AM chopping my 97 Sportster and want to put a longer than stock Paughco springer front. Anyone have any experience with raked neck cups or anyone know of a co that makes raked neck springers?

 

I'm gonna bust yer bubble here about raked trees and/or neck cups. Don't use them on a bike that hasn't had its frame raked. You can get into some serious handling problems with raked trees/cups on a stock frame. When you use 'em that way you decrease the trail and can too easily get to the point where your bike will go into a speed wobble.

Raked trees or cups are properly used to correct for too much trail caused by raking a bike's frame. The proper amount of rake on the trees or cups decreases the trail until it is near the stock bike's trail. Low speed handling stays near what the stock bike had, but you get the look of the long front end, while maintaining the bike level.

Here's a couple places to check on rake, trail, etc. -

http://www.kennedyschopper.com/raketips/rake.html
http://www.rbracing-rsr.com/rakeandtrail.html
http://www.wisil.recumbents.com/wisi...te2=yes#Actual Trail Calculator

Let me repeat: DO NOT USE RAKED TREES OR RAKED CUPS ON A STOCK FRAME!!!! You might get lucky and not reduce the trail to a dangerous point, but then you might be on the ragged edge, hit the brakes, compressing your front end, and reducing the trail even further, wobbling your poor carcass into the pavement.

 

Thanks for the info Skip but not being mechanically inclined myself I have a question. If you can't use a raked tree on a stock frame...how do you chop a stock frame? Hope this doesn't seem like a dumb question.

 

Phoenix, It goes back to rake and trail. They go hand in hand. If you increase the angle of the triple trees without rakeing the frame you will run into a trail problem which is seriously wrong. HD's trail is between 2.5 and 6" positive. It has to be right or you are asking for problems. Remeber that trail is a line straight down to the ground following the steering neck, and another line straight down from the centre of the axle. The difference is trail. It can't be negative, excessive or too small or you will crash.

 

Here's an awesome explanation on rake and trail. The whole site's pretty good too.

http://64.172.168.34/neatstuff/rakeandtrail.htm

 

The only dumb question is the one that doesn't get asked. Especially when not knowing the answer can get you a bad case of road rash or worse!

A stock frame is raked by several methods. One is to cut from the bottom of the neck to the top, leaving a small piece at the top connected. Then the connected piece is heated, a bar slipped thru the neck post, and the neck bent upward until the desired rake is achieved. Next the gap left between the neck and frame is filled with gussets welded in place.

Another method is to cut the front downtubes, heat the backbone of the frame, and bend it upward until the desired rake is achieved. The pieces are fabricated to fit in the gap left in the front legs and welded into place. This is usually called stretch, and might be seen in a description of a customized frame as "4 inches of stretch up", or "4 inches of stretch in the front legs."

A third method is similar in that the top tube (backbone) is cut, the front legs cut as before, some length is welded onto the top tube to extend it forward, and the front legs bent to meet it, often with added stretch in the downtubes at the same time. You might see this listed in the specs as "6 inches of stretch in the top tube", or "stretched 6 inches out." If it's done in combination with the front legs, it might be "6 inches out and 4 inches up", or any combination of numbers to achieve the look and rake the builder wants.

Biggest thing to remember in all this is that everything is a compromise. Less trail gives quicker handling, more trail gives more stability. As Joe said, most HDs are between 2.5 - 6 inches positive trail. Something else to remember is that the trail changes when you put on the front brakes and the front end compresses. So if you design a setup where your trail is small, compressing the front end in a hard stop might place you in a negative trail situation, and chunk you onto the pavement when the front end starts shaking rapidly from lock to lock.

My first bike was a '72 XLCH with 15' over tubes, neck raked (by the first method I described) to allow the bike to sit level. It was probably near 45 degrees, or about 15 degrees more than stock, though the builder said it was raked "7/8 inch", meaning the bottom of the neck post had been bent outward that amount. I think I could've ridden that bike from San Jose, CA where I bought it all the way to Norfolk, VA, my next duty station, without ever touching the handle bars. It also reminded me of that old Red Sovine song, "Give Me 40 Acres" (and I'll turn this rig around). It was tough keeping it up at parking lot speeds because of way too much trail.

When I rebuilt it, I went to a Corbin Gentry frame with some stretch in the front legs and backbone, resulting in a 35 degree rake. It took a 10" over Fury girder w/ a 21" front wheel to sit level. The trail was greater than a stock Sportster, but not too much greater, so it handled much better at slow speeds. But it was pretty good at high speeds, too.

Hope this helps. The sites I put in my previous post have some pretty good pictures that will really help simplify what I'm trying to say.

 

Thanks for that explanation. Hope your fingers didn't get too tired.

 

OK, been doing some searching and thinking on this. I need to correct a statement I made above about not using raked cups. The cups, which are generally around 3 degrees, will work fine on a stock frame. The cups are considered a part of the frame, so adding 3 degrees with cups, is equivalent to physically raking the frame neck. I think the 3 degree cups are about the max you can go with, due to the neck post hitting the inside of the frame neck

If you use the cups, you'll get 3 degrees of rake, which may or may not be enough to get you what you want with the overstock springer you were asking about. What length o/s is it?

You could do a mockup, or a drawing, and use the trail calculators in any of the sites mentioned elsewhere in this thread to see how much rake in the trees would give you sufficient trail. I don't know if Paughco would build a springer with any additional rake in the trees. Guess you could contact them and find out. They should at least be able to provide you with the dimensions of their springer so you could do the trail calculations.

I'm sure there are front end builders out there that could do what you need. As usual, it boils down to money. Most of the custom builders with the capabilities to do a front end are gonna hit your wallet pretty hard, a lot more than a Paughco unit.

Sorry 'bout the bum dope concerning the raked cups. (I thought I was wrong once before, but I was mistaken. But don't quote me on that to my wife!)

 

thanks for the info Skip- Paughco makes the springer fronts from 6 under to 18 over in 2-3" increments-so will do the trail calcs before ordering with the 3 degree neck cup.
Dont like road rash-had my fair share of it some years ago-old guys dont heal so quickly-lots of laughs.