Steering correction at motorway speeds

[T90]

Hi, new to this, 

I have a 2013 ford fiesta, had it for a while. I don’t mess around, I’ve done a great deal driving in many cars, all over, but I hate this thing. It’s great on corners and A roads, but the minute you reach 70 on the motorway, if there’s a slight camber or descent, I have to constantly correct the steering and it feels like the back could spin out if you tap the brakes or overtake too sharply. I know these things are notorious for oversteer, and braking causes the back to lift off, but it’s so uncomfortable, and can get really sketchy. Is it just the name of the game with these things, or could something be off?

thanks in advance

[Neb_engineer]

2 minutes ago, T90 said:

Hi, new to this, 

I have a 2013 ford fiesta, had it for a while. I don’t mess around, I’ve done a great deal driving in many cars, all over, but I hate this thing. It’s great on corners and A roads, but the minute you reach 70 on the motorway, if there’s a slight camber or descent, I have to constantly correct the steering and it feels like the back could spin out if you tap the brakes or overtake too sharply. I know these things are notorious for oversteer, and braking causes the back to lift off, but it’s so uncomfortable, and can get really sketchy. Is it just the name of the game with these things, or could something be off?

thanks in advance

have you made sure that you are running the correct tyre pressure range, the MK7.5 is notorious for bad handling especially at speed if the tyre pressure is too high, haveing experienced what you describe in mine

[Bobr]

I have a 7.5 and with the standard tyre pressures of 33 / 26 it handles perfectly at any speed.

[Neb_engineer]

12 minutes ago, Bobr said:

I have a 7.5 and with the standard tyre pressures of 33 / 26 it handles perfectly at any speed.

as i said if the pressure is too high, MK7.5s are very sensitive to running the wrong pressure

[T90]

1 hour ago, Neb_engineer said:

have you made sure that you are running the correct tyre pressure range, the MK7.5 is notorious for bad handling especially at speed if the tyre pressure is too high, haveing experienced what you describe in mine

 

29 minutes ago, Bobr said:

I have a 7.5 and with the standard tyre pressures of 33 / 26 it handles perfectly at any speed.

I have front and back at 32, thats what I was recommended, should the back be lower? I filled tyres up yesterday, it had dropped to 23 at the back, which surprised me. The front offside keeps balding quicker than the rest, but it doesn’t pull to one side specifically, just generally unpredictable handling at high speed. On a gentle camber, it generally feels like you’re going to veer off. Stay in 70 downhill, you touch the brake and it’s all over the place 😬

[T90]

I’ll try 32/26 tomorrow. If it’s as simple as that, i’ll kick myself 😂

[Neb_engineer]

9 minutes ago, T90 said:

 

I have front and back at 32, thats what I was recommended, should the back be lower? I filled tyres up yesterday, it had dropped to 23 at the back, which surprised me. The front offside keeps balding quicker than the rest, but it doesn’t pull to one side specifically, just generally unpredictable handling at high speed. On a gentle camber, it generally feels like you’re going to veer off. Stay in 70 downhill, you touch the brake and it’s all over the place 😬

on fiestas you should never be running the front and rear tyre pressure the same, that will make the car feel unstable at high speed, also the tyre pressure you pump yours up to is based off of the tyre size, i would recommend looking at the tyre size written on the side of the tyre, then consulting the owners manual/ the tyre pressure chart on the passenger's side door jam to find the correct tyre pressure you should be running, there will be two tyre pressures for each (front and rear), the lower pressure will be the lower loaded range (1-3 people) the higher pressure will be the fully laden pressure. the other thing you should be doing is every so often rotate the tyres round the car, this will increase the overall lifespan of the tyres by making sure that all the tyres wear evenly.

[T90]

3 minutes ago, Neb_engineer said:

on fiestas you should never be running the front and rear tyre pressure the same, that will make the car feel unstable at high speed, also the tyre pressure you pump yours up to is based off of the tyre size, i would recommend looking at the tyre size written on the side of the tyre, then consulting the owners manual/ the tyre pressure chart on the passenger's side door jam to find the correct tyre pressure you should be running, there will be two tyre pressures for each (front and rear), the lower pressure will be the lower loaded range (1-3 people) the higher pressure will be the fully laden pressure. the other thing you should be doing is every so often rotate the tyres round the car, this will increase the overall lifespan of the tyres by making sure that all the tyres wear evenly.

Thanks for this 👍🏻 Never occurred to me it’d make much difference, but sounds like my problem 🤦🏻‍♂️Hopefully simples then

[Neb_engineer]

Just now, T90 said:

Thanks for this 👍🏻 Never occurred to me it’d make much difference, but sounds like my problem 🤦🏻‍♂️Hopefully simples then

yeah, the more in depth explanation for why the front and rear must be run at different pressures is due to the car's weight distribution, the same tyre pressure front to rear changes the car's "balance" also due to the suspension stiffness rear and front especially as tyres are actually a component of the suspension and by over pressurizing a tyre your effectively stiffening suspension and increasing the amount of load "seen" by the shocks and springs