Suspension and Chassis Questions about your suspension? Need chassis advice?

torque arm question

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Old Jan 6, 2010 | 10:04 PM
  #1  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
torque arm question

How much of an affect does the length of the torque arm have on handling? could you just fab up some kind of pinion support or something and eliminate it altogether?
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Old Jan 6, 2010 | 10:09 PM
  #2  
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Car: 1983 Z/28
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Axle/Gears: 3.42/Zexel/PBR
Re: torque arm question

And can I ask why you are wanting to do this? you'll be losing some ride quality, and I would imagine it keeps the working angles of the U joints in check as the suspension travels. where would you attach the other end of the bracket? its designed this way for a reason why screw with it?
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Old Jan 6, 2010 | 10:17 PM
  #3  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
Re: torque arm question

I wasn't really planning on it, just wondering what would happen
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Old Jan 6, 2010 | 10:30 PM
  #4  
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From: Taylors Falls, Minnesota
Car: 1983 Z/28
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Transmission: T-56
Axle/Gears: 3.42/Zexel/PBR
Re: torque arm question

A little more reading on the operation of the torque arm suspension:

https://www.thirdgen.org/forums/susp...ml#post4393278

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Old Jan 6, 2010 | 10:49 PM
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From: Waxahachie Texas
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Engine: 5.7 Tuned Port
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Axle/Gears: 9 bolt Borg-Warner
Re: torque arm question

It keeps the pinion angle correct under extreme driving conditions,kinda like a big traction bar..
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Old Jan 6, 2010 | 11:02 PM
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Re: torque arm question

shorter arm will increase traction bite and cornering and help with braking.

this is the one i got but mines not adjustable.
http://www.jegs.com/i/Jegster/550/40097/10002/-1

biggest inprovement to be made is stepping up to a tubular tq arm and getting the mounting point off the rear of the trans. however... there are some cars running 9s in the 1/4 with a stock TQ arm setup.
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Old Jan 7, 2010 | 07:46 AM
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Re: torque arm question

Hello
I noticed that you are looking into a adjustable torque arm and something that will allow weight to transfer faster and adjust instant center. I just wanted to leave you know that UMI Performance offers a wide variety of arms that may meet you needs. Below is a link to show you what all aw have to offer.

http://www.umiperformance.com/catalo...dex&cPath=6_93

If you have any questions feel free to ask and I will be more than glad to help.
Thanks
Brad
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Old Jan 7, 2010 | 11:23 AM
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Re: torque arm question

Originally Posted by ericjon262
How much of an affect does the length of the torque arm have on handling? could you just fab up some kind of pinion support or something and eliminate it altogether?
The tq arm front pivot/mount point is what loads vertically on the chassis both upward under throttle, and downward under braking.

When the car is coasting (no throttle or brake), there is no dynamic loading of the rear axle rotation translated vertically onto the chassis, so no affect on handling.

Once the torque arm starts pushing up or pulling down on the chassis, its length has major imput to chassis balance as to where it is assiting either the front springs or rear springs in balance proportions.

Now the tricky part. While all that aboe is going on, you now consider the fore and aft weight transfer motion of the chassis under throttle and braking. The LCA angle fictiously drwn towards the vertical centerline of the Tqarm mount determines the instant center height. this height is what determines whether chassis weight motion travels over the intant center point (IC) or it travels under the IC. If it travels over the IC from front to rear under throttle then think of the IC as a teeter tooter point and the front bumper goes up as the rear bumper goes down. The lower the IC, the more this happens. The more rear the IC, the heavier the front lift weight becomes.

under braking? the same happens in reverse. You get squat. Too short of a tqarm will cause brake hop because the chassis in the rear pulls down so hard the rear wheels unload being in essence pulled upward into the chassis and cause skidding or skipping over the pavement. Heavier rate rear spring will counter this action and help prevent it, but at a cost of suspension balance laterally.

Alot of knowledge and care need to go into setup and balance to make a shorter tqarm suspension package work and can ender positive results over a stock lengh unit.
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Old Jan 7, 2010 | 11:33 AM
  #9  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
Re: torque arm question

Originally Posted by Vetruck
The tq arm front pivot/mount point is what loads vertically on the chassis both upward under throttle, and downward under braking.

