Never thought I'd be posting this....
Discussion
Write off. Now the story...
3 years ago I decided I wanted to drive a TVR, Chimaera was the dream. Having popped TVR into google I find pistonheads and start reading. Soaked up every piece of advice about driving that I saw, most often the advice of shpub and greenv8s gave to those that had just bought or were thinking about it. Watch the downshift, be careful on the downshift, for christs sake mind what your doing on the downshift was something that came up often!
Year later the dream comes true and I spend 12 months and 15000 miles driving a gorgeous 4ltr Chimaera. Got the itch for more and sold to fund a 500. 6 months later and wanting more I emptied my wallet to Mark Adams and ACT for a few upgrades. Heaven!
Over the last few months, having moved to London were I don't get to drive often, I decided it was time to sell. Got up early this morning to wash and polish the car ready for inspection by Ross (Twerlie) who was interested in buying it. We had a drive, Ross was interested and was due to call me back this evening to make an offer.
Took a friend for a drive and lunch, took a route that included one of my favourite roads (which Ross and I had driven down earlier in fact!). Approach a tight right hand bend, heavy on the brakes and down to 2nd gear, still in straight line, back end tries to overtake the front and unfortunately succeeded. Ended up drivers side smashed against a sturdy wooden garage.
No skids marks on the road, can't tell where it started to go wrong, no sign of any liquids, usual country road so a bit dusty and the odd patch of dirt/small stone.
Both passenger and myself have nothing more than one bruised elbow a piece, car on the other hand looks like a write off. Drivers footwell much smaller than I remember it, bodywork fractured most of the way down drivers side, suspension twisted, wheels stuffed, ego completely battered.
I'm off to the pub!
3 years ago I decided I wanted to drive a TVR, Chimaera was the dream. Having popped TVR into google I find pistonheads and start reading. Soaked up every piece of advice about driving that I saw, most often the advice of shpub and greenv8s gave to those that had just bought or were thinking about it. Watch the downshift, be careful on the downshift, for christs sake mind what your doing on the downshift was something that came up often!
Year later the dream comes true and I spend 12 months and 15000 miles driving a gorgeous 4ltr Chimaera. Got the itch for more and sold to fund a 500. 6 months later and wanting more I emptied my wallet to Mark Adams and ACT for a few upgrades. Heaven!
Over the last few months, having moved to London were I don't get to drive often, I decided it was time to sell. Got up early this morning to wash and polish the car ready for inspection by Ross (Twerlie) who was interested in buying it. We had a drive, Ross was interested and was due to call me back this evening to make an offer.
Took a friend for a drive and lunch, took a route that included one of my favourite roads (which Ross and I had driven down earlier in fact!). Approach a tight right hand bend, heavy on the brakes and down to 2nd gear, still in straight line, back end tries to overtake the front and unfortunately succeeded. Ended up drivers side smashed against a sturdy wooden garage.
No skids marks on the road, can't tell where it started to go wrong, no sign of any liquids, usual country road so a bit dusty and the odd patch of dirt/small stone.
Both passenger and myself have nothing more than one bruised elbow a piece, car on the other hand looks like a write off. Drivers footwell much smaller than I remember it, bodywork fractured most of the way down drivers side, suspension twisted, wheels stuffed, ego completely battered.
I'm off to the pub!
Yikes! 
All I can say "damn good job you're fine, and I hope you had protected NCB????"
Dont worry about the ego and stuff, this kinda thing can happen to anyone when least expected...
This might be like salt on a wound, but any pics to show before and after just to put some facts into heads about "this can happen to anyone"....
All I can say "damn good job you're fine, and I hope you had protected NCB????"
Dont worry about the ego and stuff, this kinda thing can happen to anyone when least expected...
This might be like salt on a wound, but any pics to show before and after just to put some facts into heads about "this can happen to anyone"....
