Suspension expert .....advice wanted
08 November 2013, 08:58 AM
#1
Suspension expert .....advice wanted
04 WRX
Bilstein coilovers
Perrin arb front & rear
Cdf alloy droplinks
18" Ultraleggeras
Falken 452.
I thought it would corner like a go-kart,it doesn't.On long fast corners the front keeps dipping to the left or right depending which way the bend is going. Look at my last album is it too low,would a roll centre kit help?Who are the best people to help sort this??
Bilstein coilovers
Perrin arb front & rear
Cdf alloy droplinks
18" Ultraleggeras
Falken 452.
I thought it would corner like a go-kart,it doesn't.On long fast corners the front keeps dipping to the left or right depending which way the bend is going. Look at my last album is it too low,would a roll centre kit help?Who are the best people to help sort this??
08 November 2013, 10:51 AM
#2
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I think some of the people on here can help but might require further information.
Some questions I have:
Can you measure the distance between the centre of the wheels up to the bottom of the arches in mm please to give an accurate recording of the current ride height?
How thick are the Perrin ARBs and if adjustable which setting are you using on each one?
What are the current geometry settings your car is set to?
Some questions I have:
Can you measure the distance between the centre of the wheels up to the bottom of the arches in mm please to give an accurate recording of the current ride height?
How thick are the Perrin ARBs and if adjustable which setting are you using on each one?
What are the current geometry settings your car is set to?
08 November 2013, 11:49 AM
#4
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It does appear to be quite low so a roll centre correction kit may well be beneficial.
What about the front ARB? Do you know the thickness and setting?
Are you able to provide the details of the Litchfield setup? I dont know what they would have set your car to.
What about the front ARB? Do you know the thickness and setting?
Are you able to provide the details of the Litchfield setup? I dont know what they would have set your car to.
08 November 2013, 04:19 PM
#6
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I would suggest thats too low - My Hawkeye STI currently sits around 360mm all round.
A roll centre correction kit would help somewhat but I'd still suggest raising the car.
This thread has a lot of useful information https://www.scoobynet.com/suspension...-settings.html
Both Arnie and Bonesetter have made some very useful comments in that thread (and many others) about ideal geometry settings and an ideal ride height for your car would be 370mm front and 360mm rear.
With your current ride height your lateral arms are probably pointing upwards torwards the outside edge so your effective roll centre has migrated below the surface of the road. This will have the effect of making the car roll more when cornering plus when loading up the outside wheel it will gain much more negative camber because the lateral arms are much further into the curve of travel than at standard height.
Think about the angle that the arms are going to move when you lift them up - they start to curve into the car and bring the wheel in with it. The higher you go the quicker the camber change occurs on the wheel. That will also have the effect of making the car feel like it is rolling when cornering - more so the lower you go.
Hope that makes sense!
A roll centre correction kit would help somewhat but I'd still suggest raising the car.
This thread has a lot of useful information https://www.scoobynet.com/suspension...-settings.html
Both Arnie and Bonesetter have made some very useful comments in that thread (and many others) about ideal geometry settings and an ideal ride height for your car would be 370mm front and 360mm rear.
With your current ride height your lateral arms are probably pointing upwards torwards the outside edge so your effective roll centre has migrated below the surface of the road. This will have the effect of making the car roll more when cornering plus when loading up the outside wheel it will gain much more negative camber because the lateral arms are much further into the curve of travel than at standard height.
Think about the angle that the arms are going to move when you lift them up - they start to curve into the car and bring the wheel in with it. The higher you go the quicker the camber change occurs on the wheel. That will also have the effect of making the car feel like it is rolling when cornering - more so the lower you go.
Hope that makes sense!
08 November 2013, 05:08 PM
#7
+1 on the too low.
I would also look at swapping the wheels and tyres, 17's are better for handling than 18's, I'm currently running 18's with falken 452's and although they are decent for normal ish driving, they are quite easy to find the limit of adhesion with, as in not fantastic when pressing on, I won't be changing my wheels but I will be going for some top quality rubber next time round.
I would also look at swapping the wheels and tyres, 17's are better for handling than 18's, I'm currently running 18's with falken 452's and although they are decent for normal ish driving, they are quite easy to find the limit of adhesion with, as in not fantastic when pressing on, I won't be changing my wheels but I will be going for some top quality rubber next time round.
