Torque Arm versus 3-link characteristics

[D-Man]

We tried for a couple of months to design an adjustable length TA for my G Body and just couldn't find room under the car for an adjustable forward mount.

The sweet spot for a 108" WB car is somewhere between 45-55" long from our calculations.

What drivetrain? 70-81 Camaro (108" wheelbase) driveshaft is 48-50" so should be room for at least that long I would think.

[carbuff]

What drivetrain? 70-81 Camaro (108" wheelbase) driveshaft is 48-50" so should be room for at least that long I would think.

As I recall on TOW, the torque arm is 52" long. We shortened it a bit from the original length which was around 54-55".

[D-Man]

As I recall on TOW, the torque arm is 52" long. We shortened it a bit from the original length which was around 54-55".

Why did you shorten it?

[Mark@lateral-dynamics]

"Reading between the lines a 3-link can have the same (high) A/S as a torque arm but without the brake hop issues?

I found pictures of your old 3-link and didn't think it was too bad as far as cabin intrusion with the centered top link. "

For a T/A, the instant center is only defined by the actual torque arm itself, changing the inclination of the lower links does not change the instant center at all. What you get it is what you have to live with. With an adjustable 3-Link, you could go to even higher A/S values if you wanted, by using steep angles of the upper and lower links - but I wouldn't recommend. Alternatively, and the real beauty of the 3 Link is the ability to go to longer IC length, which decreases the A/S but quickly calms the tendency for wheel hop. There was a time where I felt a shorter IC on any setup was a good thing, I don't at all feel that way after over a decade. For instance, on our C6 Z06, which has independent rear suspension and therefore MUCH less anti-squat due to the physics, I can put the power down on aggressive autocross just as good as I could with an aggressive IC tune on the 3-Link Camaro.

Also, the wheel hop doesn't have anything to do with the tires, except for the fact that you can drive WAY more aggressive with great tires versus street tires so you will without question see it more often.

As far as packaging, we are deep into a cool redesign of our original setup that is far easier to install and doesn't require nearly as much cutting, but it's still a ways out. The beauty of the T/A is that it is easier to install but that gap is decreasing. If "I" were to do a T/A, I'd shoot for a minimum of 60" for a typical 108" wheelbase muscle car, and frankly I'd go even longer - but it gets tough to pack all that under the car.

Let's face it, a lot of this bench racing and beyond the skill level (driving wise) of most hobbyists, but the statements are factual and based on the real world as well as theory. If your goals are to have a really cool car, drive it hard and have a great time without a lot of fuss, then some of the T/A kits out there are perfect for you. We all have our own goals so there really is not one solution to fit all. It can be hard to sift through the fierce brand loyalty, but that's not unique to this sport at all. It's an awesome hobby, so go have fun with it!

[SSLance]

What drivetrain? 70-81 Camaro (108" wheelbase) driveshaft is 48-50" so should be room for at least that long I would think.

It wasn't the length that we couldn't find room for, it was the height of an adjustable type mount.

We couldn't find a way to build an adjustable length (fore and aft) front mount for the TA that would fit under the stock floor pan of my car and still provide streetable ground clearance.

So at that point it was a "pick a length and hope it works" deal or just work on improving another rear suspension design with much easier packaging and still pretty decent results.

[D-Man]

"Reading between the lines a 3-link can have the same (high) A/S as a torque arm but without the brake hop issues?

I found pictures of your old 3-link and didn't think it was too bad as far as cabin intrusion with the centered top link. "

For a T/A, the instant center is only defined by the actual torque arm itself, changing the inclination of the lower links does not change the instant center at all. What you get it is what you have to live with. With an adjustable 3-Link, you could go to even higher A/S values if you wanted, by using steep angles of the upper and lower links - but I wouldn't recommend. Alternatively, and the real beauty of the 3 Link is the ability to go to longer IC length, which decreases the A/S but quickly calms the tendency for wheel hop. There was a time where I felt a shorter IC on any setup was a good thing, I don't at all feel that way after over a decade. For instance, on our C6 Z06, which has independent rear suspension and therefore MUCH less anti-squat due to the physics, I can put the power down on aggressive autocross just as good as I could with an aggressive IC tune on the 3-Link Camaro.

Also, the wheel hop doesn't have anything to do with the tires, except for the fact that you can drive WAY more aggressive with great tires versus street tires so you will without question see it more often.

As far as packaging, we are deep into a cool redesign of our original setup that is far easier to install and doesn't require nearly as much cutting, but it's still a ways out. The beauty of the T/A is that it is easier to install but that gap is decreasing. If "I" were to do a T/A, I'd shoot for a minimum of 60" for a typical 108" wheelbase muscle car, and frankly I'd go even longer - but it gets tough to pack all that under the car.

