DIY Trac Bar

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1) Oemy's DIY Trac Bar             2) Roger Woebbecke's DIY Trac Bar

3) Dan Kilgore's DIY Trac Bar    4) Todd Cunningham DIY Trac Bar 

5) Bruce Covey DIY Trac Bar     5) James Wing DIY Trac Bar

Here it is March 27, 2009 and I am just now adding information about my DIY Trac Bar. This is the project that stated it all. Rodger Woebbecke (AKA - Logthumper) posted his version of DIY Trac Bar on IRV2 and I said to myself, if he can do it so can I.

So, I made some carboard templates, got some 3/8" steel, cut the peices out with a cutting torch, drilled the the holes, welded the parts together, got the proper nuts/bolts, ordered the trac bar and put it all together.

It worked as designed. But, had I had it to do over again I would use a "Center Link" from a tractor 3 point hitch. You can get them at any Tractor Supply store. Another option is to buy some heavy duty heim joints and make your own bar.

But, I became a Brazel's dealer for UltraPower/UltraTrac and decided to install & test the UltraTrac trac bars.

Here is the parts list & photos of my DIY Version of the Trac Bar.

Heim joints, bar & jam nuts
Source - Motorsports of Kansas City - 913-334-0477
Contact - Brad Harrison


  • RH Poly Heim - 02088RH - $13.99
  • LH Poly Heim - 02088LH - $13.99
  • RH Jam Nut - 18260 - .99
  • LH Jam Nut - 18261 - .99
  • Bar - 421703C - $13.99


  • Nuts/Bolts/Washers - Local - $10.00
  • Red Loctite - Local Hardware - $ 3.00
  • Silicone - Local Auto parts - $ 2.00
  • Steel - A friends scrap pile - $ 0.00


  • The bar can be ordered by the inch.
  • The one listed is 17" plus about 3" for the 2 Heim joints makes the "eye" to "eye" about 20".
  • The bar should be mounted level and the coach should not be on the jacks when adjusting the Trac Bar length.
  • Add a washer to either side of the Heim joint for support.

Nuts/Bolts/Washers - Grade 8 or Better
If you use 3/8" steel you will need to replace all the nuts and bolts you take off, as they will be to short.

WARNING - Be sure to check to see that you are replacing bolts with like kind. METRIC or SAE

SAE Bolts

  • Rear End bolts - (3) 1/2"x13 - 2 1/2" long
  • Frame Bolts - (4) 1/2"x13 - 2 1/2" long
  • Trac Bar Ends - (2) 1/2 x13 - 1 3/4" long
  • Nuts - (6) 1/2x13 Locking nuts. They can either be a crush nut or a plastic insert type.

Washers - (?) 1/2" You may need them to shim the Trac Bar ends depending on how accurate you are at lining up everything and where you locate the Trac Bar mounting hole. Be aware that the jam nut is wider than the Heim joint and needs to be tightened.


  • Red Loctite thread locker.
  • Silicone sealer for the 3 rear end bolts (just a dab).


  • You will need a piece of 3/8" mild steel to make the brackets.


  • Hand tools to remove and install various nuts and bolts.
  • Torque wrench to re-torque the rear end bolts.
  • Access to a cutting torch or a plasma cutter to cut the steel plate.
  • Bench grinder and hand grinder to clean steel and smooth things up.
  • Access to a drill press and 1/2" bit or larger. I used a smaller bit to drill a pilot hole.
  • Access to an arc welder

Note - A good Impach wrench makes taking the rear end bolts out a lot easier.

The patterns are setup for a passengers side rear end mount and a drivers side frame mount. I chose this setup because I didn't have to move any wiring, cables or hoses to move.

Sample Patterns

You can download the parts list and the sample patterns in the Downloads\Misc Documents\DIY Trac Bar.

Oemy's DIY Trac Bar

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Rodger Woebbecke's DIY Trac Bar "The Originator"

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Dan Kilgore's DIY Trac Bar

Dan Kilgore took my design and added a center link from a tractor. A center link is srong enough to handle the side loads and is fully adjustable.

It should be noted that the frame rail mount hole should have been lowered and/or the rear end mount raised to have the trac bar level.

