If you haven't done it before, welding a hardtail on to a stock frame can feel a bit intimidating at first. However, with our Weld-On Hardtail Frame for 1958-1984 Harley Panhead & Shovelhead and these Hardtail Install Instructions you will be well on your way to building the chopper of your dreams.
These hardtails are proudly manufactured in Cleveland, Ohio, USA. All tubing matches the stock frame tubing diameter: upper rear tubes 1", thick walled steel and 1-1/8" diameter lower frame rails that match the stock frame.
This weld-on rear frame section converts your Shovelhead or Panhead swingarm frame into a rigid rear end with cast steel lugged axle plates for use with a 3/4" axle and disc rear brake.
How To Install A Lowbrow Weld-On Hardtail On A 1958-1984 Harley Pan or Shovelhead
We are going to be using this stock Shovelhead frame and the Lowbrow Customs '58-'84 Hardtail Kit.
Step 1: Starting at the top of the stock frame. Mark where to cut the top frame tubes away from the backbone.
Use a straight edge to mark your cut lines.
The cuts should be a little away from the backbone. Do not cut into the backbone
Step 2: Wear safety glasses or a face shield, and gloves. Cut straight down from the top on your lines where you marked the frame tubes. When the frame tubes are cut through, the frame may spring and grab the cutting disc, please use caution.
Start cutting top down, again make sure not to cut into the backbone.
Cut from the top down, wear safety glasses and gloves.
Take your time and cut smoothly on each side, be cautious when cutting the frame could spring and grab the cutting disc. Do not cut into the backbone.
Right top frame tube, cut through.
The left side, again cut downward on top of the frame.
Left side frame tube, cut through.
Step 3: Mark where to cut the top seat post lug. This time, cut close to the top frame tubes, the top frame tube section will be discarded. Then cut your lines marked, again start from the top.
Mark the top seat post lug.
Cut the lug close to the top frame tubes.
Both sides of the top seat post lug, cut through.
Step 4: Moving to the bottom rear section of the stock frame. Measure and mark where to cut the bottom frame tubes. 1-1/2" forward from the cross tube.
1-1/2" mark from the cross tube on the bottom left frame tube.
1-1/2" mark from the cross tube on the bottom right frame tube.
Step 5: Measure and mark where to cut the bottom cross tube. You will make a mark at 11/16" (or .70" if you are measuring with a digital calipers) from the inside of the side tubes. Don't measure from the lugs, measure from the actual tubes. Mark on the bottom of the cross tube also, It will be easier to cut from the bottom with the frame upside-down.
11/16" mark on the cross tube using a ruler from the bottom left frame tube.
11/16" mark on the cross tube using a ruler from the bottom right frame tube.
Step 6: Cut through the bottom tubes on each side at your 1-1/2" marks. Then flip the frame upside-down and cut through the cross tubes on each side where you marked 11/16".
Cut the right side bottom frame tube at 1-1/2" mark.
Cut the left side bottom frame tube at 1-1/2" mark.
Both bottom frame tubes are cut at the 1-1/2" marks
With the frame flipped upside-down cut the left and right cross tube at 11/16" mark.
Success!
The frame has now been cut in all the right places, and the rear section that has been cut off can be discarded. The front section of the frame will retain the existing transmission posts (rear bolt points for the transmission plate) and retains the brace that connects the seat post to the rear cross tube. This will allow the transmission mounts to stay on the frame.
Step 7: Sand the backbone smooth to accept the new hardtail.
Clean up the back bone.
Make sure to clean up both sides.
Weld prep the cut tube ends by sanding away any paint or rust near the weld areas.
Weld prep the lug post area as well where you made cuts. Clean off any paint or rust in the weld areas.
Step 8: Measure 1/2" back from the bottom tube cuts and mark to drill the rosette weld holes. This will be a cleaner look to put the rosette welds on the bottom of the lower frame rails, again flipping the frame upside-down. Make sure to use a center punch so your drill does not walk. Use a 1/4" bit to drill a hole for the rosette welds on each side. Deburr the inside of the tubes where drilled.
Measure and mark 1/2" from the cut line of the left and right bottom tubes with the frame upside-down.
Use a center punch on your mark and then drill 1/4" holes into your mark on the left and right bottom tubes for rosette welds.
Deburr all tubes where you cut to insure the bungs of the hardtail will fit properly.
Step 9: Fit the hardtail up to the front part of the stock frame. Install the bottom cross tube joints with their centering bungs loosely from left and right.
Fit the cross tube joints with the centering bungs supplied in the kit on the left and right of the cross tube.
Step 10: Bolt the transmission plate into the frame, this will help keep the the alignment of the transmission mounting points. Slide the lower tube bungs of the hardtail forward into the lower tubes of the frame. The lower bungs need to go in first and seat into the frame for the top tubes to clear the seat post lug. Use a dead blow or rubber mallet to seat the lower bungs.
Bolt the transmission plate into the frame's mounting points. Use a dead blow or rubber mallet to hammer seat the lower bungs of the hardtail into the lower frame tubes.
Step 11: Make sure the top hardtail tubes align and fit on each side of the backbone. Again use dead blow or rubber mallet to make fit if need. Test fit the two saddle pieces that are included in the kit. Center them in between top hardtail frame tubes and the seat post lug. Grind or sand the lug if necessary for a good fit of the saddle pieces. (These saddle pieces fill the gap between the seat post lug and the hard tail tubes and add reinforcement.)
Top hardtail frame tubes are aligned with the backbone while the bottom frame tube bungs are inside the lower frame tubes. 
Sliding the saddles into place. You will want to center these to the lugs.
Step 12: Using a level surface set the frame on wood blocks. Be sure to set the frame down on the lower tubes, not the seat post cross member. Install the axle in the axle slots and check that the axel is level with the bottom frame tubes.
Make sure the bottom frame tubes and axle are level with each other.
Step 13: Sight down the backbone with string to check that the frame is straight before final welding. The inside of the axle plates should be equal distance to the center line.
The right and left axle plate should be equal distance from the center line of the string.
Step 14: Put a few tack welds at each joint, then check the alignment again. If the alignment is not good, tap the frame into alignment with a hammer or cut the tack welds and take the hardtail off. Then trim the tubes as needed for the best fit.
Tack weld each joint.
More tack welding.
Step 15: Once the alignment looks good and tacked all around each joint. It's now time to finish weld. For best strength in finish welding, penetrate the weld down to the inside bungs. A gap of 1/16" to 1/8" between the tubes or sanded bevel at the tube ends where they meet will allow deeper penetration of the weld.
Finish weld.
Continue to finish weld. Notice the nice small gaps.
What the seat post lug will look like before finish welding. Notice the saddles are centered with the lug.
Once you have welded completely all of the joints, saddles and bungs, you are ready to turn this frame into a roller and keep moving along with your chopper project. Boom, that's it! You did it, you are now chopper royalty...
Heck yeah! Finished and ready to become a roller.
Drop a motor and transmission in the frame, add a wheel. Now you are one step closer to being king of the road!
Now you are looking good!
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