up 0.25 (or less) at a time. I know its an area thing and that 1.25mm has more than 0.25 extra flow of the 1mm hole.

When the rebound is sorted then I can get onto adjusting the Gold Valves for compression damping. Like diving under brakes, jolting over bumps and dipping the front when throttling off into corners.

There is so much juggling that it makes my head spin. Still I am feeling more confident with it.

Thanks again RT.

.

Robert Taylor
6th August 2009, 15:59
Thanks RT for the reply and all of your help with this.

The forks presently have a 1mm rebound hole and there will be a chance to run the bike again this weekend. I have an oil mixing chart and will take a range of oils with me so I can progresivly try thinner oils.

As it is I am expecting the forks to packdown over bumps and will thin the oil. If it still packs down I will open the 1mm rebound hole up 0.25 (or less) at a time. I know its an area thing and that 1.25mm has more than 0.25 extra flow of the 1mm hole.

When the rebound is sorted then I can get onto adjusting the Gold Valves for compression damping. Like diving under brakes, jolting over bumps and dipping the front when throttling off into corners.

There is so much juggling that it makes my head spin. Still I am feeling more confident with it.

Thanks again RT.

.

Yes the reality is that there are so many variables and so many issues to correct with the fork internals. Most people would have thrown their toys out of the cot by now and unfairly maligned the product. But perseverence always rewards!

bucketracer
8th August 2009, 20:18
.

A friend took my bike out today. The first thing he did was sit astride it and bounce the front up and down. He frowned then said “It’s a bit slow coming backup isn’t it?”

He took it out and blasted around for a few laps and his first comment when he came in was “You sure have to get your knee down fast when the front lets go”.

I am not sure whether I am more depressed because I still haven’t got the front-end right or because the answer is to “Just get your knee down fast” and steer it with the throttle.

Then the clutch shit itself.

F..k-IT I am off to take a Valium and have a lie down.

.

CookMySock
8th August 2009, 20:53
Build a shock dyno. You know you wanna. ;)

Steve

quickbuck
8th August 2009, 21:56
.

“Just get your knee down fast” and steer it with the throttle.

.

There is your answer dude.....
That was the technique I used to use at Shirrifs Road Kart Track... right up to the point it started to rain.......
Then it was all over!

All over the track, and down the grass!

Robert Taylor
9th August 2009, 09:55
Too slow rebound is one of the biggest causes of crashing and also creates harshness.

FROSTY
9th August 2009, 10:15
A thought for you dude. the amount of effort you are going to would you not be better to see if you can get your hands on a better set of forks?

Robert Taylor
9th August 2009, 10:27
A thought for you dude. the amount of effort you are going to would you not be better to see if you can get your hands on a better set of forks?

No, because once he has the rebound dialed he will have a great set of forks. The reality is that self instals are often a learning curve because when you are only doing a one off you havent got the conception of feel of what is ''correct'' compared to if you are doing them day in day out.
This guy is learning a lot and I am more than willing to help, when he gets it right he will be delighted and will have learnt a lot.

F5 Dave
9th August 2009, 11:20
There is your answer dude.....
That was the technique I used to use at Shirrifs Road Kart Track... right up to the point it started to rain.......
Then it was all over!

All over the track, and down the grass!

There only had to be a bad forecast on the radio & you'd be off at that track. I remember onto the top straight it started to rain a bit & I thought ok a few laps & I'll back off, but half way along I thought maybe I'll turn off down the hill a bit slower & I'm on my knee trying to push the bike up until I realise the track is quite some way behind me. Bloody funny.

FROSTY
10th August 2009, 11:51
No, because once he has the rebound dialed he will have a great set of forks. The reality is that self instals are often a learning curve because when you are only doing a one off you havent got the conception of feel of what is ''correct'' compared to if you are doing them day in day out.
This guy is learning a lot and I am more than willing to help, when he gets it right he will be delighted and will have learnt a lot.
I will rephrase that. Wouldn't you be better to start with a set of forks that work propperly. My reasoning being that some of the issues he is having suggest possible old damage or the effects of years of neglect. I have mental images of the effect the internals of the fork tubes could have on all the great work he's doing if theyve been full of rusty sludge for years. One of your phrases -- silk purse from sows ear springs to mind.

Robert Taylor
10th August 2009, 15:35
I will rephrase that. Wouldn't you be better to start with a set of forks that work propperly. My reasoning being that some of the issues he is having suggest possible old damage or the effects of years of neglect. I have mental images of the effect the internals of the fork tubes could have on all the great work he's doing if theyve been full of rusty sludge for years. One of your phrases -- silk purse from sows ear springs to mind.

The reality is that many brand new damper rod forks have issues with poor tolerancing and oil flow control. Those are the issues this guy is dealing with, moreso than wear issues.