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Todd Cunningham

Todd Cunningham use my basic design and built his own bar using heavy duty heim joints. He even had it powder coated.

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Bruce Covey

Bruce used the basic patterns, but modified the rear pattern to meet his needs. He also used the tractor center link.

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James Wing

The 2004 Fleetwood Flair with the Workhorse W22 chassis and Chevy Vortec 8.1L V8 gas engine has a perceived problem with stability when subjected to side pressure such as wind gusts or a passing large vehicle like a semi.

To counter this issue, aftermarket suppliers have produced nicely designed rear tracking devices that may be installed on the vehicle for a price (from $350 or so and up, plus installation) which is exorbitant in my opinion.

Taking-off from other DIY projects in the various RV forums, I have designed my own Rear Trac device, using :

  • 36" of 0.25" x 1.5" mild steel cold rolled flat stock (I used less than 30".)
  • 6.5" of 0.25"x4" mild steel plate stock
  • An adjustable three-point hitch center link that adjusts from 13 - 18" for 0.625" pins
  • 2 M14x2x55mm 10.9 bolts
  • 2 M14x2x90mm 10.9 bolts
  • 2 0.625"x2.5" Grade 8 bolts
  • 2 0.5"x1" Grade 5 bolts
  • 4 0.375"x1" Grade 5 bolts.


Since the huge exhaust pipe passes through this area on the passenger side, I would have to go above the differential and to the driverís side frame rail. But there are several pipes, including one brake line on the frame rail which are in the way. I placed a straight edge between the flat surface at the top of the ifferential (Iíll call it the vertical guide tab) and down to the frame rail to locate the center of the adjustable link relative to the frame rail and marked the location on the rail. It appeared that the distance from the frame rail to the center of that tab on top of the differential would be easily within the range of the adjustable link. I decided to aim for approximately 14.25" to allow some adjustability of the link. This would also put everything on the opposite side away from the exhaust pipe - so no fear of damaging the Trac or the exhaust pipe.

The problem was that the brake line would have to be relocated. I envisioned a 0.25" plate sliding in behind the pipes, but low enough so that the bolts holding it to the frame would be accessible without interfering with any of the pipes. Most of the pipes were high enough so they passed above the bracket location, but the brake line was in the middle of it. I tested my ability to Ďrelocateí the pipe by attempting to bend it by hand and it seemed pliable enough (careful to not put a kink in it.

So I decided to go ahead with this design - a 0.25" plate bent at 90 degrees at 3.25" to fit into the of the frame rail. This would allow two vertical 0.25"x1.5" stubs 3" long to provide the pin to the frame rail for the adjustable link. Then 0.25"x1.5" stubs 2" long ground to fit the bend radius of the 0.25" plate inserted behind it against the plate and welded together. I would use four 0.375" x 1" grade 5 bolts to hold the plate to the vertical part of the frame rail and two 0.5" x 1" grade 5 bolts to hold the plate to the frame railís flange. Actually, this wasnít the original design, but I donít want to describe the iterations that got to this.

As I looked at the differential, I noticed that the top two bolts were offset from the other bolts by what I measured to be very close to 1" and that two bolts on the passenger side were in-line enough so that it appeared that I could install a straight flat steel piece on them straight to the area where the link would have to be attached. Similarly, the two bolts on the top of the differential were also lined up so that a straight flat steel piece could be placed over them. Also, the distance of 1" was exactly what was needed for the adjustable link spacing, or so I thought.

Most of the other DIY designs referred to 0.5" grade 8 bolts. I noticed that the bolts on mine were marked Ď10.9' which is metric. I pulled one of the metric bolts from my Spicer S110 differential to see if I could find bolts to fit. The short ones needed to be replaced with 0.25" longer bolts than were in there, as do the longer ones. The surprising thing was that the threads allowed a half inch SAE bolt to fit and pull tight, but these bolts were about half way between half inch and 5/8" bolts, measuring about 0.55" - they are M14 x 2 (thread pitch). I reread the OEMY siteís recommendation and noticed he warned about using metric to replace metric, so I dropped the idea of using 0.5" SAE, besides, I donít think that they would hold against 150 ft-lbs.

