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Author Topic:   torque arm for braking ??
racinron
Dirt Roller

Total posts: 13
posted January 24, 2005 07:31 PM  
Is any one runnning both a torque arm and a pull bar? If so how long of a torque arm do you run and how do you set it up? Thanks for any info.

FASTLAP
Dirt Maniac

Total posts: 171
posted January 25, 2005 05:12 AM  
Run whatever length will fit, use rubber bushings and a chain deal up front to control brake forces. Alot like a late model without the mini spring. Pull bar mounts to the other side of driveshaft. Works well.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted January 25, 2005 07:23 AM  
we are running both. But with a solid chain instead of a spring or rubber bushing.

We set it so that at ride height the chain is just tight. Usually will set pinion anlge at say 8.5 then pull it back to 8 with the chain. Otherwise everythign else is the same.

zeroracing
Dirt Forum Champ
Total posts: 1875
posted January 25, 2005 07:27 AM  
any of you guys run 2 chains? we are going to that on a car this season, one tight, and one with just a little bit of slack in case the first chain breaks or the bolt breaks. woundering if we were the only ones doing that.

driver27
Dirt Maniac

Total posts: 194
posted January 25, 2005 09:27 AM  
If you run both, with a torque arm and chain to control braking only, what modifications do you need to do to the pullbar if any? Also, what is the advantage to this setup insead of just a pullbar only?

Thanks

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted January 25, 2005 10:05 AM  
no modifications to pullbar.

The brake arm uses the deceleration forces to help plant it harder on entry. Same as a 6th coil on a lift arm setup. I have heard the new AFCO 2 way pullbar works very well in doing the same thing but without the brake arm flopping around in there.

hobby12
Dirt Maniac

Total posts: 103
posted January 25, 2005 10:21 AM  
how does this affect the handling of the car? what does it do to it?

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted January 25, 2005 11:14 AM  
it really only effects entry and deceleration.

As you get off the gas and on the brakes the rearend will try to unwrap but the chain will catch it. All the force of the rearend rolling forward due to braking will pull try to pull the entire car down into the track, planting it better. Instead of being wasted in the rubber pullbar bushing and allowing the pinion to travel furthur down. It will have no effect from middle on because the chain will be loose, it only effects braking. When we put it on our car the driver couldnt beleive how much better the car would slow down into the corner.

racinron
Dirt Roller

Total posts: 13
posted January 25, 2005 06:24 PM  
Thanks for all the info. Is anyone runing a short torque arm say around 28" and are you doing anything to keep the front of the arm from swinging around?

FASTLAP
Dirt Maniac

Total posts: 171
posted January 25, 2005 06:33 PM  
We ran a swedge tube with a heim on both ends. One mounted to the frame rail, one to the torque arm. Got that off a Rocket chassis.

Ego Racing
Dirt Forum Champ
Total posts: 724
posted January 25, 2005 08:59 PM  
DO NOT RUN THAT SHORT OF A TORQUE ARM!!!! The shorter the faster the reacton just like a link bar. Try to stay around 36 inches. On our Late Model a change of wo inches makes a BIG difference in how the car hooks off of the corner. The shorter the arm the sooner it hooks up and the sooner it gives up.
As for location you want it to stay in line with the rearend. If you are running bird cages and the rear is free to rotate you can use a small tube fron the bar to the frame about mid way down the bar. If you are running a solid mounted rear like a three link with the mounts welded to the rear or a leaf spring you need to run a small tube from the rearend housing tube to the lift bar to triangulate it to the rearend.

sdracer12
Dirt Maniac

Total posts: 180
posted January 25, 2005 10:42 PM  
We run both arms, and like it a lot. We did have to modify the pullbar (Afco linear bearing pullbar) though. We removed the rubber brake bushing from the pullbar assembly, to allow the chain and bumper in the front of the torque arm to do it's job.

The only problem with this is it becomes difficult to set any preload on the pullbar spring.

Our pullbar is 40" center to center, and the liftbar is 36" long from rear pivot to front of brake chain.

Anyone ever use BSB's bearing pullbar in this application?

[This message has been edited by sdracer12 (edited January 25, 2005).]

donslink1
Dirt Freak

Total posts: 318
posted January 26, 2005 04:57 AM  
We run both bars too, We unbolt the pullbar from the rear end while scaling and set our preload with it unhooked and then adjust the length when the car is all setup, so the pullbar just slides in with the car at ride height.

racinron
Dirt Roller

Total posts: 13
posted January 27, 2005 06:56 PM  
Thanks for all the advice. It sounds like this is worth a try.

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