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Re: rear stifness
[Re: crgracing]
#1220809
28/05/2011 16:24
28/05/2011 16:24
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Taz
Unregistered
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Taz
Unregistered
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the only real way to improve is by fitting a thicker rear ARB, anything else to prevent wandering at the rear is pointless, as the shell sits on a metalastic set of bushes which fit to the subframe. You "could" replace the rearmost set of bushes with Alu' items as this makes a slight difference. I do believe some others have fitted a cosmetic rear seatbelt ARB ( looks VERY OEM & well made ), some have commented that this has reduced rattles a bit... probably as the old seat belt bolts were loose
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Re: rear stifness
[Re: Scuderia]
#1220842
28/05/2011 17:38
28/05/2011 17:38
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proccy
Unregistered
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proccy
Unregistered
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a 22mm whiteline ARB has helped mine quite a bit, the front braces are good too, and i added a dedra front ARB - feels quite flat and soilid to me, but i'm no expert
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Re: rear stifness
[Re: crgracing]
#1220973
28/05/2011 23:21
28/05/2011 23:21
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Duffy
Unregistered
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Duffy
Unregistered
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I've got upper/lower front braces and a 22mm whiteline rear ARB, roll is much reduced compared to OEM.
I've also got the upper rear brace, looks nice but I suspect it doesn't do a lot more!
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Re: rear stifness
[Re: crgracing]
#1220979
28/05/2011 23:35
28/05/2011 23:35
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johnnybravoturbo
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johnnybravoturbo
Unregistered
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Strut braces make no difference despite the hype,. Although i am a fan that lots of little things make a big difference. In relative terms the chassis wont twist to the extent where 1 single bar will help.Or you'll have the seem sealant cracking and the windows popping out. A well engineered roll cage which acts as safety and as an aid to structural stability is noticeable.
Strut braces are literally cosmetic.
I run a Eibach rear roll bar,which seemed to make the front end more precise on turning. The Whiteline is a little unpredictable.
I messed about quite alot around the track with my Gaz suspension and making the back too firm induced heavy overseer and issues with braking. It also didn't inspire quick cornering as you get a feel for things after time. I found the Eibach a good all round solution to the handling with very forgiving cornering no matter how much you get it wrong,.
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Re: rear stifness
[Re: crgracing]
#1221028
29/05/2011 01:25
29/05/2011 01:25
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johnnybravoturbo
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johnnybravoturbo
Unregistered
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I disagree with the comparison to Rwd,. I outhandled a Porsche GT3 RS around Donington park and i run a FWD setup. The coupe in stock form is not an agile car on the corners. With money spent in the right places you escape the limitations of the FWD. I dont suffer with oversteer unless heavy braking into a corner in the wet. Under what circumstances does your oversteer typically appear?
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Re: rear stifness
[Re: ]
#1221083
29/05/2011 10:58
29/05/2011 10:58
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Joined: Dec 2005
Posts: 9,706 Gone
Jimbo
Je suis un Coupé
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Je suis un Coupé
Joined: Dec 2005
Posts: 9,706
Gone
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I outhandled a Porsche GT3 RS around Donington park
I think there's a big difference between outhandling and having bigger balls through the corners. A GT3 RS would show a coupe a clean set of heels every day of the week and if it was my GT3 RS, I'd be a little concerned about driving it on the ragged edge too, it would be a little more expensive to fix if you got it wrong.
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Re: rear stifness
[Re: crgracing]
#1221280
29/05/2011 18:01
29/05/2011 18:01
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jonone
Unregistered
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jonone
Unregistered
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The problem is i get big understeer in fast corners. do you not mean oversteer?...understeer in fast corners sounds a little strange? As people have said, there is a few ways to stiffen the rear of the car... rear arb, solid bushes, stiffer springs, harder dampers settings,tyre pressures etc will all change how the car feels and reacts. The rear trailing arm bearings are one thing to replace, if there is play in them they effectively give you rear steering which means oversteer!
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Re: rear stifness
[Re: crgracing]
#1221346
29/05/2011 21:15
29/05/2011 21:15
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jonone
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jonone
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Thats true in low speed bends, but high speed?
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Re: rear stifness
[Re: crgracing]
#1221413
30/05/2011 00:43
30/05/2011 00:43
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jonone
Unregistered
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jonone
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Rear arb should be top priority then!
