Rear sway bars (anti roll bars) what got them and what didn't?

[Pinger]

...along with, castor/camber/toe/Ackerman angles/bump steer/roll steer/Spring rates/Shock compression & rebound rates/Frame torsional stiffness/Suspension frequency cycles/Tire & wheel weight, sidewall size & stiffness, tread width & rubber compound/etc. etc. etc.

To make a vehicle understeer less, reduce front roll stiffness & increase it in the rear.
To make a vehicle oversteer less, do just the opposite.
Of course, that's considering that no other changes are made.

By tuning a vehicle for extremely high-roll stiffness—where it's difficult to notice cornering speed due to lack of body roll—you mask one channel of communication to the driver. Nobody wants to fly blind by masking roll; you're cutting off tangible communication. Instead, it comes down to understanding and predicting what's going to happen as cornering forces build to their breaking point and beyond.
Body roll is a primary, fundamental way to inform the driver about cornering and therefore a progressive indicator of grip.
The idea is to cook up a suspension absorbent enough to keep tires planted and talking to the driver as continuously as possible.

The hearts and minds of sporty car fans often relies on a game of numbers brewed in a cauldron of 0-60 mph times, quarter-mile figures, maximum grip numbers, lap times, and nutso horsepower.
Living by those stats adds up to one-upmanship that eventually leads down a rabbit hole of irrelevance.
Mix all those ingredients together and you get an automotive Dolph Lundgren—great on paper but lacking any real charm in person.
To put it another way, when is the last time you drove a spec sheet?

Grip in the form of lateral acceleration and breakaway character is the prime offender in the modern crimes against driving fun, and it's typically measured by the force of gravity in a lateral plane. In this dynamic, a car that can most quickly negotiate a 100-, 200- or 300-foot (30/60/90m) diameter skidpad in steady-state cornering in the least amount of time against others posts the highest grip.

Of course, grip on a skidpad proves only one thing: that tires stick well and the suspension keeps them mostly upright. That's not where the joy or art of driving live, however. Better grip may mean negotiating a steady corner faster, but if you focus only on grip in the chassis engineering phase, the enjoyment of driving plummets. The breakaway character of the car's and tires' cornering ability at maximum adhesion becomes unforgiving and hard to read for many drivers.

The real shame is that this is the exact point where enthused driving becomes a dance worthy of the effort. A superior handling vehicle can be as rewarding a partner as Fred Astaire or Ginger Rogers, but fit horrendously grippy sneakers, and grace falls flat on its ass. Put simply, tires and suspension engineered for maximum possible grip deliver what they're supposed to, but in inverse proportion to fun.

A lack of suspension travel is one of the most frequent causes of horrible handling.

I have a friend who want's me to drive their Porsche Cayman. Your post describes exactly why I have no intention of driving it - but wouldn't refuse a drive of her Isuzu pick-up!

edit PS - Or an original Elan.

 

[jaywestfall]

Just a note to begin with.
GM installed larger front bars on these trucks that only came equipped with the front bar. GM's method of compensating for not having a rear bar.
Trucks with both front & rear bars had a smaller front bar than the ones just equipped with the single front one.

The rear bar from an SUV is more than adequate for C1500's.
Going too large & the trucks get tail-happy. Especially over stutter bumps such as railroad tracks. The rear suspension becomes less compliant.
Too large of a rear bar will also cause a vehicle to 'push' in the corners. A rear bar has to be somewhat compliant so as to allow the weight of the vehicle to transfer onto the outer front wheel, resulting in that tire being 'planted' as opposed to sliding over top of itself during any type of aggresive manouevering.

Sway bar technology is a science all unto itself, with many trains of thought such as 'soft suspension/ large stiff bars' to the other end of the spectrum of 'stiff suspension/small lighter bars'.
Track guys all have their various views & opinions. It all depends on the final usage of the vehicle, driver personal preference, & most importantly, track times.
Testing of such is also important. Comprimises abound. A vehicle that turns in a great 'G'-force meaurement on a 200' skid pad may not be the best in a slalom course. Alternatively, a vehicle that does well on a slalom may not generate the best of skid pad numbers. Usually, it's the vehicles that combine 'not-the-best' in each measurement that are the ones that shine in actual real-world usage. ...and generate the best track times.

Then there's the bars themselves. Solid. Hollow. Semi-hollow, (Solid centers/hollow ends.) This tech is a giant can of worms!

The install of a factory rear bar under these trucks is not done with the idea of creating a race car cabable of stellar handling performance equal to that of an actual track vehicle.
Nope. But, it will improve the handling over & above that which was not available from the factory. Allows for more confidence in the vehicle when evasive moves are suddenly required.
Throwing on some good shocks is a good idea. A vehicle is suspended by the ...ahhh...suspension. (!) Shocks control the motion of the suspension.

A rear bar will also help when towing.


