Stanchion/Brace: Differences

[mixelpix]

Hi, anyone know if the forks off a '80 special and '79 are interchangeable? Differences? General differences to look for?
Looked on http://parts.yamaha-motor.com/ & couldn't find a parts list for the '80SG, but the LG looks pretty identical. My '79SF fork assembly part #- 3H3-23101, the '80LG, 4H3-23101. I think I'm good to swap out? Both stanchion tubes are -23110
Also, I really like the idea of using a T-valve to evenly set fork air assist pressure. Thanks newmaac for that mod tip! Before I get into the forks - any suggestions on wear and damage to look for with the air assists and the forks in general? I plan on redoing seals and fluids soon enough (and perusing the archives when I get home tonight)
Thanks!
-Patrick Kennedy

[John]

If the 79 is an air fork, then they will interchange. What is the T valve you mentioned?

[mixelpix]

Mark (newmaac) mentioned it. Honestly, not sure exactly what it involves or looks like, but if I remember correctly from our conversation, there is a 'T' connector which bridges the two air valves and has a single inlet, which ensures even pressure between the two forks. -p

[DiverRay]

Patrick
Give tkat a call for a fork brace. I put one on my bike about a week ago, and it handles great! The brace will take all the play out between the handlebars and the front axle. It is $85 well spent, and he is down in Santa Clara, close to San Jose Airport.

[Jerry]

Well, the XJ has the "T" connection front and rear for the factory-stock air-adjustable suspension....

Standard and Special fork braces are not interchangeable. One - I can't remember which - is about 1mm larger where the brace mounts, top of the lower fork. Doesn't sound like much, but there it is. Tkat has some unkind things to say about folks who get the wrong one and blame him for a poor fit. Best if you get one built specifically for your bike, or at least the forks you are using.

I don't have the manuals handy, but thought the Special had the leading axle and the Standard has the stock axle-through-the-fork design. Know there are some brake caliper differences, also fender differences, between years. Hope someone who has both bikes can give a mode difinitive answer.

If you are going to rebuild any forks, consider going with progressive front springs instead of air forks. These variable-rate springs give a good ride over small bumps, but stiffen up under larger bumps to keep from bottoming out. Air just sets the amount of initial force needed to get the forks to move. More air, less give under small bumps, stiffer ride. You can do something similar with progessive springs by adding a PVC spacer at the top of the spring to pre-load it.

Several owners have gone the progressive spring route and no longer use air pressure in the front end. However, if you go the air route, take a look at the parts list for the XJ and you will see how the factory set-up works. One fill valve on the left side of the tripple-T, covered with a chrome acorn nut. Similsar set-up for the rear shocks. Pressure specs are in the service manual. Let me know if you need them. I found the best way to adjust the pressure is with a small bicycle pump, otherwise the volume is very hard to control.

[John]

The XJ forks have a couple of holes near the top of the upper tube, and the two collars with an air hose attached have two O rings that seal the forks and collars, so they probably wouldn't work on an XS without drilling the holes in the fork tube, and then I don't know if the tubes are the same diameter, and that would affect the ability of the O rings to seal the air in. The only way to install an equalizing hose would be to make a hose, with schrader valve built into a T fitting, and on each end of the hose would need a female fitting that will thread on to the schrader valves that are in the caps of the fork tubes. Good idea if the parts can be sourced. Maybe some air brake fittings from an 18 wheeler would work, as we wouldn't be using anywhere near the pressure that is found in air brake systems

[Dennyz]

The Special fork brace also sits up higher to clear the fender. Due to the different axle locations between a Special and a Standard, the fork brace mounts lower on a Special.

[mixelpix]

This is awesome! Thanks Again Everyone For All The Great Help!
-pdk

[DiverRay]

I was trying to help Patrick with the handling on his bike. If he lets TKat know what he's got, he will get the proper brace. I know the older Elevens, as I'm on #3, 1 '78 and 2 '79's. All of mine have been E or F models, as I like the "standard" handlebar/seat setup.
The progressive springs are the way to go, as they help with the little bumps, and are hard to bottom on the big potholes. The California roads are not as good as 25 years ago, as most have not been maintained. Springs and fork braces can keep both wheels in line, and on the ground.
Ray

[mixelpix]

Hey DiverRay,
Thanks for the suggestions - I have a lot of choice$ ahead of me to weigh out with this repair...