Torque Arm question(s)...

[TravisB]

Looks like you changed your mind but my lower rear controls arms are 2 degrees down at the front on my TA set up

[Ron Sutton]

Hi David!

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]

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]

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]

Haha.... great post.

[Shmoov69]

Mark, I'll show you what mine is and what Ron is talking about on the slide mount, which mine is a sway bar mount that the tube slides in. You can see it up by the transmission in the pic. Not sure what the "best" way would be and I'm sure Ron can tell you that, but this way works pretty well both on the drag strip and on the road course/auto-x. This is a homebuilt TQ arm set up that we did before the kits came out.

[Ben@SpeedTech]

If you're up to it, several folks have adapted our torque arm into cars other than the Camaros and Novas. Chatting about what's involved is a phone call rather than a type session so give our tech department a call and see if it's something we can help out with. 435-628-4300.

Click here to see pics of it.

[zo6s10]

Originally Posted by Ron Sutton

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 ...


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

That looks like everything I have ever said.

When you have the factory front suspension, My vote is improve that first. (plenty of great help here) Then work the rear end , then work the front then work the rear, front, rear and so on and so forth.
Unless someone builds it for you and beats on it, it is all in steps.

[Mr.Franco]

Thank you everyone! I've already done quite a bit of suspension work on the car:

• Koni Yellows (frt/rear)
• drop Spindles
• Complete front steering r/r
• 36mm Hollow frt sway bar/19 mm rear
• new high rate springs all around
• Strut mount caster/camber plates

The only thing left is the rear suspension and installing SFC's (trying to decide on a brand/style). I've heard different things regarding trailing arms and I've got a Spohn torque arm I've been contemplating installing (until now). Obviously good sticky tires will be next and hopefully I'll be cruising the Malibu canyons and Willow Springs in the near future.