Impressions of my huge rear sway bar
09-07-2005, 07:57 AM
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Impressions of my huge rear sway bar
As you know I installed a 1 1/4 inch speedway bar on the back to go with my 1 1/4 inch front bar. The front is extremely stiff with a 1/4 inch wall tube. It is alot stiffer then the 1 1\8th in solid bar. For the back I used 3/16 wall tube.
I also used bearing blocks on the front and bushings , but good fitting bushings on the rear and 8 rod ends in total for the 2 bars.
After installing the bar I took the car for a short ride to settle the suspension and then adjust the linkage so there was no preload on the sway bar. I found the bar in this short run extremely stiff. The car felt like it had really stiff springs.
Last night I took it for it's first real run. Carguy4sure and I went 50 miles across country to a show. 25 each way.
As I started cruising at 60 I found the bar seems to smooth out, the ride was not harsh like slow speed in town. I even put the outside wheel close to the rought edge of the road to make that side work and it felt really smooth.
I entered a few corners at about twice the recommended speed and found myself accelerating as the corner became more comfortable and would come out of the corner 15 or 20 mph faster then when I went in. I also lost my buddy Doug.
I also found not once did the car ever feel twitchy. My car is not bad but occasionally you feel that twitch. It seems to be gone. Maybe our twitch is comming from the rearend??
I feel it was a big improvement over last week without the bar. It was worth the roughtly $350 I put into the project.
The reason I went with the huge rear sway bar is because of an article I read from Herb Adams and talking to twin Turbo. 2 very knowledgabel guys.
This was taken this morning from Corvette action, posted by Kid Vette but it is taken from Herb Adams, This is what convinced me a few weeks ago.
Agian I took this from KID Vette/Corvette action/Herb Adams
Here's Herb Adams direct quote, "One reason we recommend larger, more effective stabilizer bars for Corvettes is the bars' ability to control a car's understeer characteristics. Standard Corvettes are produced at the factory with a great deal of understeer built into their suspensions.Anyone who has driven a Corvette hard into a corner has probably experienced understeer. The car "plows" or "pushes" through the corner. Regardless of the term used to describe the condition, the front tires must be pointed more into the turn to keep the car on its line (see diagram A). Oversteer is the opposite effect: the front tires are pointed outward, and the car is said to be "loose" or "hanging out" (as in diagram B). Neutral steer is the middle ground between oversteer and understeer. Both the front and rear tires are running at the same angle to the road. A Corvette set up for neutral steer will be faster in steady state cornering than one which over- or understeers because all four tires are sharing the cornering loads equally. By using the recommended stabilizer bars, your Corvette will become very close to the desired neutral steering attitude.
Factors such as the number of people in the car, road conditions, vehicle speed, and other variables can influence the handling characteristics of your car. Driving technique can compensate for these small changes if the car is close to the neutral state. In some special circumstances a slight degree of oversteer is beneficial. Certain autocross courses, for example, favor a car which oversteers somewhat. In general, though, you will probably be most comfortable in street driving conditions with a car set up to corner with a very slight amount of understeer.
It is necessary to control body roll on cars with independent suspensions because there is little anti-roll effect built in. Stabilizer bars control body roll by requiring the bar to be twisted if the body is to roll. Since larger diameter bars are harder to twist, they are more effective in limiting body roll. Stabilizer bars are used to control body roll because they have little effect on the up and down motions of the suspension. Stiffer springs can also be used to control body roll, but they also decrease the suspension's ability to absorb bumps so the ride quality is poorer.
Some of the reasons it is necessary to control body roll in cornering are for driver and passenger comfort, to limit the effects of roll steer, and to limit the loss of cornering power due to camber change. If a car rolls at too great an angle driving around a corner, like a Renault, the passengers feel like the car will tip over. Since the Corvette suspension has a considerable amount of roll-steer built in, this unwanted steering effect is reduced if body roll is reduced (roll steer is that part of the suspension geometry that causes the wheels to steer toward understeer as the body rolls.) GM always builds this into their cars on the premise that it makes them safe in spite of the driver's abilities. Performance minded drivers don't need much protection for themselves, so they don't need much roll steer.
