Thats due to the rotation of the driveshaft, the body mount should be on the driver side to counter the natural twisting of the axle from that force... based on what I've read so far.
That's correct. The panhard bar either pulls or pushes the axle mount down. Since the axle wants to twist clockwise (viewed from the front), it wants to lift the passenger side wheel, so it's best to push/pull that side down. Of course, the forces are rather small, as it's the vertical component of an almost horizontal but slightly tilted force/bar.
If the body leans 5 degrees, then the panhard bar tilted about half that (2.5 degrees). If you assume you corner at 1G (wishful thinking, but for simplicity's sake) and the rear end weights 1350 pounds (thus the lateral force is also 1350 pounds), then you get a downward force of about 60 pounds.
The torque that wants to rotate the axle housing is the same as the pinion/driveshaft torque, so if you come out of a corner in third gear (transmission ratio ~1.36), half throttle (200 lbs ft at the engine), you end up with 272 lbs ft. If the panhard axle mounting point is about 4 ft from the driver side tire (which can be considered the pivot point of the axle), then it would take a 272/4= 68 pound force at the panhard mounting point to countact axle housing torque. The panhard bar pulled the axle down with 60 pounds, so you're almost there.
That's correct. The panhard bar either pulls or pushes the axle mount down. Since the axle wants to twist clockwise (viewed from the front), it wants to lift the passenger side wheel, so it's best to push/pull that side down. Of course, the forces are rather small, as it's the vertical component of an almost horizontal but slightly tilted force/bar.
If the body leans 5 degrees, then the panhard bar tilted about half that (2.5 degrees). If you assume you corner at 1G (wishful thinking, but for simplicity's sake) and the rear end weights 1350 pounds (thus the lateral force is also 1350 pounds), then you get a downward force of about 60 pounds.
The torque that wants to rotate the axle housing is the same as the pinion/driveshaft torque, so if you come out of a corner in third gear (transmission ratio ~1.36), half throttle (200 lbs ft at the engine), you end up with 272 lbs ft. If the panhard axle mounting point is about 4 ft from the driver side tire (which can be considered the pivot point of the axle), then it would take a 272/4= 68 pound force at the panhard mounting point to countact axle housing torque. The panhard bar pulled the axle down with 60 pounds, so you're almost there.
So, I guess the theory also has practical value.
I have to apologize right off the bat for not having the info handy before making this post. I have to find the Bob Bolles book that I have stashed some place. What I seem to recall about his calculations were some what different from yours. His example, just a slight difference in location in relation to the axle made changes in the order of 100's of pounds.
I just made a quick calculation, so it's very well possible that I overlooked something.
Also, some of the panhard bars I've seen for circle track cars are very different in design from the ones you'll find on a street or road coarse car. For a car that needs handle predictable to the left, right and straight ahead, you want something that just keeps the axle in place and limit other side effects as much as possible. That means a long bar that's mounted horizontal. Circle track cars that only take left hand corners of a certain radius, they sometimes (or often) use very short ones mounted at an angle. In that case, the vertical forces can be much higher and you can get much bigger benefits, but only for that particular type of turn.
Thanks for the great tech, keep posting, more progress done, the pass. side bracket is all reinforced, needs minor triming and clean up, then another round of mock ups before it goes to the coaters...
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64 1/2 restomod coupe, cobra brakes, full roller suspension.
Helmantal, I realized too that some of the calculations you posted were for engine torque. I was thinking lateral loads from a turn was the example in the book, completely different. I'll definitely make a copy and post it.
Finally finished the pass side bracket, wich is mounted to the leaf spring
Drivers side (frame mount is done also)
Cleaerence between the rod and the back of the diff is about 1/2"
Things pending:
1.- Shorten the rod 3/4"-1 1/2"
2.-Cut out the tailpipes in order to run the brace of the PHB from the drivers side frame rail to the passenger side rail
3.- Fabricate spacers for the rod ends
4.-Powder coat everything
5.-Weld in the assembly
6.-Reroute pipes, as they are right now they will not permit the bar to be parallel to the axel.
Now a question for the experts im swaping in an 8.8 diff, should I worry with the rear of the 8.8 clearence to the PHB?
That would be the only thing that would hold me back on putting the assembly in and welding it...
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64 1/2 restomod coupe, cobra brakes, full roller suspension.
Last edited by Federico Garza; 11-16-2011 at 02:05 PM.
You might want to rethink the leaf spring mount for the panhard bar. The panhard can be subjected to many thousand pounds of force. If the panhard was moved lower or higher the resulting forces would leverage twist on the spring. This will prevent you from having any adjustment of the roll center. This is the first application I have seen leaf spring mounted, admitting very limited experiance here.
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Life is what you make of it.
17" MB Old School wheels from discount tire (a lot of people ask)
I too had concerns about that. One thing that helps is the clamp is close to the axle mount plate, so it adds a bit more rigidity to the spring. The further away from the axle mount the more flexible/torsion the leaf spring becomes.
You might want to rethink the leaf spring mount for the panhard bar. The panhard can be subjected to many thousand pounds of force. If the panhard was moved lower or higher the resulting forces would leverage twist on the spring. This will prevent you from having any adjustment of the roll center. This is the first application I have seen leaf spring mounted, admitting very limited experiance here.
From CC land... "It clamps to the spring with two 0.5" bolts and two 0.4375" (7/16") bolts. The top portion of the mount is in two parts, one of which doubles as the rear anti-swaybar end link mount on that side (based on the seat of the pants impression at the Jefferson 500 in May the anti-sway is probably coming off though). The photos above (post # 140) show this mount before it was trimmed, drilled, and painted. I did it this way because packaging the PHR on the MOPAR is difficult with the rear shocks and gas tank where they are. "
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64 1/2 restomod coupe, cobra brakes, full roller suspension.
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