Ball Joints

[Gen1GT]

My Protege has McPherson struts, and has been lowered with H&R springs. I was wondering if anyone knows of an easy way to correct the geometry of the lower ball joint/control arm. Are there longer ball joints I can get? Maybe a spacer plate between the ball joint mount and the control arm?

[ScotcH]

My Protege has McPherson struts, and has been lowered with H&R springs. I was wondering if anyone knows of an easy way to correct the geometry of the lower ball joint/control arm. Are there longer ball joints I can get? Maybe a spacer plate between the ball joint mount and the control arm?

Not sure about mazda specific, but on BMW aftermarket parts exist to make the link longer. If it is the tie rods that are off, you can replace the ball join end with a sperical end and add spacers below the bearings.

[thgear]

much talk has been given to balljoint extendters and what not in the VW community and the general conclusion by some of the more respected engineers was that extention of the balljoint itself by either spacers or what not is dangerous and puts undue stress on the whole system.

raising the car or obtaining custom made spindles is perhaps the only real way to fix the problem. As such there is ac ompany that makes said custom spindles for VW's, not sure if there is such an option of Mazda.

also what matters more is where the balljoint attaches to the HUB for geometry changes to take place, not so much where it is mounted on the control arm.

as the imaginary movement of the control arm does not change the camber curve with the spacers in place.

[rmicroys]

much talk has been given to balljoint extendters and what not in the VW community and the general conclusion by some of the more respected engineers was that extention of the balljoint itself by either spacers or what not is dangerous and puts undue stress on the whole system.

Eh? Respected engineers do this... even VW ones. This is an image from the VW Motorsport catalog for a Mk3 rally kit car from VW. It shows adjustable, caster, tie rod and lower ball joint attachments to the spindle... not sure why this isn't considered 'acceptable' if engineered appropriately if the factory supports it by making the parts.

parts 9/10 are sold in various lenths to space the lower ball joint. part 13 has a number of different sizes to space the tie rod joint up and down, and part 16 is used to adjust the caster. Completely adjustable by components, not the spindle.

http://www.mco.org/cms/modules/coppermine/albums/userpics/10391/front_spindle%7E0.jpg

[Gen1GT]

The H&R springs are only 1.5"-ish drop, so it's not a horrible change in geometry. But if Mazda can do one thing right, it's design a chassis, and I wanted the firmer springs/lower CoG, but I didn't want to screw up the stock geometry too much.

Anybody have any ideas? I'm more concerned with positive camber during hard cornering, than I am with roll-centre.

[Gen1GT]

Thanks for that rmicroys. I'm having a hard time figuring out the schematic and how it attaches to the ball joint, however.

[thgear]

you should be more concerned with the roll center than the camber!

1.5 inches is alot, remeber that the instant center is a result of triangulation, 1.5" creates a significant angle change!

i dont know about Mazdas, but on an MK4 VW 1" of drop already puts the roll center below the ground

if i were you, i would buy coilovers that allow a free range of movement, the set i have from ground control, i can move my car +2 or -2 inches.

so i raise the front end, while increasing spring rate, thereby reducing the tendancy to roll, while increasing the fight against roll.

a car that will roll less will need less camber to function,

but hey... its your car.

[thgear]

Eh? Respected engineers do this... even VW ones. This is an image from the VW Motorsport catalog for a Mk3 rally kit car from VW. It shows adjustable, caster, tie rod and lower ball joint attachments to the spindle... not sure why this isn't considered 'acceptable' if engineered appropriately if the factory supports it by making the parts.

parts 9/10 are sold in various lenths to space the lower ball joint. part 13 has a number of different sizes to space the tie rod joint up and down, and part 16 is used to adjust the caster. Completely adjustable by components, not the spindle.



well, for a rally car maybe, again i deal mainly with MK4, maybe the MK3 design is more robust.

plus if it was really that simple the guys that created the Spindle kit probably would have sold this kit instead, so..

btw its www.h2sport.com there pretty big and dont fool around, and their prices are pretty damn competetive all things considered, so its not like there doing this for a cash grab.

[Gen1GT]

The strut mount is not at an extreme angle at all(not like Mustangs or anything), although I should really figure out the geometry on my car, so I know what I'm working with.

[thgear]

food for thought.

http://forums.vwvortex.com/zerothread?id=650333&page=2

it gets more technical later on... granted this is for MK1's but yada yada yada.

and if you want to figure out your geometry, its pretty complicated since you have to measure alot of stuff, but a very quick way to check where you are in the grandscheme of thigns is just to measure your control arm connection poitns and upper strut conencting point

then you gotta figure out your cars center of gravity....

http://www.miracerros.com/mustang/t_roll_center.jpg

[Gen1GT]

Is that VW suspension? If so, yikes! That's like Mustang design. Remember, I'm on a McPherson strut, so the changes to instant centre won't be that bad.

[max attack]

I made my own roll center correction spacers for the front of my AE86 corolla,not sure how the front strut/control arm is on the protege but any machine shop should be able to help you out.This assumes of course that it's possible to place a spacer at that location.I built mine with an offset to widen the front track and make crazy camber possible if you wanted to(which you don't btw :) )
If your going to do this you'll want to make the block thickness the same or close to the amount of your drop.I built mine so the lower control arms are parallel with the ground,also look to make you steering arms parallel with control arms to limit bump steer.

[thgear]

Is that VW suspension? If so, yikes! That's like Mustang design. Remember, I'm on a McPherson strut, so the changes to instant centre won't be that bad.


um.. that IS a macstrut in the picture...

[Gen1GT]

um.. that IS a macstrut in the picture...

No it isn't. The spring and the damper are completely separate in that pic.

[ScotcH]

No it isn't. The spring and the damper are completely separate in that pic.

You're right, but it does not change the geometry, only the rate required on the spring to get the same wheel rate as true coil-over macstrut. I'm sure there is a technical name for that design, but the point is that it's not a double A-arm guess :)

[thgear]

No it isn't. The spring and the damper are completely separate in that pic.

Scotch is right

where the spring is does not matter, in fact no, VW's have the spring and damper in one unit, but the way the geometry works is still the same.

cars with the macphearson design, ie, single control arm attaching to the spindle, attaching to a damper, attaching to the body, suffer greatly when lowered, lower CG or not

therefore if they are lowered proper steps must be taken to restore initial geometry, otherwise youve done nothing to truly improve the ultimate performance of your vehicle.

[CobraStang]

I'm sure there is a technical name for that design, but the point is that it's not a double A-armModified MacPherson Strut

[ScotcH]

Modified MacPherson Strut

Lol ... yeah, like I said ... some very technical name :)

[rmicroys]

Thanks for that rmicroys. I'm having a hard time figuring out the schematic and how it attaches to the ball joint, however.

http://www.mco.org/cms/modules/coppermine/albums/userpics/10391/front_spindle%7E0.jpg

The diagram is a little complicated. There are two systems on that image. A gravel and a tarmac system (with caster).

The lower a-arm is held in right at the very bottom between part 9 (spacer) and 10 (bolt). 10 attaches to the bottom of the spindle.

Gravel:The steering rack arm is held in between the two #13 parts, held in to #8 which bolts to the spindle.

Tarmac: The steerring rack arm is held on the end of the #16 part by the #12 bolt and #13 spacer. 16 seems to bolt up under the spindle.

[Gen1GT]

I measured my suspension angles. My struts mount at 3° down toward the engine, and my lower control arms are about 6° down and inward. Sounds to me like the instant centre will be above the ground still, but quite far out if I were to draw it. I forgot to measure the distance from the strut mount to the ball joint though.