Let's face it, a lot of this bench racing and beyond the skill level (driving wise) of most hobbyists, but the statements are factual and based on the real world as well as theory. If your goals are to have a really cool car, drive it hard and have a great time without a lot of fuss, then some of the T/A kits out there are perfect for you. We all have our own goals so there really is not one solution to fit all. It can be hard to sift through the fierce brand loyalty, but that's not unique to this sport at all. It's an awesome hobby, so go have fun with it!

Yes, it's very easy in this sport to go way overboard. I'm all about building a pro-touring car that will actually get driven hard and often, not a race car so don't need every last bit of performance. But even on the street (when safe) it's easy to find the limitations of poor designs or execution. Seeing how your old system went in was actually what got me interesting in exploring the 3-link over the T/A. So if the new system has even less cutting of my tub all the better since again not building a race car. I do love to weld and fabricate so no issue there. Thanks for not doing a hard sell on your 3-link and also taking the time to answer my many questions.

It wasn't the length that we couldn't find room for, it was the height of an adjustable type mount.

We couldn't find a way to build an adjustable length (fore and aft) front mount for the TA that would fit under the stock floor pan of my car and still provide streetable ground clearance.

So at that point it was a "pick a length and hope it works" deal or just work on improving another rear suspension design with much easier packaging and still pretty decent results.

Got it. Definitely tight under there.

[OLDFLM]

Torque Arm... more than you'll ever need.

[Psydwaze]

The comment regarding torque arm length affecting wheel hop was correct. Too short of an arm is great for acceleration traction, but can lead to wheel hop under braking. Note that a 3-link or 4-link with too short of an instant center can also have these same issues. Stiffer springs and damping can help to tame wheel hop. Easy enough on a track car, but for the street the better option is to just run a longer torque arm so as not to sacrifice ride quality. Torque arm length predominantly determines the instant center length, with lower arm angle having minimal affect; only a couple percent as I recall. Altering the lower arm angle affects the roll steer characteristics of the suspension. Arms being level to the ground is preferred for predictable turn-in characteristics. Inclination of the arms running uphill toward the front of the car induces oversteer. Adjusting the vertical position of the chassis mount does not affect the instant center, but can be useful when trying to route the exhaust near the driveshaft. The "ideal" torque arm would be a decoupled design that acts as a short arm during acceleration and long arm during braking, which is not easily packaged into a street car. But in general, a torque arm can be a great option for a fun and capable street car.

We (Chassisworks) make quite a few different torque arm setups, covering the first four generations of Camaros, popular GM and Ford cars as well as custom-fit systems and complete back halves.

LINKS:

• '70-73 Camaro Version - http://www.cachassisworks.com/c-1377-torque-arm.aspx
• Product Data Sheet - http://www.cachassisworks.com/Attach...XXX_DS_WEB.pdf
• A-, F-, X-body, Chevy II and custom-fit versions here - http://www.cachassisworks.com/c-1375...spensions.aspx

Lino Chestang
Chris Alston's Chassisworks

[Steve Chryssos]

Hi D-Man,
Given your goals....

Goals are:
Fit 335 rear tires
Better ride
Better street performance with an emphasis on twisty highway driving
Predictable handling
Not concerned with the absolute lowest lap time potential.
Faster is better obviously, but not looking to win any competitions.
Not interested in a 4-link system - at all.

... A torque arm will make you very happy. It hooks well, delivers far superior ride quality and handling as compared to leaf springs, offers excellent packaging and ease of installation ...and is proven regularly and competitively at Goodguys, NMCA West, DirveAuto-X and SCCA events from coast to coast. That includes championship-winning and race-winning cars owned and driven in the real world. ... and no brake hop anywhere -- ZERO. TCI Engineering, SpeedTech and others offer excellent, readily available and fully supported Torque Arm systems. I run a Torque Arm on my own Camaro and I love it. It's rock-solid reliable, easy to tune and fun as all get out.

The Torque Arm's performance is undeniable everywhere, except on paper. Engineering discussions comparing suspension types are valid and interesting, but have you ever tried driving and racing on paper? One time, I carefully taped a sheet of paper to each tire, ran a lap and when I returned to the pits -- the paper was GONE! ..All four sheets. Dullard that I am, I just do NOT understand what happened to the paper.

