Looking for new sway bar. Can I go too big??

[340doc]

We've been slowly upgrading my sons 70 Dart. So far we have 1.03 torsion bars, QA1 upper control arms with the extra caster built in and factory BBP disc. No shocks yet. Now I'm looking at a front bar. We don't have the tabbed lower arms so looking at a kit with bolt on tabs. I've narrowed it down to two bars from Hellwig. One is 1 1/8 dia. the other is 1 1/4. The 1 1/4 bar is offset a bit to accept wheels with up to 5.75 backspace which would be good for us as we have a 17" rim with 5 1/2 BS. My question being is the 1 1/4 bar too big? I could put up with a light rub on the bar from the tire at full lock. Should I stick with the 1 1/8?

 

[MRGTX]

Yes. You can go too big. Too much sway bar and the car will just plow straight ahead under hard cornering.

Keep in mind that sway bars don’t improve traction. They may improve track times because of better body control and greater driver confidence.

 

[autoxcuda]

We've been slowly upgrading my sons 70 Dart. So far we have 1.03 torsion bars, QA1 upper control arms with the extra caster built in and factory BBP disc. No shocks yet. Now I'm looking at a front bar. We don't have the tabbed lower arms so looking at a kit with bolt on tabs. I've narrowed it down to two bars from Hellwig. One is 1 1/8 dia. the other is 1 1/4. The 1 1/4 bar is offset a bit to accept wheels with up to 5.75 backspace which would be good for us as we have a 17" rim with 5 1/2 BS. My question being is the 1 1/4 bar too big? I could put up with a light rub on the bar from the tire at full lock. Should I stick with the 1 1/8?

I think 1 1/4 tubular would be fine. You don’t have the really stiff t-bars.

Do you have a rear bar? An adjustable can help balence it out.

I have much larger 1.14” Tbars and 1 1/4” tubular front sway bar. I have a rear adjustable sway bar. But at Willow Spring Raceway the rear had too much roll stiffness that gave an oversteer/loose condition.

So I disconnected the rear bar all together. Much easier to drive and no sliding into the infield.

Now for a autocross with lower speeds and tighter corners, the rear bar may help.

Right now, I drive it with the rear bar still disconnected on the street.

 

[AJ/FormS]

My street-Barracuda has 1.03 bars and the 1.125 Hellwig. Handles nice with 235/60-14s, and 295/50-15s out back. She oversteers nice and smooth with power. With 275s it just did 180s, everywhere all the time. It was ridiculous.

 

[340doc]

I think 1 1/4 tubular would be fine. You don’t have the really stiff t-bars.

Do you have a rear bar? An adjustable can help balence it out.

I have much larger 1.14” Tbars and 1 1/4” tubular front sway bar. I have a rear adjustable sway bar. But at Willow Spring Raceway the rear had too much roll stiffness that gave an oversteer/loose condition.

So I disconnected the rear bar all together. Much easier to drive and no sliding into the infield.

Now for a autocross with lower speeds and tighter corners, the rear bar may help.

Right now, I drive it with the rear bar still disconnected on the street.

No rear bar at this time. Concentrating on the front end right now. Will be looking at new rear springs and possible a rear bar later. So it should be ok. I Appreciate your input.

 

[MileHighDart]

I'll throw my two cents in here.
I've got a similar setup on my 68 Dart. QA1 upper control arms, PST 1.03 torsion bars, subframe connectors.
And I just added boxed lower control arms, Hotchkis adjustable strut rods, and a Hotchkiss 1.5" tubular front sway bar.
I still have 15" T/A radials and some basic Monroe gasmatic shocks, so nothing fancy there.
But since doing the new lower arms, and the Hotchkiss swaybar, the car handles fantastic, feels like its glued to the road. This bar comes with weld on tabs for the lower control arms. I've never had it on an autocross track or anything, and its hard to find a place on the street where I can push it hard enough to find the limits, but its now very fun to drive on twisty curvy roads.

