M3 sway bar vs. Hotchkis sway bar

[jeremydgreat]

Any thoughts or comparisons to offer?

M3 Front Sway Bar - 26.5mm thick - link

Hotchkis Front Sway Bar - 32mm thick - link

Both are made from tubular steel. Is thicker better?

[arrutled]

according to her, thicker is better.

[BMW86]

I'm interested to know this as well. I don't understand why everyone is running the E93 28mm on our 135i coupe. It was designed for the M3 convertible and has a kink in it. The E90/92 M3 26.5mm is the same as ours but it has no kink in it. I would have thought this would be the best application for our cars because it works on the M3 sedan/coupe fine.

[mr.foo]

Thicker = stiffer (yes, we're still talking about the sway bar)

The thicker the bar, the stiffer the bar. Elsewhere, I've read that the stock 135i front sway bar is 27mm. So 26.6 is slightly softer and 30mm is a bit stiffer.

Apart from fitment (e.g. kinks and bends to fit underneath the car), thickness is a key discriminator when selecting a sway bar.

Verbally, I've been told by an SCCA GT2 race engineer that the sway bar effect is proportional to the fourth power of its diameter. This means that a small change in diameter leads to a big difference in the feel. I've used this as a general rule of thumb when upgrading my front and rear sway bars.

There's a good overview of sway bars at the subaru forum (nasioc).

[tgxmike]

Originally Posted by mr.foo

The thicker the bar, the stiffer the bar. Elsewhere, I've read that the stock 135i front sway bar is 27mm. So 26.6 is slightly softer and 30mm is a bit stiffer.

The stock bar is 27mm, but there is a small ~4-6in section in the center of the bar that is only 19mm, making the bar less stiff.

The M3 bar is the same diameter through the entire length.

[jeremydgreat]

Originally Posted by mr.foo

Thicker = stiffer (yes, we're still talking about the sway bar)

The thicker the bar, the stiffer the bar. Elsewhere, I've read that the stock 135i front sway bar is 27mm. So 26.6 is slightly softer and 30mm is a bit stiffer.

Apart from fitment (e.g. kinks and bends to fit underneath the car), thickness is a key discriminator when selecting a sway bar.

Verbally, I've been told by an SCCA GT2 race engineer that the sway bar effect is proportional to the fourth power of its diameter. This means that a small change in diameter leads to a big difference in the feel. I've used this as a general rule of thumb when upgrading my front and rear sway bars.

There's a good overview of sway bars at the subaru forum (nasioc).

Those were some helpful links. Thanks.

[infinitekidM2C]

I have the UUC rear bar and KW v2 but i can feel the front body roll still (not as bad obviously)

The UUC swaybar is also 27mm thick (i assume with no thin section) and it has two holes for adjustment. I might just go with that. Seems like the middle of the road between the M3 bar and the Hotchkis bar. it's also on sale at 15% off.

[Xyloft]

sway bars are all about ballance. a thicker sway than stock in the front will correct the understeer the car has, but if you go too thick, you may get more oversteer than you want. upgrading the rear would then be neccesary to help balance the car.

[Bizall]

Originally Posted by Xyloft

sway bars are all about ballance. a thicker sway than stock in the front will correct the understeer the car has, but if you go too thick, you may get more oversteer than you want. upgrading the rear would then be neccesary to help balance the car.

More oversteer than you want huh? I've never heard of such a thing. Must order NOW!!!

[larryn]

Originally Posted by Xyloft

sway bars are all about ballance. a thicker sway than stock in the front will correct the understeer the car has, but if you go too thick, you may get more oversteer than you want. upgrading the rear would then be neccesary to help balance the car.

I have a UUC front bar, sitting in my miscellaneous car parts pile in the corner of my garage. It belongs there. You might want to research it a bit before buying that particular bar... Or you can have mine for CHEAP, but don't say I didn't warn you.

[arrutled]

My UUC bar is in the trash. in its place is a M3 sway. FWIW

[bradford]

Originally Posted by Xyloft

sway bars are all about ballance. a thicker sway than stock in the front will correct the understeer the car has, but if you go too thick, you may get more oversteer than you want. upgrading the rear would then be neccesary to help balance the car.

WTF? No.

A stiffer REAR bar = over steer. Not front.

[M3Newbie88]

I am interested in hearing why the UCC bar is so bad.. seems like on this thread alone 3 members say its no good?

[scott135i]

That's because nearly everything UUC is trash...

[My135]

I like my Hotchkis.

[infinitekidM2C]

Originally Posted by scott135i

That's because nearly everything UUC is trash...

Not sure i would go that far.lol. but i remember Larry having lots of issues with the UUC bar because of the fit..so we should stay clear.. I will probably go with the m3 bar also

[Cisitalia]

Originally Posted by scott135i

That's because nearly everything UUC is trash...

Some truth in there for sure. When I had my E36 M3 ten years ago, I stayed a way from their products then. Still issues even now?

I will go with the E90/92 M3 version as my choice. Good conversations here and civilized too.

[Xyloft]

Originally Posted by bradford

WTF? No.

A stiffer REAR bar = over steer. Not front.

I thought the reason people upgraded their front bar was to reduce understeer?

[bradford]

Originally Posted by Xyloft

I thought the reason people upgraded their front bar was to reduce understeer?

Only to a certain extent.

It helps to limit the weight transfer and thus prevent the tire from rolling over onto the sidewall and off the contact patch. However, too much bar reduces the independent action of your suspension. There's a reason the car manufacturers don't just put massive ARBs on every car.

ARBs are supposed to be suspension fine tuning devices, but everyone on this forum seems to use them as band aid fixes for the 135i suspension woes because they're cheap.

Read this: http://www.turnfast.com/tech_handling/handling_antiroll

[BMW86]

Originally Posted by Cisitalia

Some truth in there for sure. When I had my E36 M3 ten years ago, I stayed a way from their products then. Still issues even now?

I will go with the E90/92 M3 version as my choice. Good conversations here and civilized too.

Any particular reason why you are going with the E90/92 M3 sway bar? It's nearly identical in size except it has no kink. I thought the idea behind getting a front sway was to get something bigger.

[arrutled]

Originally Posted by bradford

Only to a certain extent.

It helps to limit the weight transfer and thus prevent the tire from rolling over onto the sidewall and off the contact patch. However, too much bar reduces the independent action of your suspension. There's a reason the car manufacturers don't just put massive ARBs on every car.

ARBs are supposed to be suspension fine tuning devices, but everyone on this forum seems to use them as band aid fixes for the 135i suspension woes because they're cheap.

Read this: http://www.turnfast.com/tech_handling/handling_antiroll

You need your own thread to explain everything to everyone and then It must be stickied! I have read too many of your posts that make too much sense and then they are lost forever.

[arrutled]

Originally Posted by BMW86

Any particular reason why you are going with the E90/92 M3 sway bar? It's nearly identical in size except it has no kink. I thought the idea behind getting a front sway was to get something bigger.

The real idea behind it is to prevent roll and by that I mean control weight transfer. you can do that two ways:
stiffer springs
stiffer sways

shocks control the roll rate.