1 5/16" Front Sway Bar

[Mike Van Veghten]

Wow......!

Ok do as you please... Pick up most any good suspension book...and learn the whys and wherefores of anti-roll bars. It's not really that difficult to see.
Big bar in front...no bar in the rear....the rear "will" at some point attempt to catch the front...maybe in the rain when it's no fun to try to correct..before hitting something?

Yes...a balanced suspension...when front and rear work complementary toward each other AND...the car as a whole!

I guess I must drive my cars a little harder than most. I know what an unbalanced suspension feels like.

And just because "it feels fine"...don't mean it's right! Maybe...just "maybe"....it could be much better with just a little work!

Funny...how the "details" get lost!

Mike

[ROADRACELARK]

The set-up on my car consist of dual front bars. This will require some explanation. Using a full length early lark V8 bar that attaches only to the lower control arms, and a late lark V8 bar that you will cut off end sections that would normally mount to the lower control arm. With them stacked on top of each other, weld together in the area just ahead of where the early bar mounds to the lower arm. Finally, be sure to weld on both sides with good penetration. You will still use the frame stand-off mount, but for added strength, you will need to "box" it in. Urethane bushings are also reccomended here. For springs I used 1964 Cadillac Fleetwood springs with 3 coils removed. Trial and error..cut, install and measure,etc,etc. The Caddy coils were correct in outside dismeter, the big differens is the "wire diameter" is much larger. Upper and lower control arms have Delrin(sp) bushings with the upper shaft flipped for maximum effect. In the rear, the stock V8 leaf springs have an extra middle leaf added for stiffness, NOT added height. I used a stock rear bar from a 57' President sedan, again, with urethane bushings. The shocks are Gabriel Adjust-o-Matics on Xtra-firm. Remember guys....you have most of your weight up front...that's where you need the heavy duty stuff. If you set up TOO stiff in the rear, you'll have a real bear to handle. Trial & error depending on the model your're puttin' together. I built this car in 81' and so far it's been a blast[}] hang it out when you want, it won't when you don't want. Also known as steering with your right foot. Hope this will be of some help.


Dan Miller
Atlanta, GA

[img=left]http://static.flickr.com/57/228744729_7aff5f0118_m.jpg[/img=left]
Road Racers turn left AND right.

[sals54]

Mike and Dan are absolutely right. As I said in my earlier post, the normal day to day driving with a front only 1-1/4" bar is fine. Its only when I get into the really agressive driving that the faults of the system are found. Again, though, my 54 is not stock in height or springs. The fronts are heavy duty springs with 1-1/2 coils cut to lower it. The frontend alignment has been adjusted to give about 1 degree toe in, and the camber is set as close to 0 as the fittings allow. The rear has 3" lowering blocks. The rear also has a narrowed 9" which allows me to use 8" rims with 265-50-15 tires out back. So, the package gives me a lower center of gravity which most of the cars here do not have, more bite in the rear as in a larger footprint on the ground from the rear tires, and the larger sway bar in the front. Delrin bushings in the front and rear keep things a bit tighter than stock as well. I think its safe to say that my car is almost alone it the way its set up compared to what most here are driving. I have found that the combination of wider tires in the rear with the large sway bar do help balance the car somewhat for day to day driving. I will concede that Dan's car would whoop the hell out of me in a slalom course. It would be fun to try to keep up, though.

[buddymander]

Hey Tom-- I measured from the front edge of my front crossmember to the center of the bar and it's 6". So figure your radiator would need to be 7" from the crossmember to clear this bar. If there's room, I'll send you a kit if you're willing to put it on soon and then if you're happy, I'd be glad to trade for a brake kit. Incidentally, I found the math formula on google to compare bar diameters. Say you have a 3/4" bar and you want to compare it to a 1 1/4" bar: Let's call the 3/4" bar 3/4ths and the 1 1/4" bar 5/4ths. 3 squared is 9. 5 squared is 25. the difference is 16. 9 divided by 16 = .5625. You would have a resistance increase of 56%. That would also increase the spring resistance of one front wheel at a time. Whereas both front wheels hitting the same bump at the same time, like a speed bump, would not employ the resistance of the bar.

