Fiat Coupe Forum
- Founded by Kayjey & James Northam
- Funded by the Club for the benefit of all owners
Fiat Coupe Club UK
join the club
Fiat Coupe Forum
 
» Announced
    Posting images


» Related sites
    Main club site
    fiatcoupe.net


» External data
    owners listed
 
Who's Online Now
1 registered members (Echodelta), 118 guests, and 1 spider.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums69
Topics113,608
Posts1,341,205
Members1,802
Most Online731
Jan 14th, 2020
Top Posters(All Time)
barnacle 33,561
stan 32,122
Theresa 23,300
PeteP 21,517
bockers 21,071
JimO 17,917
Nigel 17,367
Edinburgh 16,812
RSS Feeds
Club Events
Club Information
Track Events
Rolling Road/RWYB
Social Events
Non-UK Events
Coupé Related Chat
Coupé Spotting
Coupé News/Press
Buying/Selling Advice
Insuring a Coupé
Basic FAQ's
How to Guides
Forum Issues
Technical Problems
General Maintenance
Styling
Tuning
Handling
ICE and Alarm
Coupés for Sale
Coupés Wanted
Parts for Sale
Parts Wanted
Group Buys
Business Forum
Other Vehicles for Sale/Wanted
Other Items for Sale/Wanted
Haggling/Offers
Ebay links
Other Cars
Other Websites
General Chat
Previous Thread
Next Thread
Print Thread
Page 1 of 2 1 2
rear stifness #1220730
28/05/2011 12:32
28/05/2011 12:32
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Well as i have my coop dismantled waiting for the bits to arrive, im thinking of getting a upper and lower strut brace, but what about the back? Less weight and less stifness att the back = understear right? So if thats the case ( i imagine if not wrong) how would we get the rear stiffer to perform better? So much stifness in the front should cause the rear to bounce as ther is no weight or braces that can make it equal to the front?

I was thinking about it because the front is ok and there are loads of things to do to get better grip , but the rear?

Re: rear stifness [Re: crgracing] #1220809
28/05/2011 16:24
28/05/2011 16:24

T
Taz
Unregistered
Taz
Unregistered
T



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 laugh

Re: rear stifness [Re: crgracing] #1220833
28/05/2011 17:17
28/05/2011 17:17
Joined: Nov 2006
Posts: 1,580
Melbourne, Australia
Scuderia Offline
My life on the forum
Scuderia  Offline
My life on the forum

Joined: Nov 2006
Posts: 1,580
Melbourne, Australia
Stiffness in the chassis is a different thing to stiffness in the suspension. Strut braces should stiffen the chassis only. This does not change the balance of the car as such; it just stops the suspension points from moving relative to each other. This lets the suspension work better overall; not specifically give more or less grip.

Suspension changes with a stiffer chassis will have a more precise and predictable effect.

Re: rear stifness [Re: Scuderia] #1220842
28/05/2011 17:38
28/05/2011 17:38

P
proccy
Unregistered
proccy
Unregistered
P



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

Re: rear stifness [Re: crgracing] #1220973
28/05/2011 23:21
28/05/2011 23:21

D
Duffy
Unregistered
Duffy
Unregistered
D



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!

Re: rear stifness [Re: crgracing] #1220979
28/05/2011 23:35
28/05/2011 23:35

J
johnnybravoturbo
Unregistered
johnnybravoturbo
Unregistered
J



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,.

Re: rear stifness [Re: crgracing] #1221014
29/05/2011 00:29
29/05/2011 00:29
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
trying to get the best stability on the car dosen´t mean have better grip, but it is asosiated. so where do we start from? as for all these facts what i can´t still understand is , why all this elements for the fornt and not for the back ? thats where the coop needs it right? geting all the weight and traction up in the fornt suerley we will need to get the rear sorted.what im trying to say is get it all balanced front+rear . i now weight problem is actually imposible unless we have the cash to make a RWD. getting all the cash spent on the fornt wont make us get more stability form the rear or will it?

"This does not change the balance of the car as such; it just stops the suspension points from moving relative to each other. This lets the suspension work better overall; not specifically give more or less grip"

wich means it won´t help on understeer or oversteer then?
as for the problem on the coop "in my case" is that understeer has been reduced by konis , new arms ,actually new everything, and i would like less. But oversteer is quite bad, so get that sorted if the rear is stiffer you get better stability wich means extra grip ??

Re: rear stifness [Re: crgracing] #1221028
29/05/2011 01:25
29/05/2011 01:25

J
johnnybravoturbo
Unregistered
johnnybravoturbo
Unregistered
J



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?

