Ball joint extenders (split from Motorsport Kit Porn thread)

Out of interest has anyone completed a full check of camber, castor, and bump steer readings / changes before and after these were fitted?

 

Not complete but bumpsteer definately had to be addressed. The 1.5" extenders from the group buy were too short with my added castor. I ended up purchasing longer ones to get the tie rod ends in a usable position under the hub pick ups. Castor reduces as does camber but not by much.

Gurds

 

No, but it's part of the plan for the rebuild.
Plan is build car, check geo, then add extenders, check geo.
However, I have the shorter ones Gurds mentioned, so may need to change mine as well.

daved has kindly drawn up the standard wide track geo I'm using, bar a couple of measurements I need to take when the cars built. Hope to use that as a basis for working the rest out. Somehow. Not sure how yet.

 

Double checks yours Alex as the mk2 platform hardware will possibly have different extender requirements.

Gurds

 

Alex.

I'll stick some extenders on the drawing, and, lower the suspension an identical amount. If you so wish?

Exactly how much extension do your's have?

Dave.

 

Really confused now,so are we right in saying that the GB ones which I had mine painted in Red Oxide are ok as long as regularly checked?

 

Hi Dave

The ball joint is lowered 1.5" according to the website. I don't have to hand to measure. I actually have no idea where they are.

The complication is that these require comp brake tie rod ends, which I haven't got yet. These are then mounted under the hub arm instead of on top.

So you would need to measure the thickness of the compbrake tie rod end, the thickness of the hub arm where this bolts on , and allow for machining of a shoulder in to the arm.

Or you can assume that the tie rod and hub are 1.5" as well, but you know as well as I do that assuming only makes an ass of u and me...

Anyone know the thickness of the tie rod end balls?

 

ive always pondered about ball joint extenders. What do you really have to do in order to fit these and not bugger all the geometry up?

 

What about cars that raise the top mount area? Seen quite a few of those.

 

Things is with all these mods is subject to requirement. If you want to run a car very low, you must look at wishbone angles and suspension travel. Both these elements are crucial to good handling. If the height you lower to isn't that much compared to OE and these elements stay in a usable range then extenders and top mount extension are a waste of time. A mk1 in factory trim is actually very high with lots of arch gap. Once you get into asthetically pleasing levels of lowering, you end up with little to no suspension travel and bad geometry.

Gurds

 

This is done so that the amount of bump travel is increased on very low cars.
You would still need to do the ball joints on this mod to sort out the geometry if you lowered it enough.

 

The point is to correct already buggered geometry from lowering the car a lot.
The car is designed to run 6" off the ground (for exemple). If you lower it 2" you've completely changed where the suspension travel starts from. Even though you can correct the camber and toe at this level, you can't fix the bump steer and track changes that will occur when going over bumps/cornering/etc. The ball joint extenders go a long way to fixing this.

 

This was a quick scribble I put together a few years back:



The outer tips of the w/bone and steering arms change position fractionally as they move through their respective ride height arcs (arrowed, exaggerated). They do this at a different rate to each other due to different inner mount points and different lever length.

So they are not in synch throughout the arc they scribe. As the suspension moves, the toe alters, without any active steering wheel input (but are factory set to minimise the effect).

Standard ride heights mean the ride positioning be optimised at the centre of the arcs, enabling least change throughout the suspension articulation. It's no coincidence then that people will say run the arms parallel to the ground, ie at the centre of the arc they travel through. Just below makes sense too, as the rate of change as the arcs go over-centre will be minimised by definition (there are other set up theories which argue against this, btw).

As per comments above, drop the car radically, cue wishbones pointing upwards and into a more sensitive range, becase the angles are already way over centre.

(This ignores roll centre / CofG physics, which are an additional study on top of all this).

 

Just to put this up - the Roma Tuning Golf - which adds to the confusion!

 

ok, i understand that (i should have put "further" at the end of that sentance). So apart from the balljoint extenders, what else would need to be done to realign the geometry? Ive read posts regarding flipping tierod ends and sorts of things- im not referring to stupidly low cars that are all about how quickly you can crack your sump

 

Basically you want the suspension arms and tie rods to be as closed to horizontal when the car is on the ground, and also as close to parallel as possible.

If you use the extenders, you are moving the arms down, but this doesn't affect the tie rods.
The most common thing to do is get comp brake tie rods, and mount them below the hub. You need to ensure that the distance the ball joint is moved down is the same as the distance the tie rod is moved down.

Then get geo reset and you've done as much as is realistically possible.

 

Here we go Axel.



Do you think top mounts will enjoy this happening for long!?

 

I for one think the most aesthetically pleasing cars are those on stilts!

The Safari Porkers being the ultimate!