Understeer on roundabouts


(Mike) #7

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!!


(Paul Chapman) #8

Think you are all correct about the general greasiness.

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


#9

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.


(Phil Gardner) #10

… 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…


(Frank Demes) #11

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: )


(Paul Chapman) #12

Thanks for the details


(Frank Demes) #13

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.


#14

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).


(Frank Demes) #15

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.


#16

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!).


#17

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


(Bas) #18

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.


(Roel) #19

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.


(Max M4X WW) #20

Do you have any photos of these fitted?


(Peter) #21

I’d be interested to see these also.

:slight_smile:


(Roel) #22

And here are the photos.


(Peter) #23

That’s great.

I think I’ll be doing this to mine soon.

Many thanks.

:slight_smile:


(Peter) #24

I’m keen on going for slightly over sized tyres and tyres that have better grip in the wet.

According to Oponeo’s website the range of tyre width suitable for the Twizy’s 4Bx13 rims is 125 to 165. This doesn’t consider whether they will clear the bodywork but Roel has already done that bit.

The charts below show there’s little difference in diameter by increasing width by 20mm and reducing profile from 80 to 70.

Twizy%20front%20tyre%20calc

Twizy%20rear%20tyre%20calc

I’ve done a bit of research and the wet grip rating of the OEM tyres isn’t great and, surprisingly, neither is the fuel efficiency rating?

It’s not the easiest thing searching for matching tyres of different sizes but I now have a short list of three options - shown below.

I’m favoring Goodyear at the moment but any further experience would be much appreciated.

:slight_smile:


(Bas) #25

Hi Roel,

wow great job. Loving the white indicators as well! Where’d you get them if I may ask? How’s the overall stability with these tires on? Did you push it to the limit? I’m always a bit hesitant on adding to much grip in narrow vehicles because of the chance of it tipping over!


(Roel) #26

Some years ago I bought the indicators from a fellow Twizy enthousiast in Germany. Too lazy to buy the chrome indicator lamps for it. But these lamps will fit. you only have to modify the connectors. If you don’t like to modify the connectors search for 8KA 152 134-007

It really is a no brainer to switch to the wider tires. I guarantee you a more stable ride. Roundabouts are not dangerous anymore for the immense understeer you get with the normal tyres at speed. And trust me you will not tip over with the wider ones.