[sbca96]

Buddy, the formula seems sound, but there are some factors that also
will effect the bar strength - like the length of the torsion area, and
also the lengths of the "arms" that transfer the torsional force. If
the arms are longer, they will have more leverage and less strength.
This is one reason the Impala SS guys will use a 2nd Camaro SS bar on
the front. The arms of the Camaro bar are about 1/4 to 1/2 inch less
in length - which tranlates to a flatter road race car. The bars are
the same diameter. I installed an extra Impala SS front bar on our '78
project car in place of the "tiny" (still larger than Avanti) factory
bar on the base model 2nd Gen Camaro. It will have less strength than
the SS bar would have ... but it was FREE.

I wont be burning up the track any time soon unfortunately, so if you
need instant results there are others that may be further along than I.

Tom

[leyrret]

Mike mentioned reading purpose of roll bars. One is equalizing traction front to rear. Any reference I've read says to increase traction
in front ,use smaller bar in front. We seem to be doing the opposite here. Why? I assume because of front geometry. If we can increase with a larger bar the front, to the point were the front traction is greater that rear, then we have past at some point equal front and rear, though without a rear bar it may include some body roll depending on rear suspension. If we get it equal front and rear with no rear bar and add a rear bar I would reason it would change it again. My point is there seems to be a lot to consider when try to figure effects of a bar on any particular car and it would seem it would vary in each situation. Another thing, How large is too large?

[buddymander]

My 53 studebaker truck has an 73 Olds cutlass front suspension. It came with a 1' bar. I didn't hesitate to replace it with a transam 1 1/4". I knew the difference it would make long before I discovered the mathematical formula telling me it was a 56% increase. I would have replaced it even if it had been a 1 1/8 inch bar, just for the 25% increase. Knowing the difference, there is no way I would waste my time with a smaller bar, even 1/8',NO MATTER WHAT THE PRICE. 70-81 Camaro firebird, 64-77 midsize gm can all take a 1 1/4" 70-81 Transam bar. Road racing conditions are different than street for two reasons. Racers tilt the top of the tire in to gain traction, but it eats front tires. Also, it's more common for a street driver to encounter situations where hard braking and swerving is necessary. The front of a car is the end that changes directions abruptly; the rear only follows. Lateral front movement defines the differences that require a large front bar. A rear bar only supports the anti-sway actions of the front bar, having nothing to do with traction, since the footprint of rear tires only changes by lateral momentum. Any weight transfered from the inside rear to the outside rear decreases the inside traction but at the same time increases outside traction, so what difference does it make? No mention has been made of the effect of heavy bars on changing the center of gravity. Weak bars allow the center of gravity to move outward in a turn but also allow it to move UPWARDS as well. Maybe they should be called "anti-rollover bars". But all the talk in the world is moot once you experience your own car's improvement. The added feeling of security and control of a car that you've been driving for decades is usually shocking. I've lost count of the number of cars that I've made handling and steering improvments over the last forty years, but every time I do, I can't imagine why everybody doesn't do what they can to improve their own machine. I'm changing my ebay ad to include avantis since I've recently learned that my bar kit does fit them.

[Mike Van Veghten]

Buddy -

quote:A rear bar only supports the anti-sway actions of the front bar, having nothing to do with traction, since the footprint of rear tires only changes by lateral momentum.

The above is not completely a correct statement...
The read bar WILL effect tire traction.
Fizics & geometry come heavilly into play here! Even the lowly Panhard rod (another topic!) effects traction. It "just" doesn't hold the rear end in the center of the chassis!

Too many wives tales or unknowns in this thread!