...//P// 
) - So i'm back on the hunt for another 500!.....anyone selling one? Mark.S said:
Approach a tight right hand bend, heavy on the brakes and down to 2nd gear, still in straight line, back end tries to overtake the front and unfortunately succeeded........ No skids marks on the road, can't tell where it started to go wrong
Firstly I'd echo the comments that thankfully you and your passenger walked away from this.
So presumably the explanation is that on heavy braking the rear wheels were unloaded and, on applying the extra engine braking as the clutch was released to engage 2nd gear, the rear wheels locked up. No skid marks from these wheels since there was insufficient load - they just skitted across the surface.
I'm very interested to learn from your experience and hope those with more track-craft might help with their comments on what to avoid (excessive engine braking during heavy wheel braking seems like a conflict) and what to do at that moment when the backend becomes unstable, because at that stage depressing the clutch will not unlock the rear wheels as they are still unloaded. Is it a recoverable situation?
Mark, the main bit is that you are both ok. Cars are replaceable, no matter how attached we get to them.
One explanation might be, and I stress might be, is that sometimes with high torque engines when the wheels actually lock up they then start to turn backwards, hence pulling your back end around even faster...
The early Ford diesel Vans suffered this in wet weather under heavy breaking with the engine assisting with the breaking.
Anyhow, you’re ok.
One explanation might be, and I stress might be, is that sometimes with high torque engines when the wheels actually lock up they then start to turn backwards, hence pulling your back end around even faster...
The early Ford diesel Vans suffered this in wet weather under heavy breaking with the engine assisting with the breaking.
Anyhow, you’re ok.
Mr Freefall said:
The early Ford diesel Vans suffered this in wet weather under heavy breaking with the engine assisting with the breaking.
That explains something that happened 34 years ago....
Wet roundabout, transit on its side in the middle, me lying on the passenger window, then climbing out of the rear door.
Amazed I kept my job....
Glad to hear you're ok even if pride and joy dented.
Sounds like clutch braking rather than engine braking on the downshift, while braking. Glad you're OK.
I used to come off the brakes, downshift and blip, and then back on the brakes, so the revs matched. Since then I've learned to heel'n'toe, so I don't have to come off the brakes. I know some here don't regard it as a road technique, but...
I used to come off the brakes, downshift and blip, and then back on the brakes, so the revs matched. Since then I've learned to heel'n'toe, so I don't have to come off the brakes. I know some here don't regard it as a road technique, but...
Sorry to hear this Mark, and as others have said, the main thing is that you and your passenger are OK. Cars can be repaired/replaced, but you can't! Hopefully though the car isn't as bad as it first appears.
How does this work then? Unless you stick the car into reverse, the engine is still trying to turn the wheels in a forward direction, just not as fast as they are currently turning.
This thread probably isn't the place to go into driving technique - there are several on here already (search for heel and toe or braking technique in General Gassing or this forum), but the basic problem is when you bring the clutch up after (or during) braking, and the engine revs are not matched to the road speed.
For example, you are driving at 60mph in 4th gear at 4000 rpm. You then brake to 40 mph, so now the engine speed is 2500 rpm as you are still in 4th.
You change down to 3rd, and the engine revs drop towards idle as you depress the clutch and change down a gear. As you bring the clutch up the wheels are still rotating at 40 mph, but as the clutch engages, the low revs of the engine act like a brake and try to slow them down to match the engine speed, which is now a lot lower than the 4000rpm it should be for 40mph in 3rd.
If you are braking hard, the weight transfers forwards, and you have less grip at the back. In some cases, the braking effect caused by changing down as described above is enough to overcome the remaining grip of the rear wheels, and they then lock up, which can result in the car losing control.
The best way of avoiding this is a method called "heeling and toeing", which involves blipping the throttle with the side of your foot while braking. This brings the engine revs up to the correct speed to match the new lower gear, so in the example above, you'd blip the throttle to rev the engine to 4000 rpm when you change down to 3rd.
This is quite a hard technique to learn and perfect though, so it's probably best to try it sitting in a stationary car first before trying it out for real.