 

[340doc]

I'll throw my two cents in here.
I've got a similar setup on my 68 Dart. QA1 upper control arms, PST 1.03 torsion bars, subframe connectors.
And I just added boxed lower control arms, Hotchkis adjustable strut rods, and a Hotchkiss 1.5" tubular front sway bar.
I still have 15" T/A radials and some basic Monroe gasmatic shocks, so nothing fancy there.
But since doing the new lower arms, and the Hotchkiss swaybar, the car handles fantastic, feels like its glued to the road. This bar comes with weld on tabs for the lower control arms. I've never had it on an autocross track or anything, and its hard to find a place on the street where I can push it hard enough to find the limits, but its now very fun to drive on twisty curvy roads.

Dang, that's a big bar! Yes very similar set up, thank you.

 

[GMachineDartGT]

The weld on tabs supplied with the Hotckiss hollow bar are a heavy duty version of OE tabs. In my opinion, this is the nicest bar on the market right now due to fitment, tabs and reinforced bracketry. The Hellwig 1 1/4" has bent legs for higher offset wheels, the 1 1/8" has straight legs. Either way, bolting on tabs in lieu of welding is a waste of time and effort.

 

[340doc]

I'll probably run a bead to secure the bolt on tabs once everything is set

 

[GMachineDartGT]

I'll probably run a bead to secure the bolt on tabs once everything is set

It's the tab as well. L bracket with no reinforcement

 

[72bluNblu]

Yes. You can go too big. Too much sway bar and the car will just plow straight ahead under hard cornering.

Keep in mind that sway bars don’t improve traction. They may improve track times because of better body control and greater driver confidence.

Sway bars don’t improve traction?!

Uh, how do you think they improve body control? They add wheel rate, that’s how. And specifically where it’s needed during cornering. If you think that can’t improve traction, I’m not sure what to tell you.

We've been slowly upgrading my sons 70 Dart. So far we have 1.03 torsion bars, QA1 upper control arms with the extra caster built in and factory BBP disc. No shocks yet. Now I'm looking at a front bar. We don't have the tabbed lower arms so looking at a kit with bolt on tabs. I've narrowed it down to two bars from Hellwig. One is 1 1/8 dia. the other is 1 1/4. The 1 1/4 bar is offset a bit to accept wheels with up to 5.75 backspace which would be good for us as we have a 17" rim with 5 1/2 BS. My question being is the 1 1/4 bar too big? I could put up with a light rub on the bar from the tire at full lock. Should I stick with the 1 1/8?

Can you go too big with the sway bar? Sure. It really depends on your tires- if you don’t have enough grip for the effective wheel rate the large front bar gives you the car will understeer. Just the opposite with too much bar in the back, you get oversteer as autoXcuda said.

The trick is to match the wheel rates with the capabilities of your tires and the balance of your car. If AJ is still oversteering with 235’s, 1.03’s and a solid 1.125” bar in the front with 295’s in the back though I don’t think you have much to worry about. You’d be hard pressed to find a 17” tire up front with as little grip as the tires that are available in a 235/60/14, and if those 295’s aren’t more than balancing it out you can add a bunch more front bar before it’s an issue.

Also keep in mind not all of those bars are the same. The 1 1/4” Hellwig bar is a hollow bar, pretty sure the 1 1/8” bar is solid. The Hotchkis 1.5” diameter bar is hollow too, and without knowing the wall thickness it’s almost impossible to say what the rate actually is. All three of those bars could easily have very similar rates.

 

[jos51700]

I was going to suggest mounting up a 2" bar and be done with it, and then I was going to suggest just welding up the shocks solid, and now I'm just going to keep my mouth shut and quietly step out.

 

[340doc]

Sway bars don’t improve traction?!

Uh, how do you think they improve body control? They add wheel rate, that’s how. And specifically where it’s needed during cornering. If you think that can’t improve traction, I’m not sure what to tell you.



Can you go too big with the sway bar? Sure. It really depends on your tires- if you don’t have enough grip for the effective wheel rate the large front bar gives you the car will understeer. Just the opposite with too much bar in the back, you get oversteer as autoXcuda said.

