Understeer on roundabouts

Hi all, this last week I have noticed on roundabouts that I am having more understeer than I would normally expect or have experienced in the past.

Driving at normal speeds around them, 20mph I would expect, the tyres are in good shape so not due to wear or due to anything on them to make them more slick.

Weather normal, dry conditions and actually getting warmer so finding it hard to explain.

Any suggestions at all?

Sticky Throttle pedal?

Do you mean understeer? Where the car seems to be going straight ahead instead of turning like the steering wheel is suggesting? Have you checked the camber and toe of the front tires? If they aren’t aligned properly they will have less contact with the road and therefore less steering abilities. Or have you added extra weight (maybe an extra passenger) one the rear wheels? That will also mean less contact for the front wheels. I hope this was helpful.

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whoops I have changed the title to read understeer! Not sure what I was thinking saying over, but yes it goes straight on rather than turning!

@Mads thanks for this, not added extra weight but I can certainly look to check the camber and toe, would a visit to QuickFit be able to check this?

Oh right. in that case also check tyres are not over inflated. For the same reason - contact area.

After all the salt they put on the roads they do appear to have a film of grease on them which doesn’t help.

My car understeer a lot with th summer tyres.
But with winter tyres the car is comleatly in balance.

It’s actually caused by the general greasiness of the road surface. The salt (shit!) that the throw on the roads creates a film with even the smallest hint of dampness. I have this problem both in my twizy and my smart car. It’s because they weigh so little. Just keep the speed down and watch it when driving in the country on slightly faster bends. Nearly lost it a few weeks ago. Thank goodness for high verges, or I’d have been in the field!!

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Think you are all correct about the general greasiness.

Same roads, a week later, nothing changed on the car and grips with no issues.

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The chassis is configured to under steer - it’ll do this in the dry or wet, the conditions simply change how many G’s you can pull before slip happens.

… we just need to see how difficult it would be to dial in a little more negative camber on those front wheels. I normally fit adjustable camber bolts to all my front-wheel drive cars and it works brilliantly on my Fiat Panda 4x4. I may investigate soon…

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In my opinion the under steer is a planed thing.

Cars with rear wheel drive are to be driven with a lot of discipline :wink:

So Renault added some toe in on the back(on my last 3 Twizys about half a degree) and put some smaller tires on the front.

Even with the track adjusted to zero you can’t get rid of that understeering completly.

So I did put 145/70 on the front wheels.
No understeer up to 25 miles.

Only a slight tendency to over steer when you drive it to hard.
But with the original contis you can hear when the tires begin to loose traction.

Since this year I also have 155/70 fitted to my back wheels.

They are a little smaller (3%) and shift the balance a little to the back.
with this configuration the Twizy runs like on rail road tracks.

I tried very hard to get it to drift :slight_smile: (Got a OVMS with 18,5 kW setting :wink: )

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Thanks for the details

forgot to say, that is the only combination of tires that will still fit under the original wings :wink:
You could go wider, but then you have to do some modifications.

I wouldn’t recommend removing the toe in on the rear - may lead to instability over low frequency bumps when going into droop (it’ll most likely toe out in this situation).

In my experience it´s the other way around.

Here in Berlin we have a lot of cobbled streets. Even on streets with a 25 mph limitation

Every time I got a new Twizy , I drove it for a view weeks with toe.

On wet cobblestone the Twizy tends to wiggle his tail!
Every time when a different side of the back gets traction, it moves to the other side until both tires straighten this up.

Does not happen with a adjusted Twizy.

You have to be careful with this. You are talking about longitundinal acceleration and breaking the circle of traction. I am talking about low frequency bumps, e.g. big dips in a road, where you get the most suspension travel. This is where geometry is important. If you get toe-out on droop (e.g. on the way back up and over from a deep compression moment) then it will un-settle the rear of the car as the rear axle will want to steer itself, at a time where there is little weight on the tyres! It’s dangerous, which is why OEMs have toe-in on the rear… and hopefully toe or neutral on droop (within reason!).

Fit one of these and, bang, the understeer is gone :rofl:

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Guys, just wanted to reopen this topic a little since I too have been noticing it’s hard and in some situations even impossible to drive around the fact that the stock Twizy setup is a little too safe in my opinion. I’m used to driving light weight rear wheel driven cars and would like the Twizy to act a little more entertaining, especially during acceleration from low down when there’s little pressure on the front wheels. I’ve been playing with the pressures a bit and it has improved but of course there is no getting around the fact that there is a 20mm difference between front and right tires which obviously has been done intentionally be Renault to add a little safety.

I was thinking that when my Twizy will need to have its tires changed, to opt for 135/80/13 front tires. Read on some German forums that they do this and it has neutralised the behaviour a lot they say. I’ve been looking for some images on the web and for some experiences and was wondering whether anybody here has gone down this road and what they think of it.

I put on the following combo. And trust me, by doing that cornering is as easy as you wished it to be.

Front: Nexen N’Blue HD Plus 145/70 R13 71T
Back: Nexen N’Blue HD Plus 165/70 R13 79T

And yes they fit in the original mudguards! And all looks so original.
All I needed to do on the back mudguard was to place a 1mm washer between the back leg and where the bolt goes in. Simple.

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Do you have any photos of these fitted?

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