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Re: rear stifness
[Re: ]
#1221507
30/05/2011 12:37
30/05/2011 12:37
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suba
Unregistered
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suba
Unregistered
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Thats true in low speed bends, but high speed? The same applies - a front heavy, FWD car is always going to understeer when on the power. Stiffening the rear and playing with alignment / suspension will result in lift off oversteer - so you can control what the car is doing with your right foot once it's pointing where you want it to.
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Re: rear stifness
[Re: Jimbo]
#1221563
30/05/2011 15:50
30/05/2011 15:50
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sediciRich
Unregistered
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sediciRich
Unregistered
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I outhandled a Porsche GT3 RS around Donington park
I think there's a big difference between outhandling and having bigger balls through the corners. A GT3 RS would show a coupe a clean set of heels every day of the week and if it was my GT3 RS, I'd be a little concerned about driving it on the ragged edge too, it would be a little more expensive to fix if you got it wrong. Bang on Jim, I minced a GT3RS round Donny, but the driver did not have a clue and was cleary scared, a well driven GT3 would blow a coupe into the weeds. Outhandled JBT I dont think so, if you were driving the GT3 you would blow away your own coupe lap time for sure.
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Re: rear stifness
[Re: crgracing]
#1221632
30/05/2011 19:25
30/05/2011 19:25
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suba
Unregistered
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suba
Unregistered
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When did you last have the tracking done? How did they set up the car?
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Re: rear stifness
[Re: ]
#1221677
30/05/2011 20:37
30/05/2011 20:37
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jonone
Unregistered
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jonone
Unregistered
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Thats true in low speed bends, but high speed? The same applies - a front heavy, FWD car is always going to understeer when on the power. This maybe technically true but I have never had understeer at speed? Nigel is right you should get everything checked to make sure nothing is a miss....then put the rear arb on The rear geometry is not adjustable, but in an ideal world you should set the front in line with the back, so four wheel alignment is better. The correct geometry makes a big difference on my car, so its worth getting setup properly. I have been trying to get my car to handle right for years and it is still not there, I have had my rear bearings checked and they have no play but they do have 4mm toe in on one side,I should have just changed them last time.....but I'm getting them changed soon and i'm hoping this will be the last piece in the jigsaw!
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Re: rear stifness
[Re: ]
#1221711
30/05/2011 21:39
30/05/2011 21:39
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suba
Unregistered
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suba
Unregistered
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Try turning in hard at about 80 mph with no throttle on - I promise you the car will go straight on unless you are running some very severe negative camber on the front, and a very stiff rear - even then the weight will go on the front outside wheel, and you'll go sideways when it bites. If you do the same in something mid engined the car will still go straight on, but either sideways or backwards.
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Re: rear stifness
[Re: crgracing]
#1221798
31/05/2011 00:13
31/05/2011 00:13
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suba
Unregistered
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suba
Unregistered
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LOL! I managed to get my coupe to handle as follows (with a lot of effort, and a lot of money): turn in hard with no power on (or lightly on the brakes to provoke it), rear end goes 'light' - point where you want to go before any real opposite lock is needed and power out to pull the car straight through the corner. (with a shade over 300bhp - so the rear will always follow the front when power is on) With the balance of the car and the power going through the front wheels it is very hard indeed to spin or oversteer when on the power, and understeer is inevitable. I hasten to add that these antics were all on track, I would not want to mess about as above on the road at 80mph.
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Re: rear stifness
[Re: kj16v]
#1222445
01/06/2011 17:43
01/06/2011 17:43
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suba
Unregistered
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suba
Unregistered
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Front upper strut brace makes A LOT of difference...it very easy to test this with a back to back drive with one on and then it off.
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Re: rear stifness
[Re: crgracing]
#1222653
02/06/2011 03:08
02/06/2011 03:08
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Nazo
Unregistered
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Nazo
Unregistered
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This may go against most guys experiences, but I have now changed all 4 springs from eibach to the Group Buy CountryCrusing ones.. They are more progressive and I find the rear has better handling both in corners and over bumps.
You can call them progressive springs..and they thicker then Eibachs.. Its a cheap and simple change.
I know adjustable shocks may also improve things, but everyone has different opinions.
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Re: rear stifness
[Re: crgracing]
#1223017
02/06/2011 23:09
02/06/2011 23:09
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Joined: Dec 2005
Posts: 17,367 Staffordshire
Nigel
Forum veteran
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Forum veteran
Joined: Dec 2005
Posts: 17,367
Staffordshire
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To be fair, there's only one or two people saying they make no difference and many, many people saying they've improved the handling of their car.