So on with the search. The short ones were 1.625" long and the long ones 2.75" long, which meant I need 1.875" and 3" metrics or 47.6 mm and 76.2 mm. I went to Loweís and to Home Depot, but couldnít find anything in the M14 range that were 10.9 hardness.  I ended up at a fastener specialty store that had 10.9s; M14x2x55mm and M14x2x90mm, but that was as close as he could get to what I needed. So I took them, along with some hardened steel washers to use for spacers - one on each of the shorter bolts and four on each of the longer bolts. OK, should work.

Very fortuitous, I needed the two longer bolts to be longer and I needed the washers because I had not anticipated that though the spacing was one inch, both of the bracket pieces had to be outside of that one inch, but in fact only one was - the other was inside so the net distance was 0.75" and the washers would be needed to move the driverís side differential bracket forward by 3 washer thicknesses! But I get ahead of myself.


To begin this step, I measured the distance between the two shorter bolts on the passenger side, 3.75", and the distance to the top of the vertical guide tab at the top of the differential, allowing one inch for the distance from the lower hole center to the end of the bracket, was 9". The upper end needed to be cut vertically from the 9" point. I cut the piece on a 45 degree upward angle (about 10.25" on the upper edge) using a 7"  metal cutting wheel in my Skil saw. I then located the first hole one inch from the square end (all drilled 0.625" holes are centered on the stock) and the other hole 3.75" up from it. I drilled these holes out to 0.625" and tried it on the differential. I anticipated from my measurements that I would have to grind off a portion of the part at the point where it passed by the casting near the first longer bolt. I ground out about a 0.2"x 0.5" area to allow the flat piece to sit in properly. I installed the original metric washers against the differential and installed the old bolts to just tight.

I clamped a short piece of 0.25" stock onto the end of the first piece and verified that it was virtually level (nearly parallel to a flat edge laid between the frame rails). Whether it is actually level is not that important, but it should be close. Using the anticipated 14.25"adjustable linkís measurement, I estimated the approximate location of the frame rail end of the link and determined the position of the center of the hole at the differential by marking the 14.25" location on that piece of stock. The distance on mine was 1.625" so I cut a piece of 0.25"x1.5" stock 2.625" long for that piece. I drilled the 0.625" hole one inch from one end and beveled the other end for welding (both sides - only about 0.1" should remain not beveled) . I then removed the other piece from the differential and ground the edges of the 45 degree end to prepare them for welding. I clamped these onto the welding surface, positioned so that the flat end of the short piece is flush with the top edge of the 45 degree angle, which makes the bottom edge approximately 0.375 - 0.5" above the vertical guide tab on the differential.

The second bracket was supposed to be a flat piece over the two bolts, but the location of the adjustable link was so close to the center that this method used here looked easier. (The first bracket was installed using the new bolts, the original washer between the differential flange and the bracket, and the hardened spacer washers on the outside. I tightened these two bolts to near the torque value required before the other two bolts were removed.)  I inserted the bolt through the hole in the first bracket, and with the adjustable link in place, tightened the nut on it so that it was firmly in place. I measured the distance from the center of the link bolt to the center of the driverís side bolt, which was 4.125". I added 2" for the ends and cut a piece of 0.25"x1.5" stock 6.125" long, marked and drilled two 0.625" holes 1" from each end.

I installed the piece on the link bolt and used the original metric washer behind and the first longer bolt removed to position the part so that the length of the other leg of the part could be determined. The length was 2.125" and so a piece 3.125" was cut, the hole marked and drilled one inch from one end. I installed the piece on the bolt near the center and determined that it would fit properly, tightly against the other leg of the part. I then marked both of them for positioning. After removing, beveling the areas on both pieces for welding, I located them using the marks I had made, welded them together and ground them flat. I reassembled the pieces as shown in the picture, using the original metric washer against the differential and the new bolts and washers only to discover that the parts were out of alignment by about 0.25" as described earlier. By judicious rearrangement of the washers (the original metric washer, followed by 3 hardened washers on the rearward side of the bracket part and one hardened washer forward of the bracket part), the assembly was complete and fit. I then tightened all of the new bolts to 125 - 150 ft-lbs with Loctite.

