Bending a tubular sway bar?

[69427]

Just curious. I've got a lightweight C4 tubular sway bar (24mm?) sitting on the shelf. I noticed it's very close to the basic length of a C3 sway bar, but too wide at the link attachment points due to the different bend angle.



I've got a C4 suspension under the car, but it's narrowed, so a C4 bar won't work as is. As this is a tubular bar, is it possible to (cold) bend it inward a touch, (and probably bend the endlink area the opposite direction to maintain its perpendicular direction)?

Comments? Opinions?

 

[mrvette]

I got my stock C3 rear sway bar without stock links....but noticed the ends looked VERY familiar....so heated orange/yellow with propane torch and twisted 90* and used common parts house... sway bar fittings for 20 bux

if I can do that, I can't see why that bar shouldn't work with similar treatment techniques....but you need get it glowing good and proper, obviously....

 

[JeffP1167]

isn't the sway bar heat treated though and by taking a torch too it it will weaken it?

 

[mrvette]

isn't the sway bar heat treated though and by taking a torch too it it will weaken it?

I remember reading from a good source, on a vette group, that no, it does not affect the treating....I dunno why....

at least not anything we likely to notice....

 

[69427]

I changed directions. Instead of bending the bar to match the C3 width, I'm in the process of making some custom links to attach the wider C4 bar to the lower A-arms. It's a little more work, but I'm just curious about this bar.
I'm currently running a 1.125 C3 bar on the front, and the thing understeers like a pig. The amusing part is that, with the C4 suspension under the car, I'm running basically the same wheel (spring) rates f&r and front bar size as I had with the C3 suspension, but the balance is completely different. Perhaps the C4 rear is just biting more than the old C3 geometry would allow.
So, I need to reduce the front roll stiffness. I'm using this bar as it's left over from when I bought the C4 suspension at a swap meet years ago.
This bar is 24mm in diameter, and apparently '96 was the only year it was offered. It's a little small for my taste, but it's darn lightweight (5.5 pounds versus the 11.5 pound 1 1/8 inch bar) and at first glance it will reduce the front roll stiffness too much. One thing in its favor is that the torsion part is similar length to a C3 bar, but the arms are 13% wider (43' versus 38"), attaching further out on the lower A-arm. This should, if I'm correct, mean that the bar will twist more for the same amount of wheel travel, mimicing a stiffer bar.
Depending on the amount of front roll stiffness I lose, I have two other avenues I'm exploring to recover some of it back. Pre-'96 model C4s offered a 26mm bar, so I could try to find one of them down the road (I haven't done the math yet to see what the rate difference would be), or I could step up the front (coilover) spring rate, which I've been mulling around for quite a while. I've got 375# springs on them, and if my calculations are correct, these give me roughly the same wheel rate at the 550# springs in my original C3 suspension.

 

[JeffP1167]

A stock IROC-Z 3rd gen f-body hollow front sway bar more closely resembles your stock bar. I think the are larger then the vettes though.

 

[69427]

A stock IROC-Z 3rd gen f-body hollow front sway bar more closely resembles your stock bar. I think the are larger then the vettes though.

Thanks! I'm not a Camaro expert. Which years were 3rd generation?

 

[JeffP1167]

A stock IROC-Z 3rd gen f-body hollow front sway bar more closely resembles your stock bar. I think the are larger then the vettes though.

Thanks! I'm not a Camaro expert. Which years were 3rd generation?

I think the fbodies started with that hollow bar about 87-88 and used it till like 92

firebird ws-6 of that era also good.

 

[69427]

A stock IROC-Z 3rd gen f-body hollow front sway bar more closely resembles your stock bar. I think the are larger then the vettes though.

Thanks! I'm not a Camaro expert. Which years were 3rd generation?

I think the fbodies started with that hollow bar about 87-88 and used it till like 92

firebird ws-6 of that era also good.

Anybody have a Camaro/Firebird of this vintage to give me an idea of the shape/length of the front bar?

Thanks.

 

[Twin_Turbo]

I've got a couple The Camaro bars are anywhere from 32 to 36mm thick. This is a 36 mm one, don't have measurements though (could measure next weekend or so)

 

[JeffP1167]

I've got a couple The Camaro bars are anywhere from 32 to 36mm thick. This is a 36 mm one, don't have measurements though (could measure next weekend or so)

thats the same setup joops trans am has on it. the hollow sway bar, wonderbar & power steering cooler.

 

[Twin_Turbo]

Does it have a 36mm front bar too?

 

[JeffP1167]

I'm not sure of the size it came off about a 89 IROC-Z it makes the original bar look like a paperclip though. Also about 1/2 the weight of the original one.

 

[Twin_Turbo]

IROCs usually have either the 34 or 36 mm bar depending on the susp option (WS1, 2 or 6)

 

[69427]

Thanks, guys. I appreciate the help. I might hit up a junkyard this week to look around for a Camaro bar, or anything else that might fit. The arms on the Camaro bar look too long, but that part can be modified pretty easily. I've got several measurements of clearances, tolerances, and attachment points on the present frame/suspension, so we'll see what I can find.

 

[69427]

'93 Firebird bar has possibilities.

Spent some time at the junkyard yesterday looking for a hollow bar that might fit the '69. Happened upon a '93 Firebird with a bar that looked like it might work. (Firebird bar (1.185") on top, Corvette bar (1.125") on bottom.)



I cut the excess arm length off, as I'll be keeping the same arm length as the production C3 bar. The bar wall thickness was about .185".



I've got the shortened bar installed for a trial fit. I'm going to try to put the bar links at the point where the shock attaches to the A-arm, rather than where the original C4 link attached. I have a heim joint and long bolt positioned where the final link will reside. This outer position should effectively make the bar a bit stiffer in relation to wheel travel compared to the original position. I'm hoping to come up with a three hole bar attachment configuration that will allow me to move the links to a softer or firmer position.



I've done a few torsion calculations, and it looks like this bar should be very similar in performance as the 1.125" C3 bar, but several pounds lighter.

 

[69427]

Well, I finished welding the ends back on the shortened (F-car) bar arms the other week, and got the bar and links installed back on the car. Only had the chance to put about ten miles on it, but the roll stiffness still feels very good. I'm looking forward to some track time to see what the balance feels like at higher speeds and on some stickier tires.

While driving a pickup load of stuff to the house today and trying to focus on more interesting things (car stuff), it suddenly occurred to me that I've probably raised the c/g height of the '69 with all the changes I've made the past year. I've taken about 180 pounds off the car, but most all the weight reduction points (C4 suspension, tubular sway bar, aluminum lower radiator crossmember, etc) have been below the stock c/g height. I'm still digesting the secondary issues (new c/g height vs rollcenter height) that pop up from this change.

 

[mrvette]

Well, I finished welding the ends back on the shortened (F-car) bar arms the other week, and got the bar and links installed back on the car. Only had the chance to put about ten miles on it, but the roll stiffness still feels very good. I'm looking forward to some track time to see what the balance feels like at higher speeds and on some stickier tires.

While driving a pickup load of stuff to the house today and trying to focus on more interesting things (car stuff), it suddenly occurred to me that I've probably raised the c/g height of the '69 with all the changes I've made the past year. I've taken about 180 pounds off the car, but most all the weight reduction points (C4 suspension, tubular sway bar, aluminum lower radiator crossmember, etc) have been below the stock c/g height. I'm still digesting the secondary issues (new c/g height vs rollcenter height) that pop up from this change.

INteresting, but for all that weight difference, wouldn't dropping the ride height about 1/2 inch or so, make up for that??

 

[69427]

INteresting, but for all that weight difference, wouldn't dropping the ride height about 1/2 inch or so, make up for that??

It's already as low as I can get it without ripping off the exhaust when I hit a bump.

 

[TimAT]

As thick as that bar looks where you cut it, it almost seems like you could tap it and use heim joint ends.