Zongshen RX3: Suspension System
 

Fork Disassembly and Inspection

Upper Fork Tube Disassembly

To disassemble the forks, begin by loosening the cap of the fork with a 19 mm wrench. Lower the upper fork tube to reveal the fork spring. Insert a 14 mm cone wrench, or another thin wrench, between the fork coils, and grab the lock nut below the fork cap. While holding the lock nut, remove the fork cap and washer with a 19 mm wrench.

http://www.cscmotorcycles.com/v/vspf...ge_%20(15).jpg

http://www.cscmotorcycles.com/v/vspf...ge_%20(16).jpg

Remove the fork spring, and drain the fork oil.

http://i442.photobucket.com/albums/q...pswn6qt64l.jpg

Remove the upper fork tube following the instructions in the CSC Fork Maintenance Tutorial at the following link.

http://www.cscmotorcycles.com/Articles.asp?ID=263

Lower Fork Tube Disassembly

Disassemble the fork base by removing the bolt (A) with a 2.5 mm Allen wrench.

Secure the fork base (A) in a vice. Insert a thin rod through the holes of the fork (B), and remove the inner fork tube from the base by twisting the tube in a counter clockwise direction.

http://i442.photobucket.com/albums/q...psuxbelhv4.jpg

Push the damper rod down the lower fork tube to remove the base plug (A), and disassemble the lower fork tube.

http://i442.photobucket.com/albums/q...psou6wlwhd.jpg

Fork Spring Inspection

Measure the length of the fork spring. Replace the spring if it is shorter than the minimum length.

http://i442.photobucket.com/albums/q...psr6t5pj9k.jpg

http://i442.photobucket.com/albums/q...pscxyehtbr.jpg

Shock Absorber Adjustment

Cylinder Gas Pressure

The standard gas pressure in the cylinder is 44 psi. The gas pressure influences the compression damping of the shock.

http://i442.photobucket.com/albums/q...psbg0j2d3f.jpg

Spring Preload

Loosen the Allen head bolt, and turn the locking collar (A) to adjust the spring preload. The spring preload should be set to the proper race sag for best performance. Directions for adjusting the spring preload are contained in the following thread.

http://www.chinariders.net/showthread.php?t=14677

http://i442.photobucket.com/albums/q...psbjgfwzsx.jpg

Rebound Damping

Rebound damping affects the speed at which the shock extends while recovering from compression. The shock absorber has 15 settings for rebound damping. Turning the screw clockwise slows the rebound damping. Turning the screw counter-clockwise accelerates the rebound damping.

http://i442.photobucket.com/albums/q...psmmlb51i7.jpg

Today I removed the valve cap on the stock shock absorber. Underneath I found a standard schrader valve. :tup: I measured the pressure in the shock with my tire gauge, and it read 67.5 psi. The specified press is 44 psi. Perhaps the high pressure contributed to the harsh ride I experienced with this shock absorber. ;)

I lowered the pressure to the standard setting of 44 psi. If the shock is not performing properly for you, you might want to check the air pressure. However, the shock cartridge contains very little air, so it might not make much of a difference. :shrug:

Man Spud, you're good.

Always got something cookin:yay:
http://i167.photobucket.com/albums/u...psyiagrium.jpg

:lol:

I would assume that you would want to check it with the wheel off the ground, or does it matter?

How do you access the valve? Do I have to take everything apart? My valve faces the rear. I'm thinking of removing the shock and reinstalling it with the valve facing the front. Will it fit? Will I be able to access it then?

Rebound adjustment and preload: What is a good starting setting? I am a lightweight, 160 lbs w/o gear.

The following thread describes how you set the shock spring preload.

http://www.chinariders.net/showthread.php?t=14677

You might be able to check the air pressure from the top. I can't guarantee a minor difference in air pressure will make any difference in shock performance, but it can't hurt to try. ;) However, adjusting the spring preload will certainly improve the performance of the shock. :)

The schrader valve of the stock shock absorber is located in the same position as the pressure valve on the Progressive shock absorber.

http://i442.photobucket.com/albums/q...psoyp9nz29.jpg

You must remove the saddle, fuel tank, and a small emissions canister to see the valve from the top.

http://i442.photobucket.com/albums/q...pscr2c5m8s.jpg

Remove the valve cap, and you might be able to get a small pressure gauge onto the valve, if you have small hands. ;) Lift the rear wheel to get the weight off the shock before you measure the pressure.