Now to make the frame rail bracketís backing plate, I used a 4" wide by 6.5"piece of mild steel stock - the 0.25" material was very difficult to bend. I heated it cherry red and bent it a little at a time in a large vise, heating it continuously while maintaining bending pressure until the 90 degree angle was achieved. The radius of the bend was about 0.5" to match that of the frame rail. I repeated this process on the short flange to provide a half inch stiffener flange.

Then I drilled the holes in the back using a small drill bit to provide pilot holes and to provide a pattern for drilling the frame rail. I also drilled the pilot holes in the flange of the part. I located the center and marked the locations of the vertical pieces on both flanges of the part. The centers of the holes are located 0.625" down from the upper edge and 0.625" over from the vertical edge.

I used the backing plate as a pattern to drill the holes in the frame rail before the parts were welded together. I located the center points of the flange bolts by marking the locations where the backing plate edges hit the frame rail flange with the backing plate clamped in place, and also where the flangeís inner edge contacts the backing plate.  I then measured along the flange 0.625" and inwards on the flange by the amount from the flange edge mark on the backing plate to the center of the pilot hole.

I center-punched the locations and drilled through the flange with the small pilot bit, reaming out the pilot hole in the backing plate. I also drilled the holes in the backing plate through the frame railís vertical web. I removed the backing plate and drilled the holes in the vertical web to the next size larger than 0.375" and the flange holes to 0.5". The holes in the backing plate were drilled out using a drill press (much easier) to these same sizes.

I cut two pieces of 0.25" x 1.5" stock 3" long to serve as the adjustable link tie point and I cut two pieces of 0.25"x1.5" stock 2" long to use as spacers from the tie point pieces to the back of the part. I beveled the edges of the pieces to be welded and clamped  them to the welding table to weld them. After they cooled, I ground them off flat and rounded the lower edges of the spacers so that they would fit into the frame rail bracketís backing plate. 

I drilled 0.625" holes in both of the tie point weldment pieces and assembled the link end with it's bolt to hold everything in place. (It is a good idea to put an extra washer in the assembly to give some space between the two pieces so the link can be slipped between the parts.)

I then clamped the assembled parts together and aligned them according to the markings I had made and welded them together. I avoided welding along the parts next to the half-inch holes because it is too close - I welded it on the inside all the way.


I already indicated that the two 0.25" brackets attached to the differential were installed while they were being fabricated and the first was used as a jig to locate and construct the second bracket.

The frame rail weldment can now be installed by placing it on the frame rail flange forward of the final location and then slide it rearward to position it over the drilled holes. The pipes have to be pulled, pushed or bent out of the way to get the weldment into place. The pipes must not be allowed to come close to the parts or the hardware (bolts and nuts).

The 0.375" fasteners are installed through the outside of the frame rail web without washers behind them (it might be necessary to ream the holes to get the holes to align), through the backing plate of the weldment. Install a lock washer under each nut and use Loctite if so inclined. Install the 0.5" bolts through the frame rail flange and through the bottom flange of the weldment (it might be necessary to ream the holes to get the holes to align). Install a lock washer under each nut and Loctite if so inclined.


If you havenít already done so, park the coach on a level spot, moving it back and forth to assure that the suspension is stabilized (not sure how much good that does). Then install the adjustable link using 0.625" grade 8 bolts that are 2.25 to 2.5" long with a lock washer under the nut on each end of the adjustable link. No other washers should be needed and Loctite may be used if desired. The nuts may be installed either facing forward or rearward, I chose forward on the differential end and rearward on the frame rail end, mainly because they are easier to access.

The adjustable link may be installed with either the left-hand-threaded or the right-hand-threaded end towards the frame rail side. The jam nut is on the right-hand-threaded end and since the frame rail end is most accessible, I installed the link with the right-hand-threaded end towards the frame rail. This design should result in the link being slightly downward to the frame rail when the coach is unloaded. Loaded, it should be almost perfectly level.

Now move the jam nut away from the link (toward the pivot point) and adjust the link outward until the link tightens. Tighten the jam nut against the adjustable link body. Hold the body (mine came with a pin that inserts into a hole in the body) and use a Crescent wrench to tighten the jam nut against the body. Loctite may be used, but should be unnecessary.

I made a test run of a few miles and was very pleased with the result, but I need to run with the toad behind and over rougher terrain.

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