I've driven LOTS of Coupes, in many states of tune and chassis configuration. I think I'm well qualified to comment on what works and what doesn't.
In my humble opinion, the best handling mod you can do for a Coupe is shocks and springs, followed by an uprated rear ARB. Next comes a bit more negative camber at the front, followed closely by an upper strut brace and then my lower subframe brace. Personally, I wouldn't bother with an uprated front ARB unless you've already gone VERY stiff on the rear ARB and need to balance it up a bit.
As Gunzi suggests, I reckon if you stuck a pair of braces on a standard car, the difference would be very noticeable. Adding them to a car with a host of existing handling mods will be less noticeable.
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Re: rear stifness
[Re: Nigel]
#1223080
03/06/2011 02:41
03/06/2011 02:41
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Joined: Jan 2006
Posts: 3,034 Sweden
Per
I need some sleep
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I need some sleep
Joined: Jan 2006
Posts: 3,034
Sweden
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and then my lower subframe brace. ...or any lower subframe brace.. Yes it does make a big difference, more so than the Sparco strutbrace I'd say.
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Re: rear stifness
[Re: crgracing]
#1223236
03/06/2011 16:47
03/06/2011 16:47
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sparco
Unregistered
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sparco
Unregistered
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Mmmmm i'm very interested to hear peoples views on handling and like Nigel i reckon i am pretty well placed to pass comment, all be it however on a pure race set-up. There are fundamental things that if done will improve the handling of your coupe or any car for that matter. What you then have to do is fettle your car to how you drive. Somoe people will not like a vervous and skittish rear end on a fwd, personally i quite like it as it's much faster on track but i certainly wouldn't want this in a road car where progressive handlig on the limit especially in a FWD car is absolutely a necessity otherwise you will find yourself backward into the scenery. However there is also a school of thought where some people have completely different set-ups yet are just the same on track, this is all down to the driver. However i emphasie this is on track only. On the road it needs to be a little supple. The roads in the UK are not smooth and always contain diesel, oil and other contaminents which make the road surface very slippery when wet. Unfortunately we don't have the luxury of dry weather predominently.
I agree that the strut braces will help on their own and if teamed up with better suspension and spring ratings you will get a road car handling pretty well. Everything is a compromise and the more you fettle the less time tyres, brakes and suspension lasts before it wears out. Making something stiffer will put pressure on something else further down the chain.
I'm now running 750lbs springs on the rear of my car and 850lbs on the front, with race spec dampers, every brace known to man and some serious geometry settings. My coupe is still not the best handling FWD car in the race as newer more advanced cars such as the Seat have a better foundation to begin with and more technolgy. You can only pee with the winkle you are given so to speak.
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Re: rear stifness
[Re: crgracing]
#1223268
03/06/2011 18:54
03/06/2011 18:54
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sediciRich
Unregistered
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sediciRich
Unregistered
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Nigel recall the chassis is from the 1980's, recall what cad would have been back then and the effect that would have on iterations. The base car was not of a performance starting point, the earlier generation Leon Supercopa had custom uprights I'm darn sure the later version has even more custom items (One of these also one the eurosaloons championship a few years back), also we cannot be sure without looking what type of suspension method they are employing including the design (double wish bone perhaps) and the type of antiroll bar - bars which are far removed from the bits of wire used on our cars - I know the Alfa 156 ST has hollow bars in the 50+mm range, such that the roll resistance is mainly ARB and not springs.
The Tipo design of high outer wishbone position gives a poor force application point in regards to inner wish bone position. Also the upright will lack rigidity compared to modern designs - this is very apparent with the BMW mini such as the challenge version I picked up recently on behalf of my brother and took a look round) in the mini the lower ball joint is as low as it can be, enabling the wishbone to be far more level at ride height thus less angled in the roll.
McPherson struts may not be the worst part of the tipo design but the trailing arm might well be as there is no camber recovery in roll. I think the evolution to the 156/147 chassis shows the progression to what should be superior front double wish bone and rear McPherson struts, and if you look at those alfa you will still see the Tipo underpinnings albeit with added sections to accomodate the new suspension.
The tipo along with its coupe counterpart are very flexible chassis, with the coupe probably benefitting fromt its shape over the hatch back but they cannot be a patch on modern cars iterations between lancer evolutions show how rigidity can be increased substantially without noticably radiacally changing the shape.
