This issue arose last fall but was rideable so I'm working on it now...
If i have the rebound adjusted to any setting but the fastest, the rebound becomes absurdly slow or if set to its slowest it wont rebound at all.
I am assuming I need my damper rebuilt but thought I would get some insight on here first.
I live in upstate NY, any service centers out east?
This issue is due to an O-ring on the damper shaft. When it is broken some of the pieces pass into the hole and thus increase the damping effect. The problem is well known. Change the O-Ring with a better quality and rebuild your cartridge..
today i realized that rear shock rebounds too slowly (ml7/5 - 12/2005). i remembered that i read about destroyed top out o-ring and yes - debris everywhere. i do not have spare urethane o-ring - can i assemble damper without it? i want to ride, but i do not want to reassemble it again in near future. or have i look/wait for spare o-ring? will higher quality o-ring last longer?
what about buying hydro top out on my older damper, would it fit?
2mm x 9mm o-ring is for my system, right?
expect that i have to put it on top of spring collar.
attached is disassembled rear shock - can somebody put notes into picture?
i have doc from ethan - ML75 damper overhaul.doc, but there is not exploded pic describing all rear shock parts like for duc/sc.
It is a small cap/flat head screw that threads into the valve to seal and protect the valve core from the pressure created inside the shock body.
Ethan at mavericksuspension@gmail.com has some.
5.2.3. The correct position of the IFP must now be set. With the shaft at Full Extension back out the seal head (not all the way) and pressing the IFP into the cartridge. Oil should escape out around the seal head threads as you are doing this. NOTE: The IFP should be set at 6-8mm from the end of the damper tube when the damper shaft is all the way out and the seal head is tightened against the damper tube.
in ml7/5 damper overhaul document (from ethan) there are steps:
37. With damper rod still flush with sealhead, Push IFP up to approx 5-8mm from bottom. Make sure damper rod has not moved while pushing IFP up.
38. With finger, push IFP till damper rod is fully extended.
39. With damper tube in 23mm vice blocks, tighten seal to 5-7Nm.
alpamayo wrote:
ML7/5 damper IFP height = 15mm With damper rod all the way IN.
following ml7/2 items naming:
i set it so that when damper shaft is extended out of damper tube (spring not pushed) IFP is in damper tube 15mm from bottom while adjuster rod is unscrewed 2 full turns (from max screwed position). is it correct?
while not considering different items naming all 3 descriptions can be correct - second can mean that when damper shaft is flush with seal head - IFP is 5-8mm from bottom than when damper shaft is "fully" extended (expect spring not pushed) IFP will be 15mm from bottom. alpamayos "all the way IN" can mean fully extended - IN when looking from attachment boss side.
You can vary the setting of the IFP depth and air pressure behind it to suit your riding style and preference.
I always set the IFP 5 to 15 mm with the rod all the way in. Once you pressurize (try 150psi) the damper rod will extend out fully.
You have to try different settings to get it to your liking. The position of the IFP dictates how much oil and air are in the damper and therefore it affects dampening. More oil and air = more progressive
I followed Ethan's recommendations for my ML8 rear shock (custom shim stack, IFP depth = 5mm to 8mm with rod all the way in and then pressurized it 180psi) and it is working well.
I have put a lighter weight negative spring in all my rear shocks and leave out the top bushing. I get more stroke this way for more rear suspension travel. I will have to note if the spring is abrading the top nut or rubbing on the 10 mm rod. I could cut the bushing shorter and put it back in.
I let the oil bleed out just until the piston contacts the IFP with the rod all the way in. I may end up with the rod extending nearly a 1/4 inch by the time I notice it contacting the IFP and get the top nut tight. I leave it this way since the last 1/4 inch of rod will not travel into the damper anyway. This gives me the maximum air volume under the IFP for a flatter response.
I don't have an o-ring inside the damper so I don't have to worry about it getting chewed up. I use the top out o-ring for the bottom out bumper.
This arrangement gives me more travel and a less linear response with more progression at the end of the stroke. This is what I like. Most riders will like a more linear response. I like to use most of the stroke on the small bumps since that is what I am hitting on 80 to 90 percent of the ride.
The travel increased from about 5-1/2 inches to 6-1/4 inches on the Durance and from 6-1/2 to nearly 8 inches on the ML8. Maybe that is what the 8 in ML8 stands for now.
A picture of the shock and the negative spring changes I made for both the shocks and DUC 32 forks.
There was some weird minimum purchase requirement.
I measure the travel by placing the bike upside down and measuring from the ground to the center of the rear axle. Do this in the fully extended position and then let the air out of the shock and compress it to bottom out position and measure again.
Since this time I have cut the snout off the seal head of two oil damper seal heads. On the air coil I have removed everything above the air piston. The oil damper seal head has an O-ring in it. This lets you use the space above the air piston as a negative chamber. I push the damper rod in about 2 inches and then tighten the seal head. This captures two inches of atmospheric air in this now negative air chamber. Now when you pressurize the air coil notice at what pressure the air piston rod is fully extended. It will be about 40 to 50 psig with this two inches of non pressurized air in the negative chamber. Then put in another 10 psi in the air coil so it is a higher pressure than the negative air chamber. If this isn't your riding pressure then you have to increase or decrease the amount of air in the negative chamber and the air coil.
I think it is important to keep the pressure in the air coil (below the air piston) higher than the negative chamber (above the air piston) other wise air can transfer from below the piston to above the piston. When this happens the fork will start to extend less and the ride will go sour.
The air coil rod will extend 7 inches out of the seal head with this modification. I use a 3 mm O-ring for the bottom out bumper. This gives me 170mm of travel with a 29 inch wheel on a fork that weights only 4 pounds.
The two small holes in the oil damper rod will extend above the seal head so these holes have to be plugged. I plugged them with JB Weld. I have had to redo one of them so I don't know if this is going to work. I may try brasing them closed or limit the travel to 6-1/2 inches and I think that will keep them below the O-ring in the seal head.
I only did this because I could. I don't think 3/4 inches of more travel is that big a deal. However, now when someone asks me how much travel I have on that fork I can say 170 mm. I made the longer stanchon gaurds from Home Depot shop vac tubes.
A more accurate way to measure would be to put the bike in a rack and measure the straight line between point A (fully extended) and B (fully compressed). I did a plumb line and rotated the bike so point A and B lined up on the same spot on the floor. I did this with my standard ML8 and got 6.5 inches. I used an old damaged rear hub I had laying around and a tie down strap with a ratchet. I put the tie down strap around the seat support and the hub. I let all the air out of the shock. I used the tie down strap to fully compress the shock.
I got the same measurement with the ML8 upside down on the floor. That may just be a coincidence. The position of the handle bar and the seat would affect this.
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Originally Posted by LaXCarp
Originally Posted by mikesee
now i would like to have more complex idea about ml7/5 damper specifics.