The trick is to match the wheel rates with the capabilities of your tires and the balance of your car. If AJ is still oversteering with 235’s, 1.03’s and a solid 1.125” bar in the front with 295’s in the back though I don’t think you have much to worry about. You’d be hard pressed to find a 17” tire up front with as little grip as the tires that are available in a 235/60/14, and if those 295’s aren’t more than balancing it out you can add a bunch more front bar before it’s an issue.

Also keep in mind not all of those bars are the same. The 1 1/4” Hellwig bar is a hollow bar, pretty sure the 1 1/8” bar is solid. The Hotchkis 1.5” diameter bar is hollow too, and without knowing the wall thickness it’s almost impossible to say what the rate actually is. All three of those bars could easily have very similar rates.

Thanks blu. I value your opinion on topics like this, as you always give a good explanation.

 

[340doc]

It's the tab as well. L bracket with no reinforcement

I see what your saying. Thanks.

 

[72bluNblu]

Thanks blu. I value your opinion on topics like this, as you always give a good explanation.

Hey thanks! I just try to relate some of the stuff I’ve learned from building my cars, hopefully people can learn from my successes and my failures.

 

[MRGTX]

I try to relate some of the stuff I've learned from bashing Miatas around autocross courses...and high school physics class too.

Sway bars don’t improve traction?!

Uh, how do you think they improve body control? They add wheel rate, that’s how. And specifically where it’s needed during cornering. If you think that can’t improve traction, I’m not sure what to tell you.
...

The biggest benefits of sway bars, IMO is improving driver confidence. If properly matched to spring rates and properly tuned front vs rear, they can certainly improve lap times too but a sway bar does not net any traction gain. It merely controls where the load is carried.
In a turn, a sway bar reduces load on the inside wheel and increases the load on the outside wheel. As we know, increasing the load on the outside wheel does not increase friction proportionately. On the contrary, it results in a net loss of grip.

How would you correct for a car that is understeering? If you say "stiffer sway bar," I don't know what to tell you. Just give it a try....then log into the forum from the bushes while you wait for the wrecker and let us know it went.

Ok. Fine... In a case where your car is losing grip due to excessive positive camber under load, increasing sway bar stiffness and decreasing compression of the outside suspension can correct for this geometry problem and improve grip. Maybe that is a relevant concern when looking at factory alignment specs on our old cars.

 

[72bluNblu]

I try to relate some of the stuff I've learned from bashing Miatas around autocross courses...and high school physics class too.



The biggest benefits of sway bars, IMO is improving driver confidence. If properly matched to spring rates and properly tuned front vs rear, they can certainly improve lap times too but a sway bar does not net any traction gain. It merely controls where the load is carried.
In a turn, a sway bar reduces load on the inside wheel and increases the load on the outside wheel. As we know, increasing the load on the outside wheel does not increase friction proportionately. On the contrary, it results in a net loss of grip.

How would you correct for a car that is understeering? If you say "stiffer sway bar," I don't know what to tell you. Just give it a try....then log into the forum from the bushes while you wait for the wrecker and let us know it went.

Ok. Fine... In a case where your car is losing grip due to excessive positive camber under load, increasing sway bar stiffness and decreasing compression of the outside suspension can correct for this geometry problem and improve grip. Maybe that is a relevant concern when looking at factory alignment specs on our old cars.

If you don’t think that controlling where load is carried on the suspension effects your traction, your high school physics teacher failed you miserably.

You say you’re not adding traction, well, that’s a silly way to look at it. By that definition only tire compound will ever add to your traction. All any suspension is ever doing is keeping you from losing traction. So just run without it, it’s not adding traction by your logic.

And why do you need to improve an understeering car with a stiffer sway bar? That doesn’t say anything about what a sway bar does. Sure, you can be in understeer if you’re already too stiff in the front, and adding front sway bar won’t help that. But that doesn’t mean a sway bar can’t improve traction, it just means they’re not always the solution to a particular problem. Of course, you could be in understeer because your front suspension is too soft and you’re bottoming it out on braking and entry, in which case adding wheel rate might actually help. You’re vastly oversimplifying, and your own “camber issue” example shows that. There’s a lot of possibility’s that you’re just flat out ignoring.