There are many threads here suggesting that:
1) A torque arm will cause your car to "endo" (flip over forward) under braking and burst into flames.
2) A 4-link will bind in corners causing your car to flip over sideways and burst into flames.
3) You should wait patiently for the emergence of a 3-link to be hand delivered by a unicorn and packaged carefully in pixie dust.

For you and anyone else who rolls up on this thread, take all of this technical information with a grain of salt. We race and test pro-touring cars 30 weeks per year. Torque arms and four link cars swap the lead at each event -- lap after lap. The actual difference in performance can frequently be measured in tenths or hundredths of a second. 4-links win some races and torque arms win some races. Get to an event and see for yourself. Better yet, ask for ride-a-longs. If the day comes when an easy-to-install 3 link exists, I will be sure sing its praises as one of many great options -- all of which perform very well in the real world.

In the meantime, enjoy your car. A torque arm will suit your goals and exceed your expectations.

Thanks,
Steve

[Rod]

We race and test pro-touring cars 30 weeks per year. Torque arms and four link cars swap the lead at each event -- lap after lap. The actual difference in performance can frequently be measured in tenths or hundredths of a second. 4-links win some races and torque arms win some races. Get to an event and see for yourself. Better yet, ask for ride-a-longs.

well said Steve, its hard to explain HOW much time we spend racing and testing, I think most would be amazed, we totaled up days away from the shop at racing events not including weekends and I was out 39 days from the shop, thats not any weekend days included, and still had to keep building a business

[Steve Chryssos]

Thanks... Here you go folks. Get the popcorn, I found a video. ZERO (ZEE RO) brake hop with Torque Arm. Chad Ryker's Camaro with TCI Torque Arm. Our great hobby has added Speed Stop competitions to many events. ...and most events require FULL STOP at the termination of each run. Throughout each run, throttle and brake application are best described as AGGRESSIVE. ..and this video is ancient, by the way. Technology has advanced over the years with the greatest changes taking place with respect to tire grip and available horsepower. There is so much available grip with 200 tread wear tires, it feels like your eye balls are being sucked out of your skull under braking -- and no brake hop.
Steve

[D-Man]

The comment regarding torque arm length affecting wheel hop was correct. Too short of an arm is great for acceleration traction, but can lead to wheel hop under braking. Note that a 3-link or 4-link with too short of an instant center can also have these same issues. Stiffer springs and damping can help to tame wheel hop. Easy enough on a track car, but for the street the better option is to just run a longer torque arm so as not to sacrifice ride quality. Torque arm length predominantly determines the instant center length, with lower arm angle having minimal affect; only a couple percent as I recall. Altering the lower arm angle affects the roll steer characteristics of the suspension. Arms being level to the ground is preferred for predictable turn-in characteristics. Inclination of the arms running uphill toward the front of the car induces oversteer. Adjusting the vertical position of the chassis mount does not affect the instant center, but can be useful when trying to route the exhaust near the driveshaft. The "ideal" torque arm would be a decoupled design that acts as a short arm during acceleration and long arm during braking, which is not easily packaged into a street car. But in general, a torque arm can be a great option for a fun and capable street car.

We (Chassisworks) make quite a few different torque arm setups, covering the first four generations of Camaros, popular GM and Ford cars as well as custom-fit systems and complete back halves.

LINKS:

• '70-73 Camaro Version - http://www.cachassisworks.com/c-1377-torque-arm.aspx
• Product Data Sheet - http://www.cachassisworks.com/Attach...XXX_DS_WEB.pdf
• A-, F-, X-body, Chevy II and custom-fit versions here - http://www.cachassisworks.com/c-1375...spensions.aspx

Lino Chestang
Chris Alston's Chassisworks

Thanks for putting that into laymans terms. I really like the CA torque arm. Obviously a lot of thought and engineering went into it.
At what length roughly does wheel hop start to come into play with a torque arm?

Hi D-Man,
Given your goals....


... A torque arm will make you very happy. It hooks well, delivers far superior ride quality and handling as compared to leaf springs, offers excellent packaging and ease of installation ...and is proven regularly and competitively at Goodguys, NMCA West, DirveAuto-X and SCCA events from coast to coast. That includes championship-winning and race-winning cars owned and driven in the real world. ... and no brake hop anywhere -- ZERO. TCI Engineering, SpeedTech and others offer excellent, readily available and fully supported Torque Arm systems. I run a Torque Arm on my own Camaro and I love it. It's rock-solid reliable, easy to tune and fun as all get out.

The Torque Arm's performance is undeniable everywhere, except on paper. Engineering discussions comparing suspension types are valid and interesting, but have you ever tried driving and racing on paper? One time, I carefully taped a sheet of paper to each tire, ran a lap and when I returned to the pits -- the paper was GONE! ..All four sheets. Dullard that I am, I just do NOT understand what happened to the paper.