The fiat is not a great place to start from or rather its original design was a mass market road car which then tried to become a sports car - fiat did do a few things Tipo to coupe like wider track, then the turbo models got substantially beefier uprights, but as you know alfa went further with the 916.
When they races the 155 d2 everything was custom, but they had to keep the same rear suspension configuration, a thorn in their side, but nothing was shared with the production vehicle aside from the chassis mounting points. This is not quite the same for the 156 ST where you can see a production front and rear sub frame (modiefed for a plate brace at the front) and modified production wish bones, the uprights again a near as custom as they can be. Although its unfair to compare home brews with factory challenge cars which the likes of the Clio cup and Leon supercopa are, developed on €100K+ budgets
850 fronts Marco!, maybe I can go stiffer! Currently 627 and tons of understeer, rear was wound up for Trevs last race still didnt seem to help.
I estimate eibachs to be 70Nmm so 400lb/ft as a guess.
Last edited by sediciRich; 03/06/2011 19:33.
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Re: rear stifness
[Re: ]
#1223273
03/06/2011 19:16
03/06/2011 19:16
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suba
Unregistered
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suba
Unregistered
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The Tipo design of high outer wishbone position gives a poor force application point in regards to inner wish bone position. Also the upright will lack rigidity compared to modern designs - this is very apparent with the BMW mini such as the challenge version I picked up recently on behalf of my brother and took a look round) in the mini the lower ball joint is as low as it can be, enabling the wishbone to be far more level at ride height thus less angled in the roll.
This is why lowering a coupe does not help make it handle - nice description Rich!
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Re: rear stifness
[Re: crgracing]
#1223388
04/06/2011 08:50
04/06/2011 08:50
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sparco
Unregistered
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sparco
Unregistered
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The standard fronts are indeed about 400lbs and the rears 350 maybe. Not sure about the Eibachs Nigel and you know how secretive Eibach are when it comes to spring rates!
Very informed reply Rich and right on the money. Technological advances in chassis design make a world of difference and even a standard modern clio or the like will outhandle a well sorted coupe. Rich i have loads of springs if you need any to try mate.
That's why i love making my car go se well, it's bucks the trend and makes people see what it is really capapble of in the right hands and with the right set-up. Yes i do have to drive it like i've stolen it but is that not just more fun again. Come and watch me through the twisty section of knockhill and there is lterally nothing any quicker down through there. That's not my own opinion that's people standing watching. That makes me proud to be competeing in my old Fiat!
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Re: rear stifness
[Re: ]
#1223420
04/06/2011 11:20
04/06/2011 11:20
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sediciRich
Unregistered
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sediciRich
Unregistered
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Suba -Well its is off set by the lower CofG, but when the angles get extreme its bad. I was upset by that mini, it had everything I wished the fiat had, no wonder they handle well.
Still the Stilo had rear beam suspension a totally retro grade step over the tipo based designs.
Marco, are they 60mm I'd like to give it a stab, I noted the lap time change you found on the front increase in rate.
Last edited by sediciRich; 04/06/2011 11:28.
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Re: rear stifness
[Re: crgracing]
#1223427
04/06/2011 11:33
04/06/2011 11:33
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sparco
Unregistered
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sparco
Unregistered
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Yes i have 60mm fronts, 650's 750's spare.
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Re: rear stifness
[Re: crgracing]
#1223438
04/06/2011 12:28
04/06/2011 12:28
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jonone
Unregistered
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jonone
Unregistered
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Std front springs are surely not 400lb?
The Gaz road/trackday kit was sold with 425lb front springs and that's rock solid on the road!
When I had the 8" 425lb springs on the front of my car all I got was a crashy ride and loads of wheel spin.
The problem with my Gaz setup is, if you use a tender spring the platform between the springs rubs against the body, so I have been forced to use one single rate spring, I have ended up with a 300lb front spring, which for me is about right on the road, I would like less body roll but when you up the poundage the ride goes to pot. My only other option is to get a dual rate or progressive spring made so you still get a decent ride.
There is a debate if the eibachs are progressive or not, maybe this is how they hide there poundage? but i will be shocked if they are more than 300lb
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Re: rear stifness
[Re: crgracing]
#1223968
06/06/2011 10:29
06/06/2011 10:29
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gassy
Unregistered
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gassy
Unregistered
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Im swapping the rear suspension on my fiat tipo for a alfa gtv remove spare wheel well tank in boot powerflex bushes it can be done to a coupe aswell tipo
Last edited by gassy; 06/06/2011 10:35.
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