Re: rear stifness [Re: ] #1221083
29/05/2011 10:58
29/05/2011 10:58
Joined: Dec 2005
Posts: 9,706
Gone
J
Jimbo Offline
Je suis un Coupé
Jimbo  Offline
Je suis un Coupé
J

Joined: Dec 2005
Posts: 9,706
Gone
Originally Posted By: johnnybravoturbo

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.

Re: rear stifness [Re: crgracing] #1221102
29/05/2011 11:55
29/05/2011 11:55
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
The problem is i get big understeer in fast corners. Accelerating in th corners i get a loss of traction but quite normal for a 300hp fwd.

Re: rear stifness [Re: crgracing] #1221280
29/05/2011 18:01
29/05/2011 18:01

J
jonone
Unregistered
jonone
Unregistered
J



Originally Posted By: crgracing
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!

Re: rear stifness [Re: crgracing] #1221329
29/05/2011 20:30
29/05/2011 20:30
Joined: Dec 2005
Posts: 9,706
Gone
J
Jimbo Offline
Je suis un Coupé
Jimbo  Offline
Je suis un Coupé
J

Joined: Dec 2005
Posts: 9,706
Gone
The coupe will always understeer if you enter a little too fast, it will give an initial turn in then just plough straight on.
Adapting driving to suit the chassis is probably the cheapest way of sorting the issue.

Re: rear stifness [Re: crgracing] #1221346
29/05/2011 21:15
29/05/2011 21:15

J
jonone
Unregistered
jonone
Unregistered
J



Thats true in low speed bends, but high speed?

Re: rear stifness [Re: crgracing] #1221385
29/05/2011 23:06
29/05/2011 23:06
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Nop, the problem is understeer. As for the oversteer i get is quite normal.

Re: rear stifness [Re: crgracing] #1221413
30/05/2011 00:43
30/05/2011 00:43

J
jonone
Unregistered
jonone
Unregistered
J



Rear arb should be top priority then!

Re: rear stifness [Re: crgracing] #1221457
30/05/2011 10:30
30/05/2011 10:30
Joined: Jan 2006
Posts: 3,034
Sweden
Per Offline
I need some sleep
Per  Offline
I need some sleep

Joined: Jan 2006
Posts: 3,034
Sweden
Been looking at recent BMW´s Audi´s etc, I will look into transverse stiffening brace over the "prop-tunnel", which many cars use nowadays (actually it's already on the Golf Mk3). Just in front of the rear axle.

Problem for my Coupe and many others might be the big exaust which is a bit in the way.

Re: rear stifness [Re: crgracing] #1221459
30/05/2011 10:41
30/05/2011 10:41
Joined: Dec 2005
Posts: 17,367
Staffordshire
Nigel Offline
Forum veteran
Nigel  Offline
Forum veteran

Joined: Dec 2005
Posts: 17,367
Staffordshire
Top priority really ought to be an investigation into why the car is understeering in fast corners - it should be perfectly planted

My guess would be rear radius arm bushes, poor tracking setting, or incorrect camber

Is it the same for left AND right bends?


[Linked Image]
Re: rear stifness [Re: ] #1221507
30/05/2011 12:37
30/05/2011 12:37

S
suba
Unregistered
suba
Unregistered
S



Originally Posted By: jonone
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.

Re: rear stifness [Re: Jimbo] #1221563
30/05/2011 15:50
30/05/2011 15:50

S
sediciRich
Unregistered
sediciRich
Unregistered
S



Originally Posted By: Jimbo
Originally Posted By: johnnybravoturbo

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.

Re: rear stifness [Re: crgracing] #1221569
30/05/2011 15:57
30/05/2011 15:57
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Actually never thought about that nigel , but when taking corners to the left it understeers more than to the right. I should get the rear checkd to see if everything is ok.

Re: rear stifness [Re: crgracing] #1221606
30/05/2011 17:47
30/05/2011 17:47
Joined: Dec 2005
Posts: 17,367
Staffordshire
Nigel Offline
Forum veteran
Nigel  Offline
Forum veteran

Joined: Dec 2005
Posts: 17,367
Staffordshire
That confirms my theory that you have a fundamental geometry issue - you need to solve this before you start playing with suspension settings, otherwise you're just going to be masking the problem


[Linked Image]
Re: rear stifness [Re: crgracing] #1221624
30/05/2011 19:01
30/05/2011 19:01
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Well ill have to eliminate, bearings, shocks and springs as they are new

Re: rear stifness [Re: crgracing] #1221632
30/05/2011 19:25
30/05/2011 19:25

S
suba
Unregistered
suba
Unregistered
S



When did you last have the tracking done? How did they set up the car?

