Rock Shox Mag 21 style air needle valve

[FluffyChicken]

RTV is basically a two part "Room Temperature Vulcanising" silicone and used for making moulds etc.

It can also refer to what is basically a Marine Grade sealant, used in harsh wet places, e.g. showers, aquariums, outside etc and can come in a cartridge like the normal bath sealant.
e.g. http://www.ebay.co.uk/itm/HA6-RTV-MARIN ... iPIpybid6A
Shore (flexibility/hardness) rating varies. above is ShoreA:25
See what the others have tried, I've not made any this way yet other than filling in older MAG30/10


I still think the nitrile is going to be too hard, O-Ring use a hard 'rubber' I have a length of 8mm O-Ring nitrile cord too, been there tried that.

 

[dencal]

Re:

Ok get it, is also called red silicone, the one used on mechanical field in very hot situations with oil and mechanical stess, like the one used on the basement of the engine cylinders and so on

 

[FluffyChicken]

The silicone valves will stiffen some in time. They do start out fairly soft, depending on just which RTV sealant you used.

Rebound tends to be relatively quick on Mag style forks, quicker than on a modern fork. You should hear the noise of oil flowing thru the ports on rebound.

You can adjust rebound speed by changing the oil weight. 7.5W (or 50/50 mix of same brand 5W and 10W) might do just the trick to slow your rebound. Beware, however, that if the rebound is too slow, the fork will "pack down" over rapid stutter bumps. Stock oil recommendation for the Mag 10 was 8wt ATF (automatic transmission fluid). 5wt would have a more rapid rebound. 10wt might feel slow, especially for lighter riders, running lower pressures.

What do you weigh? 45psi would be appropriate for someone in the 200#, typically. When I weighed 165#, I used 41psi. Today, at 225, it's 52psi.

Raising the oil height would allow you to run less pressure and yet still resist bottoming. Try it closer to 45mm from the top of the leg, fully compressed.

Here's a tuning guide, from this site:

http://www.retrobike.co.uk/gallery2/v/M ... d.jpg.html

J

These are 1994 MAG10s, so identical to the 94+ MAG21 for setup as all had the newer internals
5wt would be standard '93 onwards, The older MAG20/30 used 8wt as standard.
This is a better guide http://www.retrobike.co.uk/gallery2/v/M ... 4.pdf.html

At 72kg you are pretty much the 'standard' user
5cm* oil height at 5wt @40PSI should be great. Then using an allen key in the top turn to alter compression setting to your liking and riding
maybe try a height of 4.5cm in case you have long travel setup and will stiffen up as mentioned near the end of the travel.

(*that is with the fork fully compressed, pump the oil in as you do it to remove air from the lower chambers, can take a while if you really must get it all out ;-))

 

[dencal]

Re:

Hi Fluffy, and thanks.
Sorry but I cannot understand the procedure mentioned by you "pump the oil in as you do it to remove air from the lower chambers", i pour the oil from the bottle, never pump it in, and never remove the air, just press the fork down, should I pump the oil instead or create vacuum, and how? Sorry but I jus want to follow the best way for setup my fork....

 

[FSXStumpy]

He means, after pouring in the oil to the leg, move the inner leg up and down in the outer a few times. This will expel any air that was trapped under the damper piston. Then re-check and top-up the oil level to the desired height.

J

 

[FluffyChicken]

He means, after pouring in the oil to the leg, move the inner leg up and down in the outer a few times. This will expel any air that was trapped under the damper piston. Then re-check and top-up the oil level to the desired height.

J

That's what I mean

 

[Thias]

Hey guys!

Inspired by this thread I tried to make my own replacement valves out of Silicone. My first try is a standard 1K silicone that I had left over from my bath renovation...

My mold is made out of aluminium tube, 8mm inner diameter. Cut it a bit longer than the original valve rubber. Closed the bottom with some tesa strips and pinned a few little holes to allow the air to escape.


I smeared a bit of oil on the insides so the silicone would slide out when hardened. Then filled the silicone in and left it alone for to days. Was not long enough thou..



As you can see, the right "plug" got damaged while sliding it out. They were not cured completely. So I had to wait another week before my attempt to make the hole for the ball needle.

Yesterday I did that eventually, using a thin needle. Then slid it into the Mags Valve cap, lubed the ball needle and filled some 250 psi.

....

Seems to hold the air. I tried to slide the ball needle in and out a few times. That went OK. So now I will wait a few days and see, whether it holds the pressure or not.

Wish me luck!

 

[dencal]

Good job !

Mine looks good after 1 month, also maded with very economic bath silicone.Next time i will use the High-Temp Red RTV Silicone.

Soon i will post the photos of my Gary Fisher !

 

[dencal]

Re:

Here my baby, ready to go...

 

[FSXStumpy]

Awesome!

I use the black high-temp RTV (Just because it's black, LOL), and my mould is wooden, which allows the RTV to cure more quickly - 2 days seems to work well.

Gotta get a good solid coat of grease in the mold first.

Excellent results, though! Another Mag rides again!

J