I had an 8.5 hour drive home from Darkest Cornwall yesterday due to the sheer volume of traffic, this unexpected issue meant I need to 'hurry up a bit' when the road cleared. 

 

For the time in a combined 3 years of ownership (2 Yeti family) I had a squeeky bum moment in the car; if any of you are familiar with M5 junction 11a northbound (B carriageway) you'll know that the approach is slightly uphill with a gentle right hand bend at the top. 

 

Approaching the apex the front end went really light and understeered front lane 3, across lane 2 towards the shelf, if you've ever driven a Minor 1000 at speed and had the car lift you'll know the feeling. 

 

Not a nice moment, and never happened before and indeed didn't happen at a similar speed in the 1.6 tdi Greenline earlier in the year at the same place. 

 

Not a tyre issue as the car lifted as the top of the rise was approached, I don't think I have a broken front spring, and the dampers feel ok and not worn out.  

 

Anyone else noted this effect?

What was the actual tyre pressures at the heat the tyres were at after 8.5 hours of a drive and what was the ambient and road surface temperatures? 

 

That is what can happen with some vehicles at sometimes on some roads.

Many have driven a Minor 1000 and many other vehicles and experienced Oo-sh!t moments. 

 

Roads get resurfaced, weather and road & air temperatures change, wind direction and atmospheric pressure change and so can vehicles as they suspension and tyre rubber ages. 

Actually knowing what tyres are fitted, and indeed what sort of payload distribution you had on would help here.

I'm guessing that extra luggage weight may have contributed to the light front end?

There were 2 adults and a child aboard, one suitcase for a long weekend, tyre pressures as standard for 215/60/16 Michelins, weather hot, road surface appeared consistent across the three lanes and was fine. I wasn't just hoofing it, as lifetime biker I have a gyroscope in my backside and notice road surface changes and grip levels.

 

The car was not even slightly overloaded and I'd been at the speed limit for a good 5 minutes so the tyres weren't cold,  I took the corner on a rising throttle as usual, acceleration from 60-70mph is quite brisk, and a great deal quicker than the Greenline which is of course a fair bit lower to start with.

 

 

I will check today for a soft tyre, broken springs and leaking shocks.

 

 

 

 

 

If that was a one off I would suspect contamination of the road surface.

On 23/04/2022 at 10:48, Urrell said:

If that was a one off I would suspect contamination of the road surface.

 

Exactly what I was thinking.  Localised diesel spill maybe?  Having experienced one such on the bike a few years back it's scary how the grip just suddenly disappears (though not as scary as the bill for the fairing plastics 😱).  On a bike you can sometimes get a warning if you notice the smell, although that can be very dependent on wind direction and other atmospheric conditions  Not so much in a car.

 

Classic spots for diesel spills are roundabouts and curved slip roads, due to the combination of centrifugal force and an optimistically over-filled diesel tank.  It was a roundabout where I had my diesel-induced off.  I have to say that the smell wasn't all that obvious even when I was sitting on it on my backside.  It clearly wasn't a fresh spill, though, so maybe the worst of the aromatics had had a chance to evaporate.  It was still horribly slippery nonetheless.

I have a well defined self preservation instinct especially for diesel spills, I'm not convinced this was the issue. 

 

I think this was brisk acceleration approaching a slight crest on a bend in the road with a strong cross wind, the wind suddenly got under the front end causing understeer. 

 

If this was a spill or road defect there would have been a pile of wrecked cars on the shelf at the location.