 Torsion bars explained, Help me understand |
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| ahdoman |
  Aug 12 2009, 09:43 PM
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#1
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It's phonetic...Ah-D-O-Man (Audioman)  Group: Members Posts: 667 Joined: 7-November 05 From: Santa Clarita, Ca. Member No.: 5,084 Region Association: Southern California  |
Hey all,
I understand the concept of correct suspension geometry but I don't fully understand the purpose of the torsion bar and what affect reindexing has. I'm asking this because I need to lower the car a little (running 14" Fuchs) to get the stance correct. I know the proper way to do this is to use struts that have been lowered and their arms bent but I don't have the budget for that and don't want to tear up my /6 suspension doing it. |
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| ChrisFoley |
Aug 13 2009, 01:01 AM
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#2
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I am Tangerine Racing Group: Members Posts: 7,920 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None 
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QUOTE(ahdoman @ Aug 12 2009, 10:43 PM)  I don't fully understand the purpose of the torsion bar and what affect reindexing has. This really belongs in the garage, not the Paddock, as it has nothing to do with competition per se. It is a general maintenance and adjustment issue. Torsion bars are just straight springs. The advantage is low CG and compact design. Ride height is changed by turning the screws on the torsion bar adjuster arms. If you get to the end of screw adjustment before reaching the desired ride height it becomes necessary to remove the adjuster arm and re-index it by one spline on the torsion bar. |
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| ahdoman |
Aug 13 2009, 09:42 AM
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#3
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It's phonetic...Ah-D-O-Man (Audioman) Group: Members Posts: 667 Joined: 7-November 05 From: Santa Clarita, Ca. Member No.: 5,084 Region Association: Southern California |
Thanks Chris. I put this in the Paddock because I am trying to get the car setup for AX as well as local canyon drives. (My appologies for not making that clear in my initial statement). I just wasn't sure if there was an ideal "indexing" setup on the torsion bars that would make them work better and need help finding that formula.
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| ghuff |
Aug 13 2009, 09:44 AM
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#4
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This is certainly not what I expected down here. Group: Members Posts: 849 Joined: 21-May 09 From: Bodymore Murderland Member No.: 10,389 Region Association: MidAtlantic Region |
QUOTE(ahdoman @ Aug 13 2009, 07:42 AM) Thanks Chris. I put this in the Paddock because I am trying to get the car setup for AX as well as local canyon drives. (My appologies for not making that clear in my initial statement). I just wasn't sure if there was an ideal "indexing" setup on the torsion bars that would make them work better and need help finding that formula. I guess indexing is sort of a pre-load you set in a way then refine your ride height from there. Am I wrong? I am learning too. Never had a car with torsion bars, too young. |
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| ChrisFoley |
Aug 13 2009, 11:56 AM
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#5
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I am Tangerine Racing Group: Members Posts: 7,920 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None
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QUOTE I guess indexing is sort of a pre-load you set in a way then refine your ride height from there. That's about right. It can be a bit of trial and error finding the correct starting position if the front end has been apart and no notes or markings were made. Preferably you want the adjuster screw near the middle of its range when the car is on the ground at the desired ride height, but as long as the arm isn't all the way to one extreme. With only 32 splines, a move of one spline equals more than 10 degrees of rotation. |
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| r_towle |
Aug 13 2009, 07:51 PM
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#6
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Custom Member Group: Members Posts: 24,571 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States
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Try to keep the lower part of the a-arm not go past horizontal.
As you lower it, you may experience bump steer. Rich |
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| Chris Hamilton |
Aug 14 2009, 01:51 AM
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#7
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Senior Member Group: Members Posts: 611 Joined: 7-March 06 From: Berkeley, CA Member No.: 5,687 |
If you play with the torsion bars be careful to put them in the same direction they came out. They get twisted the same direction over and over. If you put them in backwards and reverse that direction they can break.
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| ChrisFoley |
Aug 14 2009, 05:57 AM
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#8
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I am Tangerine Racing Group: Members Posts: 7,920 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None
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QUOTE(Chris Hamilton @ Aug 14 2009, 02:51 AM) If you put them in backwards and reverse that direction they can break. That can only happen if you reverse the side they are in, not if you turn them end for end. |
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| Chris Hamilton |
Aug 14 2009, 10:31 AM
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#9
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Senior Member Group: Members Posts: 611 Joined: 7-March 06 From: Berkeley, CA Member No.: 5,687 |
Yep, the important part is to make sure the twisting force when it's in the car happens in the same direction as the bar is worn to.
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