Suspension guru's needed, stanced boys need not apply

[DanClio]

Hi all,

Hopefully someone can give some info about Clio suspension and set ups etc. Basically I used to do a bit of club racing, and even in this you would need to have a decent understanding of roll centres, adjusting geometery and its effects etc. Having a bit of a poke around the trophy's front end whilst changing a few bushes I noticed that the standard roll centre is actually hilairious. A rough calculation shows its below the level of the ground, quite a distance from the CofG and therefore the load transfer during a corner must be quite high. Is there any merit in trying to increase the height of the roll axis to improve conering grip or is it best to just leave it alone? The other advantage would be increased camber recovery in roll. As it is at the moment the car will actually lose camber as the suspension is compressed.

Also, the only reason I can think why Renault would design the front suspension in this way is to counter for the low roll centre and high CofG at the rear due to the torsion beam. By doing this giving the car a more natural tendancy to understeer. Is this correct or is there another reason?

Cheers in advance,
Dan

 

[MG cup]

Definite benefit to adjusting roll centre, there are a few on here trying it on here by different means at the minute. Best solution is to copy the cup racer design if your handy with a spanner and know a machinist.

On a side note I cant see how you are getting positive camber with compression on a standard trophy. You will get negative until the wishbone becomes level and then you will start seeing some positive.

 

[DanClio]

This is what I mean, as standard on the trophy, wishbones are pointing upwards. I did think about going the cup racer route but I think the ball joint holes will start the oval if you keep standard hubs. Changing to Laguna hubs is one answer but can't guarantee steering geo etc will be the same and involves modifying where the strut bolts on etc. For simplicity I want to keep the Clio hubs.

Also as an aside. Do the cup racers still run a negative scrub radius? Trying to work out why they would favour an et48 offset wheel.

Cheers,
Dan

 

[NorthloopCup]

Myself and BIGASH have a roll centre corrector kit that has been used on my car and will be used on his car. It will be vigorously tested on road and track by us both before it's available as a kit, but initial impressions just from using it on my car were very very good.
It is designed to work with standard hubs as well to make life easier, and we will also be offering a kit to reduce/remove bumpsteer from lowered clios.

The Clio is one of a very few cars out there that still handles relatively well even when the roll centres have gone rediculous!

 

[DanClio]

This is true. The roll centre differntial front to rear seems to help on that respect. Will be interesting to see your solution as in main ball joint extenders aren't ideal for slick tyres due to extra loadings on the bottom of the hub. I managed to oval 2 sets of front hubs on my race car without using extenders! Should be adequate for the road although I doubt the full benefit will be felt. Only other way is to change where is wishbone picks up on the subframe but this is quite involved. Do you have any pics you can send me or any links of similar designs. Only to satisfy my own curiosity if its ok with you?

That's good to hear that it did make a positive difference. Obviously the rear would have to be lowered to keep the roll couple short and the chassis biased towards understeer. Did you experience any need to alter spring rates with the higher roll centre at all?

Cheers,
Dan

 

[sprintcup]

Myself and BIGASH have a roll centre corrector kit that has been used on my car and will be used on his car. It will be vigorously tested on road and track by us both before it's available as a kit, but initial impressions just from using it on my car were very very good.
It is designed to work with standard hubs as well to make life easier, and we will also be offering a kit to reduce/remove bumpsteer from lowered clios.

The Clio is one of a very few cars out there that still handles relatively well even when the roll centres have gone rediculous!

Off topic, I hope you'll be able to do a version for the Cup without the sperical bearing if that's possible as it's not allowed in the class I run in, but would like to fit this kit to mine.

Regards Russ...........

 

[DanClio]

Also off topic... Could you not use something like this within your regulations?

http://www.ebay.co.uk/itm/VW-GOLF-L...arts_Vehicles_CarParts_SM&hash=item20ce392829

Easiest way to extend the pivot point although it will only be about 40mm which i don't think is enough really. Also Clio ball joints are 16mm I think.

 

[mr.pink87]

Also off topic... Could you not use something like this within your regulations?

http://www.ebay.co.uk/itm/VW-GOLF-L...arts_Vehicles_CarParts_SM&hash=item20ce392829

Easiest way to extend the pivot point although it will only be about 40mm which i don't think is enough really. Also Clio ball joints are 16mm I think.

Good idea. Anyone on here able to knock some up?

 

[NorthloopCup]

Off topic, I hope you'll be able to do a version for the Cup without the sperical bearing if that's possible as it's not allowed in the class I run in, but would like to fit this kit to mine.