As far as improveming lap times, improving traction is the number one way to do that. If driver confidence is a bigger factor then it’s inexperienced drivers that’s the problem. Which is exactly what you see in Miata racing, because that’s entry level competition. So yeah, maybe a bunch of inexperienced drivers like you’re used to seeing just use sway bars as their magic feather, because they don’t have a clue what’s actually going on. Might not want to use them as your example.

 

[supertruck]

When considering a sway bar size, it helps to consider the front and rear roll angle in hard cornering. You want a balanced setup, or as close as you can get it. You don't want the front to out roll the rear, or vice versa. Wouldn't be real noticeable in every day street driving, but if you're gonna do track days or something similar it would make a big difference. Of course, a sway bar alone won't fix everything. You have to consider spring rates and shocks, along with ride heights and weight distribution.

 

[MRGTX]

If you don’t think that controlling where load is carried on the suspension effects your traction, your high school physics teacher failed you miserably.

You say you’re not adding traction, well, that’s a silly way to look at it. By that definition only tire compound will ever add to your traction. All any suspension is ever doing is keeping you from losing traction. So just run without it, it’s not adding traction by your logic.

And why do you need to improve an understeering car with a stiffer sway bar? That doesn’t say anything about what a sway bar does. Sure, you can be in understeer if you’re already too stiff in the front, and adding front sway bar won’t help that. But that doesn’t mean a sway bar can’t improve traction, it just means they’re not always the solution to a particular problem. Of course, you could be in understeer because your front suspension is too soft and you’re bottoming it out on braking and entry, in which case adding wheel rate might actually help. You’re vastly oversimplifying, and your own “camber issue” example shows that. There’s a lot of possibility’s that you’re just flat out ignoring.

As far as improveming lap times, improving traction is the number one way to do that. If driver confidence is a bigger factor then it’s inexperienced drivers that’s the problem. Which is exactly what you see in Miata racing, because that’s entry level competition. So yeah, maybe a bunch of inexperienced drivers like you’re used to seeing just use sway bars as their magic feather, because they don’t have a clue what’s actually going on. Might not want to use them as your example.

Ya know, I’m usually the first one to give you a thumbs up and I’ve learned a lot from your posts...but not only do I think you’re not correct on this one, you’re kinda being a dick about it.

Also, do you not know how autocross works? Your comment seems to indicate that you don’t. Definitely check it out some time. You’d be an instant celebrity if you brought the Duster/Demon! I’m no pro but there were a few years where I hit the course frequently and had a blast with it. It’s possibly the most fun I’ve had in any car.

On topic; the “what do sway bars do?” debate is a complex one and difficult to talk about in generalities. This has been debated forever on discussion forums.

I will say that as a general rule, stiffen your sway bar on an axle, that axle will dynamically grip less. I believe that this is the most helpful answer for the OP.

YES. You can have too much sway bar.

 

[72bluNblu]

Ya know, I’m usually the first one to give you a thumbs up and I’ve learned a lot from your posts...but not only do I think you’re not correct on this one, you’re kinda being a dick about it.

Also, do you not know how autocross works? Your comment seems to indicate that you don’t. Definitely check it out some time. You’d be an instant celebrity if you brought the Duster/Demon! I’m no pro but there were a few years where I hit the course frequently and had a blast with it. It’s possibly the most fun I’ve had in any car.

On topic; the “what do sway bars do?” debate is a complex one and difficult to talk about in generalities. This has been debated forever on discussion forums.

I will say that as a general rule, stiffen your sway bar on an axle, that axle will dynamically grip less. I believe that this is the most helpful answer for the OP.

YES. You can have too much sway bar.

