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Suspension for beginners

Just replied to a PM and it got a bit long winded talking of lift off oversteer and camber. It took me so long to write I'm going to post it up here so I can reference to it again.

It was in reply to a question as to whether a person should just get front camber bolts fitted and not bother with rear adjustment. Specifically it was regarding the FN2 but applies to all cars really as the theory is the same.

Not a problem.

It really does depend on if you are going to track the car and/or how hard you would ever drive on a public road.

I'll explain the benefits of the rear settings on the Fast Road Set-up.

All FN2 Type Rs came out of the factory with geometry within Honda tolerances, i.e. if camber or alignment is too great then the car will go back to 'finishing' and the suspension fettled with to try and achieve the the specified tolerances.

No car will be released where they do not meet that specification, however since there is no camber adjustment on the front and the rear suspension is a torsion beam, which ordinarily would not allow camber adjustment, the specifications are quite wide and easy for the production line to produce.

Specifically looking at the rear, the car can come from Honda with positive camber, where the top of the wheels are further apart than the bottom. That means that in a straight line the outside of the tyres has more pressure on the tarmac. Now for example, introduce a right hand corner into the equation, the suspension loads up and compresses on the left as the weight of the car shifts to the left. Due to the lean of the car, the positive camber is exaggerated on the left hand side of the car, the side that is doing all of the gripping and the outside tyre now only has a very small contact patch with which to grip.

If the car had negative camber to start with, you don't need lots of grip in a straight line, just enough to braking and accelerating (drive wheels obviously), in the same scenario, the car goes into the bend. The tops of the wheels are now closer together than the bottom. The car leans into the bend, effectively adding positive camber to the left hand side of the car. Now, because the camber is already negative, the left tyre will now be flat on the tarmac, have the biggest contact patch and give the best grip when you need it.

Obviously this is a good as it will add more grip and increase the speed you can carry through a corner. My car now grips well enough on the rear that it can lift the inside rear wheel in a corner.

What Jeremy Clarkson found so appealing in the EP3 but lacking in the FN2.

Now the next bit is slightly harder to understand and unless you drive on the limit, even harder to use on the open road.

The toe of the rear wheels ideally would be set to be toed in, where the fronts of the tyres are closer together than the rear, and this is all to do with lift off oversteer and controlling it.

You go into the right hand bend and you are carrying a bit too much speed into the corner and you start to drift wide. The front is scrabbling for grip and you let off the throttle but don't touch the brakes. The weight of the car now shifts to the front and the back should go 'light'.

Now from the factory the characteristic of the FN2 is that the car will continue to run wide until the front eventually get enough grip to turn as tightly as you are wanting and if you've done it early enough you make it round the bend. If you think of it, it is all about getting the nose of the car pointing out of the bend and then you can put the power back on.

Setting the toe in on the rear, means that when the car goes light on the rear as the weight shifts, the left hand rear tyre can be used to break traction and 'tuck in' the nose of the car in the bend.

This is called light off oversteer. Now the reason why it is controllable with toe in, is that the right hand tyre is not pointing into the corner as much as the fronts or the left ear and does not break traction to the same extent. The rear end is now turning faster than the front, and the front end should now have gripped, where previously it had lost traction. When the angle of the car is pointing through the corner, you can apply a little more throttle and the back end will now grip as the weight transfers. The right hand tyre can grip easily and then gives the left hand one the ability to find grip.

Now this all is happening in split seconds and to do this you need the reactions of a cat, but I've made it sound more dramatic than it really is. If you are doing it properly it is the fastest was to get a car round a corner as you can get all four wheels breaking traction and you get a four wheel drift, but it is also desirable if you have carried too much entry speed into a corner. It is the front wheel drive equivalent of balancing a car on the throttle.

This does seem to counter the effect of camber I described above, but it is complementary, as if you cannot get good grip in the first place, you will just end up sliding off the road backwards.

An easy way to see it in action is to find a quiet, big roundabout. If you go round the roundabout, gradually increasing speed you will start to drift wide. In a car that has not been set-up properly when to start to go wide, all you can do is lift off and wait for the front to grip. In a car that has been set-up properly the rear end will start to come round and you can start playing with the throttle to balance the front and rear.

Like I said, you might not ever get into a situation on the road, or you may depending how you drive.

Still, you can appreciate just adding grip to the front is not the full story in setting up the geometry of the car.

Hope this helps.

John
 
John, Toe in on the rear is designed to improve rear end stability and is there to minimise how reactive the rear is on corner entry and to be stable in a straight line. Toe out is where the rear becomes more lively and helps kills understeer through lift off oversteer/weight transfer.

It's the same on the front, toe out increase turn in/handling, toe in increases straight line stability.
 
John, Toe in on the rear is designed to improve rear end stability and is there to minimise how reactive the rear is on corner entry and to be stable in a straight line. Toe out is where the rear becomes more lively and helps kills understeer through lift off oversteer/weight transfer.

