QUOTE(Brian Fuerbach @ Sep 26 2022, 09:36 PM) 
Just going to drive it for awhile before making any changes.
Great job - came a long way since your original thread and you now know how to refine it if you choose.
Full Version: Rear sway bars - Good or Bad ?
Just going to drive it for awhile before making any changes.
Great job - came a long way since your original thread and you now know how to refine it if you choose.
Funny, but I do not see any discussion around engine conversions. When you add rear weight, SBC, big aluminum six, 915 gear box, big CV's, you have to increase the rear spring rate, which effects the whole car. When I upgraded to a 2.7 six and 3.2 six with stock gear box, I had to upgrade the rear springs to 140 lb or the stock spring bottomed out. Of course I went bigger torsion bars up front to compensate. When I replaced the 914 gear box, with a 915 gear box with 108mm CV's, I once again bottomed out the 140 lb springs. I now run 200 lb rear springs, with no rear sway bar. I will probably put it back on for comparison. Note, a rear sway bar does nothing except in the corners and will add oversteer, hence the name sway bar. So you can run less spring rate with a rear sway bar and the car will ride nicer and not come into play, except in corners.
QUOTE(Steve @ Sep 27 2022, 11:59 AM)
Funny, but I do not see any discussion around engine conversions. When you add rear weight, SBC, big aluminum six, 915 gear box, big CV's, you have to increase the rear spring rate, which effects the whole car. When I upgraded to a 2.7 six and 3.2 six with stock gear box, I had to upgrade the rear springs to 140 lb or the stock spring bottomed out. Of course I went bigger torsion bars up front to compensate. When I replaced the 914 gear box, with a 915 gear box with 108mm CV's, I once again bottomed out the 140 lb springs. I now run 200 lb rear springs, with no rear sway bar. I will probably put it back on for comparison. Note, a rear sway bar does nothing except in the corners and will add oversteer, hence the name sway bar. So you can run less spring rate with a rear sway bar and the car will ride nicer and not come into play, except in corners.
When I went to the 4.0L six and the Cayman gearbox, I added about 400Lbs to the rear of the car. I have 140LB rear springs and a stock rear sway bar. The ride is fine, but the extra weight induced bad understeer. I took out the aftermarket torsion bars on the front, but the understeer was still there. So I bought a new, heavier adjustable rear bar that should help get the car back to neutral handling. The bar that comes off the car will go on Betty's stock 4 cylinder to replace the damaged one.
I have read "How to make your car handle" over and and over. The parts cannot be changed without considering how it affects the suspension as a whole.
Clay & Steve significant modifications like each of you has undertaken just make the underlying tuning principles even more important to get back to the ride and handling you want.
140# rear springs i
19mm front sway bar
just added the 19mm torsion bars.
Can't find enough twisty roads!
19mm front sway bar
just added the 19mm torsion bars.
Can't find enough twisty roads!
Years ago I had a stock '74 2.0 with 16mm front and rear bars. I found it to oversteer. I tried an aftermarket 19mm bar and found it better but a bit understeery. This was with stock rear springs, I'd guess some mildly stiffer springs like 100 lb/in would've fixed that.
On the racecar with much stiffer suspension I ran a 22mm front bar and a 16mm rear bar and was happy with that. When I went even stiffer, like 500 lb/in front springs and 350 rears, I had to eliminate the rear bar to get the balance I wanted. I understand this is typical for very stiffly sprung cars.
On the racecar with much stiffer suspension I ran a 22mm front bar and a 16mm rear bar and was happy with that. When I went even stiffer, like 500 lb/in front springs and 350 rears, I had to eliminate the rear bar to get the balance I wanted. I understand this is typical for very stiffly sprung cars.
QUOTE(Brian Fuerbach @ Sep 26 2022, 06:36 PM)
Last night was the first drive with the stock rear bar installed.
Drove my usual fun run out Santiago Canyon road to Cook’s Corner and back to Orange. Big 70+mph sweepers. First thing I noticed is the steering was lighter around the corners and one hand was all that was needed to feel
comfortable at speed. The car feels a lot more lively but more controllable at the same time as the rear seems to follow the front track more closely. All I can say to myself is “why did you wait so long?”
Very tight corners like intersections are also better but the first hard one scared me a bit as I turned in like I had before, muscle it in and push through. That doesn’t work any longer or should I say is no longer required. Turn in is much improved. My front bar is an adjustable 19mm gpr/tarett set to full soft. Now if things prove to lively for me in the future I can stiffen up the the front to induce some push. Just going to drive it for awhile before making any changes. I cant comment on the stock front and rear bar combo but the 19 front on full soft and 16 rear feels right as I dont think I would want the rear any more lively.
Great news. Happy it worked out so well. Todd
Now put some Hoosier A7's on and start at double the spring rate!
Having owned only a few of these funtastic cars (8 I think?) over the last 50 years, only my first was bought new in 1973, when the time came the advice was "heavier springs and no rear bar, so that's what I did, put 140s in the rear, and the stock front bar up front." as has been stated a couple of times now. When I returned to my ace mechanic who did a lot of racing as did most everyone who worked there it seemed, he asked "why you doing that?" to which I said because you said that was best. Then he gave me the best advice he ever gave me and it was just this simple: "LEARN TO DRIVE THE CAR YOU HAVE!" and that is what I did after that. The average person could not tell you if a car had "anti-sway" or "stabilizer" bars in the rear or not with an otherwise properly tuned suspension.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.