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Topic: Rear axle squaring and jacobs ladder bind.
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Page 1 of 1 of 5 replies
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November 11, 2013 at
04:06:49 PM
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Joined:
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11/02/2013
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5
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This is on a J&J 87.5"/40" chassis being raced in a non-wing class. I square the rear axle with 5" (raised rail) and 6" blocks. The axle is adjusted to be parallel to the motor plate, the bird cages are timed. The torque ball and the jacobs ladder have no bind. Then I put weight in the seat to simulate the driver and adjust the torsion bars using 3.75" and 4.75" blocks. At this point I get a slight bind in the heim joint pin at the RR bird cage. If I adjust the heim joint 1/2 to 1 turn the pin becomes free again. Is this common? Am I doing something wrong? Why isn't the chassis squared with the ride height blocks?
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November 11, 2013 at
04:14:17 PM
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Joined:
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09/02/2009
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454
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Setting the car down on stagger and with tilt in the cage (turns in RR) causes the frame to kind of side load the suspension. Sometimes this will make something feel bound up. I always step on the rear bumper and bounce the car a couple times and then check to see if I have any binds anywhere.
Loose is when you hit the wall with the rear of the
car, tight is when you hit the wall with the front of
the car. Horsepower is how fast you hit the wall and
torque is how far you move the wall.
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November 11, 2013 at
05:00:14 PM
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Joined:
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08/25/2008
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80
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Reply to:
Posted By: rbc on November 11 2013 at 04:06:49 PM
This is on a J&J 87.5"/40" chassis being raced in a non-wing class. I square the rear axle with 5" (raised rail) and 6" blocks. The axle is adjusted to be parallel to the motor plate, the bird cages are timed. The torque ball and the jacobs ladder have no bind. Then I put weight in the seat to simulate the driver and adjust the torsion bars using 3.75" and 4.75" blocks. At this point I get a slight bind in the heim joint pin at the RR bird cage. If I adjust the heim joint 1/2 to 1 turn the pin becomes free again. Is this common? Am I doing something wrong? Why isn't the chassis squared with the ride height blocks?
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Maybe I'm wrong but it appears that your block heights aren't adding up. A typical 5" & 6" block (for squaring) is to simulate a car at ride height with the driver and blocks around 3" & 4". You're blocking the car lower which could bind things up. As the rear of the car gets lower, that is going to move the jacobs ladder angle up and try to pull the rear end to the left in the car. In my opinion, if you want to block the car that low, try squaring everything with 5.5" & 6.5" blocks to simulate more your ride height with your block settings. Just is where I would start and what I would do if I ran into that issue.....
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November 11, 2013 at
07:54:08 PM
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09/30/2005
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1387
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your car is going to natrally load the hiem of the ladder under range of movement while the chassis is static, expessially without the soft sidewalls allowing the arc of movement to scew, im under the understanding this is all being performed on the stands not the ground with tires on and weight on the tires, most importantly here, is your tourque ball still moving respectabally free...
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November 11, 2013 at
07:56:20 PM
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Joined:
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09/30/2005
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1387
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check for bent arms, or , too short of ladder.. just a thought?
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November 11, 2013 at
11:12:28 PM
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11/02/2013
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Sorry, my sequence was a little off. I square the car on the jack stands. I set the torsion bars with the ride height blocks on the jack stands. The driver weight I added with the tires on the ground. Dirtdevil, the torque ball is free both on the jack stands and on the ground. It's just the heim joint pin that has a little bind.
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