[AdamCali65]

Hey all,

I am contemplating a 3/4" rear sway bar. I have on the '65 subframe connectors, a 1 inch front sway bar, gas a just shocks all around, 1 inch 620# lowering springs up front and 1 inch lowering leafs in the back, etc. I am hoping for your opinions on running a rear sway bar on a car that is driven only on weekends (not a daily driver at all), I dont care much about stiffness just fun, sometimes I take the car to the canyons, and I am looking for more performance and stability in the rear end. What do you all think?

I have heard that a rear bar can induce oversteer but if the front and rear are matched (like 1 inch up front 3/4" in the back) it works out nicely.

Thanks,
Adam

 

[rex1965]

Unfortunately, you need to be the judge whether you need a rear sway bar. If you have too much body roll, or the front end always wants to slide out on the curves or corners, then you could add a rear sway bar. There are many factors to take into account when setting up the suspension, whether its for racing or just having fun, the rule of the thumb is the stiffest axle will be the one to slide out first, what this means if the rear becomes the stiffest axle then it will slide out first in the corners. Like I said there are many factors, like center of gravity, spring stiffness, geometry of the steering and front end components, stiffness of the sway bars. One thing you don't want is too much body roll where the suspension bottoms out, this is a bad condition, but you want the softest suspension where it doesn't bottom out. I hope you are understanding what I am saying. I'm not an expert, but I have raced at speed in my 67 mustang conv. My 2004 Mustang convertible acts like it is glued to the road and to my surprise it doesn't have a rear sway bar, only a big one up front. It's all about getting it set up right for your vehicle. n My 2 cts. Good Luck.

 

[AdamCali65]

I completely understand and I think the rear bar will work well in my setup and I need some more stiffness to counteract body roll and add some stability. I wanted to see what you guys thought and thanks for the response.

 

[kenash]

Yu probably know this, but, be aware when you increase the rear bar dis, you increase your oversteer potential. I run a 1" from bar and a 5/8" rear with progressive rate springs and 4.5 leaf rears. My car is well balanced.
Good luck...

 

[AdamCali65]

Awesome! Good to know and thanks for the response.

 

[Ivy66GT]

Both the comments above are different sides of the same issue. If the front is the softest, more roll, then a stiffer rear will simply lift the inside rear wheel and make for instant oversteer. I spun my '77 BMW for that very reason after which I removed the factory rear roll bar and left if on the shelf until the week before I sold the car 20 years later. It looked like a good idea but it didn't do much to improve handling and made high speed handling worse.

 

[paul289]

The vast majority of leaf spring cars do not need rear sway bars. What sway bars actually do is increase weight transfer by lifting the inside wheel, which is exactly what you don't want in a rear-wheel drive car. Only when the body roll is excessive, should you install one. If you have bad understeer, and you install a sway bar, you just lower the rear end's handling ability to match the front. You're probably best off performing a Shelby drop with improved caster. That will help raise the front end's handling ability to match the rear.

Still, if you do want a rear sway bar, I'd stay away from the one that mounts the bar on top of the axle. It seriously compromises exhaust clearance, and I've had my exhaust torn out by it on a couple occasions. Get the adjustable Shelby style one that mounts the bar to the chassis, then you can fine-tune it to your car. Or there's this TCP sway bar that mounts under the axle so it won't interfere with the exhaust.

 

[AdamCali65]

Ivy66gt,

My front end is the stiffest (1 inch sway bar, 620# 1 inch lowering sprigs, KYB Gas a just, poly bushings, refurbished everything, etc) but my rear end feels loose and rolls more than the front does. So I was looking at a sway bar primarily to help with overall stability of the rear end and to aid with handling. Now, my rear end is not worn out or anything, the leafs are in great shape, just changed out the bushings for the leafs for polys, the car has subframe connectors and KYB gas a just in the rear as well, and the rear has been lowered 1 inch. I dont drive the car in autocross or drag racing but I do like to have some fun with it and it sees some canyons by the beach. I am just trying to get the record straight on rear bars unless there really isn't a definite answer lol.

 

[AdamCali65]

paul289,

I think in my case, the front handles much much better than the rear. The front end has had the most work done to it, and I am looking into a rear sway bar due to the fact that I feel the rear rolling more than the front. Also, the rear end feels loose (old car, I know) and was hoping that a rear bar would help with stability. I have basically read that installing a 1 inch sway bar with a 5/8-3/4" rear bar will balance the car out, any word on this? I have also heard that an overly large rear bar, or an upgraded rear bar with a stock front bar will induce snap oversteer. I dont autocross the car I am just looking for a way to stabilize the rear end just a little more without going to a Watts link or panhard bar.

Also, if I do this rear sway bar, I was looking into the Addco one: http://www.cjponyparts.com/addco-sway-bar-rear-three-quarter-inch-kit-1965-1966/p/RSB1/. I have seen the other ones that go straight up and straight across the axle, this one seems to mount to the frame rails and is fitted to the shape of the rear axle with plenty of clearance for my dual exhausts. Is this the one you are referring to? Thanks.

 

[paul289]

Depending on your driving abilities, some looseness is actually faster. I had a similar combo for quite a while, with the 620 springs, 1-1/8" front sway bar, and a Shelby drop. My 3/4" bar helped bring the handling more towards neutral from understeer, but it still felt a bit sloppy. As a rule of thumb, adding rear bar increases oversteer. There's really no way around it. If you're oversteering already, then a rear bar will only make it worse.

I might suggest looking at your wheels and tires if you want to improve responsiveness and handling. In your case, 16" or 17" wheels with 215 width tires in the front on 7" wide wheels and 245 width tires in the rear on 8" wheels would help improve response and rear end grip dramatically. Otherwise, there aren't many good ways to improve a leaf spring suspension. The KYBs are probably alright for occasional spirited driving, but I'd personally recommend Konis, especially adjustable ones, for driving near the limit. Bilstein is also a good budget option, but they're not really adjustable. I found that the KYBs don't damp nearly enough for any serious performance driving. Right now I have KYB Gas-A-Justs in the front and Koni Yellows in the rear, and the front end wallows over bumps while the rear stays controlled. Many racers will tell you that next to tires, shocks are the most important part of a performance suspension system.

That Addco bar is what I had, and it does mount to the axle. Perhaps my exhaust was bent poorly, but the removal of 1 1/2" of clearance above the axle caused it to impact the exhaust on some larger bumps, which pulled the hangers free.

 

[AdamCali65]

paul289,

In terms of tires, the car has 15x7 inch wheels with 225 width up front and 235 width in the back. I could probably go bigger in terms of rim size and that will help with grip.

At the moment the car doesn't oversteer much in fact it handles pretty well but the rear end needs something, it just feels loose...and I was assuming its a rear sway bar. I guess in the end what I will do, is take all your guy's advice and keep it in mind but I will try the rear sway bar and then see if it is what I want. I might like the way it drives I might hate it. Either way I think I just have to try for myself and I appreciate all the responses. Thanks again.

 

[paul289]

If you do decide to do the sway bar, just approach the limits gently. The limits may be lower with the bar, so just be wary. If you can find an adjustable bar, or a 5/8" bar, use that instead of the 3/4" Addco. I do think that a rear bar does improve responsiveness in the rear, so if that's what you're going for, it should do the job, but leaf springs have their limits for responsiveness.

 

[AdamCali65]

Paul,

I understand, and I think I am more in the mind set of expecting responsiveness and overall help to stability (looseness and such) than fixing major steering problems (because there really isnt one other than it is an old car, although it has been improved a lot). Thanks again.