Spacers & the maths of loading..!

[TimR]

It gets talked about from time to time. Increases in loading and the influence on steering....
Am I going mad though..?
Look at these pics. They show the disc ( bell face dia ) an oem wheel from behind, Pro Race ( after market wheel) and spacer etcetc...

Bear with whilst I switch to desktop to annotate...


edit- you gotta luv a rusty disc !

 

[TimR]

Lft to right-
1) standard wheel with spacer in situ ( spacer dia 147.5mm)
2) standard wheel mated face 147.5mm ( near enough)
3) spacer in situ on after market rim...clearly shy in dia by 20mm( 10mm all round)
4 )Ater market rim shows how much designed structural area is not used by the spacer ( out ring)
5) Disc with spacer in situ
6) disc with spacer in situ- clearly describes the outer ring that gets left unused by OEM wheels but that after market wheels are designed to use....

So, am I going mad because to my mind, I am not comfortable fitting rims with 167+mm dia mated area to spacers where they cover 147mmdia...when the disc bell has 167mm to offer....

What say you learned gentlemen ?

Grtzzz...!

 

[azapa]

It's just ratios. There are 3 important points - the shock mounting point, the wishbone pivot, and the distance to the hub flange, that you add distance to with the spacer. A 20mm spacer mover the point XX% out, therefore suspension will be YY% softer.

Then there is unsprung weight, with is probably a lot more compromised by bolt weight than the flange itself.

But hey, the result looks so good, that unless the car is really being stressed, makes it worthwhile to most owners.

 

[TimR]

You havent really read my question mate...!

Perhaps the most relevant pics are 3, 4 & 6...!?

 

[Zep]

I wouldn’t be too happy fitting the aftermarket wheel where the outer ring of the hub face wasn’t in contact with the brake disc or spacer face.

Given that the majority of the face is against the locating surface and it is on the spigot ring it would probably be ok, but it wouldn’t look right and so most of the time, it isn’t right.

 

[TimR]

Interesting...
That is exactly the issue Im driving at...!

My feelings too but not because of looks so much..
All the Ferrari spacers I askes about ( 108 PCD ) are the same 147mm....but I have no idea how the Ferrari wheels are(hub?)
You used to have a GS Zep...are the wheels designed with 147mm hub face..on what, 18/19" rims ?

 

[azapa]

You havent really read my question mate...!

Perhaps the most relevant pics are 3, 4 & 6...!?

true! I shuffled off and grabbed a coffee. No idea on the maths, then, but if your question is: "can i fit spacers of a diameter smaller than my standard hubs" my answer would be: I can't do the maths, but would not do it myself!

 

[Zep]

Interesting...
That is exactly the issue Im driving at...!

My feelings too but not because of looks so much..
All the Ferrari spacers I askes about ( 108 PCD ) are the same 147mm....but I have no idea how the Ferrari wheels are(hub?)
You used to have a GS Zep...are the wheels designed with 147mm hub face..on what, 18/19" rims ?

The GS wheels were (are) 19”. I never measured them but I do have an old brake disc (yes I am a clepto) and the witness marks seem to suggest the face diameter is around 151mm.

It should be noted that there is a small step in the face of the disc where the edge of the wheel would be.

 

[TimR]

true! I shuffled off and grabbed a coffee. No idea on the maths, then, but if your question is: "can i fit spacers of a diameter smaller than my standard hubs" my answer would be: I can't do the maths, but would not do it myself!

My question was “ am I mad?” - I can’t do the maths either but concur with your considered reply....

 

[Zep]

Looking again at the pics, it’s clear that on your aftermarket wheels the outer ring has not been on the hub (it looks too clean). So apart from it looking really weird, it’s probably ok.

 

[Zep]

But it will look weird.

 

[TimR]

Looking again at the pics, it’s clear that on your aftermarket wheels the outer ring has not been on the hub (it looks too clean). So apart from it looking really weird, it’s probably ok.

Well spotted...
I must take a closer look....it might be a slight relief on the disc is at play...?

 

[Zep]

Well spotted...
I must take a closer look....it might be a slight relief on the disc is at play...?

Yes, it’s only a couple of mm, but it will do. Your problem is that with the larger hub on your wheels there will be a step between the wheels and the hub which would freak out my OCD. Your results may differ!

 

[Zep]

There are a few places that will make a spacer any size you like. Google “custom wheel spacers”. Have them made bigger and apart from it being a lump of unsprung weight (and the other stuff on other threads), Bob’s your mothers brother.

 

[TimR]

Fair play...
I’m interested in why the discs have the relief machined into the face now...!