Torque Arm question(s)... [Archive]

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DavidBoren

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

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:idea:
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 :bow:

zo6s10

10-04-2014, 12:17 PM

Vince@Meanstreets

10-04-2014, 12:24 PM

WTF happened? with spell check and FF^^^

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

Just sayin.

DavidBoren

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

10-04-2014, 01:22 PM

Check out Tyler, s10 frame. It is super light.
http://www.youtube.com/channel/UCTs67QQ89pK4Ww0oz3MGYdw
Adam at Road Atlanta (Tall AFX Spindles, leafs and homeade caltracs)
http://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.php?PHPSESSID=15db19777e138cca8894d58154f740 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.

DavidBoren

10-04-2014, 02:10 PM

Wow, thanks, Eric. I replied to your PM before I saw your post here.

DavidBoren

10-04-2014, 06:59 PM

Looking at the truck arm suspension brings up a couple new questions.

Is it as adjustable as the 3-link torque arm suspension?

Right now I am going to essentially build a rear suspension balanced to the grip possible from a relatively stock front suspension. But as I improve my driving skills and understanding of suspensions, I would eventually like to rebuild the front end for more grip. And at that point, I will need to be able to adjust my rear suspension to be balanced.

I have some more questions about the geometry of the truck arms, but I might save that for a new thread. Right now, given my intentions, would it be better to build a truck arm or 3-link/torque arm suspension? I do want to be able to adjust it as my skills and understanding improve. And I would like to be able to adjust it to match any grip improvements I make to the front.

zo6s10

10-10-2014, 04:13 PM

More links = more adjustable. Adjustments can help us or really hurt us. You have to limit yourself.

DavidBoren

10-10-2014, 07:33 PM

Given that this is going to be my first time building a suspension, I think that I am going to go with the truck arm.

It will limit the amount of adjustment possible, which will actually be a good thing for me.

The adjustments will be more simple to understand. And if I outgrow the truck arm suspension, in the way that I find myself needing the ability to make more finite adjustments. I can always build a 3-link/torque arm set-up.

But, honestly, the S10 is going to be my daily driver. And once I install the Ridetech Tru Turn G-body A-arms and coilovers, and the CPP spindles with C5 hubs, which is my planned front suspension, I doubt I will need to ever change that. So the amount of possible grip up front isn't going to change once I get that installed and dialed in.

If a truck arm suspension is capable of balancing the rear grip to the grip available in the front, then I will not ever have the need for changing from the truck arm.

This is going to be my daily driver, so it's not really an ever evolving racecar. Yes, I will have adjustable shocks/coilovers and an adjustable panhard bar, and I will adjust them for my autocross events. But once I get this suspension dialed in and balanced, I am going to move on to something else.

And that will be racercar.

TravisB

10-28-2014, 05:06 AM

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

10-30-2014, 03:10 PM

Hi David!

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.

:cheers:

Mr.Franco

11-18-2014, 11:26 AM

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

11-18-2014, 02:50 PM

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. :sarcasm_smiley:

:cheers:

mitch_04

11-18-2014, 03:44 PM

Haha.... great post.

Shmoov69

11-19-2014, 12:45 PM

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

11-19-2014, 02:59 PM

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 (http://www.speedtechperformance.com/index.cfm/page/ptype=product/product_id=9/category_id=23/mode=prod/prd9.htm) to see pics of it.

zo6s10

11-19-2014, 05:53 PM

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
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
Blah blah blah blah blah blah blah blah blah blah blah blah blah blah blah
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...

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

:cheers:

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

11-19-2014, 08:17 PM

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.