Regards Russ...........

Don't worry Russ this was mentioned by James and has been taken into consideration. We have a option that will work for you!

 

[DanClio]

I probably could but will await BIGASH and Northloop's version as it will have been proven on and off track. The last thing you want is to use the wrong grade of steel or something and risk a ball joint snapping whilst your on the limit. If you were to do this, your track rods would need modifying to suit also.

Another question I had for the racers I have just remembered. Where is the centre of gravity on a 1*2? On saloon cars it's usually around the centre of the engine in the front then at the boot floor at the rear. I haven't had my car on any corner weight scales to check.

Dan

 

[NorthloopCup]

Good idea. Anyone on here able to knock some up?

This is one of the options that we will have available. The problem with that type of design is you are limited to how far you can go before you run the risk of breakage.
Even if you get them heat treated they can break.

 

[NorthloopCup]

I probably could but will await BIGASH and Northloop's version as it will have been proven on and off track. The last thing you want is to use the wrong grade of steel or something and risk a ball joint snapping whilst your on the limit. If you were to do this, your track rods would need modifying to suit also.

This is the very reason why the product will be tested rigorously. We will not sell anything that isn't up to the job. It will also be made from the correct grade of material rest assured.

The kit for the track rods will also be available as a option.

 

[sprintcup]

Hope this becomes a good thread on suspension set up as for me this is when you get the big gains on these cars.
I'll await your test results and you can use my car as a ginny pig if needed^^^^
I'd like to ask if you think the OE top mounts will let this mod down in anyway, as again I have to retain this item as well, when you see the movement and angles the strut top gets too when you turn the wheel it's an eye opener.

Regards Russ......

 

[DanClio]

In regards to the standard top mounts, they aren't as bad a everyone thinks. The main things they affect is camber recover,y and the instant centre as the car moves about. Solid mounts come into there own in competition as it makes setting camber and other geo changes and their effects more repeatable and consistent. If you can't change your top mounts then there isn't anything you can do unless ypu cheat obviously! Best thing you can do with most off these things is test them in different situations and if it makes the car quicker then happy days

Another question for the racers, do any of you run a wider front track like the cup race cars do? I realise this means having to use longer shafts unless your only going 5mm wider or less. I see a lot of Clio with a wide track on the front are all these running spacers? If so how are they performing? Theoretically the should turn in better but need high spring rates and therefore a reduction a grip? I seem to remember standard cup racer springs being ridiculously hard. Any one got any info?

Cheers.

 

[MG cup]

Just for reference to you Dan, this is a cup racer setup.

The track rod end isn't fully tight in that picture.

I can't comment on what BIGASH and NORTHLOOP CUP are doing but if you just make up a spherical joint holder for the bottom arm and an extender pin to meet up with the standard pinch type hub then you don't need to extend the track, driveshafts etc etc.

I don't know about altering all the cofg, roll resistance etc etc but if you get a good relation between the steering arm and wishbone angles and make them pivot from similar points then you are onto a winner.

Fronts on cup racers are around 1000lb iirc and rears are 500lb

 

[DanClio]

Thanks for that Mr. Suede! Very useful pic. Perfect to get an idea of how much you need to adjust the track rod height relative the the control arm. Only trouble with standard Clio hubs is the slotted ball joint. I wouldn't have thought it will offer enough clamping force to resist the leverage created by extending the ball joint and thus will go oval very quickly with sticky tyres on a track. Hopefully this is something Northloopcup's version will address. That's what I had heard about the spring rate but seems incredibly stiff when compared with the standard car, although they did run slick tyres and need to compensate for the arb being standard still too I think (correct me if I'm wrong). Also strange the standard car has a higher spring rate at the rear from what I have found out!

31.9 N/mm Front
50 something N/mm Rear

The main thing with cup racer/laguna hub is the distance the strut is bolted from the hub face. Do you happen to know if the et48.5 of the cup racers takes the scrub radius to postive? It's pretty hard to tell from the pic without seeing the top of the strut. Also worth noting that the KPA is massive on the racers. Probably not ideal for them but better than using a narrow track! Normally in a racecar you try to find a balance between caster and KPA which is hard to do on a macphearson strut due to packaging etc.

I want this thread to be where people share info about the Clio's suspension design so to better understand the effects of changing it. Hopefully we get some more good information, from people in the know. I don't expect people to share information on the setups on thier racecars but any general info about 1*2's would be great! be worth starting a thread with a better title though!