There are many threads here suggesting that:
1) A torque arm will cause your car to "endo" (flip over forward) under braking and burst into flames.
2) A 4-link will bind in corners causing your car to flip over sideways and burst into flames.
3) You should wait patiently for the emergence of a 3-link to be hand delivered by a unicorn and packaged carefully in pixie dust.

For you and anyone else who rolls up on this thread, take all of this technical information with a grain of salt. We race and test pro-touring cars 30 weeks per year. Torque arms and four link cars swap the lead at each event -- lap after lap. The actual difference in performance can frequently be measured in tenths or hundredths of a second. 4-links win some races and torque arms win some races. Get to an event and see for yourself. Better yet, ask for ride-a-longs. If the day comes when an easy-to-install 3 link exists, I will be sure sing its praises as one of many great options -- all of which perform very well in the real world.

In the meantime, enjoy your car. A torque arm will suit your goals and exceed your expectations.

Thanks,
Steve

It's good to hear real world experience. You've never seen wheel hop on a TA car?

Also, same question as above. At what length would you start to be concerned about wheel hop?


Another question for all.
What's your favorite joint (at the crossmember) for a torque arm and what joint would you stay away from? Performance vs noise vs longevity.

[Psydwaze]

At what length roughly does wheel hop start to come into play with a torque arm?

Minimum length depends on many variables. We run ours as short as 33" for a specifically designed '65-70 Mustang suspension; 36" for Cougars. This was originally designed for use in our pushrod rear coil-over, a short-travel and generally stiffer sprung system intended for track day and road race use. The stiffer spring rate is necessary for the limited amount of travel (3.5" travel shock with roughly 1:1 ratio rocker arm) and can better manage the torque arm under braking. Not sure if this was explained previously, but the torque arm basically has an opposite reaction at each end. Acceleration tries to roll the pinion snout upward, causing the arm to push upward at the chassis mount and conversely downward at the rear end housing. Shorter arms plant the tires harder than a longer arm due to the difference in effective leverage. The opposite is also true under braking in which the arm pulls downward at the chassis mount and attempts to lift the rear end housing, at least it does so until there is enough lift to cause a loss of traction. Basically, it lifts, skids, regrips and repeats... wheel hop. Extremely long answer for how short of an arm you can run, but felt I needed to explain as 33" is considered too short for a comfortably sprung street car. However we can get away with it on a stiffer sprung car that normally sees smooth road courses. Plenty have been sold for street cars though, cause you know... FUN! Our complete list of arm lengths is 33, 36, 46, 49 and 56 inches.
Mustang Pushrod Suspension - http://www.cachassisworks.com/Attach...-FD_DS_WEB.pdf

What's your favorite joint (at the crossmember) for a torque arm and what joint would you stay away from? Performance vs noise vs longevity.

We use two styles, a dog-bone endlink and a sliding eye with single pivot-ball joint. The dog-bone is used on the short torque arm Mustang system. Due to the under-slung watts link and low roll center, trailing arm angle and roll steer come into play as a tuning means. More roll steer on this system improves turn-in, but creates lateral misalignment at the chassis end of the arm. Therefore we needed a mount that allowed lateral movement as well as fore and aft without being soft like a bushing. ---- The eye style mount is for our system that uses a rear mounted watts link or panhard bar with a higher roll center. Lower arms can be left level; roll steer and arm misalignment are minimal; about 1/16" at most. At four to five feet in length the misalignment isn't an issue so we only require a sliding mechanism to account for the travel arch of the lower arms. We actually offer the slider eye as a spherical pivot or a urethane bushing eye for reduced noise. Either material is fine at longer arm lengths. Personal preference is pivots over bushings, but I'm more of a lowered car, low profile tires, louder exhaust kind of guy.
http://www.cachassisworks.com/Attach...WEB.pdf#page=3

[CSG]

The front mount that Maximum Motorsports builds on their TA is my go to favorite.