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08 November 2013, 05:56 PM
#8
Hi there
I would go with Roll centre kit if yours car is lowered,we are running Roll centre and this transformed drive on our wagon
Yes you can go with raising ride height and not going with Roll centre kit,but still I would choose Roll centre kit
Jura
I would go with Roll centre kit if yours car is lowered,we are running Roll centre and this transformed drive on our wagon
Yes you can go with raising ride height and not going with Roll centre kit,but still I would choose Roll centre kit
Jura
09 November 2013, 06:28 AM
#14
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It all depends where you going to use your car and how much you want to be spending...
1st things 1st... you've got average tyres , so dont expect much from them... Some decent tyres like AD08's or even now old but still good RE070's would be night and day.... There are also equivalents which i hear my track boys raving about. Nankang nankang ns-2r's or federal 959 rsr's which were amazing in wet and dry with pretty competitive price tag too..
I'm following Arnies and Bonesetters advice too and it all makes sense, but this thing one size fits all sometimes doesnt work with all of us... 360mm all around is not the correct way either as front has to sit higher then rear as its much heavier ... The center correction kit is a must IMO if you running coilovers . I've done my Geo with Rich@FBtuning as he's doing most work on my car and knows his stuff very well too.... The way we adjusted it was me sitting in the car measuring all corners to be equal. He had no corner weight scales , but that way is the best thing to go without corner weighing. She sits now 330mm/350mm with the suporting mods, roll center kit , alk etc etc...
What camber and toe are you running , the alignment sheet would help to see what have they done....
1st things 1st... you've got average tyres , so dont expect much from them... Some decent tyres like AD08's or even now old but still good RE070's would be night and day.... There are also equivalents which i hear my track boys raving about. Nankang nankang ns-2r's or federal 959 rsr's which were amazing in wet and dry with pretty competitive price tag too..
I'm following Arnies and Bonesetters advice too and it all makes sense, but this thing one size fits all sometimes doesnt work with all of us... 360mm all around is not the correct way either as front has to sit higher then rear as its much heavier ... The center correction kit is a must IMO if you running coilovers . I've done my Geo with Rich@FBtuning as he's doing most work on my car and knows his stuff very well too.... The way we adjusted it was me sitting in the car measuring all corners to be equal. He had no corner weight scales , but that way is the best thing to go without corner weighing. She sits now 330mm/350mm with the suporting mods, roll center kit , alk etc etc...
What camber and toe are you running , the alignment sheet would help to see what have they done....
09 November 2013, 10:07 AM
#15
Some great advise from folk here, all good.
What dia front arb have you got fitted. 25 rear (and on middle setting) is fairly hefty rear roll resistance. Do you get understeer?
As for the height, yes 370/360 is a good benchmark, but your car should still drive nicely at at 350-355mm front and 340-345mm at the back if you don't want to go too high
This height would still need RC correction, but at the moment, as said your RC will be much too low. Raising the height of the car and fitting RC kit is not too expensive and with decent geo dialled in will help things enormously.
Chevron, while pretty good are pretty pricey too
Plus, going about things this way you will learn alot about the suspension and how different changes effects the way the car behaves. I wouldn't sweat on the tyres too much for now
Looking good btw Mantazini
I do like those wheels
What dia front arb have you got fitted. 25 rear (and on middle setting) is fairly hefty rear roll resistance. Do you get understeer?
As for the height, yes 370/360 is a good benchmark, but your car should still drive nicely at at 350-355mm front and 340-345mm at the back if you don't want to go too high
This height would still need RC correction, but at the moment, as said your RC will be much too low. Raising the height of the car and fitting RC kit is not too expensive and with decent geo dialled in will help things enormously.
Chevron, while pretty good are pretty pricey too
Plus, going about things this way you will learn alot about the suspension and how different changes effects the way the car behaves. I wouldn't sweat on the tyres too much for nowLooking good btw Mantazini
I do like those wheels
15 November 2013, 07:45 PM
#18
Not all good advice here- for instance the rear should be higher than the front - subarus work better with positive rake.
What is right is that the car is too low and the roll centre is below the road surface - which will make it roll in corners just as you're describing.
What is right is that the car is too low and the roll centre is below the road surface - which will make it roll in corners just as you're describing.
16 November 2013, 06:33 AM
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Not all good advice here- for instance the rear should be higher than the front - subarus work better with positive rake.
