.50 taller ball joints?

[UNGN]

Bumpsteer is tricky to completely remove over the entire range of motion, especially for a drag car that can go from full extension to full compression and back to full extension.

For a lowered street car, it much easier. Lowering the inner tierod or raising the outer tierod generally gets rid of most of the bump steer in a lowered G-body. Tall lower ball joints raise the outer tie rod and reduce bump steer as does lowering the Centerlink so it is almost on the skid plate.

 

[pontiacgp]

It doesn't always work out as simple as that.
http://www.longacreracing.com/technical-articles.aspx?item=8162

It doesn't have to be complicated either. With the tie rod assembly parallel to the lower control arm that means the tie rods are pointing to the instant center which will give me almost no bumpsteer.

 

[Clarmo]

It doen't have to be complicated either. The reason I have my tie rod assembly parallel to the lower control arms and why I use a tall lover ball joint but a stock on on top is so I can keep the instant center as close to the wheel as possible. With the tie rod assembly parallel to the lower control arm that means the tie rods are pointing to the instant center which will give me almost no bumpsteer.

I agree, it is actually a simple theory BUT unless you actually measure it with a very accurate device of some sort, you are only guessing. ANY changes to the steering and suspension will greatly affect the bump steer.

You say a taller lower and stock upper keeps the instant center closer to the wheel BUT it would get even closer if you installed a taller upper also. And I'm pretty sure keeping the tie rods exactly parallel to the LCA will not give you 0 bumpsteer.

 

[Clarmo]

 

[Clarmo]

I'm also not saying installing a taller lower BJ doesn't help fix factory geometry that would reduce the bumper steer in these cars.

Now I'm curious...I have a bone stock 4 door Malibu with 20,000 original miles on it that I'll put on my aligner. Then I'll post some findings when i get it out of storage.

 

[pontiacgp]

I agree, it is actually a simple theory BUT unless you actually measure it with a very accurate device of some sort, you are only guessing. ANY changes to the steering and suspension will greatly affect the bump steer.

You say a taller lower and stock upper keeps the instant center closer to the wheel BUT it would get even closer if you installed a taller upper also. And I'm pretty sure keeping the tie rods exactly parallel to the LCA will not give you 0 bumpsteer.

I realized I misspoke about the tall upper so I removed that. As far as the tie rods being parallel to the lower why would you think that would not give you almost no bumpsteer. If the tie rod assembly was parallel and moved consistently with the lower then it would always be pointing to the IC

I have access to all the tool and gauges but it's a friggen daily driver street car. I have had one of the best metric circle track car fabricators in my GP and he said he has never been in a metric (G body) that sat so flat around corners. My son has a BMW 335 XI and he told me he had to really push to keep up to me on a nice windy road. Maybe I should upgrade the suspension to use bump stops like the suspension the pro late models I worked on. If I wanted to spend hours and hours I could probably take seconds off my trip to the beer store.

 

[UNGN]

And I'm pretty sure keeping the tie rods exactly parallel to the LCA will not give you 0 bumpsteer.

The only way parallel LCA & Tie rod would make zero bumpsteer is if they had the attachment points were in the same spots, and the tie rod is a little higher than the balljoint, especially with a tall ball joint...but it can be close.

Now it just depends where the LCA lower bushing is in relation to the inner tie rod.

With the B-body spindle than everyone knows has inherent bump steer, the outer tie rod is significantly lower than the ball joint:

So in this case, tall ball joint might line up the pickup points of both LCA and tie rod, making parallel LCA/Tie rod the ideal solution.

I put tall LBJ's on my B-body braked T-Type and with a Howe center link at full down, bumpsteer was virtually gone. I have since swapped this out for 12" LS1 brakes, but this summer I will probably switch back to the B-body 12" brakes.

 

[Clarmo]

As far as the tie rods being parallel to the lower why would you think that would not give you almost no bumpsteer. If the tie rod assembly was parallel and moved consistently with the lower then it would always be pointing to the IC

The inner tie rod pivot point would have to be in exactly the same spot as the LCA inner bushing pivot for your theory to work.
If your car is set up stiff and handle around corners I doubt it moves enough to affect bump steer. And really not enough for you to feel it. The fact that you’ve installed taller lowers to correct your factory camber swing issues...like UNGN explained before, is the real reason your car handles better.

“Taller ball joints will turn the bad 4 degree swing into about a good 2-3 degree swing, so if they are zero at rest, they will go to about 1 positive at full droop and around 1 negative full up. How much it changes depends on the ride height and static camber, but the camber swing is definitely smaller AND better with tall ball joints.”

 

[pontiacgp]

I worked on G body circle track cars for years. We ran on 1/4, 3/8 and 1/2 mile tracks so each track required their own set up. It's easy to make straight line speed but you need to keep that speed up though the corners to carry the speed coming out of the corner. We had to maintain the stock connection points in the suspension and leave the engine in the stock position. To rotate through a corner you need the front end planted down throughout the corner and this is a problem with the G body with it's anti dive system derived by the uneven upper control arms. The engine sitting so far forward and too high that puts too much pressure on the front outside suspension. In the G body on the 1/4 mile track we had an 1100 right front spring along with 36 mm hollow sway bar. Even with the front hoop with 4 down tubes the frame still moved on the right side. The corners were short in the 1/4 mile track so the anti dive didn't have too much effect. The 3/8 was sort of doable but the 1/2 mile we could not keep up with the 2nd gen Camaros on the track. The Camaro has no anti dive and the engine sits further back lower in the Camaro. The Camaro is also helped with the real leaf suspension over the 4 point suspension in a G body. The G body was so friggin frustrating trying to set it up to keep the nose in the ground in the corners. I put in countless hours along with the crew trying get eh G body to work and we ran up front at every track we ran at so we did something right. The other thing is setting up a car you need to have the weight of the driver in the driver seat, once you set it up if you add a passenger of two or anything in the trunk you need to set everything up again if you want to be perfect. We set our race cars to work best with less than 1/2 tank, it's amazing even with a few lbs of fuel how much that effects the car.

This is why I don't go overboard trying to set my G body up because unless I fix the issues these G bodies are born with. I tweaked the steering arm to line up the tie rods to the lower control are on the F body spindles and run 660 lbs front springs with the 36 mm hollow swaybar. The front springs are cut and I have a 1/2" tall screw in lower ball joint, the car is lowered close to 3" so the suspension doesn't travel much. I have cut 170 lbs springs in the rear with an F body sway bar and the GP seems to like that set up. I might change the upper so I can use equal length control arms but as far as moving the engine back and down that's a negative, like I said this my daily driver in the summer and with the condition of the roads I just hope nothing breaks

 

[melloelky]

This is good stuff.I was at a car club open house and started talking(ok i got cornered)to a guy that sells alignment machines throughout the state.this kids ego was so big they had to let him in through the overhead door..the only way i could get out of this conversation was to inquire about an alignment machine that would measure the bumpsteer if i could compress the suspension.he started to fumble and back petal and i was gone b*tches!! sure i wanted to know.. but i didn't really didn't want to know.you know? 🙂
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