The camber effects of body roll are caused by the fact that, as the body rolls, the tires roll with it. This causes the camber to increase on the outside tires, which reduces their cornering power, if body roll is minimized, the outside tires can remain perpendicular to the ground and deliver maximum cornering traction. The best way to limit body roll is to install bigger (and therefore stiffer] stabilizer bars. It is also an advantage to connect the stabilizer bars to the control arms with steel joints lo eliminate lost motion.
If a car, such as a Corvette, is equipped with both a front stabilizer bar and a rear stabilizer bar it is possible to control the amount of understeer and oversteer. When a larger rear stabilizer bar is used, the car will move toward the oversteer side of handling. If a large enough rear bar is used, the car will oversteer."
[Online]
I also used bearing blocks on the front and bushings , but good fitting bushings on the rear and 8 rod ends in total for the 2 bars.
After installing the bar I took the car for a short ride to settle the suspension and then adjust the linkage so there was no preload on the sway bar. I found the bar in this short run extremely stiff. The car felt like it had really stiff springs.
Last night I took it for it's first real run. Carguy4sure and I went 50 miles across country to a show. 25 each way.
As I started cruising at 60 I found the bar seems to smooth out, the ride was not harsh like slow speed in town. I even put the outside wheel close to the rought edge of the road to make that side work and it felt really smooth.
I entered a few corners at about twice the recommended speed and found myself accelerating as the corner became more comfortable and would come out of the corner 15 or 20 mph faster then when I went in. I also lost my buddy Doug.
I also found not once did the car ever feel twitchy. My car is not bad but occasionally you feel that twitch. It seems to be gone. Maybe our twitch is comming from the rearend??
I feel it was a big improvement over last week without the bar. It was worth the roughtly $350 I put into the project.
The reason I went with the huge rear sway bar is because of an article I read from Herb Adams and talking to twin Turbo. 2 very knowledgabel guys.
This was taken this morning from Corvette action, posted by Kid Vette but it is taken from Herb Adams, This is what convinced me a few weeks ago.
Agian I took this from KID Vette/Corvette action/Herb Adams
Here's Herb Adams direct quote, "One reason we recommend larger, more effective stabilizer bars for Corvettes is the bars' ability to control a car's understeer characteristics. Standard Corvettes are produced at the factory with a great deal of understeer built into their suspensions.Anyone who has driven a Corvette hard into a corner has probably experienced understeer. The car "plows" or "pushes" through the corner. Regardless of the term used to describe the condition, the front tires must be pointed more into the turn to keep the car on its line (see diagram A). Oversteer is the opposite effect: the front tires are pointed outward, and the car is said to be "loose" or "hanging out" (as in diagram B). Neutral steer is the middle ground between oversteer and understeer. Both the front and rear tires are running at the same angle to the road. A Corvette set up for neutral steer will be faster in steady state cornering than one which over- or understeers because all four tires are sharing the cornering loads equally. By using the recommended stabilizer bars, your Corvette will become very close to the desired neutral steering attitude.
Factors such as the number of people in the car, road conditions, vehicle speed, and other variables can influence the handling characteristics of your car. Driving technique can compensate for these small changes if the car is close to the neutral state. In some special circumstances a slight degree of oversteer is beneficial. Certain autocross courses, for example, favor a car which oversteers somewhat. In general, though, you will probably be most comfortable in street driving conditions with a car set up to corner with a very slight amount of understeer.
It is necessary to control body roll on cars with independent suspensions because there is little anti-roll effect built in. Stabilizer bars control body roll by requiring the bar to be twisted if the body is to roll. Since larger diameter bars are harder to twist, they are more effective in limiting body roll. Stabilizer bars are used to control body roll because they have little effect on the up and down motions of the suspension. Stiffer springs can also be used to control body roll, but they also decrease the suspension's ability to absorb bumps so the ride quality is poorer.