 

[MG cup]

Im not sure how much the KPA is changed tbh but I would imagine there is an increase. the laguna hubs are larger as a hole, never taken any measuremnts from wheel mounting face to strut mounting holes.

As far as scrub radius, im unsure if its positive\negative....never checked tbh. With full setup fitted including 48.5 et wheels the tyre is nearly touching the strut with some camber bolts in so about 15mm without....so as close as you can get really. You can fit smaller bolts to adjust camber and scrub radius but I don't think there is much benefit other than braking stability to having it negative so I would rather have the best suited camber rather than scrub radius...no?

 

[MG cup]

What is the conversion from Lb to Nm, I can't find anything.

 

[Tony Hunter]

Well you divide Newtons by 4.46 for pounds

Newton to kilograms divide 9.81

if that helps.

 

[DanClio]

Here is a picture of the hubs together on Ian Speed's thread about his Clio cup. Its not a brilliant angle but you can clearly see how much bigger the hub is.

http://www.cliosport.net/forum/showthread.php?540049-newbie-with-a-clio-cup-race-car/page28

Main thing I noticed from this view is the difference in distance between the ball joint centre and wheel bearing/wheels centre. Looks alot larger on the Cup hub which would give the car a better roll couple to start with, then it had been spaced down further. I think renault knew there would be merit in adjusting this from the start. Something which didn't follow through to road cars, probably due to cost.

I agree about camber being preferable to scrub but the whole system has to work as a package, and you can adjust them independantly. If you have loads of scrub it can make a car twitchy and unstable under braking, normally fwd race cars dont use more than 10-40mm positive scrub, less in the wet normally. Which is why I was curious about the cup racers as it does look to be negative still. Only reason I can think for Renault doing this is to overcome another issue which would cause instablity under braking.

I have been looking into the anti dive/squat characteristics of the Clio, and basic drawings show that the car is much more resistant to anti squat due the torsion beam rear than is it to anti dive under braking. This may be one reason the car is designed to be more stable on the brakes. The side view instant centre of the front suspension is far behind the car and due to macphearson strut there isnt a great deal you can do about it.

I find spring rates a PITA sometimes. Everyone seems to quote different units! The ones I have above are supposed to be directly from the engineer responsible for developing the clio rates from factory. There orginally quoted in daNm/mm!

 

[MG cup]

Im probably being stupid but which one of those would convert lbs as in spring tension to Nm?

Basically what would the racers 1000lb fronts and 500lb rears convert to in Nm?

Well you divide Newtons by 4.46 for pounds

Newton to kilograms divide 9.81

if that helps.

 

[MG cup]

Not really clued up on anti dive etc etc etc, Im a grease monkey after all so "that will do" is my usual mantra lol.

I think trying to redisgn the wheel on a monocoque shell isn't really possible without severe sessions with a grinder.

Get your camber, caster, tracking, bump steer, roll centres right and try to get the wheel as close to your struts or the point of turn then your doing pretty good for a clubman car tbh, most just have coilovers whacked on and driven hard so your at an advantage straight away.

All IMO offcourse.

 

[shiftspark]

I am not sure that northloops/bigash mod would be legal in the sprint road going class. (Russ)

 

[Tony Hunter]

Im probably being stupid but which one of those would convert lbs as in spring tension to Nm?

Basically what would the racers 1000lb fronts and 500lb rears convert to in Nm?

[h=1][/h]







[h=2]Easy Answer:[/h]Multiply the weight in pounds by 4.44822162.


[h=3]Long Answer:[/h]You must break the computation into the classical equation F = ma, then perform conversion on all of the units involved in that computation.

* 1 pound-force = (1 slug)*(1 ft/s/s)
* 1 newton = (1 kg)*(1 m/s/s)

It is then a matter of solving the equations:

1 lbf = (1 slug)*(1 ft/s/s)
1 N = (1 kg)*(1 m/s/s)

Divide out the forces, moving each to the other side of the equation and leaving the other side with zero.

0 = [(1 slug)*(1 ft/s/s)] / 1 lbf
0 = [(1 kg)*(1 m/s/s)] / 1 N

 

[Tony Hunter]

.

 

[DanClio]

Not really clued up on anti dive etc etc etc, Im a grease monkey after all so "that will do" is my usual mantra lol.

I think trying to redisgn the wheel on a monocoque shell isn't really possible without severe sessions with a grinder.

