Torque Arm question(s)... - Lateral-g Forums

DavidBoren · #1 10-03-2014, 06:05 PM

First post, so be gentle. I just found this website through searching for suspension design theory. Read Ron Sutton's write-ups, and figured I was in the right place.

Now, this is more a question of general design theory, pertaining to the 3-link rear suspension and a torque arm. Although I am just looking for basic design principles and theory, the purpose of this research is to build a rear suspension for a standard cab, long bed 1982 2wd S-10 for use as a daily driver and auto-X vehicle. Spirited driving, with emphasis on neutral/predictable handling. This is not an all out race suspension question or build. The compromise is that I will not be slamming/bagging/dropping the truck to the point that it is too low to use as a truck. I still want to be able to go over speed bumps without worry and haul couches, etc.

My question(s):
Knowing that a torque arm will be incorporated into the design from the start, is it best to mount the lower and upper links parallel to the ground, and let the forward mounting point of the torque arm dictate the instant center?

Would you want the torque arm forward mounting point to be level (in side view) with the upper link arm, or the lower links?

Would you want the torque arm mounted level (from side view) with the lower links on the axle?

I plan to make everything as adjustable as possible, with an adjustable panhard bar centering the axle laterally. And I plan to use the rod end links throughout all linking points. The forward end of the torque arm will be in a sliding sleeve, not the shackle/dogbone set-up. Upper 3-link arm will be offset to the passenger side. All mounting points will be double shear, using 1/4" plate, with adjustment holes drilled 1" apart.

I do not know about where it would be best to mount the shocks. I want to use coilovers front and rear. I plan on keeping the truck at its stock ride height, just lowering the rear to be level. I would like to set up the suspension properly to avoid needing a rear sway bar, but I'm not 100% opposed to adding one if I need to.

Other than that, weight distribution efforts will be made to lessen the forward bias associated with pickup trucks. Fiberglass fenders and hood, mounting the engine further back, manual brakes and steering. Still keeping climate control. This is not a V8 swap. Symmetrical disc brakes with 12" rotors and dual piston calipers, dialed in with an adjustable proportioning valve.

Well, that is the plan so far. I am just trying for a nice neutral, easy to handle truck that I can drive confidently every day, and have fun on the track on the weekends. Any help would be greatly appreciated.

zo6s10 · #2 10-04-2014, 12:15 PM

Nice first post!
I replied over at s10f. If I knew you were serious I would have sent you here

As I said there look at a truck arm. It's strong, for a truck :lol: and simple. Don't know much about a TA setup. Think Ron has both, maybe ask him.
$5000 Mustang [url]http://www.pro-touring.com/threads/38420-5000-budget-Mustang/page2?p=346087#post346087[/url]

American Motors Xperimental [url]http://www.lateral-g.net/forums/showpost.php4?p=386265&;postcount=7[/url]

And I'm supscribed for Ron's answer

zo6s10 · #3 10-04-2014, 12:17 PM

Quote:

Originally Posted by zo6s10

Nice first post!
I replied over at s10f. If I knew you were serious I would have sent you here

As I said there look at a truck arm. It's strong, for a truck :lol: and simple. Don't know much about a TA setup. Think Ron has both, maybe ask him.
$5000 Mustang [url]http://www.pro-touring.com/threads/38420-5000-budget-Mustang/page2?p=346087#post346087[/url]

American Motors Xperimental [url]http://www.lateral-g.net/forums/showpost.php4?p=386265&;postcount=7[/url]

And I'm supscribed for Ron's answer

WTF happened? with spell check and FF^^^

Vince@Meanstreets · #4 10-04-2014, 12:24 PM

Quote:

Originally Posted by zo6s10

WTF happened? with spell check and FF^^^

im not gonna say it was aliens, but it was aliens. or Skynet.

Just sayin.

DavidBoren · #5 10-04-2014, 12:46 PM

I will look into a truck arm, for sure. Thank you for the suggestion.

I had never even heard of it before seeing it mentioned in Ron's rear suspension write-up. It looks bare bones simple, and sturdy. Both are qualities that I am looking for. I am curious about the adjustability of the truck arm suspension, as I would like to be able to adjust it to learn more about how different settings affect the handling.

I am not going to fool myself into thinking that I am educated enough or experienced enough to tackle fabricating a front suspension for this truck. So the front is going to be basically stock, except for proven aftermarket, bolt-on's.

I have heard good things about the S10 being used in auto-X, so the front end can't be all that bad of a starting point.

Anyways, thank you for the replies. I look forward to learning from you guys. It looks like I came to the right place.

zo6s10 · #6 10-04-2014, 01:22 PM

Check out Tyler, s10 frame. It is super light.
https://www.youtube.com/channel/UCTs67QQ89pK4Ww0oz3MGYdw
Adam at Road Atlanta (Tall AFX Spindles, leafs and homeade caltracs)
https://www.youtube.com/watch?v=G-A9ZYCrv2
Tyson aka rentedmule. He is the man! all bolt on, pulled leaf (or 3) and one hell of a driver!
http://www.pro-tourings10.com/index....43&topic=150.0

^^^those are the guys you should talk to. Tyson might try to give me some credit but he runs his daily driver and won his class last year! He also drives it in Canada snow. He is my hero. I have only driven poly bushed and dropped to the ground junk. Working on a full frame but don't want to give out the info yet.

