Rebound damping - Wrist Twisters
 
Thread Tools Display Modes
post #1 of 8 Old 10-24-2014, 02:18 PM Thread Starter
Tirone
 
Join Date: Aug 2014
Location: Punta Gorda
Posts: 39
Rep Power: 1
 
Rebound damping

I am aware of what rebound damping is. I am just curious as to how the adjuster physically works on a stock rear shock. Is the piston stem hollow? If so, it's position on the bottom of the shock would require it to be double bored, a fluid passage in and back out for return. Seems a lot of work for a bottom mounted adjustment that could have gone somewhere else on the shock. Just curious.

cooper714 is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 10-24-2014, 04:36 PM
`
 
zaq123's Avatar
 
Join Date: Apr 2009
Location: here n' there
Posts: 3,842
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 17

bottom of the shock is the easiest way to place the adjuster. Thing of your front fork but mounted upside down. (Not to be confused with USD forks, which have its cartridge mounted the same way as conventional forks, the same side up)

Obviously shock stem is hollow with the rebound needle inside which restricts/ de-restricts bypass port of the valve. Stock adjuster simply pushes the needle up and down with adjuster's conical shape. Unlike Ohlins shock that actually has precise clicker adjuster. Both doing the same thing - closing or opening the bypass port.

zaq123 is offline  
post #3 of 8 Old 10-24-2014, 06:03 PM Thread Starter
Tirone
 
Join Date: Aug 2014
Location: Punta Gorda
Posts: 39
Rep Power: 1
 
Many thanks, I was able to put that much together. It just makes little design sense. The stem couldn't just be hollow as rebound damping in the rear shock would require shock oil to be pushed past the adjuster without restriction (that would be compression damping) and return the oil under restriction at the return stroke. Seems that would require reservoir space or two channels in the shock stem. There would be little left of the shock stem, given it's outside diameter, with two bore holes down it's inside, and why? The reservoir is on top, why not control it there. It is a curiosity. If I could remove the screw, all the shock oil would be expelled in a pressurized rush? Unloaded the adjuster doesn't seem to have enough tension to be under pressure.

cooper714 is offline  
post #4 of 8 Old 10-24-2014, 06:25 PM
`
 
zaq123's Avatar
 
Join Date: Apr 2009
Location: here n' there
Posts: 3,842
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 17

Quote:
Originally Posted by cooper714 View Post
Many thanks, I was able to put that much together. It just makes little design sense. The stem couldn't just be hollow as rebound damping in the rear shock would require shock oil to be pushed past the adjuster without restriction (that would be compression damping) and return the oil under restriction at the return stroke. Seems that would require reservoir space or two channels in the shock stem. There would be little left of the shock stem, given it's outside diameter, with two bore holes down it's inside, and why? The reservoir is on top, why not control it there. It is a curiosity. If I could remove the screw, all the shock oil would be expelled in a pressurized rush? Unloaded the adjuster doesn't seem to have enough tension to be under pressure.
you got it all wrong. Stock adjuster is simply pushes the needle up or down the stem with its conical shape. Compression circuit has nothing to do with rebound. It's valve is located near reservoir, hence its on top of the shock. This pic should help.

zaq123 is offline  
post #5 of 8 Old 10-24-2014, 06:50 PM Thread Starter
Tirone
 
Join Date: Aug 2014
Location: Punta Gorda
Posts: 39
Rep Power: 1
 
Bottle?
Yep, I am missing the obvious.
Pic is a no show.
Thanks for taking the time to make this clear to me.

cooper714 is offline  
post #6 of 8 Old 10-24-2014, 06:51 PM
`
 
zaq123's Avatar
 
Join Date: Apr 2009
Location: here n' there
Posts: 3,842
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 17

Quote:
Originally Posted by cooper714 View Post
Bottle? Yep, I am missing the obvious. Pic is a no show. Thanks for taking the time to make this clear to me.
lol. I meant needle. Attachment 85106

zaq123 is offline  
post #7 of 8 Old 10-24-2014, 06:55 PM Thread Starter
Tirone
 
Join Date: Aug 2014
Location: Punta Gorda
Posts: 39
Rep Power: 1
 
Perfectly clear now. I was picturing fluid movement, the movable rod idea did not occur to me. Very helpful.

cooper714 is offline  
post #8 of 8 Old 10-25-2014, 05:26 AM
`
 
zaq123's Avatar
 
Join Date: Apr 2009
Location: here n' there
Posts: 3,842
Rep Power: 1
 

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 17

Quote:
Originally Posted by cooper714 View Post
Perfectly clear now. I was picturing fluid movement, the movable rod idea did not occur to me. Very helpful.
that's not exactly your 919 shock though. 919 shock is a little less complex and somewhat primitive. For example: remote reservoir is pretty much useless on OEM unit. It has a reverse bladder design which is still a mystery.

zaq123 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Wrist Twisters forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome