Car snaps sideways under braking: why?

[Slipper man]

I would definitely pop the wheels off and have a good look around. Apart from all the issues raised about pads wearing, I would take a good look at all the suspension bushes and at the De Deon tube. Worn bushes or cracked tube could do what you describe.

[Wahey]

the only time I have had something similar was with a snapped wishbone. The car was still driveable and carried good speed through corners but didn't like braking. Also a bit iffy with a broken rear subframe!

 

I guess these things are very obvious but I didn't spot them initially. First thoughts were brake issues.

 

 

[peter_964rs]

Ok, I finally worked up the courage to un-trailer the car and jack it up and inspect.

 

Brakes seemed fine - I swapped out pads from Pagid RS14 to stock Caterham whatevertheyare's.

 

Only anomaly - on the left rear spring/damper combination, with the two locking rings into which one inserts a screwdriver to adjust ride height, the bottom locking ring was loose and several turns below the ring which tensions the spring itself. If you see what I mean.

 

Can anyone confirm this is why the car snapped sideways as it did, so I can use it as an excuse instead of simply poor driving ☹️ ? I had a good look everywhere else in the rear end of the car and found nothing arwy.

[Myles]

It sure as hell ain't gonna help...

 

...but was the upper lock-ring moving freely and/or at a noticeably different height to the one on the RH shock-body???

 

I'd have thought that you'd have noticed a quite obvious difference in cornering behaviour on LH vs. RH'ers if this was the case though...

 

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[peter_964rs]

It was loose, but I didn't notice the car misbehaving on left-hand versus right-hand bends. Usually, however, the car would be loaded equally on all four wheels when cornering, and heavier on the rear when accelerating out of corners, so that might mask the problem? Whereas under heavy braking there'd be very little weight over the rear and that might account for the different behaviour on what was the fastest part of the circuit?

 

Lesson learned: always spanner-check the whole car before and after every event ☹️

[peter_964rs]

I re-read my post and realised that, of course, the car would be equally loaded on the outside wheels in cornering, most heavily, and also equally loaded but more lightly on the inside. If that makes sense. So maybe compression kept the spring platform tight in cornering but uncompression allowed it to suddenly move when heavily braking?