How about you stop assuming I haven't done stuff, or don't understand what you're talking about just because I don't agree with you? The fact is I've been to autocrosses. I started driving them over 20 years ago actually. I've driven road courses as well. I haven't been in a few years, but needless to say I know "how they work".

The simple fact is you dramatically oversimplified your explanation. Sway bars are not just a band aid for driver's confidence, they are a specialized tool for controlling and tuning a suspension and something that can dramatically IMPROVE TRACTION if used correctly in the right situations. Of course you can run too much sway bar. You can also run too little sway bar. That seems to be where your understanding is quite lacking, if the handling of your car is telling you that your suspension needs a sway bar it will IMPROVE traction. And that goes exactly to my point-

On an A-body with decent tire compounds and only 1.03" torsion bars up front, you'd need a custom made sway bar to go too big. The OP is planning on 17" rims, and is looking at a sway bar that allows enough backspace to run tires that are at least 245's. There isn't an off the shelf sway bar for an A-body on the market that would be too much for that set up. That's my point.

This isn't a Miata, it's a nose heavy musclecar that still only has a ~230 lb/in wheel rate.

 

[AJ/FormS]

Sway bars don’t improve traction?!
Uh, how do you think they improve body control? They add wheel rate, that’s how. And specifically where it’s needed during cornering. If you think that can’t improve traction, I’m not sure what to tell you.
Can you go too big with the sway bar? Sure. It really depends on your tires- if you don’t have enough grip for the effective wheel rate the large front bar gives you the car will understeer. Just the opposite with too much bar in the back, you get oversteer as autoXcuda said.
The trick is to match the wheel rates with the capabilities of your tires and the balance of your car. If AJ is still oversteering with 235’s, 1.03’s and a solid 1.125” bar in the front with 295’s in the back though I don’t think you have much to worry about. You’d be hard pressed to find a 17” tire up front with as little grip as the tires that are available in a 235/60/14, and if those 295’s aren’t more than balancing it out you can add a bunch more front bar before it’s an issue.
Also keep in mind not all of those bars are the same. The 1 1/4” Hellwig bar is a hollow bar, pretty sure the 1 1/8” bar is solid. The Hotchkis 1.5” diameter bar is hollow too, and without knowing the wall thickness it’s almost impossible to say what the rate actually is. All three of those bars could easily have very similar rates.

Hyup my Hellwig 1.125 is solid.My arms were tabbed.But the straight-armed bar is slightly too narrow so the links are not vertical. Doesn't seem to be a big deal.
My car was set up to run some soft-compound sticky 245-15s back in 2004 . F1s or something,I forget.I lowered the car, quite a bit at that time. It's a streeter and most of the roads are concrete. I set it up low enough that when pushed, it would settle on the bumpstops and wheel around the turns pretty good. But those tires burned off in a few weeks and because they were more than double the cost of the BFGs, and I was in a bind at the time (College for my eldest), I backed off the program for a few years. Instead,I raised the car up a bit to better use the front bar, installed some lightweight 7.5wheels I had with the 235s and found that cornering, while diminished,wasn't all that much worse. And in fact,while slower, it seemed to be more fun. Because the tires weren't saving myazz anymore, I actually had to learn to drive,go figure. By the time College was done, and daughter was self-supporting, I was several years older, and was quite enjoying the driving style I had come to adopt; so I just never went back to the F1s.
And you are right about the BFGs.They only work reasonably well for the first few thousand miles; then they get hard, and skate for the rest of their useful lives.After I learned to drive the skates,they're fairly predictable, and for me, it actually became more fun. I am talking all street tho. And I must admit, by 2012, I was coming 59, and slamming around turns too fast and skating thru them with careful power application, was not as important to me as it had been 10 years earlier.That chapter was drawing to a close.
You are also right about the 295s being a balancing act for the too-much front bar for the not sticky enough front tires, and the too-stiff shocks all 'round. On the street it seems I at least, could get away with crap. I mean go-carts have no suspension at all and those young kids seem to be having a whale of a time. I got just enough compliance so I can still see,lol, and most of that is in the air pressures. Works for me.
You are right about a lot of stuff.And when it comes to chassis work, you and AutoX are, IMO, top-tier.

