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Discussion Starter · #1 ·
Scored this SB&F girder that Im gonna use on a 97xl build, its 10 over and has about 9 degrees of built in rake. I sketched up the concept of my build in CAD and without raking the neck to 45-50 degrees to compensate for the girders "fake rake" im gonna have 0 trail.

Im thinking of doing something similar to what J F Byrd did to his,
(http://i399.photobucket.com/albums/pp76/Byrdster/MVC-016S.jpg)
stretch the backbone and gooseneck the down tubes but I'd like to hear what you'd all suggest is the best way to rake an Evo Sporty. Some pics would be great too.

Heres a pic of the Girder.

 

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If you're measuring 9 degrees of built-in rake on this thing, some thing is wrong; I'm gonna guess that the linkage arms were switched top to bottom. The shorter linkages go on the bottom. Maybe take a look.
 

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If you're measuring 9 degrees of built-in rake on this thing, some thing is wrong; I'm gonna guess that the linkage arms were switched top to bottom. The shorter linkages go on the bottom. Maybe take a look.
The upper and lower links on my SB&F girder are the same length, as they should be. I'm guessing he's got the lower tree turned around 180º. It should be positioned so that the lower pivolt bolt is behind the stem.

Bob
 

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Discussion Starter · #5 ·
Hmm maybe built in rake isnt the best way to describe it, i guess the problem is the offset. if this was just a set of ten over tubes i could toss em on and it would only add trail.... but the offset on this girder is about 7" greater than stock trees. in this case to calculate trail should i still be drawing the line thru the center of the neck tube? Does offset effect trail the same way raked trees would?
 

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read and calculate.

http://www.rbracing-rsr.com/rakeandtrail.html

http://rawge.bravepages.com/minichoppers/trail/Rake_Trail.htm

These two articles will help you understand. You will always measure through the center of your neck, as that is where your pivot point is. That girder looks as though it was made for an extremely raked frame, because it has a lot of offset built into the trees. You may not be able to use it for what you want to accomplish without some re-engineering because of the offset. It is not safe to run a frontend that has negative trail, as it will be very unstable at speed. Excessive trail will give you "flop" when you turn the bars from side to side, and be hard to manuever at low speeds. Hopeyou can make some sense of this.
 

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Discussion Starter · #7 ·
Thanks for the links, that calculator is great and yep just like i thought, the only way i can run this girder is with a 47 degree neck rake. Im going to do exact measurements eventually and probably go the the gooseneck route but in the mean time anyone whos chopped there late model sporty if you could share your method thatd be great. thanks.
 

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Discussion Starter · #9 ·
The upper and lower links on my SB&F girder are the same length, as they should be. I'm guessing he's got the lower tree turned around 180º. It should be positioned so that the lower pivolt bolt is behind the stem.

Bob
Your right.

This is 100% the issue, with the lower tree on backwards it creates a couple inches of offset difference between itself and the top tree, in turn adding about 9 degrees rake. Im going to flip it around but its kind of cool knowing i could flip it around, rake my front end to 45 and still have ideal trail. Thanks Bob.
 

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Thanks for the links, that calculator is great and yep just like i thought, the only way i can run this girder is with a 47 degree neck rake. Im going to do exact measurements eventually and probably go the the gooseneck route but in the mean time anyone whos chopped there late model sporty if you could share your method thatd be great. thanks.
You said in an earlier message that the off-set was 7 inches more than the stock front end. I really have trouble believing that you've got 9 1/2 inches of off-set or that a 47 degree neck is all you can run it on. That sounds miles off.
 

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Here's a pic of my evo sporty. Not exactly JJ material, but she's raked to 47°. I dropped the top tube when I did the frame so I could use my stock forks.
 

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Discussion Starter · #12 ·
You said in an earlier message that the off-set was 7 inches more than the stock front end. I really have trouble believing that you've got 9 1/2 inches of off-set or that a 47 degree neck is all you can run it on. That sounds miles off.
Thanks for the input but problems been solved, with the lower tree backwards (how I picked it up) just made no sense and was totally fubar... it was basically a set of 15degree raked triple trees with a 6.5" offset and 10 over forks.... try to figure out a way to run that haha.
 
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