What is right is that the car is too low and the roll centre is below the road surface - which will make it roll in corners just as you're describing.
What is right is that the car is too low and the roll centre is below the road surface - which will make it roll in corners just as you're describing.
Would be interesting to know his theory ... i see some new bicycle being reinvented here
..... The rest of advice has been given or repeated what people who race or drive their cars on track have been used for years with proper explanation how it works... It's all debatable but people like Arnie , John Felsetad , Chevron Motorsport are good enough examples for me the way they setup their cars.... Plenty of threads on Nasioc from Guys who race too ...
Last edited by mantazini; 16 November 2013 at 06:41 AM.
16 November 2013, 06:49 AM
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http://forums.nasioc.com/forums/show....php?t=1896023
http://forums.nasioc.com/forums/show....php?t=1900666
Ryan aka Prodriverules knows his stuff very well so you should be fine , but dont be afraid to fine tune the Arbs for your own liking , it might be different to ours ...
19 November 2013, 08:57 PM
#22
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babble babble.
Right then. Quick ~Suspension 101 for the uninitiated.
Subaru Impreza runs McPherson struts all round. You measure roll centre at each end by taking an imaginary line through the inner and outer pivots on the lower arms and taking that line through the centre of the car and keep going till it crosses a line drawn through the upper strut mount at 90 degrees to the leg. This intersection is then drawn back to the centre of the tyre contact patch.
Where the left and right final lines cross the centreline of the car is the instantaneous roll centre.
The centre of gravity sits away from this and the distance from the roll centre to the CoG gives rise to a ROLL TORQUE as you generate lateral g from cornering.
Got it?
So, a typical simple Strut setup like a Mk4 Escort gave a 4" drop in roll centre with 1" drop.
Any McPherson car will do a similar thing. Drop it, it roll more. You therefore need stiffer springs to resist the roll. This can be stiffer coils or a stiffer roll bar. Does the same job. Ish.
Now. Connect the front and rear roll centre and you get the roll axis. O.E. the Scooby will roll to put the back outer corner down. This lifts the inner front giving understeer.
Lowering the front more than the rear moves the axis so it rolls pushing the front outer corner down.
Roll centre correction kits are a new bolt on outer ball joint that is longer making the arm angled more and lifting the roll centre back up.
Lower the car 1". Put a 1" longer ball joint in and you have the same effective roll centre with CoG 1" lower so less roll. In theory. But your rear roll centre has plummeted and your front has not= a massive unhelpful roll axis change and very much understeer unless you fit a very big rear ARB to support the back from diving under cornering.
ALK is different. The Subaru has anti lift/anti squat as standard and the kit lowers and moves the rear front arm mount out. This removes the anti lift/squat to prevent the car stiffening under braking and pulling it's own front wheels off the ground under power.
The kit gives more Castor which is A GOOD THING.
Castor is camber when you want it and less tyre wear when you don't. Win-Win.
Lowering the car is always going to ruin all the good work the Subaru engineers designed into the car- which was then ruined by the accountants who fitted crap suspension.
My car is still a work in progress. I'm playing with ride height and springs, etc and already have a car that is plush, supple and out corners nearly everything but actually sits slightly higher than standard right now. Looks pants but I'm inside so I don't give a f***.
Right then. Quick ~Suspension 101 for the uninitiated.
Subaru Impreza runs McPherson struts all round. You measure roll centre at each end by taking an imaginary line through the inner and outer pivots on the lower arms and taking that line through the centre of the car and keep going till it crosses a line drawn through the upper strut mount at 90 degrees to the leg. This intersection is then drawn back to the centre of the tyre contact patch.
Where the left and right final lines cross the centreline of the car is the instantaneous roll centre.
The centre of gravity sits away from this and the distance from the roll centre to the CoG gives rise to a ROLL TORQUE as you generate lateral g from cornering.
Got it?
So, a typical simple Strut setup like a Mk4 Escort gave a 4" drop in roll centre with 1" drop.
Any McPherson car will do a similar thing. Drop it, it roll more. You therefore need stiffer springs to resist the roll. This can be stiffer coils or a stiffer roll bar. Does the same job. Ish.
Now. Connect the front and rear roll centre and you get the roll axis. O.E. the Scooby will roll to put the back outer corner down. This lifts the inner front giving understeer.
Lowering the front more than the rear moves the axis so it rolls pushing the front outer corner down.
Roll centre correction kits are a new bolt on outer ball joint that is longer making the arm angled more and lifting the roll centre back up.
Lower the car 1". Put a 1" longer ball joint in and you have the same effective roll centre with CoG 1" lower so less roll. In theory. But your rear roll centre has plummeted and your front has not= a massive unhelpful roll axis change and very much understeer unless you fit a very big rear ARB to support the back from diving under cornering.
ALK is different. The Subaru has anti lift/anti squat as standard and the kit lowers and moves the rear front arm mount out. This removes the anti lift/squat to prevent the car stiffening under braking and pulling it's own front wheels off the ground under power.
The kit gives more Castor which is A GOOD THING.
Castor is camber when you want it and less tyre wear when you don't. Win-Win.
Lowering the car is always going to ruin all the good work the Subaru engineers designed into the car- which was then ruined by the accountants who fitted crap suspension.
My car is still a work in progress. I'm playing with ride height and springs, etc and already have a car that is plush, supple and out corners nearly everything but actually sits slightly higher than standard right now. Looks pants but I'm inside so I don't give a f***.
19 November 2013, 09:53 PM
#26
babble babble.
Right then. Quick ~Suspension 101 for the uninitiated.
Subaru Impreza runs McPherson struts all round. You measure roll centre at each end by taking an imaginary line through the inner and outer pivots on the lower arms and taking that line through the centre of the car and keep going till it crosses a line drawn through the upper strut mount at 90 degrees to the leg. This intersection is then drawn back to the centre of the tyre contact patch.
Where the left and right final lines cross the centreline of the car is the instantaneous roll centre.
The centre of gravity sits away from this and the distance from the roll centre to the CoG gives rise to a ROLL TORQUE as you generate lateral g from cornering.
Got it?
So, a typical simple Strut setup like a Mk4 Escort gave a 4" drop in roll centre with 1" drop.
Any McPherson car will do a similar thing. Drop it, it roll more. You therefore need stiffer springs to resist the roll. This can be stiffer coils or a stiffer roll bar. Does the same job. Ish.
Now. Connect the front and rear roll centre and you get the roll axis. O.E. the Scooby will roll to put the back outer corner down. This lifts the inner front giving understeer.
Lowering the front more than the rear moves the axis so it rolls pushing the front outer corner down.
Roll centre correction kits are a new bolt on outer ball joint that is longer making the arm angled more and lifting the roll centre back up.
Lower the car 1". Put a 1" longer ball joint in and you have the same effective roll centre with CoG 1" lower so less roll. In theory. But your rear roll centre has plummeted and your front has not= a massive unhelpful roll axis change and very much understeer unless you fit a very big rear ARB to support the back from diving under cornering.
ALK is different. The Subaru has anti lift/anti squat as standard and the kit lowers and moves the rear front arm mount out. This removes the anti lift/squat to prevent the car stiffening under braking and pulling it's own front wheels off the ground under power.
The kit gives more Castor which is A GOOD THING.
Castor is camber when you want it and less tyre wear when you don't. Win-Win.
Lowering the car is always going to ruin all the good work the Subaru engineers designed into the car- which was then ruined by the accountants who fitted crap suspension.
My car is still a work in progress. I'm playing with ride height and springs, etc and already have a car that is plush, supple and out corners nearly everything but actually sits slightly higher than standard right now. Looks pants but I'm inside so I don't give a f***.
Right then. Quick ~Suspension 101 for the uninitiated.
Subaru Impreza runs McPherson struts all round. You measure roll centre at each end by taking an imaginary line through the inner and outer pivots on the lower arms and taking that line through the centre of the car and keep going till it crosses a line drawn through the upper strut mount at 90 degrees to the leg. This intersection is then drawn back to the centre of the tyre contact patch.
Where the left and right final lines cross the centreline of the car is the instantaneous roll centre.
The centre of gravity sits away from this and the distance from the roll centre to the CoG gives rise to a ROLL TORQUE as you generate lateral g from cornering.
Got it?
So, a typical simple Strut setup like a Mk4 Escort gave a 4" drop in roll centre with 1" drop.
Any McPherson car will do a similar thing. Drop it, it roll more. You therefore need stiffer springs to resist the roll. This can be stiffer coils or a stiffer roll bar. Does the same job. Ish.