Get your camber, caster, tracking, bump steer, roll centres right and try to get the wheel as close to your struts or the point of turn then your doing pretty good for a clubman car tbh, most just have coilovers whacked on and driven hard so your at an advantage straight away.

All IMO offcourse.

Anti dive/squat took me a while to get my head around, its relatively simple in principle but I wouldn't have any idea of how to design it into a chassis, only tune it a little I can work all this stuff out but when it comes to putting it on a car it normally gets a bit more Heath Robinson! Lol.

I absolutely agree mate. Changing suspension pick up points is a massive job and realistically not required, on a car where they are pretty good from factory. All these things are important but things like bump steer, roll centres, scrub, KPA, spring rate and roll rate are difficult to change at an average trackday or race weekend. Other adjustable settings are nice to play with and will give you a decent enough car but doing the ground work first and arriving with a theoretically good setup and tuning from there I think will always give a better end result.

I'm not interested in racing my car but do take an interest in its original design and why decisions were made against the norm as far as suspension set up goes. Lessons must have been learnt from the 1*2 shape clio cup racers as they were launched in 2002? So upgrades (et45 wheels on all 182's?) must have either followed from the experience in racing or continuing development of the car.

@ shiftspark. Hmm, well before running that mod people would need to check whether it complies to their regs. I think it would be nice for them to develop it even if its is just for the track dayers.

 

[mark123]

Thanks for that Mr. Suede! Very useful pic. Perfect to get an idea of how much you need to adjust the track rod height relative the the control arm. Only trouble with standard Clio hubs is the slotted ball joint. I wouldn't have thought it will offer enough clamping force to resist the leverage created by extending the ball joint and thus will go oval very quickly with sticky tyres on a track. Hopefully this is something Northloopcup's version will address. That's what I had heard about the spring rate but seems incredibly stiff when compared with the standard car, although they did run slick tyres and need to compensate for the arb being standard still too I think (correct me if I'm wrong). Also strange the standard car has a higher spring rate at the rear from what I have found out!

31.9 N/mm Front
50 something N/mm Rear

The main thing with cup racer/laguna hub is the distance the strut is bolted from the hub face. Do you happen to know if the et48.5 of the cup racers takes the scrub radius to postive? It's pretty hard to tell from the pic without seeing the top of the strut. Also worth noting that the KPA is massive on the racers. Probably not ideal for them but better than using a narrow track! Normally in a racecar you try to find a balance between caster and KPA which is hard to do on a macphearson strut due to packaging etc.

I want this thread to be where people share info about the Clio's suspension design so to better understand the effects of changing it. Hopefully we get some more good information, from people in the know. I don't expect people to share information on the setups on thier racecars but any general info about 1*2's would be great! be worth starting a thread with a better title though!

With the std rear spring position and cup racer being different don't you need to factor that in before comparing the spring rate? I've not thought it through fully but I would have thought a 50 N/mm in the std spring position would equate to something smaller when the spring is moved out to be over the shock, less leverage so lower spring rate required for the same effect. Same applies when comparing front to rear I would have thought as the front spring is much closer to the wheel than the std rear spring position.

 

[Tony Hunter]

With the std rear spring position and cup racer being different don't you need to factor that in before comparing the spring rate? I've not thought it through fully but I would have thought a 50 N/mm in the std spring position would equate to something smaller when the spring is moved out to be over the shock, less leverage so lower spring rate required for the same effect. Same applies when comparing front to rear I would have thought as the front spring is much closer to the wheel than the std rear spring position.

Something like that Mark, yes.

 

[frenchthing]

Not cheap but i have used this company for my 106 and they are great quality

I beleive they also do the longer cup racer type...

 

[Tony Hunter]

Ooo, I like those.

 

[frenchthing]

They aint cheap mate... 500€ iirc???

Also im not a fan of running a rod end on the outboard joint.. The threads create massive stress areas and unless you massively over spec the rod end it coukd shear under heavy impact...

My wishbones run a proper housing and spherical:

I then got a longer pin to go up into the hub and drop the wishbone down a touch:

As you can see the std item is a fair bit shorter:

I think the material was EN24T steel from memory...

 

[MG cup]

Not cheap but i have used this company for my 106 and they are great quality

I beleive they also do the longer cup racer type...

That's exactly what I have been trying to tell people to build.

If you took the end piece from your wishbone and welded it to the drilled piece on above picture, then all you need is a pin machining like you have done and a spherical. Much stronger than the threaded rod end as you say.

