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Has any one had experience of using the spacers and are they a benefit to the handling? There are two sizes 20mm fast road and 30mm race, I think 20mm would be the choice for a Hillclimb car. Your opinions and experiences would be appreciated. Many thanks.

It’s hard to argue against the physics. Whether it’s noticeable or not? Who knows!

My intial thought is it would totaly screw the ball joint articulation and affect driveshaft running angles as well but am I missing something
Graham

My thoughts too Graham. It's totally lost on me!! Do you put a pair onto each side or what? I'm not the brightest light in the mechanical engineering box so need a guided tour.......

Wouldn’t these lower the centre of gravity, a bit ?

They are intended to be fitted to the lower ball joint to lower it's centre, reduce the King Pin Angle and lower the roll centre of the car - I haven't actually run the numbers to see if this is true or not.

If fitting these, if it's not in the instructions, you would most definitely need to puck up the rebound stop and if dialing in any extra negative camber, by a fair bit to stop the lower ball joint from getting snapped off.

If the theory on which these work is real and worthwhile, a smarter approach would be to have a new hub cast extending out the lower ball joint and then machining it's mount to a corrected angle.

The theory of Roll Centre

http://www.thecartech.com/subjects/auto ... Center.htm

I don't think these would alter driveshaft angles when fitted to the bottom, but I would suspect some slight change in ball joint to lower arm angle. But then if you have already lowered your car with Hi-Los you have already changed the drive shaft angle and adding 20mm to the lower part of the hub would put the lower arm and ball joint back towards there standard angle.

Here’s a picture of the lower ball joint spacers that are fitted to my estate. They’re Mondo Sport but are the same in operation to the Owens ones.
As mentioned above they push the lower arm down back towards its standard position in order to correct the roll centre. The spacers pictured in the first post and two different length options so you have one length or the other depending on you ride height and requirements. I believe they were developed for Miglias that must use standard hubs hence them being a bolt on part rather than a fully redesigned upright.

Thank you everyone for the replies

Lowering the lower ball joint will raise the Roll Centre slightly.

I thought these spacers were intended to reduce Bump Steer (I haven't checked the geometry, though)?

andy1071 wrote:Lowering the lower ball joint will raise the Roll Centre slightly.

I thought these spacers were intended to reduce Bump Steer (I haven't checked the geometry, though)?

Isn’t that when you space the track rod end to get them level at rest?

bump steer will change a large amount with a caster angle change

The Bump Steer changing with caster change is due to the height change of the Track-rod End relative to the Upper and Lower Ball-joints (think of the Knuckle/Hub Carrier rotating when looked at from the side of the car -the Track-rod End tends to move more in the vertical direction than the Ball-joints).

Changing the height of the suspension (and nothing else) will not change the Bump Steer.

When viewing the suspension from the front of the car, the relationship between the suspension Arms and the Track-rod controls the bump steer
-the relationship between the wishbone inner joints and the steering rack inner ball, and the relationship between the outer ball joints and the Track-rod end
(the height tends to be more critical than the sideways position)

If the steering rack was at the same height as the upper wishbone inner joint, then the track-rod would be at the same angle, and in-line with, the upper wishbone.
Similarly, if the steering rack was at the level of the lower wishbone inner joint, then the track-rod would be at the same angle, and in-linewith, the lower wishbone.
So when the Steering rack is positioned somewhere inbetween, the Track-rod angle should be proportionally between the wishbones.

Hope this makes sense?
I have tried to find a good picture on the web, but without success.

The positions I describe are the "starting positions" when designing the suspension, and usually the position of the Track-rod End is moved to change the bump steer.
Moving it up and down tends to have a large effect, and moving it in and out tends to have a smaller effect.

Moving it 9mm sounds like a very large amount (having said that, it is desirable to try and making the position less sensitive to change, to allow for production tolerances), but I wouldn't necessarily say it is wrong.
-As a reference, the Lotus Elan is VERY sensitive to Steering-rack height position -to 1 or 2mm!

Please remember that these are not absolutes, all suspension systems are a compromise and balancing act of all the different factors (I have only talked about a few here...! )