When the car is coasting (no throttle or brake), there is no dynamic loading of the rear axle rotation translated vertically onto the chassis, so no affect on handling.

Once the torque arm starts pushing up or pulling down on the chassis, its length has major imput to chassis balance as to where it is assiting either the front springs or rear springs in balance proportions.

Now the tricky part. While all that aboe is going on, you now consider the fore and aft weight transfer motion of the chassis under throttle and braking. The LCA angle fictiously drwn towards the vertical centerline of the Tqarm mount determines the instant center height. this height is what determines whether chassis weight motion travels over the intant center point (IC) or it travels under the IC. If it travels over the IC from front to rear under throttle then think of the IC as a teeter tooter point and the front bumper goes up as the rear bumper goes down. The lower the IC, the more this happens. The more rear the IC, the heavier the front lift weight becomes.

under braking? the same happens in reverse. You get squat. Too short of a tqarm will cause brake hop because the chassis in the rear pulls down so hard the rear wheels unload being in essence pulled upward into the chassis and cause skidding or skipping over the pavement. Heavier rate rear spring will counter this action and help prevent it, but at a cost of suspension balance laterally.

Alot of knowledge and care need to go into setup and balance to make a shorter tqarm suspension package work and can ender positive results over a stock lengh unit.
Thank you, thats the kind of info I was looking for!
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Old Jan 7, 2010 | 11:43 AM
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Re: torque arm question

First thing I thought of when this was mentioned was this: >Link
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Old Jan 7, 2010 | 11:58 AM
  #11  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
Re: torque arm question

Originally Posted by Scorpner
First thing I thought of when this was mentioned was this: >Link

Thats pretty cool, but does it work?
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Old Jan 7, 2010 | 12:13 PM
  #12  
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Car: 85 SC, 86 Berlinetta
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Re: torque arm question

I was wondering the same thing.
Haven't seen anyone that has one comment on it yet.
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Old Jan 7, 2010 | 03:23 PM
  #13  
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Re: torque arm question

id be interested to see what vetruck or norm peterson have to say about that design.
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Old Jan 7, 2010 | 11:43 PM
  #14  
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Re: torque arm question

Yes I know about it. That is Jasons design. I have never driven on it but I can imagine it gets a slop feel to it with throttle modulation coming through and off a corner from trailbaking. you had better be very smooth, and the road be smooth also or I would imagine a bobbling feel like something is broken. I would much rather have a torque absorber link with a predictable spring tension give.

I would certainly like to try it. The thought is in the right track, but I think I personally woulkd be hammering it and it would feel like a broken trans mount.
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Old Jan 7, 2010 | 11:46 PM
  #15  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
Re: torque arm question

Thats what I was thinking, ya, i bet that hanging (I know it's somewhat controlled not just loose) torque arm would be loud going back and forth
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Old Jan 7, 2010 | 11:54 PM
  #16  
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Car: 85 Camaro IROC
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: open rear, 3.42 gears
Re: torque arm question

what i would like to see, is instead of a rubber bump stop that just slams into it and provides no "transition" would be a small shock absorber.
it could only take half a second or a second to fully transition and would get rid of the "broken link" feeling that i think it would be bound to have.
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Old Jan 8, 2010 | 12:06 AM
  #17  
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From: South Carolina
Car: 85 2M6, 87 'Bird 88 'burb
Engine: LX9, LG4, L05
Transmission: F23, 700r4, 700R4
Axle/Gears: 3.63, 2.73, 4.10
Re: torque arm question

Originally Posted by RED_DRAGON_85
what i would like to see, is instead of a rubber bump stop that just slams into it and provides no "transition" would be a small shock absorber.
it could only take half a second or a second to fully transition and would get rid of the "broken link" feeling that i think it would be bound to have.

maybe a moped shock would work.
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Old Jan 8, 2010 | 12:54 AM
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Re: torque arm question

Guys, this is what I mean when I say torque absorber. We do not need a little shock absorber.

This is a single biscut TS that would take the place of the sliding link in Jasons decoupler design. It would help keep tension agansit the snubber even under braking where it would just barely decouple enough to prevent wheelhop under extreeme braking. The length could be adjusted accordingly to each cars desired need of length and tension.

Last edited by Vetruck; Oct 24, 2010 at 06:18 PM.
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