Rear Sway Bar?

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wheelsport

wheelsport

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I installed an after market sway bar on the front of my '65 Barracuda but the rear end feels like it will come loose on hard higher speed turns. I told the club's Barracuda expert that I am thinking of installing a rear sway bar. His comment was installing extra rear spring leaves would work better than a sway bar. Is he correct?
 
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My opinion is that driving style can be a factor in this. I personally like a firm but not hard feeling spring coupled with big front sway and smallish rear sway. BUT I also do not unload the suspension once turn is initiated and rely on soft compound tires with sidewall to take up some slack. This setup can be prone to rebound, but like I said driving style can have a factor.

I do not drive on road course track to be transparent. street Hoonigan.
 
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wheelsport said:
I installed an after market sway bar on the front of my '65 Barracuda but the rear end feels like it will come loose on hard higher speed turns. I told the club's Barracuda expert that I am thinking of installing a rear sway bar. His comment was installing extra rear spring leaves would work better than a sway bar. Is he correct?
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if the rear end feels like it’s going to come loose, that is an over-steer condition.

DO NOT stiffen the rear roll resistance (rear spring or rear sway bar). Add more front roll resistance (thicker sway and/or T-bar)

the video below is what happens with too much rear resistance at high speed cornering. My rear sway bar has been disconnected ever since. Might be ok for lower speed handing. But not 70+ mph curves. Especially a dog-leg with a bump accelerating into straightaway.

Every car combination can be different. Make adjustments to what you feel.

fast forward to minute 1:39 then play

 
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Dana67Dart said:
At least you kept it flat!
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wheels down is always a good thing. :steering:

had to get tire partially dismounted off bead to get the dirt and brush stuck between the bead and tire out (2 o’clock position in picture below)… Would have be a hellacious vibration

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Was a clean brand new motor…

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Pretty much any new vehicle has both front and rear stabilizer bars. What people overlook is even if its still a unibody is has stiffening rails front to rear. That's so the 2 stabilizer bars dont twist the unibody chassis so bad that the dang doors dont close. Look at Mustang, even a RAV4. A rear bar isn't as stong as front bar. It's just a little something more when needed. For our old a-bodies... wedont have radial tuned suspension, coil springs, struts, etc... Most of them didn't even have a front stabilizer bar. Some did get a front bar but it wasn't all that. Aftermarket offers front bars that are much more than OEM. Some police cars (later model diplomats and others) got rear bars but again its a smaller/weaker bar. Those still didn't handle like todays vehicles.
Bottom line, if you'll add a rear bar, add subframe connectors.
 
I agree with autoxcuda what you're describing sounds more like you still need to stiffen the front end more, not the rear. But that's just based on your description.

Whether or not you'll need a rear bar depends entirely on the rest of your suspension set up. What torsion bars are you running up front? Which aftermarket sway bar did you install up front? What springs do you have in the back? And what tires are you running?

Typically, because these cars are usually heavy in the front and light in the rear they need a lot more spring rate up front. The factory set up was very undersprung in the front and only slightly undersprung in the back, which is why on a lot of A-bodies people have issues with oversteer if they mount a rear sway bar. But it depends entirely on how your car is set up, my Duster makes pretty good use of a rear sway bar but I have a much higher spring rate in the front than I do in the back, and run wider tires in the back than I do in the front as well.
 
autoxcuda said:
if the rear end feels like it’s going to come loose, that is an over-steer condition.

DO NOT stiffen the rear roll resistance (rear spring or rear sway bar). Add more front roll resistance (thicker sway and/or T-bar)

the video below is what happens with too much rear resistance at high speed cornering. My rear sway bar has been disconnected ever since. Might be ok for lower speed handing. But not 70+ mph curves. Especially a dog-leg with a bump accelerating into straightaway.

Every car combination can be different. Make adjustments to what you feel.

fast forward to minute 1:39 then play

Click to expand...

