Coilover top mounts

pdsman53 · Postby **pdsman53** » Mon Sep 03, 2018 8:42 pm

I have been researching coilovers, for my NA8 track day car...which is registered, but only to drive to and from the track.
I have been advised by a well known supplier of Coilovers....that top mounts with adjustable camber plates, are not necessary on double wishbone suspension.
I assume that it's because of the geometry, that they are not required.
Does anyone have any background info to support the discussion?

Magpie · Postby **Magpie** » Mon Sep 03, 2018 9:09 pm

In double wishbone the damper is not structural. Whereas in McPherson strut the damper is and hence the use of camber plates.

track_addict · Postby **track_addict** » Mon Sep 03, 2018 9:10 pm

Nothing to with geometry. Having adjustable top mounts has zero effect on a double wishbone set up. You need to get either offset bushings, adjustable arms or extended lower ball joints to get more camber. Luckily, these cars are some of the most raced in the world. There is endless info out there, regarding suspension set up.

Sent from my iPhone using Tapatalk

JBT · Postby **JBT** » Mon Sep 03, 2018 9:18 pm

The diagram here may help your understanding of the system.
https://grabcad.com/requests/double-wishbone-suspension-system
You could completely remove the shock and spring and the geometry won't change.

pdsman53 · Postby **pdsman53** » Mon Sep 03, 2018 9:39 pm

Thanks guys,
From your replies, I've interpreted (and correct me if I'm wrong) that because of the geometry of the double wishbone....ie the wishbone pivot point centrelines are parallel to the shock shaft centreline....hence, there is no misalignment...regardless of camber settings.

RS2000 · Postby **RS2000** » Mon Sep 03, 2018 9:42 pm

Google some diagrams or photos of McPherson strut & double wishbone suspension construction.

With struts, the spring & shock (or coilover) top mount is also the suspension top pivot point, so camber plates can be used to adjust camber.
With double wishbone, the spring & shock (or coilover) is independent of the wishbone suspension pivot points.

Nuddy · Postby **Nuddy** » Tue Sep 04, 2018 1:14 am

pdsman53 wrote:Thanks guys,
From your replies, I've interpreted (and correct me if I'm wrong) that because of the geometry of the double wishbone....ie the wishbone pivot point centrelines are parallel to the shock shaft centreline....hence, there is no misalignment...regardless of camber settings.

You are wrong. The wishbone pivot points may or may not be parallel with with the shock shaft centreline and that does not matter to anything.
MX-5s have a 'no compromise' suspension. The spring is for springing, the damper is for damping. They don't do other jobs.

manga_blue · Postby **manga_blue** » Tue Sep 04, 2018 10:26 am

JBT wrote:The diagram here may help your understanding of the system.
https://grabcad.com/requests/double-wishbone-suspension-system
You could completely remove the shock and spring and the geometry won't change.

Excellent link, JBT

and it follows from there that, with the tops of the shocks having absolutely no role in setting suspension geometry on any unequal length, non-parallel A-arm setup, that adding a strut brace to the tops of the shock towers does absolutely stuff-all to the geometry too.

greenMachine · Postby **greenMachine** » Tue Sep 04, 2018 2:31 pm

manga_blue wrote:
JBT wrote:The diagram here may help your understanding of the system.
https://grabcad.com/requests/double-wishbone-suspension-system
You could completely remove the shock and spring and the geometry won't change.

Excellent link, JBT

and it follows from there that, with the tops of the shocks having absolutely no role in setting suspension geometry on any unequal length, non-parallel A-arm setup, that adding a strut brace to the tops of the shock towers does absolutely stuff-all to the geometry too.

Ummm ... no.

Assuming the brace is actually bracing something and eliminating or reducing movement, it will stiffen the structure and/or prevent deflection when suspension/shock loads are fed in. While the geometry of that corner may not be affected directly, the geometry relative to the other corners and the car in general will be improved. Structural stiffness is A Good Thing, and more is generally held to be better.

:mrgreen:

Postby **NitroDann** » Tue Sep 04, 2018 3:15 pm

..maybe.

Both front tyres are bending the chassis to the same side, so it really needs to tie the firewall in.. but the firewall can be permanentloy deformed with your fingers so I'm not sure that helps so much on an MX5 either.

2c

Dann

hks_kansei · Postby **hks_kansei** » Tue Sep 04, 2018 6:23 pm

The strut brace is one of the most effective things to install on an MX5

It not only provides a convenient handle to rest on when working under the bonnet, but the end plates also provide a raise lip that prevents your beer from being tipped over accidentally.

noobee · Postby **noobee** » Tue Sep 04, 2018 7:09 pm

hks_kansei wrote:The strut brace is one of the most effective things to install on an MX5

It not only provides a convenient handle to rest on when working under the bonnet, but the end plates also provide a raise lip that prevents your beer from being tipped over accidentally.

and this is the only reason mine is going back on

StuwieP · Postby **StuwieP** » Mon Nov 26, 2018 9:37 pm

hks_kansei wrote:The strut brace is one of the most effective things to install on an MX5

It not only provides a convenient handle to rest on when working under the bonnet, but the end plates also provide a raise lip that prevents your beer from being tipped over accidentally.

I wasn't thinking about a strut brace until I read this.

Now it's at the top of my list.