Some of the reasons it is necessary to control body roll in cornering are for driver and passenger comfort, to limit the effects of roll steer, and to limit the loss of cornering power due to camber change. If a car rolls at too great an angle driving around a corner, like a Renault, the passengers feel like the car will tip over. Since the Corvette suspension has a considerable amount of roll-steer built in, this unwanted steering effect is reduced if body roll is reduced (roll steer is that part of the suspension geometry that causes the wheels to steer toward understeer as the body rolls.) GM always builds this into their cars on the premise that it makes them safe in spite of the driver's abilities. Performance minded drivers don't need much protection for themselves, so they don't need much roll steer.
The camber effects of body roll are caused by the fact that, as the body rolls, the tires roll with it. This causes the camber to increase on the outside tires, which reduces their cornering power, if body roll is minimized, the outside tires can remain perpendicular to the ground and deliver maximum cornering traction. The best way to limit body roll is to install bigger (and therefore stiffer] stabilizer bars. It is also an advantage to connect the stabilizer bars to the control arms with steel joints lo eliminate lost motion.
If a car, such as a Corvette, is equipped with both a front stabilizer bar and a rear stabilizer bar it is possible to control the amount of understeer and oversteer. When a larger rear stabilizer bar is used, the car will move toward the oversteer side of handling. If a large enough rear bar is used, the car will oversteer."
[Online]
09-07-2005, 09:02 AM
#3
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St. Jude Donor '09
Yes! Herb Adams is the man!! 
The designer of the WS6 suspension for the TransAm, and GMs foremost authority on making good systems better!
It is interesting to note that although the Camaro and Firebird lines were so similar, their suspensions were from 2 different schools of thought:
Firebird (from Adams) with lighter springs for a nice ride, and large sway bars for body control; and Camaro with heavy springs to control the body motion and a lighter sway bar for "fine tuning" I suppose, which makes for a harsher ride. At least until the 4th gen in which case there was no real difference at all.
Thanks for the write up Norval!! Putting this into my basket of goodies for when I start tweaking on my own setup!
The designer of the WS6 suspension for the TransAm, and GMs foremost authority on making good systems better!
It is interesting to note that although the Camaro and Firebird lines were so similar, their suspensions were from 2 different schools of thought:
Firebird (from Adams) with lighter springs for a nice ride, and large sway bars for body control; and Camaro with heavy springs to control the body motion and a lighter sway bar for "fine tuning" I suppose, which makes for a harsher ride. At least until the 4th gen in which case there was no real difference at all.
Thanks for the write up Norval!! Putting this into my basket of goodies for when I start tweaking on my own setup!
09-07-2005, 09:26 AM
#4
Melting Slicks
I've always been in the soft springs and tight anti-roll bars camp. Glad to hear it is working for you, especially since everything else about your car is in such good order. With a cage stiffening the frame I would've thought it would have been tighter than otherwise.
-Chris
-Chris
09-07-2005, 10:12 AM
#7
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St. Jude Donor '05-'06
So if I have the stock wimpy 3/4 bar on the front and added a 3/4 bar to the back would it have the same effect (reduced because of size of cause) of neautralizing the steering?
09-07-2005, 10:28 AM
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Originally Posted by BerniesVette
Norval,
I bet you will be looking for that Saleen, now that you have your suspension cornering the way you want it to.
Bernie
I bet you will be looking for that Saleen, now that you have your suspension cornering the way you want it to.
Bernie
A front brace is still on my list of things to do but with the blower belt it is tough. I do want to work something.
The corners were posted at 35 mph and I was close to 70, as I progressed into the corner it felt right so I picked it up to 85 or so comming out and it still felt great but I was cautious.
Another problem i am running into is fuel slosh. I am taking the right angle corners really hard and flooding the engine slightly with the hard cornering. The motor hesitates for a beat and then carries on normally.
09-07-2005, 10:30 AM
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Originally Posted by stingry
So if I have the stock wimpy 3/4 bar on the front and added a 3/4 bar to the back would it have the same effect (reduced because of size of cause) of neautralizing the steering?
