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libra springs 
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post libra springs
i touched on a subject the other day on suspension but thought i would expand on what has happened.

i presently have protech shocks all round the car with 8" 250lb springs 2.25id at the front and 12" 450lb springs 2.25id at the rear.
The arb's are set for the middle settings ish and i always thought it was a little soft for me. I have been reviewing the elise/exige forums for input and so based on the information calculated i decided buy 400lb springs for the front and 600lb springs for the rear's with the same spring lengths. On first drive i thought the rears felt about right but the front was absolutely wrong. On power the nose would lift and then bounce when off power and don't get me going about going around corners, i think i was going to write the car off "LETHAL".
i then proceeded to change the fronts to 300lb springs with the arb's set fully out with the shocks set to the minimum, this felt absolutely perfect for me in always but the rears felt wrong. I have just received 500lb rear springs and was going to adjust the rear arb's to the maximum with the shock set at soft as well. I shall fit these springs tonight/tomorrow and give more feedback on the results. i am hopeful to find what i think is a high performance setting for the road and then if i complete a track day i set the shocks to fully to the right at a hard setting and will find a very good optimum.

Remember this is just how i like it, but doesn't mean this is right for everyone but thought it was worth discussing what others feel and what they have on they're cars

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Tue Mar 15, 2016 4:29 pm
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Joined: Mon Jul 13, 2015 6:32 pm
Posts: 535
GTM: Libra
Post Re: libra springs
Interesting. I find car set up fascinating which is why I do think I'll install ARB's to my car (either now or soon after the car is roadworthy), it'll help to find the right balance for me.

Sounds like you are homing in on a good set up for you and we're all different as you say. When you say that you have the front ARB fully out does this mean the drop links are as far towards the hub as possible and thus fully hard? In most circumstances with a mid-engined car you'd find the rear bar set softer than the front will be the way to go but obviously roll bar design, spring rate, damper settings all have an influence and mean whats usually the norm may not be right on your car.

Looking forward to see how you get on with the 500b rear springs and full hard rear ARB setting. Also, try and find a road with a few undulations and give it some beans to see how the car behaves - you may find that quite stiff springs will need a bit more damper stiffness to control oscillations when things get a bit bumpy. Very stiff ARB settings would tend to make the (uncontrolled) oscillation worse.


Tue Mar 15, 2016 9:07 pm
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
Yes as far to to hubs as possible. I found on a track the rear suspension travelled to much which also upset the rear balance on cornering and the nose lifted to much on the opposite corner causing oversteer to easily, I trying to find the optimum

I changed the rear springs and adjusted the arb's at the rear, so will hopefully take it for a spin soon

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Thu Mar 17, 2016 12:34 am
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Location: Kano north Nigeria
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Post Re: libra springs
madmazturbo wrote:
Yes as far to to hubs as possible. I found on a track the rear suspension travelled to much which also upset the rear balance on cornering and the nose lifted to much on the opposite corner causing oversteer to easily, I trying to find the optimum

I changed the rear springs and adjusted the arb's at the rear, so will hopefully take it for a spin soon


Delete taking it for a spin :roll: keep it pointing where you want to go
John


Thu Mar 17, 2016 4:09 am
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
lol,
I took the car for an enthusiastic spin to work today and i think the springs are about right now and i'm happy with the handling now. It seem to have enough travel on the springs but also dampens well enough to absorb the crappy roads we drive on.

Just have get the tracking right and look at the cambers/castor angles again before i get it done :roll:

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Thu Mar 17, 2016 5:11 pm
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Joined: Mon Jul 13, 2015 6:32 pm
Posts: 535
GTM: Libra
Post Re: libra springs
Sounds like you've arrived at a good set up :)

Should be able to lay down the supercharged power better now :lol:


Sun Mar 20, 2016 10:24 am
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
It is a lot better around long bends now, plus it only spins a little in first now on the straights.

So I had to give a 0-60 blast just for a laugh up and down an empty industrial estate with my mate with a timer in the passenger seat. I am happy to say it works out just over 3seconds but definitely under 3.5seconds.

Very quick :twisted:

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Sun Mar 20, 2016 10:36 pm
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Joined: Sun Oct 19, 2014 10:10 pm
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Location: Bristol
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Post Re: libra springs
madmazturbo wrote:
It is a lot better around long bends now, plus it only spins a little in first now on the straights.

So I had to give a 0-60 blast just for a laugh up and down an empty industrial estate with my mate with a timer in the passenger seat. I am happy to say it works out just over 3seconds but definitely under 3.5seconds.

Very quick :twisted:


That is proper quick! That is megabucks supercar territory!


Sun Mar 20, 2016 10:42 pm
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
It also explains how I was able to pull away from a gt3 Porsche with ease :D

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Sun Mar 20, 2016 10:54 pm
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Joined: Mon Jul 13, 2015 6:32 pm
Posts: 535
GTM: Libra
Post Re: libra springs
Jesus...as Sanz says, that is proper quick..

What sort of power does your beastie have out of interest? It must have some Mumbo as the Aussies would say.


Mon Mar 21, 2016 1:15 pm
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
:lol:
It's as slow as i can make it and is running 9psi boost from the rotrex making 350bhp i can't remember the torque exactly but was around 240lbft

link below running up in 4th gear on you tube from about 30mph to 130mph

https://www.youtube.com/watch?v=3xef1_Senyc

I don't want anymore power than what i have as it is bordering on to much or exciting as it is.

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Mon Mar 21, 2016 1:35 pm
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Joined: Tue Oct 30, 2007 8:44 am
Posts: 655
Location: Chester le Street
Post Re: libra springs
A few years back I did the full calculations for Libra spring rate using data from Bob Snooks car and the formulae from Alan Staniforths excellent books on suspension design.

It was published on this (earlier) forum and was also stolen by Team GTM and appeared on their forum.

Somebody out there may still have a copy?

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Tue Mar 22, 2016 7:38 pm
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Post Re: libra springs
gtmdriver wrote:
A few years back I did the full calculations for Libra spring rate using data from Bob Snooks car and the formulae from Alan Staniforths excellent books on suspension design.

It was published on this (earlier) forum and was also stolen by Team GTM and appeared on their forum.

Somebody out there may still have a copy?


I'm afraid it may have been me who "stole" the information. I'm sorry for that :oops: It was just too good not to share :D

The original thread

spring-rate-length-t271.html


Tue Mar 22, 2016 9:21 pm
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Looking like a GTM

Joined: Sun Apr 04, 2010 10:11 pm
Posts: 230
Location: Cwmbran, South Wales
GTM: Libra
Post Re: libra springs
That's a good write up :shock:

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Colin


Spin up the Rotrex

GTM Libra Honda 2.0l rotrex type r
Mondeo Titanium x sport 200
BMW 320d M Sport


Tue Mar 22, 2016 10:23 pm
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Joined: Tue Oct 30, 2007 8:44 am
Posts: 655
Location: Chester le Street
Post Re: libra springs
Thanks for finding that series of posts.

So there you are. According to the data supplied by Bob the calculated spring rates to give a Libra a ride on the firm side of sporty should be

200 lb/in Front
320 lb/in Rear

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Tue Mar 22, 2016 10:53 pm
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