60 replies to this topic

[james_ly]

I don't think you will get any sort of objective answer from this forum. Most people just buy something, pay someone else to fit and geo it and have a polarised view that their setup is best.

 

After 100+ hours of geoing + spring rate testing my personal advice is stick to close to the OEM ride heights as possible.  As you are keen on mainly tracking it maybe step up 25% to 45% on spring rates, but if you want to absorb those undulations on the tarmac on Folly and Avon Rise I think going stiffer would be unwise.

 

As a pre-cursor, when you go to the track next time, you could do some fast laps with your current setup, come back in and crank the rebound rates up say 4 or 5 clicks on your coilovers - you will be shocked at how much effect it has I am sure.

 

I think there's some misinformation here. The higher spring rate cars are obviously faster on track, any of the race series are evidence of that. As for Castle Combe, well Folly isn't really a corner and while you may lose time over Avon Rise, you'll gain at all the other corners as the rest of the track is smooth.

 

Finally, you can fit these to sort the bump steer when you lower https://www.elisepar...-raiser-plates/  

[WrightStuff]

Are the raiser plates standard on the VXT ?

[siztenboots]

Are the raiser plates standard on the VXT ?

 

yes

[Nev]

I think there's some misinformation here. The higher spring rate cars are obviously faster on track, any of the race series are evidence of that. As for Castle Combe, well Folly isn't really a corner and while you may lose time over Avon Rise, you'll gain at all the other corners as the rest of the track is smooth.

 

Finally, you can fit these to sort the bump steer when you lower https://www.elisepar...-raiser-plates/  

 

 

What spring rates do you have on your car?

 

Those raiser plates are just 2 or 3 mm, they do naff all really if you consider people/the OP are lowering their cars by up to 40mm. Even the EP adjustable bump steer arms only allow a 10mm change.

 

The only really substantial off the shelf parts to correct the wishbone angles when lowering your car is either the EP GT hubs or the Nitron Race hubs which raise the hub 40mm vertically. Both are extremely expensive though.  

Edited by Nev, 03 January 2017 - 11:15 AM.

[james_ly]

 

I think there's some misinformation here. The higher spring rate cars are obviously faster on track, any of the race series are evidence of that. As for Castle Combe, well Folly isn't really a corner and while you may lose time over Avon Rise, you'll gain at all the other corners as the rest of the track is smooth.

 

Finally, you can fit these to sort the bump steer when you lower https://www.elisepar...-raiser-plates/  

 

 

What's your spring rates then on your NA?

 

Those raiser plates are just 2 or 3 mm, they do naff all really if you consider people/the OP are lowering their cars by up to 40mm. Even the EP adjustable bump steer arms only allow a 10mm change.

 

The only really substantial off the shelf parts to correct the situation of lowering your car is either the EP GT hubs or the Nitron Race hubs which raise the hub 40mm vertically. Both are extremely expensive though.  

 

 

Sorry forgot the Turbo had the raiser plates as standard. They raise the NA rack by 10mm which does make a difference. NSS are 350/450, which is about halfway between the Bilsteins and the higher spring rate NTRs.  

[Nev]

The riser plates are not 10mm, I have a pair in my garage, can take a photo of them next to a ruler or with a vernier on them if you insist.

Edited by Nev, 03 January 2017 - 11:16 AM.

[Exmantaa]

Raising the rack a few mm's has a considerable effect on the bumpsteer behaviour and has no relation to the mm's you lowered your car.

Re-read Alex' extensive work on VX bumpsteer behavior and maybe suspension kinematics of a doubble wishbone suspension in gerneral...

Edited by Exmantaa, 03 January 2017 - 11:18 AM.

[Nev]

Raising the rack a few mm's has a considerable effect on the bumpsteer behaviour and has no relation to the mm's you lowered your car. Re-read Alex' extensive work on bumpsteer behavior...