Mike

[59r2]

An interesting point, I was never happy with the way my larks handled turns ,so I just got a 1" front bar and the 3/4" back bar from dave tbo for my 59. I have been driving my new 08 chev van since sept one, which we all know is top heavy. I still have my 97chev van and the 08 has bars front and rear the 97 dosen"t. The dia of the front of the 08 is slightly smaller , seeing this is the state of the art for 08 van in handling ,I have to agree that two bars work better than one big one in front. Dave's bar are not on the lark yet but I will compare it to my 60 which only has a bar on front and report back if anybody would like to know? joe

1959 HARDTOP R2 clone
1960 conv
SDC member since 1972

[buddymander]

My hawk came with a skimpy 3/4" bar in fron. Not really a sway bar, more a stabilizer bar. My wife says a large bar in front is better than two small bars. I agree with her........ Experience is the best teacher, and with that comes a lot of trial and error. Anything else is assumption and simple math without all variables. I myself have tried everything I stated. Joseph, there is ONE thing I haven't tried...YET--I would like to see how your Lark handles with only the REAR bar installed. Now that would be an interesting experiment, don't you think? I'm looking forward to your test results.

[leyrret]

As I've said before I have 1" front & 3/4 rear and mine oversteers. So if I put a larger front bar on it what would be the effect? Will it
oversteer more or less. As soon as I have car running(changing ignition)I'm going to disconnect rear bar to see what it does.

[buddymander]

Finally--somebody willing to actually turn a wrench and do a lil experimentation, You go RRet. But I can guarantee you that my 1 5/16" bar http://cgi.ebay.com/ebaymotors/ws/eB...MESE:IT&ih=016 by itself will outperform any 1" bar--no matter what size bar you have in back. And I mean a money back guarantee.

[sbca96]

I am a little leery about welding anything onto the lower a-arm to put
the GM style end-links. I know that these lower arms will fatigue and
break at the lower outer steel bushing holes (saw one on a '63 Wagon
years ago). I would be afraid of the weld causing a temper change on
the stamping and maybe some stress points. Luckily this Wagon was in
a parking lot at the time, had the collapse happened 3 minutes before
then he (and family) would have been on the freeway!!

I would actually be less concerned about drilling extra holes in the
arm - than welding to it. I wonder if you could make a part that uses
the slot in the flange, and an extra bolt hole underneath? Holes are
not known to create stress points, as they dont have corners to crack.
A second hole near the factory one wont have any effect.

Tom

[leyrret]

Thats what I have in mind for mine. The pin area has a reenforcement built into it. I plan on fabricating attachment brackets using frame steel and tying to the reenforcement with bolts.
I did a little more research. It seems that the view that traction lost on inside wheel by body roll is gained on outside wheel is true only to a point. From what I've discovered traction lost on inside is not switched entirely to outside. Some is lost. As far as body roll two bars are better than one, but in terms of traction front to rear MAY not be necessary, depending on your particular situation. Bigger may not necessarily be better as can limit suspension travel on inside wheel and pull it off the ground.

[buddymander]

I know these are good points because I researched them all myself. As a matter of fact, my first kit was a bolt in one. But if you look at the picture, the center point of the aframe bracket is centered on the spring. The bolts would have to be placed on either side of the spring. A hole outboard of the spring would weaken the aframe in that area since the coil spring is supported by an added layer of steel, like the trunnion. My bracket matches up with the center of the spring; center of the steel reinforcement. The aframe is single strength on both sides of the spring where the holes would be. I think that holes there would definitely weaken the aframe. The original sway bar can get by with a clip and a bolt because it really isn't working very hard. I'm going to weld that slot closed when I put in the cadillac springs. I have a friend who roadraces a camaro, and he only runs a 1 1/8" bar so that he won't raise the inside tire on turns, but he leans the wheels in to compensate, eating the tires up. A rear bar will add to the anti-roll effect, and I would recommend one if you only have a one inch front bar. But the loss of control around a corner is mostly in the steering department, so the large front bar is necessary to maintain the correct geometry, not just to control sway. If you look under most new cars, you'll see a huge front bar. If your inside wheel is coming off the ground....I suggest changing your camber settings and buying stock in goodyear.