HOW TO BUILD A NARROW HARLEY FRONT END
Trimming the fat on your stock Harley-Davidson is a big part of the game when it comes to building a chopper. Choppers are supposed to be lean, mean, fast, and skinny, a perfect combo for splitting lanes. Less is more.
With that in mind, the Lowbrow Customs 39mm Narrow Triple Tree Kit makes building a skinny Harley front end hassle-free. These beautiful and sleek triple trees work with the stock 39mm fork legs, or extended 39mm fork tubes, and pair with an assortment of other custom parts to let you build the front end of your dreams.
The Lowbrow Customs 39mm Narrow Triple Tree Kit
WATCH VIDEO: HOW TO INSTALL LOWBROW 39MM NARROW TRIPLE TREES
Get all the knowledge you need for this project as Tim Fiorucci walks you through installing the Lowbrow Customs Narrow Triple Tree kit.
He shows you how to install them on a stock 2001 Harley-Davidson Sportster frame using stock lower legs.
He then shows you installed narrow triple trees on a 2007 EFI Sportster Gasbox Full Frame Chopper. This method works perfectly for any motorcycle that accepts fork cups, such as Gasbox Sportster and Big Twin Full Frames, as well as most Harley Big Twins.
Lastly, he finishes off this narrow Sportster front end with some of our Premium Dust Covers and special 39mm Fork Brace for Narrow Trees.
Narrow Triple Trees and Fork Brace installed on a 2007 EFI Sportster Gasbox Full Frame.
WHAT IS INCLUDED IN THE KIT?
- Upper & Lower Billet 6061 Aluminum Triple Trees
- 1" Diameter Clear Zinc Plated Steering Stem with Snap Ring
- Custom, Chrome-Plated Stem Nut
- Stubby 'OEM-style' Axle with Washer & Nut
- Pinch Bolt Hardware For Stem & Fork Tubes
Lowbrow Customs Narrow Triple Trees come 1" narrower than stock and are designed around 39mm front ends. These are beautifully machined out of 6061 aluminum. Also included is a custom 1" stem with a snap ring clip for the bottom and a chrome-plated, custom made stem bolt for the top. Because these trees are 1" narrower than stock, we also provide a 1" narrower, stepped axle that works perfectly with the stock 39mm lower legs. The proper washers and nut for the axle are also included.
The two longer bolts secure the stem to the upper and lower triple trees.
The four shorter bolts pinch the tubes at the top and bottom tree.
The custom 1" stem will include a snap ring clip and a custom made, chromed stem bolt for the top.
The custom axle is 1" narrower to accommodate the narrow trees and work with your stock lower legs. It includes the correct washer and nut.
IMPORTANT NOTES: Because these triple trees are 1" narrower than stock, you must use a front spool wheel with a hub that is 3-3/4" wide, or narrower. A wider hub will not work properly for this application while using stock lower legs. A stock wheel and brake setup will not work with narrow trees.
WHAT ARE SOME OF THE KEY FEATURES?
We designed our custom Harley triple trees with both style and function in mind. The top tree has 3-1/2" center to center holes for standard Harley riser spacing. These holes are countersunk on the bottom to allow you to mount T-Bars, Rabbit Ears, or any kind of handlebar riser you like with flush allen head bolts.
3-1/2" center to center handlebar mounting holes allows for a wide variety of direct fitments.
The counter sunk holes on the bottom allow for allen head bolts to almost disappear for a super clean look.
The bottom tree is machined and ready to accept the hidden fork stop necessary for your application. If installing on a stock Sportster frame, use SKU 015220 Pro One Internal Fork Stop Kit. For use on any frame that utilizes neck cups (such as Gasbox full frames and most Harley Big Twins) use SKU 015354 Cycle Standard Stainless Steel Internal Fork Stop Kit.
The 3 bolt holes on the bottom tree near the stem hole are for integrated hidden fork stops.
The headlight mount on the lower tree is countersunk large enough to accept either an allenhead bolt or a stud with nut and washer. This will allow you to easily install basically any headlight you desire without having to modify the lower tree. When installed, the mounting hardware will be recessed to keep things looking clean and simple.
We also know how hard it is to remove bearings and stems from bottom stock triple trees. For that reason, we designed these trees to use a simple pinch bolt so installing and removing the stem is quick and easy with basic hand tools.
Headlight mounting hole on the bottom is counter sunk and made wide enough to accept a washer with a hex or allen head bolt to completely disappear from the bottom of the tree.
INSTALLING A NARROW TRIPLE TREE KIT IN 6 STEPS
There are many ways to use these Narrow Triple Trees but today we are going to show you how install them on a 2001 stock Sportster frame.
STEP 1: STEM AND TRIPLE TREE PREP
First things first you need to determine what internal fork stop / cups you are running. With a stock neck on a Sportster there are no cups. The Timken races get pressed inside the neck. So, we needed to use a Pro One Hidden / Internal Fork Stop Kit to add fork stops to our bike using these custom triple trees. And, yes, the Pro One kit says it's for Softails, but it will work for Sportsters as well in this case!