Have you got a link Frenchthing?

 

[MG cup]

Anti dive/squat took me a while to get my head around, its relatively simple in principle but I wouldn't have any idea of how to design it into a chassis, only tune it a little I can work all this stuff out but when it comes to putting it on a car it normally gets a bit more Heath Robinson! Lol.

I absolutely agree mate. Changing suspension pick up points is a massive job and realistically not required, on a car where they are pretty good from factory. All these things are important but things like bump steer, roll centres, scrub, KPA, spring rate and roll rate are difficult to change at an average trackday or race weekend. Other adjustable settings are nice to play with and will give you a decent enough car but doing the ground work first and arriving with a theoretically good setup and tuning from there I think will always give a better end result.

I'm not interested in racing my car but do take an interest in its original design and why decisions were made against the norm as far as suspension set up goes. Lessons must have been learnt from the 1*2 shape clio cup racers as they were launched in 2002? So upgrades (et45 wheels on all 182's?) must have either followed from the experience in racing or continuing development of the car.

@ shiftspark. Hmm, well before running that mod people would need to check whether it complies to their regs. I think it would be nice for them to develop it even if its is just for the track dayers.

Its not that I don't understand it, I have just never looked too far into things mate.

If you look at a mk1 clio shell, it doesn't appear to change any except the outer panels and the rear wheel tubs. From phase 1 to 2 the adjustments in geometry have all been made with wishbones,subframes,hubs and things like that, I honestly don't think the shell has changed much fundamentally throughout the evolution.

 

[frenchthing]

http://www.tricompetition.com/


If anyone wishes to contact them i have the direct email for the best english speaker there.. I'll try and hunt it out... theyre mostly peugeot motorsport but do a few renault parts too

 

[MG cup]

Some nice bits on there. The only issue with what they sell for the Clio is it doesn't adjust the roll centre but allows camber\widening of track. At £440 they are quite expensive, then you would have to get them to make custom pins which is something they offer as well.

 

[Chip-mk1]

With regards to shafts, the front hub nuts mount onto a relatively long thread, so you can no doubt get away with doing what I did when I widetracked my valver and putting a spacer onto the CV before you slide it through the hub.

Geometry wise, some custom balljoints with both extra track and longer pins is what we could all do with someone producing for sensible money, especially if you want to run the car fairly need, but I would want a decent quality joint in it and a very high quality pin, as saving money is one thing but the amount of load through these parts dictates they need to be very strong to be safe.

Dont forget if you lower the bottom pivot for the hub too much you will also want to look at lowering the steering arm as well in order to prevent too much bump steer from occurring, as a lot of the changes you want to make to improve the suspension geometry can have a negative effect on steering geometry.

 

[frenchthing]

The front hubs may well locate with a long thread but in spacing it out your going to reduch the splines contact area..

Probably not an issue if your sneaking 10mm a side but custom shafts would be the best way.. There not as expensive as people make out..

As for altering rack/steering arms im sure i saw rod end type ends to suit a clio on TRIs site... I made my own arms and used a 5/8unf outer joint with a 1/2" bore then fitted it under (as opposed to on top) if the arm on the 106 strut.. Ive yet to remove the springs and measure bump thru the suspension travel but at least now i can adjust it with differet thickness spacers..

 

[Chip-mk1]

The front hubs may well locate with a long thread but in spacing it out your going to reduch the splines contact area.

Indeed, but as its at least twice the size it needs to be losing a bit isnt going to have any negative effect, ive never head of a clio failing on those splines TBH.

Probably not an issue if your sneaking 10mm a side but custom shafts would be the best way..

10mm is about the most you would manage because of the limits of the thread anyway, thats exactly the sort of gain I was referring to TBH, anymore and without a doubt custom shafts are the only option.

 

[frenchthing]

Also, have i just read.... Cup racers run 1000lb fronts!!!!!!!

Jeez... Maybe on a seam welded shell running a proper weld in cage tieing in front turrets and with a short life expectency..., but on a std shell even with a basic cage that'll start cracking within a year imo....

 

[Chip-mk1]

Also, have i just read.... Cup racers run 1000lb fronts!!!!!!!

Jeez... Maybe on a seam welded shell running a proper weld in cage tieing in front turrets and with a short life expectency..., but on a std shell even with a basic cage that'll start cracking within a year imo....

To quote a slogan from another site I use a lot : "Suspension harder than multiplying in roman numerals"