Re: rear stifness [Re: crgracing] #1221635
30/05/2011 19:32
30/05/2011 19:32
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
i ve never had the rear tracked actually. i thought you couldn't track the rear wheels ?? only the front right?

Re: rear stifness [Re: ] #1221677
30/05/2011 20:37
30/05/2011 20:37

J
jonone
Unregistered
jonone
Unregistered
J



Originally Posted By: suba
Originally Posted By: jonone
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 laugh
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!

Re: rear stifness [Re: ] #1221711
30/05/2011 21:39
30/05/2011 21:39

S
suba
Unregistered
suba
Unregistered
S



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. laugh

Re: rear stifness [Re: crgracing] #1221747
30/05/2011 22:52
30/05/2011 22:52
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Ill try that out suba in the next few days as ive got the coop in the garge with no cambelt busy waiting for the bits. On friday ill try it out. With no throttle ? Why ? To not oversteer i imagine?

Re: rear stifness [Re: crgracing] #1221774
30/05/2011 23:35
30/05/2011 23:35
Joined: Aug 2007
Posts: 8,057
Southsea
G
Gunzi Offline
Club member 189, Former Club President
Gunzi  Offline
Club member 189, Former Club President
Je suis un Coupé
G

Joined: Aug 2007
Posts: 8,057
Southsea
I have a feeling suba was replying to jonone, and his comment wasn't directly aimed at you smile

Re: rear stifness [Re: crgracing] #1221782
30/05/2011 23:41
30/05/2011 23:41
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Upsss didnt see jonone's post.

Re: rear stifness [Re: crgracing] #1221798
31/05/2011 00:13
31/05/2011 00:13

S
suba
Unregistered
suba
Unregistered
S



LOL! smile

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. smile

Re: rear stifness [Re: ] #1222442
01/06/2011 17:21
01/06/2011 17:21
Joined: Feb 2008
Posts: 1,725
London
kj16v Offline
My life on the forum
kj16v  Offline
My life on the forum

Joined: Feb 2008
Posts: 1,725
London
Originally Posted By: johnnybravoturbo
Strut braces make no difference despite the hype...


I'm so glad you said that! I kind of suspected that might be the case. Even so, I had a rear ARB and front strut brace on my list of things to get, but now I can save my money on the brace laugh

Re: rear stifness [Re: crgracing] #1222443
01/06/2011 17:41
01/06/2011 17:41
Joined: Aug 2007
Posts: 8,057
Southsea
G
Gunzi Offline
Club member 189, Former Club President
Gunzi  Offline
Club member 189, Former Club President
Je suis un Coupé
G

Joined: Aug 2007
Posts: 8,057
Southsea
I'm going to stick my neck out here and say that I did notice a difference with a top and lower brace fitted. Personally I noticed a sharper turn in and as such less understeer at low speed corners. I don't track my car so can't comment on that, only on road use. Any doubters are welcome to come and drive my standard car with and without the strut braces. Bring your own OEM lower wishbone bolts as i'm not sure what I've done with mine!

Re: rear stifness [Re: kj16v] #1222445
01/06/2011 17:43
01/06/2011 17:43

S
suba
Unregistered
suba
Unregistered
S



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.

Re: rear stifness [Re: crgracing] #1222476
01/06/2011 19:33
01/06/2011 19:33
Joined: Jul 2007
Posts: 792
Stafford
sandytim Offline
Enjoying the ride
sandytim  Offline
Enjoying the ride

Joined: Jul 2007
Posts: 792
Stafford
I added a top brace and was impressed with the improvement in the feel of the front end.
I then added Nigels lower brace and was very very happy with the results.
One of the best improvements for the money spent.


[Linked Image]
Re: rear stifness [Re: crgracing] #1222653
02/06/2011 03:08
02/06/2011 03:08

N
Nazo
Unregistered
Nazo
Unregistered
N



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.

Re: rear stifness [Re: crgracing] #1222690
02/06/2011 10:06
02/06/2011 10:06
Joined: Jan 2008
Posts: 1,289
spain
crgracing Offline OP
My job on the forum
crgracing  Offline OP
My job on the forum

Joined: Jan 2008
Posts: 1,289
spain
Theres something that i find a bit strange, why are there so many diferent opinions ? I thought that the struts improve alot the handling, but i see peopele saying that it dosent make any diference.

Re: rear stifness [Re: crgracing] #1222707
02/06/2011 10:36
02/06/2011 10:36
Joined: Aug 2007
Posts: 8,057
Southsea
G
Gunzi Offline
Club member 189, Former Club President
Gunzi  Offline
Club member 189, Former Club President
Je suis un Coupé
G

Joined: Aug 2007
Posts: 8,057
Southsea
I can only guess that those who say they don't make a difference have either not tried them as a first modification on thier car becuase they thought it'd make no difference, or have done them after heavily modifying the rest of their suspension and as such when they were finally added didn't notice much of a difference. Or perhaps some other unknown reason?!

