P-32 Build it Yourself Track Bar

[max49]

After looking and reading Dale's website, here on the forums, Ultra Track and Super Steer instructions for a week or so, I finally got under the MH to see what mine really looks like.
I only saw pictures of 2 completely different P-32 configurations. One was attached to the differential and one was attached to the U Bolts under the spring. This one is took a lot of iron, drilling welding and time to build and must weigh close to a hundred lbs.
The other pic on Dales sight that is attached to the differential is also well built. It is supposed to be a P-32 but the bolts going to the pumpkin are much bigger than mine. They appear to need a 3/4" wrench which means they are probably 1/2" bolts.

I got started on mine today late and ran out of sulight. It appears that it is going to be much easier than I thought; that is, if I can attach it to the differential. I have 14 bolts in my diff. and I can easily use 4 of them at the top, in fact they in place now and I'll tack them in place and take it back off and weld them good.
My only concern at this time is that my differential bolts are only 8MM, about 5/16". I did buy some longer 8 MM bolts in 10.9 grade. Because of this, I see no reason to over build the rest of the track bar. I would much rather bend the bar or the steel attached to the diff. than to break the bolts off going into the pumpkin.
My bar will be quite short, about 12 to 14"
I really don't quite understand why or how this track bar helps but everybody seems to agree that a rear track bar should be the first suspension upgrade. My MH handles just fine as long as the wind is blowing just right or not at all.
So my question is, how strong does it need to be? Does the whole body and frame shift very much and need to be very strong or does it just need a little help to keep it from shifting. If I've been doing OK for 7 years with no track bar, so I'm hoping that this is something that at least can't hurt any thing and hopefull will help some.
Has any one else installed one to a P-32 differential with the 8MM bolts?

I went to Mudocks and bought a tractor 3 Point hitch link for the bar and then went to Harbor Freight and just happened to see this, the handle comes off and those doo dads act as lock nuts

http://www.harborfreight.com/5400-lb...dle-66889.html
so I bought it too. I'll take the hooks of and will be able to use a 1/2" pin through it.
I'll decide tomorrow which will be the keeper and which goes back to the store. Any thoughts on this?

[George Schweikle]

Max,

A track bar (Panhard bar) works by eliminating the side-to-side movement allowed by the suspension; in your case, the leaf springs supporting the rear axle. The springs, mounts, and shackles allow some degree of movement, and this is magnified by the rear overhang. When the wind blows or an 18 wheeler passes, the rear moves sideways, and you need to correct with the steering. A track bar resists any side-to-side movement of the axle, yet allows it to move up and down. However, the movable end of the track bar travels through an arc as it moves up and down and, the shorter the bar, the more this arc affects the axle location by actually making it move a little sideways but far less than loose springs & shackles. To view this, take a piece of wood the length of your proposed bar, move it up or down as far as you think your suspension moves, and see how much difference there is in overall distance between mounting points when the bar is straight vs. at the upper or lower movement - it's not much but the longer the bar, the less sideways movement. The Blue Ox track bar on my Safari TREK mounts to the leaf spring axle perch on one end and the frame at the other end. I prefer this design over one that only runs from the differential to the frame (although they sell both designs depending on the particular chassis). The addition of this bar made a significant improvement in the handling of my 29 ft. MH in windy conditions.

http://blueox.com/Uploads/AppGuides/TT2300.pdf

Regarding strength; the commercially sold track bars for P-32 chassis are designed to be used on the longest length built, so must have an appropriate safety margin for the highest anticipated weight. I viewed the pictures on OEMY's website, and the track bar looks pretty strong. If you downsize too much from this design, and the track bar fails, the leaf springs will still control the rear axle location, but you will then have to remove the broken or bent parts.

Originally Posted by max49

......I really don't quite understand why or how this track bar helps but everybody seems to agree that a rear track bar should be the first suspension upgrade. My MH handles just fine as long as the wind is blowing just right or not at all....

So my question is, how strong does it need to be? Does the whole body and frame shift very much and need to be very strong or does it just need a little help to keep it from shifting. If I've been doing OK for 7 years with no track bar, so I'm hoping that this is something that at least can't hurt any thing and hopeful will help some.