Ron Sutton · #7 10-30-2014, 03:10 PM

Hi David!

Quote:

Originally Posted by DavidBoren

First post, so be gentle. I just found this website through searching for suspension design theory. Read Ron Sutton's write-ups, and figured I was in the right place.

Now, this is more a question of general design theory, pertaining to the 3-link rear suspension and a torque arm. Although I am just looking for basic design principles and theory, the purpose of this research is to build a rear suspension for a standard cab, long bed 1982 2wd S-10 for use as a daily driver and auto-X vehicle. Spirited driving, with emphasis on neutral/predictable handling. This is not an all out race suspension question or build. The compromise is that I will not be slamming/bagging/dropping the truck to the point that it is too low to use as a truck. I still want to be able to go over speed bumps without worry and haul couches, etc.

My question(s):
Knowing that a torque arm will be incorporated into the design from the start, is it best to mount the lower and upper links parallel to the ground, and let the forward mounting point of the torque arm dictate the instant center?

Would you want the torque arm forward mounting point to be level (in side view) with the upper link arm, or the lower links?

Would you want the torque arm mounted level (from side view) with the lower links on the axle?

I plan to make everything as adjustable as possible, with an adjustable panhard bar centering the axle laterally. And I plan to use the rod end links throughout all linking points. The forward end of the torque arm will be in a sliding sleeve, not the shackle/dogbone set-up. Upper 3-link arm will be offset to the passenger side. All mounting points will be double shear, using 1/4" plate, with adjustment holes drilled 1" apart.

I do not know about where it would be best to mount the shocks. I want to use coilovers front and rear. I plan on keeping the truck at its stock ride height, just lowering the rear to be level. I would like to set up the suspension properly to avoid needing a rear sway bar, but I'm not 100% opposed to adding one if I need to.

Other than that, weight distribution efforts will be made to lessen the forward bias associated with pickup trucks. Fiberglass fenders and hood, mounting the engine further back, manual brakes and steering. Still keeping climate control. This is not a V8 swap. Symmetrical disc brakes with 12" rotors and dual piston calipers, dialed in with an adjustable proportioning valve.

Well, that is the plan so far. I am just trying for a nice neutral, easy to handle truck that I can drive confidently every day, and have fun on the track on the weekends. Any help would be greatly appreciated.

David, sorry for just getting to your post, but I've been busy with client suspension projects.

Your post has a conflict in it ... look at the bold areas ... in that you're referring to utilizing a 3-link and a torque arm rear suspension. I should clarify: you can't run both ... or at least you shouldn't ... as you will run into binding issues. You should choose between a 3-link or a torque arm rear suspension.

They have things in common ... in that they both use 2 lower links. And both have 3 "links". In a true 3-Link, the 3rd link ... aka upper link or top link ... attaches to the housing above axle centerline ... and goes how many ever inches forward to the mounting brackets. They typically use rod ends on each ... so none of the 3 links attach rigid to the housing. Most 3-link suspensions have the upper link slightly longer than the lower links, equal in length or up to 50% shorter than the lower links. The top link can be ran in the center ... or offset to reduce torque steer.

A torque arm on the other hand, bolts rigid to the rear end housing (and has adjustment for pinion angle). They typically mount at the frame with a slide or pivot straps (so it doesn't bind the suspension). While it is common for torque arm designs to be quite long ... say 40-55" ... and connect to the chassis near the transmission ... that is not an absolute, as some designs are shorter. Most torque arms mount around the diff & run down low ... either under or along side the drive shaft.

I hope this clarifies things some & you choose a rear suspension strategy that best meets your needs & goals.

Mr.Franco · #8 11-18-2014, 11:26 AM

Quote:

Originally Posted by Ron Sutton

A torque arm on the other hand, bolts rigid to the rear end housing (and has adjustment for pinion angle). They typically mount at the frame with a slide or pivot straps (so it doesn't bind the suspension).

On a stock 82+ F-Body, the torque arm is a stamped piece of steal that can twist and spring back as the rear "solid" axle oscillates (example: if your going into a right corner, the right suspension will compress).

My question: If a person installs an aftermarket tubular torque arm (more rigid), will this limit the travel (causing a bind) and thus inhibiting the suspension to plant the tires as needed?

I know originally the aftermarket torque arm was designed for drag racing (plant the tires for launching/acceleration) and as we know, the suspension for drag is different for road racing.

-Mark

Ron Sutton · #9 11-18-2014, 02:50 PM

Quote:

Originally Posted by Mr.Franco

On a stock 82+ F-Body, the torque arm is a stamped piece of steal that can twist and spring back as the rear "solid" axle oscillates (example: if your going into a right corner, the right suspension will compress).

My question: If a person installs an aftermarket tubular torque arm (more rigid), will this limit the travel (causing a bind) and thus inhibiting the suspension to plant the tires as needed?

I know originally the aftermarket torque arm was designed for drag racing (plant the tires for launching/acceleration) and as we know, the suspension for drag is different for road racing.

-Mark

Hi Mark,

Correctly designed Torque Arm rear suspensions typically mount at the frame with a slide or pivot straps ... so it doesn't bind the suspension.

Holy cow ... that may be my shortest answer ever. We can't have that ...

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Whew ... there ... now I feel much better.

mitch_04 · #10 11-18-2014, 03:44 PM

Haha.... great post.