Sway Bar Question

[mikerob97]

Does anyone know why the Cabrio's come with a larger front sway bar (21mm) than the coupe or the sedan (20mm)?

[loganhopeless]

If you had a box without a top, and a box with a top, which one would twist more? Larger sway bar means more rigidity. You sacrifice that when you don't have a hard top.


Sent from my iPhone using Tapatalk

[Streichholzschächtelchen]

They did everything they could to give the car better rigidity than a block of velveeta cheese. 21mm is a good amount more rigid than 20mm. (21^4)/(20^4) The rear could use a stiffer sway, makes the ass end kick out more. Verts don't really need rear strut bars since the box the top folds into is strong, but a front strut bar would be of greatest significance on a vert.

[mikerob97]

these responses are curious...I never considered that the sway bar contributed to chassis rigidity...are you guys sure about this explanation?

[Mwishlist]

My (completely uninformed?) opinion, I don't think the sway contributes to chassis rigidity. But I think the stiffer sway helps to combat the additional flex in the convertible chassis.

Also, my first car was a 1966 289 Mustang, but I wanted a 1969 mach 1.

[Streichholzschächtelchen]

It's for roll but roll allows more twisting to occur. the weight ends up more disproportionally distributed with softer sways than with beefy sways.

[Streichholzschächtelchen]

I gotta proof read more often. Just get 22mm front and 19mm rear sways with a front strut bar and if you still have cash a cross brace like ejknights will also make the car handle better.

[mr2peak]

Sway bars do nothing for chassis rigidity. Fact.

It has to do with where the weight is on convertibles, and making up for the difference in chassis rigidity by meddling with the suspension setup.

M Technic convertibles came with the stock convertible front bar, and the M3 14.5mm rear bar. Springs, different dampers and bumpstops as well. That sway configuration is a good place to start if you're looking for a stock upgrade.

[mikerob97]

Sway bars do nothing for chassis rigidity. Fact.

It has to do with where the weight is on convertibles, and making up for the difference in chassis rigidity by meddling with the suspension setup.

M Technic convertibles came with the stock convertible front bar, and the M3 14.5mm rear bar. Springs, different dampers and bumpstops as well. That sway configuration is a good place to start if you're looking for a stock upgrade.

Thanks mrpeak - your reply makes good sense.

The reason for my ask is because I am finishing my winter suspension & brake refresh. The new setup for my 1991 Cabriolet is, H&R sport springs with Bilstein Sport struts and shocks. I have replaced the control arm bushings, the rear subframe mounts, trailing arm bushings and the differential carrier all with poly. I have installed the M3 (14mm) rear sway bar. I have moved the front sway bar attachment point from the control arms to the front strut housings. Now the dilemma - I have both an M3 (19mm) front and my stock Cabrio (21mm) front sway bar available ready to install.

Your thoughts?

[mr2peak]

Drive it, push it to the limit. Get in a fast corner with neutral power, and try adding gas. Same thing, but lift this time. Do it in a large parking lot with plenty of room to spin.

You need to test and tune, everything else is just a guess. I'd personally start with the lighter bar.

[mikerob97]

Thanks for the input. I will start with the M3 (19mm) bar up front and see how it drives. Look for significant understeer or oversteer...and then adjust with the larger front bar accordingly...

[mikerob97]

My (completely uninformed?) opinion, I don't think the sway contributes to chassis rigidity. But I think the stiffer sway helps to combat the additional flex in the convertible chassis.

Also, my first car was a 1966 289 Mustang, but I wanted a 1969 mach 1.

I sure miss the mach1...nothing quite like a built 351W with a Ford Toploader (4 speed) behind it and a 3.5:1 traction-loc rear end...

[Mwishlist]

I sure miss the mach1...nothing quite like a built 351W with a Ford Toploader (4 speed) behind it and a 3.5:1 traction-loc rear end...

Yep, my brother had one growing up. I loved that car!

[mr2peak]

Thanks for the input. I will start with the M3 (19mm) bar up front and see how it drives. Look for significant understeer or oversteer...and then adjust with the larger front bar accordingly...

Nope, M3 bar in the rear. Cabrio has a larger front bar already

[mikerob97]

Nope, M3 bar in the rear. Cabrio has a larger front bar already

I already have installed the M3 14mm sway bar in the rear and will now be installing the M3 19mm sway bar in the front using the strut mounted attachment points.