To install a GM sway bar on a non-factory equipped truck you'll need...
- The sway bar from an SUV. This includes the end links, the frame mount brackets & the nuts & bolts for the brackets.
The nuts & bolts are important. There's a key on the nuts that prevents the nut from turning inside the frame when tightening or removing. Like a fender nut/bolt combo. It's near impossible to get any type of wrench/socket in there to hold them.
- 2x 3" Heavy Duty muffler clamps. H/D because they're longer & of a heavier gauge. Regular M/clamps are not long enough to get everything that's going to be mounted on them to fit.
- I also recommend to replace the bushings on the end links with urethane.
I got the ones for mine from the local auto parts store. Take one of the the originals with you. The replacements were in a divided plastic container of various sizes allowing me to pick & choose the ones I needed.
The factory rubber ones are one piece. The urethane ones are of a two piece design. So, you'll require 8 pieces.
For the diff mounts, they also were also replaced with urethane. They are a split design so that they just slip over the bar. No need to slide them on over the ends of the bar. The came with shells equipped with grease zerks.
The ones I used had the same bolt hole center-to-center measurements as the c-to-c measurements of the muffler clamp U-bots.
I took one of the original rubber ones with me to figure the size. You could also just measure the factory bar with a dial caliper to get the right size.

Install.
- Lube the bushings with synthetic grease. Urethane doesn't like regular Dino-grease.
- Diassemble the end links from the frame brackets & the bar.
- Slip the U-bolts for the muffler clamps through the opening of where the shock brackets are welded to the diff. One will face towards the front of the vehicle, the other towards the rear.
- Slip the other 1/2 of the M/clamps over the U-bolts.
- Install the sway bar bushings over the bar, along the shells.
For this next part, a third hand really helps.
- Install the shells/bushings on to the muffler clamps & bolt them loosely until both sides are installed.
- Once that's done, snug the nuts up tight enough to just hold the bar in place, without it being able to move around on it's own, yet loose enough that it can be moved by hand.
- Align the bar so that is parallel to the diff. The U-bolt ends may get hung up on the shock mount due to their length, which can prevent the bar from being mounted parallel. Trimmage of the U-bolt may be required.
- Once the bar is parallel, tighten down that assembly.

This next part of the assembly requires that the weight of the vehicle is on the wheels. The vehicle needs to be on a level surface.

- Assemble the end links onto the bar with the new bushings.
- Assemble the frame mounts to the end links.
- Swing the ends of the bar with that assembly up to the frame.
- *Important* The end links have to be perpendicular to the bar. Straight up & down. Not leaning forward or to the rear.
- Trace the frame mount position on the frame with an awl or some chalk.
- Mark that front mounting hole for the bracket on the frame. You'll only be able to mark that front one as the rear one is blocked by the end link.
- You may also find that there is a big rivet sitting right underneath where the frame bracket goes. Don't remove that rivet. Drill a larger than required in the frame bracket so that the rivet fits inside that hole.
- Remove the brackets from the end links.
-Place that bracket up against the frame in the marked position & mark that rear hole.
- Drill the four holes for the bracket in the frame.
- Install the brackets using the original specific nuts & bolts. Use some red loc-tite on the nuts & bolts.
- Swing the bar back up into postion & install the end links into the frame brackets.
Go back & check that all the nuts & bolts are tight.
Lube the diff bushings via the grease zerks.

Now, get out there & carve some corners & enjoy the feeling of the truck being more connected, front-to-rear.

I bit the bullet and bought the Energy Suspension Bushing master Kit 3.18107R (Red). My 98 C1500 ext cab did not have a factory installed rear sway bar, and the Belltech kit requires drilling into the frame, which makes me nervous.....great write up, Sir!

 

[DJackson1357]

If you install the factory rear sway bar on a K1500 pickup I’d recommend using the GMT800 SUV end links. They are longer and will put the bar closer to the proper angle. The holes on the bar need slightly opened in the center to fit the new end links but it literally takes 20 seconds with a die grinder. Not sure if that would help on a C1500.

Also, I installed both rear air bags and the rear sway bar. Lost enough rear compliance I ended up taking the bar back off later. Handling was nice but ride quality suffered more than I wanted.

 

[TacosnBeer]

Holy crap I love this conversation!

 

[TacosnBeer]

...along with, castor/camber/toe/Ackerman angles/bump steer/roll steer/Spring rates/Shock compression & rebound rates/Frame torsional stiffness/Suspension frequency cycles/Tire & wheel weight, sidewall size & stiffness, tread width & rubber compound/etc. etc. etc.

To make a vehicle understeer less, reduce front roll stiffness & increase it in the rear.
To make a vehicle oversteer less, do just the opposite.
Of course, that's considering that no other changes are made.