 

[meathead66]

It's a streeter and most of the roads are concrete.

I dunno ‘bout that cause every time I go to to Manitoba and Saskatchewan they are all gravel,dirt and clay. Prolly need “double sway bars” and double gravel guards.

 

[MRGTX]

How about you stop assuming I haven't done stuff, or don't understand what you're talking about just because I don't agree with you? The fact is I've been to autocrosses. I started driving them over 20 years ago actually. I've driven road courses as well. I haven't been in a few years, but needless to say I know "how they work".
...

Thanks for the good info in the follow up. For the record, I know that you know your stuff. You've proven that many times. I've also seen that you occasionally piss people off with your choice of wording and I know that I can do the same! Absolutely no offense was intended with my comments...but I will insist that your attempt at a "burn" about the association between Miatas and inexperienced drivers was ignorant at best and I reserve the right to tell you to shut your mouth about that. I'd just love to see your face as you get lapped by 100rwhp Miatas on a road course. You're in for a shock!

So I think we're both over-simplifying this in the way that we believe to be most helpful.
The question was "can I go too big?" and the answer to this remains "yes!" The suspension needs to be tuned as a system...and it sounds like we agree on that point. Just throwing a bigger bar at a suspension usually doesn't achieve the result of more grip. This thread from a few years back, remains a great discussion on the topic.

Sway Bar Theory and front end grip

I do see your point that the available bars on the market for A-Body Mopars might not be "too much" and that's a fair point. I honestly don't know what else is out there so I'll have to take your word on that. I can also see that the change in camber on these cars is really dramatic as you move the suspension through its range...so given the relatively soft 1.03" torsion bars in the OP's case, I can imagine that the sway bar's affects of disadvantageous distribution of load on the outside tire and loss of independence of the front suspension is probably less important than controlling the camber by reducing roll/compression of the outside suspension.

I hope the OP has some time and money to test and tune to taste.

FWIW, I the bigger Hellwig bar on my car (with 1.14" torsion bars) and I believe that it provides a net improvement even if the ultimate grip is not greater.

 

[oi81b4uu812b4]

Unless all of you are planning on having a custom bent sway bar, old Mopars with torsion bars are really limited to (4) manufacturer's and only (2) of those fit without cobbling **** to get them on. There is really only slight handling differences between the (3) manufacturer's sway bars and the handling characteristics they produce for the average street driven car. Last I checked a custom bent bar runs around $500 +.

And being a Dad, you are probably more concerned about improving the handling some on your Father/ Son project car so he doesn't get out braked by a modern sedan in front of him that's slamming on the brakes, or taking a corner in an old car with body roll issues a new car takes with ease.

Generally if you have stiff torsion bars/ springs you can use a less stiff sway bar. If you run softer torsion bars you can run a little stiffer sway bar. And don't think this means you can keep your Slant 6 torsion bars and run the biggest sway you can find. It needs to be a little closer set up than that.

There are only a few people on here that can tell you why they like their setup when pushing the limits, and that's because they autocross their car. So where one person likes Hotchkis another person will like Hellwig and then there are people that like stock Mopar sway bars... Aftermarket larger diameter sway bars are usually always an improvement over stock sway bars and will work for a majority of purchasers. But to complete it, you really need to upgrade your shocks too, and I favor Hotchkis in that area.

Have fun with it. Teach him some skills. We are building the next generation that loves the same cars.

 

[AJ/FormS]

I dunno ‘bout that cause every time I go to to Manitoba and Saskatchewan they are all gravel,dirt and clay. Prolly need “double sway bars” and double gravel guards.

When you take a streeter onto a gravel road things can get ugly in a hurry, very ugly.
But lemmee tell ya,
if you find an acre or five of gravel, you can have a real good time; just don't catch a tire on a berm unless it's spinning. Second gear and give 'er! It works better if the gravel is wet, cuz you still gotta be able to see some of the time.