[D-Man]

Minimum length depends on many variables. We run ours as short as 33" for a specifically designed '65-70 Mustang suspension; 36" for Cougars. This was originally designed for use in our pushrod rear coil-over, a short-travel and generally stiffer sprung system intended for track day and road race use. The stiffer spring rate is necessary for the limited amount of travel (3.5" travel shock with roughly 1:1 ratio rocker arm) and can better manage the torque arm under braking. Not sure if this was explained previously, but the torque arm basically has an opposite reaction at each end. Acceleration tries to roll the pinion snout upward, causing the arm to push upward at the chassis mount and conversely downward at the rear end housing. Shorter arms plant the tires harder than a longer arm due to the difference in effective leverage. The opposite is also true under braking in which the arm pulls downward at the chassis mount and attempts to lift the rear end housing, at least it does so until there is enough lift to cause a loss of traction. Basically, it lifts, skids, regrips and repeats... wheel hop. Extremely long answer for how short of an arm you can run, but felt I needed to explain as 33" is considered too short for a comfortably sprung street car. However we can get away with it on a stiffer sprung car that normally sees smooth road courses. Plenty have been sold for street cars though, cause you know... FUN! Our complete list of arm lengths is 33, 36, 46, 49 and 56 inches.
Mustang Pushrod Suspension - http://www.cachassisworks.com/Attach...-FD_DS_WEB.pdf


We use two styles, a dog-bone endlink and a sliding eye with single pivot-ball joint. The dog-bone is used on the short torque arm Mustang system. Due to the under-slung watts link and low roll center, trailing arm angle and roll steer come into play as a tuning means. More roll steer on this system improves turn-in, but creates lateral misalignment at the chassis end of the arm. Therefore we needed a mount that allowed lateral movement as well as fore and aft without being soft like a bushing. ---- The eye style mount is for our system that uses a rear mounted watts link or panhard bar with a higher roll center. Lower arms can be left level; roll steer and arm misalignment are minimal; about 1/16" at most. At four to five feet in length the misalignment isn't an issue so we only require a sliding mechanism to account for the travel arch of the lower arms. We actually offer the slider eye as a spherical pivot or a urethane bushing eye for reduced noise. Either material is fine at longer arm lengths. Personal preference is pivots over bushings, but I'm more of a lowered car, low profile tires, louder exhaust kind of guy.
http://www.cachassisworks.com/Attach...WEB.pdf#page=3

Thanks for the detailed explanation on TA length. I am considering trying a shorter arm for better hook up, but do plan on only slightly stiffer rate springs than what a late model muscle car might use. Maybe 36 inches long to start unless that's way off the mark for that spring rate.

I like your slider/spherical pivot. Looks like one could even slide in a bushing end if the spherical end was too harsh for them.
Does CA sell TA parts separate or only with the kits?

[Psydwaze]

Thanks for the detailed explanation on TA length. I am considering trying a shorter arm for better hook up, but do plan on only slightly stiffer rate springs than what a late model muscle car might use. Maybe 36 inches long to start unless that's way off the mark for that spring rate.

I like your slider/spherical pivot. Looks like one could even slide in a bushing end if the spherical end was too harsh for them.
Does CA sell TA parts separate or only with the kits?

Sorry for the extremely delayed response. I would start longer than 36" as that is probably the limit before you start running into tuning issues and rather short suspension travel requirements to make it all work well together.

This torque arm comes in 46, 49 and 56-inch lengths. Click View Options. Bushing-end slider and weld fixture with mounting tabs is also available.
http://www.cachassisworks.com/p-3737...ersal-fit.aspx

Weld-in chassis crossmember and Watts link are available on this page.
http://www.cachassisworks.com/c-1502...atts-link.aspx

Not sure if I posted this previously. We designed a really unique pinion-angle and alignment mechanism at the lower housing mount. Uses a serrated washer stack and threaded inserts to make installation and setup a breeze.

[D-Man]

That alignment function is a nice touch that I haven't seen on any other arm. I'll give you a call when I ready to dive in.

[amargari]

If doing home fabrication, are the S197 (2005-2014) Mustangs a decent starting point for a 3 link?

[Twentyover]

If doing home fabrication for a torque arm, I found the Mathis book Mustang Performance Handbook #2 helpful

[JMcD]

If doing home fabrication, are the S197 (2005-2014) Mustangs a decent starting point for a 3 link?

Having started with one of these....yes and no.

They’re wide and made for high offset wheels. Needed to take a couple inches per side off to fit +59 offset 19x12 wheels under stock 2nd gen Camaro fenders. Custom axles needed as a result.

LCA mounts on the axle side are about the right height to work with the front spring pocket on a significantly lowered PT car.

UCA mount on the axle side is relatively low, good for packaging, but not great for running high amounts of A/S with a longer than stock upper arm. Driveshaft will hit the forward attachment point.

Spring mounts are on the axle, so something custom is needed for a coil over mount or you’ll need to figure out a way to make upper spring and shock mounts.



31 spline axles and good sized brakes are nice pros. They’re cheap and plentiful in junkyards. Good differential and ratio options for cheap too.