Front Stabilzer Bar Links: How Important

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
Post Reply
User avatar
ClutchFork
Master Standardshifter
Posts: 1564
Joined: Wed Mar 06, 2013 2:55 pm
Cars: 2001 S10 2.0L manual
Location: Detroit MI

Front Stabilzer Bar Links: How Important

Post by ClutchFork » Sat Sep 29, 2018 12:44 pm

So when we (ClutchDisk and I) got the 92 5.0 Mustang it would kind of twist to the side some on hard acceleration. I thought it was that the tires were breaking traction but didn't hear any squealing. The shop said the front stabilizer bar links were both broken. Since we replaced the broken links it does not twist like that anymore and today I even got on it while still coming out of a curve from a boulevard turn and it tracked beautifully. So the question is, can that be fully attributable to the stabilizer bar?
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

Rope-Pusher
Master Standardshifter
Posts: 10792
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Front Stabilzer Bar Links: How Important

Post by Rope-Pusher » Sun Sep 30, 2018 10:16 am

ClutchFork wrote:
Sat Sep 29, 2018 12:44 pm
So when we (ClutchDisk and I) got the 92 5.0 Mustang it would kind of twist to the side some on hard acceleration. I thought it was that the tires were breaking traction but didn't hear any squealing. The shop said the front stabilizer bar links were both broken. Since we replaced the broken links it does not twist like that anymore and today I even got on it while still coming out of a curve from a boulevard turn and it tracked beautifully. So the question is, can that be fully attributable to the stabilizer bar?
Image
Whale,
it could happen to be due to the change in the ratio of front-2-back roll stiffness.

The suspensions at both ends of the car have been designed with a certain amount of roll stiffness, and the ratio of front-2-back roll stiffness is also carefully chosen. All things being equal, when roll stiffness is increased, the car corners "flatter", i.e. the body leans less in turns. Stabilizer bars (a.k.a "Sway bars", or "anti-sway bars") are NOT the only means of achieving roll stiffness, but they are important for tuning the total amount of roll stiffness and also in setting the front-2-back roll stiffness ratio. The total amount of roll stiffness affects body lean in curves and the ratio of front-2-back roll stiffness affects how the vehicle handles.

When your front links were broken, the front stabilizer bar was nonfunctional. The car had less overall roll stiffness and the front-2-rear roll stiffness ratio was changed. Roll stiffness is one of the factors that determines side-2-side weight transfer. In general, if you increase the roll stiffness, MORE weight is transferred to the tire in the outside of a turn and the tire on the inside of the turn unloads, or loses grip to the pavement. If a car is designed with not much front suspension roll stiffness, besides the body leaning, the inside front tire is gripping better. Same goes for the rear roll stiffness. On a RWD vehicle, if the majority of the roll stiffness is in the rear suspension, the inside rear wheel will have less grip and can't transmit as cornering force to the pavement. This is "Uber-Steyr". If the car has an open differential, then the amount of power that can be applied to accelerate the vehicle will be limited by the inside rear wheel grip. As the wheel spins, it also loses lateral grip, and the rear of the vehicle starts to slide to the outside of the curve, i.e. "Power-Uber-Steyr" and you have to "Steer toward the skid" to keep from performing a complete do-si-do. If the front suspension carries most of the total roll stiffness, the rear stays planted, but the front inside wheel unloads and can't grip the pavement and you have to crank in more steering input to maintain the turn radius, i.e. "Un-Der-Steyr".

My buddy Pierre disconnected the stabilizer bars at BOTH ends of his ice racer, because he'd rather have less weight transfer, keeping as much grip as possible on all 4 tires, and live with the body roll - you don't get to really high g-levels when racing out on a frozen lake, so there wasn't a lot of body roll going to happen anyway, right?
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

User avatar
ClutchFork
Master Standardshifter
Posts: 1564
Joined: Wed Mar 06, 2013 2:55 pm
Cars: 2001 S10 2.0L manual
Location: Detroit MI

Re: Front Stabilzer Bar Links: How Important

Post by ClutchFork » Sun Sep 30, 2018 12:47 pm

Thanks, but your explanation seems to pertain mostly to cornering. But would the front stabilizer bar have an effect on straight line acceleration and maintaining straight tracking? I suspect that the answer is, if the car is accelerating in a straight line and breaks traction it will start turning away from the straight line and if the front stabilizer bar is disconnected, that effect will happen more easily and to a greater degree.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

Rope-Pusher
Master Standardshifter
Posts: 10792
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: Front Stabilzer Bar Links: How Important

Post by Rope-Pusher » Sun Sep 30, 2018 1:06 pm

ClutchFork wrote:
Sun Sep 30, 2018 12:47 pm
Thanks, but your explanation seems to pertain mostly to cornering. But would the front stabilizer bar have an effect on straight line acceleration and maintaining straight tracking? I suspect that the answer is, if the car is accelerating in a straight line and breaks traction it will start turning away from the straight line and if the front stabilizer bar is disconnected, that effect will happen more easily and to a greater degree.
In a vehicle with a longitudinal driveline, there is a moment applied through the motor mounts that tries to roll the vehicle and the roll stiffness must act against this, so a lot of the same things apply as when cornering.

If you look at a picture of a production vehicle that lifts its front wheels under acceleration, the one side always comes off the ground sooner and lifts higher. After the front wheels both come off the ground, the rear roll stiffness is all you have to work with.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

User avatar
ClutchFork
Master Standardshifter
Posts: 1564
Joined: Wed Mar 06, 2013 2:55 pm
Cars: 2001 S10 2.0L manual
Location: Detroit MI

Re: Front Stabilzer Bar Links: How Important

Post by ClutchFork » Sun Sep 30, 2018 11:57 pm

Thanks. Now I think I get it. I remember the car always twisted to the left before the stabilizer bar was fixed.

Google tells me the front left tire comes up first and the right rear tire plants harder. So I am thinking that with both left tires lightening up and the right rear planting harder, perhaps the push on the right side that is not countered by equal push on the left side causes the car to twist left. Well anyway, she now seems to be tracking straight on harder acceleration so we are in business. I say harder acceleration because I don't know that I have ever matted the pedal in this thing. Have to try that sometime soon though.

Just a couple remaining repairs: coolant leak think at timing cover from changing out the water pump and the hood latch broke. But we are getting there after we had the radiator, water pump, oil pan, serp belt, clutch cable, and fuel tank replaced.

Fuel gauge funky. We fill tank and it only reads about 5/8 full. Can't put any more in or it spits back.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

Post Reply