Standard vs. Special Forks

[Toolmaker Tim]

I know there has been some discussion about changing from one fork type to the other, that some combinations make for bad handling. I seem to remember standard forks in a Special tripletree is a bad idea. Right now I have 2 standard forks and 17" rear wheels. The standard forks are in better shape than the 79SF's forks are. If I put the standard forks on the SF would I be asking for trouble if I didn't change the triple tree?

[natemoen]

It changes.the geometry of the bike for the worse if you mix forks and triple trees. So standard forks only go with standard trees and special forks only go with special trees. That is unless you are adding a sidecar and then apparently it helps to mix.

[DGXSER]

For Better or Worse.....last time I heard that cost me 20 years so far.

Yep mixing the triple trees and the forks either increases or decreases the trail. Look up Fred's "Why I ride a side car" thread. He explains it in detail there. Essentially it has to do with the way Yamaha mounted the axle in front of the fork on Specials and under on Standards. They changed the tripple tree orientation to creat the same trail in either setup. So swapping one way you increase trail, the other you decrease it. IIRC, increasing Trail will "slow" the steering, decreasing it will make it "quicker".

[crazy steve]

...would I be asking for trouble if I didn't change the triple tree?

Yes; this will reduce your trail too much. It's wanted on a sidecar setup as it reduces steering effort, but isn't a good idea otherwise. It also gives you light, responsive steering but under the right (or wrong) conditions you can end up up with a 'tank-slapper'. If you're willing to install a steering damper, then I'd say go for it, but otherwise I wouldn't do it.

Standard trees aren't hard to find (or expensive), so there's really no reason to do this...

[fredintoon]

Hi Tim,
like they said, I run Standard 'trees with my Special forks to reduce the steering trail to give my sidecar rig lighter steering.
What you propose is to fit Standard forks into your Special 'trees. This will increase the steering trail to make the bike steer more heavily.
I'd advise against doing that.
Swapping forks 'trees and all won't change the handling but note that " 'trees and all " ain't the end of it.
You will also have to swap in the Standard front fender and the Standard headlight ears which may also lock you into a Standard rectangular headlight.
And a good thing, you will get to replace those Weird Harold Special calipers with normal ones.

[Toolmaker Tim]

Weird Harold Special

That's Funny! Ok, if I change the forks, I change the trees, fenders,calipers, ect. Now,what is the surest way to know if the triple trees are standards or specials? Short of asking "Weird Harold."

Also, how does the rear tire size inter all of the steering geometry? Does going to a 17" tire change things? I can get around the engine, carbs and electricals fairly well, but the suspension is a new frontier.

[DGXSER]

Hey Tim,

The 17" rear tire will simply make finding a tire the right size a little more of a challenge, and increase the rear height of the bike a bit. So for the vertically challanged, flat footing becomes even tougher.

The Special trees are different I know, but I do not know exactly how, never owned a standard.

Side note, I was just up to SB Indiana Yesterday. Spent Thursday night at the Marriott RI on Niles, ate at Kildares. Helping ND out with their new hockey arena.

[Toolmaker Tim]

Around the Bend

Wow, if you drove down 933 you went right past where I work! The north sde of SB is about the only place where things are happening! Newsweek just rated South Bend as one of the Top Ten dying cities in the US. As long as you stay north of State Road 23 you are safe, the other side..... not so much. I live on the very west edge of the city, right down the street from one of the 3 high schools that the state is getting ready to take over due to poor performance Things are always geting built over there in DomerLand. If Notre Dame wasn't here we would have to turn out the lights.

[bikerphil]

Standard lower TT has pinch bolts in the front, Specials are on the side.

[crazy steve]

Standard lower TT has pinch bolts in the front, Specials are on the side.

... and the top tree is 'flatter' on the Special. If you look carefully, you'll notice that the standard tree has more 'offset' than the special; this is the distance from the fork tube holes to the steering stem. This offset difference is what changes the steering geometry. It may not look like much, but it makes a marked difference in how the bike handles...

[Toolmaker Tim]

Shocks, Gold Emulators, and other things

Thank you guys, like I said, I'm going to be taking a crash(hope not) course in suspension here. I'm sure I will have more questions.

There was a thread about using VT1100 shocks on our bikes. When I went looking for them on Fleabay I saw there were 2 types of suspensions listed, A&B. Does anyone know the difference?

Bikerphil, didn't ypu put the Mikes XS emulators in your forks?

[cywelchjr]

Thank you guys, like I said, I'm going to be taking a crash(hope not) course in suspension here. I'm sure I will have more questions.

There was a thread about using VT1100 shocks on our bikes. When I went looking for them on Fleabay I saw there were 2 types of suspensions listed, A&B. Does anyone know the difference?

Bikerphil, didn't ypu put the Mikes XS emulators in your forks?

I don't know if it was bikerphil, but someone did, but I understand they will work for a special but not for a standard, at least not without some sort of modifications to either the emulators and/or the forks.

[bikerphil]

Yep, it was me, they work just fine too, here's the thread......

http://www.xs11.com/forum/showthread...ight=emulators

[Toolmaker Tim]

Emulators

Phil if I understand what you did correctly, the special needed no mods and the standards will need a adapter bushing on the top of the damper rod.

[bikerphil]

Phil if I understand what you did correctly, the special needed no mods and the standards will need a adapter bushing on the top of the damper rod.

Correct Tim. I'll be pulling my emulators out shortly for a 5K mile inspection. I will report back, pretty sure everything will be fine with them. They give you a nice feel of the road and improved riding confidence.