Also a tube is better in torsion then a solid . There is a neutral axis down the center of a solid that is nothing but weight.
Speedway bar sold by Coleman are under $100 american or about $135 CDN
09-07-2005, 10:40 AM
#10
Norval, actually no, you can't compare your car and his. He has a transverse leaf which offers some roll control, you have none so adding the same bar makes his car oversteer a lot more.
Last edited by Twin_Turbo; 09-07-2005 at 10:46 AM.
09-07-2005, 10:43 AM
#11
Le Mans Master
Just FYI...when I used to auto-cross, I tried a 3/4 in. bar on the rear on my 68 (profile pic). I had 1- 1/8 bar in front. I had excessive over-steer, both with hoosier auto-cross tires and 12 inch road-race slicks. I backed way off the adjusters on the back bar, and got it where I wanted it. It may have reacted with the 7 leaf spring in a cumulitive way... 
09-07-2005, 10:46 AM
#12
Team Owner
#1. I don't feel safe driving any of the older vettes like our c-3's unless they have suspension mods.
#2. I have been driving around with VB&P street/slalom all poly kit with some substitutions and the 3/4 rear sway for @ 17 years. so I do not know how it would drive without it. Every time that I intended to remove it and do back to back testing something else comes up and it doesn't get done.
#3. I consider my car to have very neutral steering. I have to apply lots of power to get the rear to come around. On the hit of the gas - like in a freeway on ramp - the rear will try to come around - back off and it snaps right back behind me. It's never gone on around since I went to good wide "AA" traction Z-rated tires
#4. I wonder how your rear bar really compares to my spaced down 3/4 sway which virtually eliminates the angular binding caused by the poor product sold by Vette Brakes and probably most of the other resellers.
#5. When are you coming out West and we'll spend some hours out at the road racing track playing cat and mouse.
#2. I have been driving around with VB&P street/slalom all poly kit with some substitutions and the 3/4 rear sway for @ 17 years. so I do not know how it would drive without it. Every time that I intended to remove it and do back to back testing something else comes up and it doesn't get done.
#3. I consider my car to have very neutral steering. I have to apply lots of power to get the rear to come around. On the hit of the gas - like in a freeway on ramp - the rear will try to come around - back off and it snaps right back behind me. It's never gone on around since I went to good wide "AA" traction Z-rated tires
#4. I wonder how your rear bar really compares to my spaced down 3/4 sway which virtually eliminates the angular binding caused by the poor product sold by Vette Brakes and probably most of the other resellers.
#5. When are you coming out West and we'll spend some hours out at the road racing track playing cat and mouse.
09-07-2005, 11:28 AM
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Originally Posted by Twin_Turbo
Norval, actually no, you can't compare your car and his. He has a transverse leaf which offers some roll control, you have none so adding the same bar makes his car oversteer a lot more.
Actually VBP doesn't recommend a rear roll bar with their suspensions.
Brian and I only have one more week to compare our cornering before his car goes away for the winter.
Brian is Vettr a new guy on the forum with the hot 73 383 stroker and a complete VBP suspension. Sure is a fun car to chase around after
09-07-2005, 11:30 AM
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Originally Posted by big_G
Just FYI...when I used to auto-cross, I tried a 3/4 in. bar on the rear on my 68 (profile pic). I had 1- 1/8 bar in front. I had excessive over-steer, both with hoosier auto-cross tires and 12 inch road-race slicks. I backed way off the adjusters on the back bar, and got it where I wanted it. It may have reacted with the 7 leaf spring in a cumulitive way...
I am running coilovers so my rear suspension is really totally independent. Again a parking lot will tell is I suffer from oversteer or not.
09-07-2005, 11:36 AM
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Originally Posted by gkull
#1. I don't feel safe driving any of the older vettes like our c-3's unless they have suspension mods.
