No rebound damping at all?

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Smousley1995
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No rebound damping at all?

Post by Smousley1995 »

So yesterday I went to go for a ride because it was dryish and the first few corners the front end was all over the place. I stopped and bounced on the forks and they were springy as hell! There was little or no compression damping and on the rebound they sprung right back up and bounced up and down a few times as though there was no oil in them what so ever.... :smt009
Now you'll have to forgive me because I know barely anything about forks!
I know mine definitely have oil in them as they were fine a few days ago and none has leaked out.
Other than that I can't give you any more detail...
Any ideas?
Thanks :smt001
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banner001
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Re: No rebound damping at all?

Post by banner001 »

what have you set the preload to, and what are your current rebound settings?

how much do you weigh, and what have to set your sag settings at?

FYI, unless you have SP forks, you have no compression damper control.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Smousley1995
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My Bike: Zxr 400 L 1993
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Re: No rebound damping at all?

Post by Smousley1995 »

I haven't touched the forks since I've had the bike so I have no idea what the preload or rebound is set to.
I weigh 70kg and again haven't set the sag or anything.
But a few days ago they felt perfectly fine and had rebound damping whereas now they just bounce a hell of a lot and I haven't touched anything :smt017
Do the standard forks have rebound adjustment?
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banner001
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Re: No rebound damping at all?

Post by banner001 »

front fork preload is set using a 22mm spanner/socket on the top of the fork, screw it in to increase the preload (hardens the fork and reduces the amount of sag).

front fork rebound damper is set using a slotted screwdriver on top of the fork, screw it in to increase the rebound damping (reduces the rebound speed of the fork).

as for why they suddenly have changed, no idea, maybe a bit of dirl is lodged in the rebound hole so its constantly on, and you're 100% sure that they have not leaked all their oil out...admitadly this would be very unlikely, and WILL be noticible as all that oil has to go somewhere.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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KwakKwak
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Re: No rebound damping at all?

Post by KwakKwak »

Spring preload is 5th mark from the top, rebound damping is the 7th click from fully turned in position (screwdriver adjust)
Could be a damaged or weak fork spring, or you've put a shitload of weight on and have not noticed yet :smt002
Does the low seat height reflect the low intelligence? Easier to get an asshole onto.
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Smousley1995
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Re: No rebound damping at all?

Post by Smousley1995 »

I'll have a check at what the preload and rebound is set to when I get out of work, I have a feeling When I start playing with suspension I'm never going to be able to stop :smt005 and I'm certain no oil has leaked out and even more certain I haven't gained a few hundred kilos :pmsl
After doing a bit of research I am led to believe we have cartridge forks not damper rod forks, is this correct?
And if so then the only way I can see why they're not working is if the seal between the rebound piston and cartridge or the seal between the rebound piston rod (connecting the rebound piston to the top of the forks) and the top of the cartridge has packed in. This image might help - I know they're conventional forks but from what I can tell it's basically the same for our upside downies.
http://levelfive.com/IMAGES/Illustratio ... allout.jpg
Apologies if that makes no sense, it's all based on an hours research of forks confuddled
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KwakKwak
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Re: No rebound damping at all?

Post by KwakKwak »

Cartridge type, yes, the rebound damping can be a bit of a pain to count the clicks, I messed about with it for yonks, feeling and counting the clicks.
Bear in mind also my suspension knowledge is limited to getting that fooking rear shock off at the minute, and now I'm going to have to remove the swing arm as I said you'd be lazy if you didn't check it, so thanks alot :pmsl
Check the fork settings first, they're for a 68kg rider so you're in the ball park. Could a twat have messed with them without your knowledge??
Does the low seat height reflect the low intelligence? Easier to get an asshole onto.
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Smousley1995
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Re: No rebound damping at all?

Post by Smousley1995 »

I can't wait to play with it now! I never knew we had rebound adjustment, so I never bothered with the pre-load because it seemed fine :wanker
Haha yeah you did say it! Wouldn't want to be lazy now :smt002
Looks like I'm going to have to take both ends off now then :smt013 I'll check the rebound to see if anyone played with it but I'll probably have to take the forks apart and check the seals and check for dirt confuddled
Cheers for your help!
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Smousley1995
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Re: No rebound damping at all?

Post by Smousley1995 »

Alright so now I am totally and utterly confused confuddled
So I got home and checked the rebound adjuster. The adjusters were sticking up a fair bit out of the top and screwed down more than 6 clicks each and when screwed in there is a lot more rebound and also seems like more compression damping too!
However one of them screws out anti clockwise 27 clicks while the other one doesn't seat! It keeps screwing down further and further into the fork until it's way below the surface :smt017
My other two forks from my other bike, one has 13 clicks and the other has 17 clicks! I'm not seeing any sort of pattern here...
The good news is I have rebound damping again but I'm still not sure if something broke in the fork because unless someone messed about with the adjusters it changed on its own...
Also I have no idea what it's meant to be like so I'm so much more confused than when I started
Someone help me :smt010
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KwakKwak
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Re: No rebound damping at all?

Post by KwakKwak »

12 clicks, not a click more, not a click less. Somethings kerfooked in there, get the wallet out :smt010
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banner001
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Re: No rebound damping at all?

Post by banner001 »

if the damper rod nut has not been fully seated before you screw the fork top on you can get an "odd" number of clicks", my forks were the same until i made sure that the damper rod nut was fully screwed down.

is for one just "turning and turning" thats a worse problem, i think it means that someone has stripped the threads that the damper needle screws into, if you need a replacement damper rod/fork top, ive got one sitting on my bench at the moment.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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Smousley1995
Posts: 140
Joined: Wed Apr 03, 2013 9:22 am
My Bike: Zxr 400 L 1993
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Re: No rebound damping at all?

Post by Smousley1995 »

When you say the damper rod nut, is that the nut that connects the damper rod to the fork top?

I've realised it's only one fork that's lost rebound damping (the one where the adjuster screws down and down). If I screw the other forks adjuster down there's lots but the other one does nothing.
So I'm going to change the internals on the broken one for the internals off one of my spare forks (the two spare have leaking seals so I can't put them straight in vsad )
When I re-fill the fork with oil can I just pour the required amount in the top or do I have to do exactly what the manual says?
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Smousley1995
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Re: No rebound damping at all?

Post by Smousley1995 »

I've sorted it :excited
Turns out the damper rod nut had came off the fork top so the damper rod wasn't attached to anything and that broke some nylon parts! And that's why the adjuster went all the way down.... And I screwed the nut all the way down and it has twelve lovely clicks now with the internals out of a different fork biggrin
I wander what will break on my bike next week.... :pmsl
Thanks for your help!
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banner001
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Re: No rebound damping at all?

Post by banner001 »

glad to be of help :D
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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