[max49]

Thanks for that explanation George, now I understand what it does and why a longer bar may be better. I'm going to have to go with the short bar to the differential since it's all done now. At least our MH don't have a a lot of suspension travel. I took it for a 20 miles test drive in perfect conditions and I could not really tell any difference but I hope it helps when the wind starts broadsiding me. I had all the iron and hardware except the bar and 4 metric bolts so I've got about $35 and 4 or 5 hrs. in it.

[Bumperfood]

Yo seem to be quite ingenious and your idea looks like it could be suitable,however I have a question for you. On each end, do you have a rubber bushing on the track bar itself, or did you mount them solid with no give? I ask because it would seem to me the stess on the differential bolts could cause them to break if there was even the slightest amount of movement back and forth.

[max49]

Originally Posted by Bumperfood

Yo seem to be quite ingenious and your idea looks like it could be suitable,however I have a question for you. On each end, do you have a rubber bushing on the track bar itself, or did you mount them solid with no give? I ask because it would seem to me the stess on the differential bolts could cause them to break if there was even the slightest amount of movement back and forth.

I thought it was too easy too, I guess the saying " no pain no gain" is true again. I started worrying about breaking off the 8 MM bolts in the differntial, I also worried about the very short (15" bar") because of my friends here on the forum. I decided, that I would take it off and go from the bottom of the U Bolts on the axle and to the frame on the opposite side. I started this today and I think it's a good thing I did. When I jacked up the frame, not the axle, so I could get under it, allowing the axle to hang or droop, I noticed it was starting to bend the bracket I built and attached to the frame. I could easily make the bracket stronger but the last thing I want to be the 'weak link' is the differential bolts.
I have removed the differential track bar and wrote that work off and have started completely over. I've almost got the mount that goes to the U Bolts finished and will start on the frame mount soon.
I hope my little Lincoln WeldPak 100 with flux core wire can penetrate enough to make it strong enough.
The U Bolt nuts were a SOB in a very uncomfortable position, me 1/2 drive impact would not phase them, I have to use a 2' breaker bar with a 4' cheater to budge them a 1/8th of a revolution at a turn, not fun at all, laying on my back in landscape gravel under the MH. It's a challenge and gives me something to do but the $600 UP and SS track bar sure looks nice, but I still have to install it. The hardest part is crawling under the MH numerous times , getting it blocked up for safety is an accomplishment too.

Now that I see how it works , I don't think it's a good idea to mount it to the differential, at least on a P-32. If you use your rear jacks, they tend to try to rip your track bar in half, am I understanding this right and is the rear spring mount to opposite side frame going to do the same thing? If so, does that mean I can't raise the rear tire off the ground with the leveling jacks to change a tire?

I welcome constructive advice on this as I'll be working on it again tomorrow 11-23.

[George Schweikle]

Hi Max,

I suspect the rear suspension travel when lifting with a leveling jack could theoretically be seen when hitting a really big bump in the road, so the track bar you bought has to be strong enough to withstand this (thats why the pieces are so big). The sideways movement you mention that looks like it "would rip your track bar in half" is very small compared to the up and down movement of the suspension. This, of course, is limited by the travel allowed by the rear leaf springs, not the track bar. And, the springs and mounting shackles also allow the sideways movement that you want to limit with the track bar.

I calculated the sideways movement (the "arc" travelled) of of a 3 ft. track bar at 6 in. "drop" (which might be more than the spring will allow), and the movement is 1/2 inch. A 3 inch movement from level, which is more likely, means the axle will move sideways 1/8 inch. The best way to measure the axle drop is to measure the distance from the top of a rear tire to the wheel opening as the coach sits on the ground, than compare this to the measurement when you lift that wheel off the ground with a leveling jack.

Note. While the slight sideways movement issue may seem contradictory to the control improvement desired from a track bar, the uncontrolled movement of a leaf spring suspension can be much more than this. That's why the track bar improves stability from side winds or passing trucks.

Originally Posted by max49

.....the $600 UP and SS track bar sure looks nice, but I still have to install it. The hardest part is crawling under the MH numerous times , getting it blocked up for safety is an accomplishment too.

Now that I see how it works , I don't think it's a good idea to mount it to the differential, at least on a P-32. If you use your rear jacks, they tend to try to rip your track bar in half, am I understanding this right and is the rear spring mount to opposite side frame going to do the same thing? If so, does that mean I can't raise the rear tire off the ground with the leveling jacks to change a tire?

I welcome constructive advice on this as I'll be working on it again tomorrow 11-23.