#4. I wonder how your rear bar really compares to my spaced down 3/4 sway which virtually eliminates the angular binding caused by the poor product sold by Vette Brakes and probably most of the other resellers.
#5. When are you coming out West and we'll spend some hours out at the road racing track playing cat and mouse.
#4. I wonder how your rear bar really compares to my spaced down 3/4 sway which virtually eliminates the angular binding caused by the poor product sold by Vette Brakes and probably most of the other resellers.
#5. When are you coming out West and we'll spend some hours out at the road racing track playing cat and mouse.
I agree with the 1st statement. Compared to stock I am way ahead. Doug/Carguy4sure could atest to this. He follows me into the corners.
My bar is completely bind free. Set the car on jack stands, remove the tires and coilover springs and shocks and I set up each end by undoing the other and moving the suspension from full droop to fully bottomed without any binding. I then disconnected that link, moved to the other side, connected that link and once again tested for freedom of movement.
That is the big advantage of coilovers. 3 or 4 minutes and the spring and shock are out for testing and I do test regularly for suspenison problems. I visually inspect almost weekly. Since most is hand built I am watching for problems. Hate to discover one at 100 plus.
Cat and mouse George?? I like playing that with Brain. You would hand me my butt.
09-07-2005, 11:45 AM
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This is my mouse . Brain/Vettr
He is alot of fun chasing aroung the country and keeps me working at catching him.
'It is one mean sounding 73 383 stroker motor, 390 gears, 5 speed Tremec and a great suspension.
I have enjoyed running with him and Doug this summer.
He also has 17 inch rubber all around.
Missed chasing him last night. I think the new sway bar might just do the trick.
He is alot of fun chasing aroung the country and keeps me working at catching him.
'It is one mean sounding 73 383 stroker motor, 390 gears, 5 speed Tremec and a great suspension.
I have enjoyed running with him and Doug this summer.
He also has 17 inch rubber all around.
Missed chasing him last night. I think the new sway bar might just do the trick.
09-07-2005, 12:59 PM
#17
Originally Posted by norvalwilhelm
Actually VBP doesn't recommend a rear roll bar with their suspensions.
Brian and I only have one more week to compare our cornering before his car goes away for the winter.
Brian is Vettr a new guy on the forum with the hot 73 383 stroker and a complete VBP suspension. Sure is a fun car to chase around after
Brian and I only have one more week to compare our cornering before his car goes away for the winter.
Brian is Vettr a new guy on the forum with the hot 73 383 stroker and a complete VBP suspension. Sure is a fun car to chase around after
09-07-2005, 01:07 PM
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Marck all I really know is it worked out great for me. The stability even when passing was greatly improved. Makes me wonder if part of the twitchyness in our cars might be comming from the rearend.
I make a change, drive the car, make the next change. It really helps to see if you are moving in the right direction.
I have you to thank for pushing me into the coilovers. Cost me alot of money and alot of effort but the adjustability and easy removal is well worth it.
Not to mention the handling. I really feel the effect of the rear bar is very noticable now and it might be because of the coilovers and the effect the bar had on them.
I make a change, drive the car, make the next change. It really helps to see if you are moving in the right direction.
I have you to thank for pushing me into the coilovers. Cost me alot of money and alot of effort but the adjustability and easy removal is well worth it.
Not to mention the handling. I really feel the effect of the rear bar is very noticable now and it might be because of the coilovers and the effect the bar had on them.
09-07-2005, 01:19 PM
#20
Yes, it worked great for you..but for someone w/ a transverse leaf 3/4 is kind of big because of the added involvement of the spring 
So, it's working for you..then it should work for me, I may get the same bar..or a tad smaller a I have much stiffer springs & shocks. Those coil overs are neat ... and the more you tinker the more the virtue of them is exposed. it's not for nothing that the true racers run coil overs.
So, it's working for you..then it should work for me, I may get the same bar..or a tad smaller a I have much stiffer springs & shocks. Those coil overs are neat ... and the more you tinker the more the virtue of them is exposed. it's not for nothing that the true racers run coil overs.