Re: rear stifness [Re: crgracing] #1223017
02/06/2011 23:09
02/06/2011 23:09
Joined: Dec 2005
Posts: 17,367
Staffordshire
Nigel Offline
Forum veteran
Nigel  Offline
Forum veteran

Joined: Dec 2005
Posts: 17,367
Staffordshire
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.


[Linked Image]
Re: rear stifness [Re: Nigel] #1223080
03/06/2011 02:41
03/06/2011 02:41
Joined: Jan 2006
Posts: 3,034
Sweden
Per Offline
I need some sleep
Per  Offline
I need some sleep

Joined: Jan 2006
Posts: 3,034
Sweden
Originally Posted By: Nigel
and then my lower subframe brace.

...or any lower subframe brace.. smile
Yes it does make a big difference, more so than the Sparco strutbrace I'd say.

Re: rear stifness [Re: crgracing] #1223236
03/06/2011 16:47
03/06/2011 16:47

S
sparco
Unregistered
sparco
Unregistered
S



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.

Re: rear stifness [Re: crgracing] #1223254
03/06/2011 17:51
03/06/2011 17:51
Joined: Dec 2005
Posts: 17,367
Staffordshire
Nigel Offline
Forum veteran
Nigel  Offline
Forum veteran

Joined: Dec 2005
Posts: 17,367
Staffordshire
Very interesting and informed view Marco

I was a passenger around Curborough in a Clio 200 Cup and I was staggered at the precision of the steering AND the compliancy of the chassis (normally these are mutually exclusive on a FWD road car)

I wonder what it is about the Coupe that makes it such a poor starting point. Seeing as the vast majority of the geometry can be changed (albeit expensively, in some cases), there's no reason why it shouldn't be able to be as good as something like the Seat Leon you compete against.

I'm beginning to think its probably down the the iffy weight distribution. Great for traction off the line, but counter-productive almost everywhere else.

I know the Leon will have the benefit of several more years development and chassis knowledge, but should it really be THAT far ahead of the Coupe? What else does it have?

Just as a matter of interest, you say you're running 750/850 lb springs - do you know what standard is, or maybe what Eibachs run at?


[Linked Image]
Re: rear stifness [Re: crgracing] #1223268
03/06/2011 18:54
03/06/2011 18:54

S
sediciRich
Unregistered
sediciRich
Unregistered
S



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.
Re: rear stifness [Re: ] #1223273
03/06/2011 19:16
03/06/2011 19:16

S
suba
Unregistered
suba
Unregistered
S



Originally Posted By: sediciRich


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!

Re: rear stifness [Re: crgracing] #1223388
04/06/2011 08:50
04/06/2011 08:50

S
sparco
Unregistered
sparco
Unregistered
S



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!

Re: rear stifness [Re: crgracing] #1223406
04/06/2011 10:30
04/06/2011 10:30
Joined: Aug 2007
Posts: 8,057
Southsea
G
Gunzi Offline
Club member 189, Former Club President
Gunzi  Offline
Club member 189, Former Club President
Je suis un Coupé
G

Joined: Aug 2007
Posts: 8,057
Southsea
Is there anytrhing that can be done to increase the rigidity of the chassis aside from the usual bracing? For example the Nova crowd seam weld their engine bays before fitting the 2.0 engines. Is this something which you have done Sparco, or did Fiat provide a rigid engine bay to start with?

Re: rear stifness [Re: ] #1223420
04/06/2011 11:20
04/06/2011 11:20

S
sediciRich
Unregistered
sediciRich
Unregistered
S



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.
Re: rear stifness [Re: crgracing] #1223427
04/06/2011 11:33
04/06/2011 11:33

S
sparco
Unregistered
sparco
Unregistered
S



Yes i have 60mm fronts, 650's 750's spare.

Re: rear stifness [Re: crgracing] #1223438
04/06/2011 12:28
04/06/2011 12:28

J
jonone
Unregistered
jonone
Unregistered
J



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

Re: rear stifness [Re: crgracing] #1223968
06/06/2011 10:29
06/06/2011 10:29

G
gassy
Unregistered
gassy
Unregistered
G



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.
Page 1 of 2 1 2

Powered by UBB.threads™ PHP Forum Software 7.7.1
(Release build 20190129)
PHP: 7.3.33 Page Time: 0.020s Queries: 15 (0.007s) Memory: 0.9672 MB (Peak: 1.2813 MB) Data Comp: Off Server Time: 2024-05-02 12:21:45 UTC