If you cannot access the pressure valve from the top, I wouldn't worry about it. I'm beginning to doubt a small difference in air pressure will have much effect on the performance of the stock shock absorber. ;)

With my understanding of suspension wich is some what limited but with a good ME guess; I don't think chages in air pressure will make any noticeable pre-load difference. These are not air spring shocks like in many mountain bikes. The air pressure is there to minamaize oil foaming while working the shock hard. So the pressure is in the oil damping circuit and thus acts equally on the top and bottom of the internal piston and valving.

I'm sure you are correct. :) There is very little air in the cartridge. ;)

Spud, would it be possible to attach a flexible extension on the valve and then zip tie it to an accessible location?

Yes, that might be possible, George.

AZRider, something like the part below coupled with a bit of tubing might make for remote acces to the valve and the ability to easily make pressure adjustments. Though keep in mind the pressure might spike dramatically during normal shock operations; I would at least buy tubing rated 200 to 300 psi.

Neither spud or I think the pressure will make much difference but this is simply an untested theory. Testing a theory with observation and experiment is the only way to progress with real knowledge. So I say give it a try and report back!

http://www.amazon.com/Zjskin-Degree-...XEBRE22AP4AE7C

Ideas?

If you read the thread at the link I posted earlier, I believe you will find some suggestions therein. ;) However, the best way to adjust the spring preload is to set the race sag properly, and this can vary slightly with tire selection, equipment installed, loaded weight, et cetera.

I stated this earlier, but I will repeat it once more, since it is significant. ;) The stock shock absorber doesn't hold much air. If you hold the schrader valve down for less than a second, all the air will be released. Obviously, the air volume inside the shock body is very limited. Therefore, if you wish to add air to the shock, I suggest you use a hand pump, or set the pressure regulator on your mechanical pump to 45 psi. Otherwise, you risk blowing an oil seal in the shock. ;)

Thanks for the link 3banger, that's exactly what I had in mind, coupled with a small bicycle pump. Next time I take the bike apart for a valve adjustment, I'll take a closer look at what I'll need.

When I tested the pressure in my shock it was 150psi. i let it down to around 30.psi.
but the shock does not extend itself at that pressure so it needs more pressure than that
it's possable that there is no pressure in it at all now as it doesn't feel like it on the bench
....
a word of caution ... I took the preload adjustments all the way to the top to lower the seat height.... which it did.... but the ride was really rough ( it has always been with this bike) ... i am trying to fit a weaker spring to it right now...
but in so doing ( raising the preload nuts to the top of the shock) i inadvertantly bottomed out the shock the stroke is extreamily short on this shock and every inch you raise the nuts you lower the shock piston.... Yes the shock will bottom out and the spring will not even be compressed at all.... weird but that is how they made it
so My solution is with the shock on the bench, is to extend the shock fully... and adjust the preload nuts to the top of the spring enough to hold the spring solidly there. and then re install it....
this will give me maximum shock travel and also maximum seat height ( to my dismay)
I think the only way to lower this beast is with a lowering kit or make your own Modified horseshoe/dog bone that is longer that will alow the rear swing arm to go up without affecting the shock or it's length.
....
so as your adjusting the sag you may well find that you bottom out on bumps there is very little room to play with here with this short acting shock.
Bob........

for those that have messed with the preload and want it to have full use of the shock stroke I suggest raising the bike and get the rear wheel off the ground
and then move the pre-load nuts to the top of the spring and then lock them down there....
it's not the best solution but it will give you the full stroke of the short shock
as far as sag..... this bike doesn't have any sag ! the spring is too hard for that
a weaker spring is needed..... and that is where I am at right now!
if I find one I will let ya all know all the details of the spring... because this has been a bitch to discover on my own !

.....
Bob.......

It seems to me that the RX4 has a different spring and nut in the rx3 there is one with a bolt versus in the rx4 two nuts, but I could be wrong in the rx3 the spring is relatively soft.If I'm not mistaken, you can try to get the spring from the rx3

Hola, ese amortiguador que marca es? Se instala facil como el original, su tamaño es el mismo que el original, donde lo puedo comprar

Hola, ese amortiguador que marca es? Se instala facil como el original, su tamaño es el mismo que el original, donde lo puedo comprar.