We are using a Pro One Hidden Fork Stop Kit. We put the largest slot faced towards the rear of the triple tree and will be installing the Timken race with the stop towards the rear of the neck. This will give us the best steering radius.
On a workbench you will want to prepare the trees before installing them onto the frame. You will first lightly install the hidden fork stop plate onto the bottom triple tree. You will need to determine what orientation you would like to use and what way you are going to have the Timken race with the built in fork stop face.
We chose to put the Timken race with the stop on the back side of the neck. We also wanted the largest steering radius possible for this build, so we orientated the hidden fork stop plate with the larger slotted section faced towards the rear of the triple tree.
You will only need to use three of the screws from the kit. Make sure to use Blue Loctite and do not fully tighten these down yet, the stem and pinch bolt for the stem needs to be torqued and set first.
When installing the stem, it should glide in pretty nice. If not theres a nifty trick below to help you.
Next you will install the clip onto the 1" stem with snap ring pliers. Now the stem is ready to be installed into the bottom triple tree. If the stem doesn't slide right in and feels a bit tight, do not beat it in! Here's a neat trick.
Take one of the longer pinch bolts and carefully thread it in the opposite direction on the bottom tree. Once it reaches the middle pinch area, place a flat washer blocking the hole.
Tighten the bolt to the washer and watch as it slightly push the pinch area away from itself. The stem should now fall in to place now like butter.
Install the longer pinch bolt backwards carefully until it reaches the split in the back of the triple tree. Grab any old washer and insert into the crack blocking the other side of the hole.
Tighten down gently and watch the split open every so slightly.
It doesn't take much and it will open it up enough to slip the stem in.
Push the stem in. Make sure to get the clip is flush to the bottom of the tree. 
Orientate the clip in a way thats eye pleasing to you.
Remove the washer and pinch bolt from opposite side. Install the pinch bolt the correct way and make sure to use Blue Loctite. Torque to 30 foot lbs.
Once the stem is fully flush and the clip is touching the bottom of the triple tree. Remove the pinch bolt and install the pinch bolt the correct way. Use Blue Loctite and torque it to 30 foot lbs.
Torque down the three hidden fork stop plate screws.
Finally torque down the three screws on the hidden fork stop plate.
STEP 2: PREPARING THE NECK ON THE FRAME
Depending on the year range, your Sportster may or may not have a fork lock tab for a padlock welded to the frame. In our case we are using a stock 2001 Sportster frame and in fact it does have the fork lock tab.
This is not something we can use anymore and will definitely be getting in the way of our fancy new triple trees, so that needs to be cut off and smoothed out.
The fork lock is in the freakin' way man!
Tootaloo fork lock!
While you have the angle grinder out you should also cut off the stock fork stop on the top of the neck. It's going to be in the way of the headlight mount on the bottom tree.
Though you will see in a little bit this is a good reference point when lining up your timken race with the internal fork stop.
This is your stock fork stop. Its also got to go because it will be in the way of your headlight mount.
See it's totally in the way!
If your stock fork Timken race is still in the neck be sure to tap that out with a drift or punch. Next, before pressing in the new Timken race with the internal fork stop we need to figure out if we have enough room or not to press this race in to be fully seated.
Because there is an internal fork stop hanging off the race there could be not enough clearance in the neck which could cause the race no to seat properly. You will want to use your calipers and figured this out on your frame. Do not take our measurements as an exact solution because every frame / situation could be different.
Measure the distance from where the race sits in the neck to the face of the neck, then measure the distance of the race to the hidden fork stop.
First measure the distance from where the race sits to the end of the neck. We found ours to be at .565". Then measure the race length before the internal fork stop which we measured .535" so we need to make sure we have at least .030" of clearance ground away on the rear part of the neck where the internal stop is going to live.
Lining up the center of the Timken internal fork stop mark each side on the rear portion of the neck to give you a guide.
Center and line up your race in the neck and make a few marks of the width of the fork stop on the race and that's where you will be sanding or grinding away material. Get to grinding. Measure again from where the race sits in the neck to where you have ground down and if you are under your clearance measurement needed then you are good to go.
Grind some relief in the neck where the internal fork stop will live based on your measurements.
Do a little at a time and keep measuring until you have the desired clearance.
STEP 3: INSTALLING THE RACE WITH INTERNAL FORK STOP
Using the stock fork stop located on the top of the neck and the center weld seam on the frame it self as guides, center the timken race with the internal fork stop in the neck.
Using a combination square you can line up the center of the hidden fork stop then on the opposite side make a mark that is directly center which will help you locate the center on the front of the neck.
Using the mark you just made on the front of the race, you can now measure the center of the stock fork stop and make a mark as well. Line up both marks and use the Lowbrow Internal Fork Lock Installation Tool with the Fast Eddy Co No. 11 tool line up your marks and press race in slowly.
We found it easiest by marking the center of the stock fork stop and then the opposite center of the race using a combination square to help line up the race in the neck. Lining up the mark on the stock fork stop with the line on the front of the race makes it super simple.