My sway bar is .125 diameter, which is much heavier than a stock way bar. Unfortunately, I still have the 13" mini wheels with 185/70 radials all around. The suspension is original in good condition with some replaced parts. Doing the higher speed turns the rear end still has grip but makes me wonder if it will swing out if pushed a little harder.
 
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All I can tell you i I love rear sway bars. I had a 70 T/A challenger with both bars (factory) and it handled like it was on rails. Best handling old mopar I've ever owned.
 
66fs said:
Two different animals.
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Yes I know but I've had this experience with a lot of different vehicles. I also owed a 68 formula s car and it handled very well with all the stock parts. A lot of different things come into play with this. I was only making a remark.
 
wheelsport said:
My sway bar is .125 diameter, which is much heavier than a stock way bar.
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I assume you mean 1.125"?

It still matters what your torsion bar diameter is, and the spring rate of your rear springs.

Also, as for adding a leaf vs adding a rear bar, both will ultimately increase your roll stiffness. The biggest difference is that the sway bar will pretty much only increase the roll stiffness, whereas adding another leaf will increase the overall stiffness of the suspension. As I said earlier, the leaf spring stiffness in the back from the factory wasn't that far off even if you've upgraded to larger radial tires. Most mopars set up for handling are only going up to 120 to 130 lb/in springs in the back, factory XHD's were already 110 lb/in. Meanwhile, most of the torsion bar spring rates are being increased to 250-300 lb/in for the more serious handling cars.

LO23M8B said:
All I can tell you i I love rear sway bars. I had a 70 T/A challenger with both bars (factory) and it handled like it was on rails. Best handling old mopar I've ever owned.
Click to expand...

Just depends on the suspension set up.

66fs said:
Two different animals.
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Not as different as you'd like to believe. Front to rear weight bias isn't that different, same basic chassis construction, etc.

The higher front wheel rate is probably the biggest effective difference, which is what makes the addition of a rear bar a good idea. All in all, it comes down more to how the suspension is set up than A vs. E body.
 
LO23M8B said:
Yes I know but I've had this experience with a lot of different vehicles. I also owed a 68 formula s car and it handled very well with all the stock parts. A lot of different things come into play with this. I was only making a remark.
Click to expand...

There low speed street type handling (like autocross) and higher speed track stuff.

In the lower speed stuff getting the car to turn (under steer) can be more advantageous and easier to manage.
 
wheelsport said:
My sway bar is .125 diameter, which is much heavier than a stock way bar. Unfortunately, I still have the 13" mini wheels with 185/70 radials all around. The suspension is original in good condition with some replaced parts. Doing the higher speed turns the rear end still has grip but makes me wonder if it will swing out if pushed a little harder.
Click to expand...

so you have not actually experienced the rear end skidding or sliding out ?

this is just a worry at this point?

sounds like and original /6 torsion bars and rear leaf springs. With 13” rims, it probably has small 9” drums front and rear. Does it still have a /6 motor?

With those 185/70/13 tires at 50-60mph curves like you see in my video, you’ve got grip and sidewall roll over issues. You need to address that to some degree first.

On curves or freeway on-ramp with post MPH signs are you exceeding 10-20 mph over posted?
 
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I think for low speed street driving, rear bars can be great. Everything has its place. Much like when you take a car to the drag strip. Most people disconnect the front sway bar is so equipped.
 
autoxcuda said:
so you have not actually experienced the rear end skidding or sliding out ?

this is just a worry at this point?

sounds like and original /6 torsion bars and rear leaf springs. With 13” rims, it probably has small 9” drums front and rear. Does it still have a /6 motor?

With those 185/70/13 tires at 50-60mph curves like you see in my video, you’ve got grip and sidewall roll over issues. You need to address that to some degree first.

On curves or freeway on-ramp with post MPH signs are you exceeding 10-20 mph over posted?
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Its the original V/8 with 100,300 on original engine and automatic that have never been out. And yes about 10 over.
 
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