 

I have read all his good stuff and I have done all my own investigation on this, in depth, both on paper and in practice and probably spent upwards of 100 hours making changes and experimenting many many different combos.

 

I can tell you for sure that raising the centre of the rack 2mm will not compensate for a 40mm ride height drop! Even forgetting the effect of the rack arms on the toe in, just think of the effect of the wishbone angles starting at a far higher angle (due to lowering). No amount of adjustment on the rack height will ever have an effect on this matter, as the wishbone angle is affected by the ride height (and not the rack height).

 

Edited by Nev, 03 January 2017 - 11:26 AM.

[Exmantaa]

I'm just stating that a 40mm drop in ride height does not relate/can be compensated with a "40mm higher steering rack placement". These do not directly relate.

Things become far mor complex once lowered beyond a certain point, as the wishbones angles and roll centre become plainly wrong. As Alex perfectly demonstrated with his bumpsteer curves.

Edited by Exmantaa, 03 January 2017 - 11:31 AM.

[james_ly]

The riser plates are not 10mm, I have a pair in my garage, can take a photo of them next to a ruler or with a vernier on them if you insist.

 

I fitted them at the weekend and had to push the rack up by about 10mm.

 

According to Eliseparts it's 8mm actually... https://www.elisepar...-raiser-plates/  

[alexb]

The difference is that the raiser plate changes the geometry and hence the bumpsteer curve. Lowering changes which part of the curve you actually use. Or perhaps better, it changes the origin. The springs determine the interval (bump-droop) of the curve that you use. As long as you're in an approximately linear part of the curve, you're kind of OK. The part where it becomes interesting is where the curve swings back on itself (you have a positive change in toe up to a certain point and after that it turns into a negative change). In the rear that's used to get some kind of steering rear wheel action when one side is in bump and the other in droop (i.e. cornering). BTW, in such a situation where one side is in bump, the other in droop it's called rollsteer, not bumpsteer. In the front you can use it to change Ackermann angles, as Exmantaa and I have discussed quite a while ago. Issue with both bump and rollsteer is to know what you're doing

[siztenboots]

illustration I did a while back , I can't remember if its front or rear , but it looks like front characteristics

[Exmantaa]

That's the rear Lotus Elise curve. And of an S1 if I'm not mistaken, so the VX rear curve may look slightly different. (Alex?)

 

You have to look to the toe in/out gain from the relative ride heigt position. as the static geo settings is done at your set right height.

Take +20 / - 30mm bump travel from that ride height position and you will see a very different toe-behavior from the OEM height or Aimy's height. Especially in the droop part, where at -30mm droop the OEM sees only -0.1mm toe change and Aimy will see almost -0.4mm change.

Edited by Exmantaa, 03 January 2017 - 01:30 PM.

[siztenboots]

That's the rear Lotus Elise curve. And of an S1 if I'm not mistaken, so the VX rear curve may look slightly different. (Alex?)

 

You have to look to the toe in/out gain from the relative ride heigt position. as the static geo settings is done at your set right height.

Take +20 / - 30mm bump travel from that ride height position and you will see a very different toe-behavior from the OEM height or Aimy's height. Especially in the droop part, where at -30mm droop the OEM sees only -0.1mm toe change and Aimy will see almost -0.4mm change.

 

yes , you are 100% right, I look again now and see bump gives toe-in , the opposite of front

[The Batman]

Superior s1

[CHILL Gone DUTCH]

Superior s1

 

mmmmmm

[Foxy]

I remember when we used to talk about ginsters pasties...

[Ormes]

...all I did was start yet another "which suspension" thread.

[smiley]

...all I did was start yet another "which suspension" thread.

 

Try again. Now with brake pads.

[The Batman]

or with backbox's

 

having had most shocks currently available my favourite where nitron NTR and im waiting for a set of them or 2 ways to come up for sale and i will move back as im not a fan of quantums

Edited by The Batman, 03 January 2017 - 08:48 PM.