Now. Connect the front and rear roll centre and you get the roll axis. O.E. the Scooby will roll to put the back outer corner down. This lifts the inner front giving understeer.
Lowering the front more than the rear moves the axis so it rolls pushing the front outer corner down.
Roll centre correction kits are a new bolt on outer ball joint that is longer making the arm angled more and lifting the roll centre back up.
Lower the car 1". Put a 1" longer ball joint in and you have the same effective roll centre with CoG 1" lower so less roll. In theory. But your rear roll centre has plummeted and your front has not= a massive unhelpful roll axis change and very much understeer unless you fit a very big rear ARB to support the back from diving under cornering.
ALK is different. The Subaru has anti lift/anti squat as standard and the kit lowers and moves the rear front arm mount out. This removes the anti lift/squat to prevent the car stiffening under braking and pulling it's own front wheels off the ground under power.
The kit gives more Castor which is A GOOD THING.
Castor is camber when you want it and less tyre wear when you don't. Win-Win.
Lowering the car is always going to ruin all the good work the Subaru engineers designed into the car- which was then ruined by the accountants who fitted crap suspension.
My car is still a work in progress. I'm playing with ride height and springs, etc and already have a car that is plush, supple and out corners nearly everything but actually sits slightly higher than standard right now. Looks pants but I'm inside so I don't give a f***.
20 November 2013, 07:43 AM
#27
change front drop links to,originalls are week,some rubber with 4 pins and plastic cup,super crap design.
He race on competitions, (time attack,hill climbs)he will take your car for spin after mods to have a look how it drive.
and bilsteins are coilovers which he recommend as best,he knows them very well.
I paid 300 for full set up.
Last edited by fawor; 20 November 2013 at 08:05 AM.
21 November 2013, 04:19 PM
#28
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Another quick question... what spring rate are you using?
I am just wondering if you are finding the initial rate too soft as I know alot of European coilovers use progressive springs on their coilovers.
Jerrick
I am just wondering if you are finding the initial rate too soft as I know alot of European coilovers use progressive springs on their coilovers.
Jerrick
23 November 2013, 03:22 PM
#30
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Ditchy,
I'm mid playing for Winter right now so the car's plenty mismatched until the next set of springs arrive.
Prior to the messing, I have Whiteline ALK, rear 22mm ARBset mid point with O.E> links and Whiteline monuts and bushes.
O.E. front ARB, but Whiteline rack bushes. ER Series BC Coilovers, with long travel and plusher valving. 6kg and helpers front and 4kg and helpers with rubber top mounts rear.
Now it's on 5kg 200mm fronts waiting for longer 4.5kg 260mm as the helpers are off and I have not enough travel for dampers. Plus waiting for a stiffer 3kg 50mm helper pair for the 4kg rears to balance the fronts and get the full travel and ride height for anything the weather can throw at me.
I'll fit the camber bolts and sort the GEO once I have the ride heights and corner weights sorted.
It's having time to play is the problem. Crap weather and work asking me to cover for sickness as my entire base is being threatened with redundancy and sickness has gone through the roof as a result.
I only have till January and I'm going to be working a long way from home so I want it sorted by then. (Red marks for Summer, White for Winter) I can switch it round pretty quickly then.
I'm mid playing for Winter right now so the car's plenty mismatched until the next set of springs arrive.
Prior to the messing, I have Whiteline ALK, rear 22mm ARBset mid point with O.E> links and Whiteline monuts and bushes.
O.E. front ARB, but Whiteline rack bushes. ER Series BC Coilovers, with long travel and plusher valving. 6kg and helpers front and 4kg and helpers with rubber top mounts rear.
Now it's on 5kg 200mm fronts waiting for longer 4.5kg 260mm as the helpers are off and I have not enough travel for dampers. Plus waiting for a stiffer 3kg 50mm helper pair for the 4kg rears to balance the fronts and get the full travel and ride height for anything the weather can throw at me.
I'll fit the camber bolts and sort the GEO once I have the ride heights and corner weights sorted.
It's having time to play is the problem. Crap weather and work asking me to cover for sickness as my entire base is being threatened with redundancy and sickness has gone through the roof as a result.
I only have till January and I'm going to be working a long way from home so I want it sorted by then. (Red marks for Summer, White for Winter) I can switch it round pretty quickly then.