We used the Fast Eddy Co. No. 11 Neck Cup Installation Tool and the Lowbrow Customs Internal Fork Stop Race installation tool to press in the race with ease. You may want to pull the tool on and off a few times to make sure you are lined up properly before fully seating the race.
If it's crooked or off, its easier to knock it out with a drift and start over when its not fully seated.
Slowly cranking down the Fast Eddy tool and setting the internal fork stop race.
Internal fork stop race installed with ample clearance.
Once the race is installed and your confident it is centered. Now would be a good time to cut off that stock fork stop.
STEP 4: INSTALLING THE TREES
Before installing the bottom tree onto the frame you need to put the Lowbrow Customs Spacer on top of the Internal Fork Stop Plate. Then you must install the greased bearing onto the stem.
Before installing the bottom tree and stem through the neck you will need to install two parts. A Lowbrow Customs spacer to give just a little bit of relief from the bearing and tree, and the greased up Timken bearing. You will have to use a bearing installation tool and or a perfectly sized piece of pipe to knock the bearing down onto the step of the stem.
Time to install the stem into the neck.
Drop your greased top neck bearing on top over the stem.
Now you can install the bottom tree / stem through the bottom of the neck. Place the greased up top bearing in the top of the neck, then place your dust shield over that.
Next place the dust shield over top of the greased bearing and then the top tree over top of the dust shield, Lastly loosely install the stem bolt.
You can now put your top tree on and finish it off with the top stem chromed bolt. Do not fully tighten this bolt down so that once you get the legs on you can adjust the neck play.
STEP 5: INSTALL THE FORK LEGS
Before installing your legs there are couple ways to finish them off. If you cleaned up your legs but your dust covers are missing or in poor shape, don't worry, we've got you covered.
We made some killer Premium Chrome Fork Seal Covers to finish your lower legs off. Also, if you are running some longer tubes and need to tighten things up, or you are just interested in some extra stability and rigidity with your stock tubes, we also have a Narrow Glide Fork Brace that will go in place of the dust shield covers. The fork seal covers and fork brace would get installed before this next step.
You could cap off your Stock lower legs with some new Lowbrow Customs Premium Seal Shield Covers.
The other option is if you have longer fork tubes to run a fork brace. This is Lowbrow Customs Narrow fork brace that lines up perfectly with the Narrow Triple Trees.
With using your stock lowers you need to make sure to use the proper leg for each side of the trees. The right leg will have the larger hole and pinch bolt, and the left leg will have a smaller hole with no pinch bolt.
When installing the legs into the trees, be sure not to twist. Also make sure you are using the correct leg for each side. Right leg will have the larger axle hole and pinch bolt.
Inserting the legs once you get to the top tree. We like to make the cap flush with the top of the tree. Tighten down the top pinch bolts only to secure the legs into place.
Install the four smaller pinch bolts into the trees loosely. Slide each leg into position one at a time. Make sure to not twist the legs when inserting them into the trees. This causes zig zag patterns to form on the legs. You should always just slide them up and wiggle until they find there way home.
Once at the top, get the bottom of the tube cap flush with the top of the tree and then lock the top pinch bolt down. Do not tighten the bottom pinch bolts just yet, leave them loose so we can adjust the neck bearings.
Move your forks left and right and make sure they are moving the same distance to each side. If it is in fact equally moving left to right you have set your Timken race properly.
With both legs on you can now triple check how straight your internal fork stop is by moving the trees left to right. If the fork is going more to one side then the other, your race isn't properly centered and you will have to take everything off and knock out that race and start again.
Tighten down the top stem bolt and adjust your neck bearing preload. 
Pull towards and push away on the legs centered in the frame, you want to make sure there is no play in the front end this way.
Continue to adjust and tighten stem bolt till you find the right amount of movement in the forks.
Next you will want to adjust your neck bearings load and tighten the top stem bolt to desired neck play. You want to pull up and down on the legs as well to make sure there is no up and down movement.
Lastly make sure to torque down all 6 pinch bolts to 30 foot lbs. The bottom stem pinch should have already been torqued on the work bench, but you can double check that one if you would like.
STEP 6: INSTALL YOUR FRONT WHEEL, HEADLIGHT, AND HANDLEBARS
Grease up that axle and get her in there. Torque axle and axle pinch bolt to factory specs.
Line up your hub to the holes on the lower legs and install the axle. Don't forget to grease the axle up before installing it. Use proper spacers for the wheel you are using.
Once the axle is thru the spacer, wheel, and spacer, it will go through the left leg. You will then put the large washer first, then the lock washer second, and lastly the nut.
Torque the axle nut first to factory spec so that it pulls everything towards the left leg. Then you will torque the axle pinch bolt on the right leg to factory spec.
Torque the axle on the left side first, then torque the pinch bolt on your right leg.
Installed headlight. You can see how close the mount is on this Gasbox chopper frame.
Install your headlight. Again, If you left that stock fork stop on because you were using it for measuring stuff, it is going to be in the way of the headlight mount. It's got to be cut off. 
Installed headlight and handlebars.
Install your handlebars and dial in your grips and controls.
Thats it, your new sick as all hell, narrow front end is complete! WOOOHOOOO!
Weeeeeeee!
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