By tuning a vehicle for extremely high-roll stiffness—where it's difficult to notice cornering speed due to lack of body roll—you mask one channel of communication to the driver. Nobody wants to fly blind by masking roll; you're cutting off tangible communication. Instead, it comes down to understanding and predicting what's going to happen as cornering forces build to their breaking point and beyond.
Body roll is a primary, fundamental way to inform the driver about cornering and therefore a progressive indicator of grip.
The idea is to cook up a suspension absorbent enough to keep tires planted and talking to the driver as continuously as possible.

The hearts and minds of sporty car fans often relies on a game of numbers brewed in a cauldron of 0-60 mph times, quarter-mile figures, maximum grip numbers, lap times, and nutso horsepower.
Living by those stats adds up to one-upmanship that eventually leads down a rabbit hole of irrelevance.
Mix all those ingredients together and you get an automotive Dolph Lundgren—great on paper but lacking any real charm in person.
To put it another way, when is the last time you drove a spec sheet?

Grip in the form of lateral acceleration and breakaway character is the prime offender in the modern crimes against driving fun, and it's typically measured by the force of gravity in a lateral plane. In this dynamic, a car that can most quickly negotiate a 100-, 200- or 300-foot (30/60/90m) diameter skidpad in steady-state cornering in the least amount of time against others posts the highest grip.

Of course, grip on a skidpad proves only one thing: that tires stick well and the suspension keeps them mostly upright. That's not where the joy or art of driving live, however. Better grip may mean negotiating a steady corner faster, but if you focus only on grip in the chassis engineering phase, the enjoyment of driving plummets. The breakaway character of the car's and tires' cornering ability at maximum adhesion becomes unforgiving and hard to read for many drivers.

The real shame is that this is the exact point where enthused driving becomes a dance worthy of the effort. A superior handling vehicle can be as rewarding a partner as Fred Astaire or Ginger Rogers, but fit horrendously grippy sneakers, and grace falls flat on its ass. Put simply, tires and suspension engineered for maximum possible grip deliver what they're supposed to, but in inverse proportion to fun.

A lack of suspension travel is one of the most frequent causes of horrible handling.

BAHAHA Automotive Dolph Lundgrun!

Yeah, dont wanna lose the most important communication between man and machine - the ASS! I used to road race back in the day - Karts for years and cars for a short time... a good portion of it is feel and what the driver likes. I prefer a little loose but not a fan of a **** ton of body roll. I can work with sloppy a lil more that I can with too stiff.

Ginger Rogers with a side of Sofia Vergara ... wait, are we still talking about cornering?

 

[SuperTramp]

Thank you
Sewlow!

 

[Pinger]

Had a crawl under mine today and there's no brackets on the axle for a rear bar.

 

[Pinger]

Pix! I have pix!

This shows the M/clamp mounted to the diff. This is the same method of mounting sway bars that the aftermarket Co.'s use.
It also shows why the U-bolts may have to be trimmed. This is mine before they were. You can see why as that one leg is just a bit too long for the mount to slide right back inside the shock mount in order to get the bar parallel to the diff housing.

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This pic shows why you can't mark that one hole for the frame bracket with the upright installed. This is under my '97 before I replaced the rubber bushings.
...and I made a bit of an error, not that it matters, but it's the bolts that have the key on them to prevent it from turning inside the frame rail. Not the nuts.

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Finished.

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Now, for you guys with more than a 6" rear drop, you may have to shorten the uprights in some manner. If those are too long, what happens is that bar ends up sitting on too much of angle, too close to the pumpkin cover. On hard suspension compressions, the bar may hit the cover as the bar swings through it's travel. A bit of 'massaging' with a hammer can allow for clearance in that area. Keep an eye on where the bar touches. It's actually more of a scuff. Too much hammering could put the cover into the crown gear. It doesn't take much to get the clearance required.

What diameter is that bar you fitted and what diameter of bar is on the front?

 

[Erik the Awful]

For anyone who's enjoying the conversation, you really need to check out this book. Herb Adams was a GM engineer who did a lot of their design work. Back in the day I hated the sloppy, lazy feeling of GM cars with their soft shocks and huge sway bars, but when you're hammering corner 2 at Barber Motorsports Park in a well-built BMW 325 and a Camaro rips around you like you're standing still, you gotta give respect.
https://www.amazon.com/Chassis-Engi...=1598976894&sprefix=herb+adams,aps,274&sr=8-1

 

[Erik the Awful]

Chapman made great claims about the rigidity of his backbone chassis but when it suited him he was a Grade A BSer! A brilliant engineer though who really understood the intricacies of suspension and weight transference better and before anyone else did.

True, but combine that backbone with a monocoque, and you get an incredibly rigid chassis.

Funny story - years ago when I was deployed we had a soapbox derby. People were building ladder frames, one guy built an old-school aircraft-style rib-and-spar frame. Thinking of Lotus, I put a single upright 2x4 under a sheet of plywood with flat 2x4s at either end for the axles. It was plenty strong and weighed about half as much as the other carts. In the end the motorpool guys won because they used actual wheel bearings on their cart - I had a whittled 2x4 with aluminum can and soap bearings.