It's the same on the front, toe out increase turn in/handling, toe in increases straight line stability.

Write a book bro.
 
John, Toe in on the rear is designed to improve rear end stability and is there to minimise how reactive the rear is on corner entry and to be stable in a straight line. Toe out is where the rear becomes more lively and helps kills understeer through lift off oversteer/weight transfer.

It's the same on the front, toe out increase turn in/handling, toe in increases straight line stability.

Fair play. Thinking about it, the outside tyre that is getting loaded up is already pointing into the corner.

Does make sense, and the only reason I didn't get lift off oversteer in the FN2 before the FRSU was probably only due to the front end not having enough grip. :lol:

I was right though that toe in at the rear makes lift off oversteer more controllable, I just got there the wrong way.
 
Yeah the combination of a bit of toe in and the camber will help keep the rear planted and should always want to come back in line if it starts to step out a bit. For most road use toe in is the right way to go as it's safe and predictable, the car in theory should go to understeer before oversteer, making it easier to control at the limit. Toe out can make it more twitchy and unpredictable but ultimately quicker on the track, but can promote a more lively rear end on the road which can be a bit unnerving. A lot of it comes down to driving style and preferences more than anything.
 
Does make sense, and the only reason I didn't get lift off oversteer in the FN2 before the FRSU was probably only due to the front end not having enough grip. :lol:

Rach's 206 gives out amazing lift off oversteer, not as good as the EP3, but its there non the less.

LOOS is good, as it's fun, but not as killworthy as RWD oversteer.
 
Yeah the combination of a bit of toe in and the camber will help keep the rear planted and should always want to come back in line if it starts to step out a bit. For most road use toe in is the right way to go as it's safe and predictable, the car in theory should go to understeer before oversteer, making it easier to control at the limit. Toe out can make it more twitchy and unpredictable but ultimately quicker on the track, but can promote a more lively rear end on the road which can be a bit unnerving. A lot of it comes down to driving style and preferences more than anything.

Book.

I want a book.

Or at least a leaflet.

:lol:
 
Any words on how it would effect normal commuter driving? Someone said it wears the outer edge of the tyres faster?
 
Any words on how it would effect normal commuter driving? Someone said it wears the outer edge of the tyres faster?

Toe in would have a tendancy to wear the inside of the tyre and toe out would effect the outer edge of the tyre more.
 
Is it worth it then?

It'll only be a dramatic effect combined with lots of other factors. The toe adjustment be it in or out, on the road won't drastically effect tyre wear, but can make a difference to the handling. Setting the toe is part of any geometry set-up no matter how basic so it's going to be done anyway, and a bit of toe in on the rear for example for stability isn't going to knacker your tyres.
 
It'll only be a dramatic effect combined with lots of other factors. The toe adjustment be it in or out, on the road won't drastically effect tyre wear, but can make a difference to the handling. Setting the toe is part of any geometry set-up no matter how basic so it's going to be done anyway, and a bit of toe in on the rear for example for stability isn't going to knacker your tyres.

See the previous owners of my CTR didn't finish the job of tuning it - so the task has been handed down to me :) BC coilovers work a treat but a couple things that are lacking are perhaps the FRSU and the acceleration from static. I'll sort the FRSU first and then see what everyone else has to say about the next best thing.
 
See the previous owners of my CTR didn't finish the job of tuning it - so the task has been handed down to me :) BC coilovers work a treat but a couple things that are lacking are perhaps the FRSU and the acceleration from static. I'll sort the FRSU first and then see what everyone else has to say about the next best thing.

That's it, if you've not had the geometry set-up since the coilovers went on, it has far more potential to knacker your tyres than having the car set-up properly :)
 
That's it, if you've not had the geometry set-up since the coilovers went on, it has far more potential to knacker your tyres than having the car set-up properly :)

Yes exactly, they had (for some unknown reason) adjusted the front coilovers higher than the rear two - resulted in the car wondering all over the place when you put your foot down. That's all sorted now, got the front down and it handles fine ;)
 
It seems that a lot of CTRs have incorrect geometry settings which can make the car spin very easily.

When taking a roundabout at high speeds, my car tends to "throw it's back" outwards while the front wheels keep nice grip. Feels like the back of the car is too light to stay on the ground.
Is this a problem that can be solved?
It's like my car oversteers on roundabouts.

I'm running RE050A's so I doubt that's a weak link.
When using budget tires (40£ tires) before, this was much worse, only the front was skidding as well, keeping it more or less balanced. Now the main problem is traction on the rear of the car.

Any solutions? Does the FRSU help prevent this issue?
 
Instead of starting a new thred i'll try here.

Does anybody know where I can get a full geometry setup done in the Wesy Midlands? I know ABP performance do it but anywhere closer as those guys are based in Crewe.

Many thanks

One new happy EP3 Type R owner :)
 
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