Mr Freefall said:
One explanation might be, and I stress might be, is that sometimes with high torque engines when the wheels actually lock up they then start to turn backwards, hence pulling your back end around even faster...
How does this work then? Unless you stick the car into reverse, the engine is still trying to turn the wheels in a forward direction, just not as fast as they are currently turning. This thread probably isn't the place to go into driving technique - there are several on here already (search for heel and toe or braking technique in General Gassing or this forum), but the basic problem is when you bring the clutch up after (or during) braking, and the engine revs are not matched to the road speed.
For example, you are driving at 60mph in 4th gear at 4000 rpm. You then brake to 40 mph, so now the engine speed is 2500 rpm as you are still in 4th.
You change down to 3rd, and the engine revs drop towards idle as you depress the clutch and change down a gear. As you bring the clutch up the wheels are still rotating at 40 mph, but as the clutch engages, the low revs of the engine act like a brake and try to slow them down to match the engine speed, which is now a lot lower than the 4000rpm it should be for 40mph in 3rd.
If you are braking hard, the weight transfers forwards, and you have less grip at the back. In some cases, the braking effect caused by changing down as described above is enough to overcome the remaining grip of the rear wheels, and they then lock up, which can result in the car losing control.
The best way of avoiding this is a method called "heeling and toeing", which involves blipping the throttle with the side of your foot while braking. This brings the engine revs up to the correct speed to match the new lower gear, so in the example above, you'd blip the throttle to rev the engine to 4000 rpm when you change down to 3rd.
This is quite a hard technique to learn and perfect though, so it's probably best to try it sitting in a stationary car first before trying it out for real.
Oh no!
Glad to hear you are both OK.
A lucky escape.
Im trying to get out of the habit of any engine braking but its quite a hard habit to brake.
I heel and toe on down shifts* any way so its not such a problem. I have been gradully adjusting the pedals to get the right place and I just need to pull the brake up a bit now to get it perfect.
BUT...
On a bigger piece of road I tried to purposely get a feel for what happens when it goes wrong just incase it ever catches me out when Im not aware.
Didn't even have to give it huge revs to get the wrong motions to start happening. Didnt let it fully go of course, just got a feel for it. Hope it never catches me out.
* always have, even in FWD. Just for the fun/hell/sound of it.
>> Edited by DustyC on Tuesday 18th May 11:46
Glad to hear you are both OK.
A lucky escape.
Im trying to get out of the habit of any engine braking but its quite a hard habit to brake.
I heel and toe on down shifts* any way so its not such a problem. I have been gradully adjusting the pedals to get the right place and I just need to pull the brake up a bit now to get it perfect.
BUT...
On a bigger piece of road I tried to purposely get a feel for what happens when it goes wrong just incase it ever catches me out when Im not aware.
Didn't even have to give it huge revs to get the wrong motions to start happening. Didnt let it fully go of course, just got a feel for it. Hope it never catches me out.
* always have, even in FWD. Just for the fun/hell/sound of it.
>> Edited by DustyC on Tuesday 18th May 11:46
Glad you’re OK - could have been much worse by the sounds of it. Also interesting (and reassuring) to hear that you had a side on impact (with so little protection) and that barring a bruise you are OK.
Talking about driving technique when someone’s lost it does seem a bit crass but it is useful to think about it as it could happen to any of us and we might not all walk away. I think it almost impossible for anyone other than Mark to work out precisely what happened. But engine braking in itself is not a major problem, the problem is a sudden change in braking force when turning i.e. letting the clutch out too quickly/without balancing the revs.
Reading this forum I too had the doctrine of "never engine brake" beaten in to me and I now think it is a risky doctrine to follow. As a general rule it is fine but it can cause more problems than it solves. For example, going around a bend and having to lift off due to an unforeseen problem etc. In my early days driving the Griff, this situation terrified me with thoughts of spinning. At Oulton Park I did spin through not lifting off in a corner and as a result went wide over a curb and lost control. I learnt on an airfield driving course that it is not only possible but positively safe to lift off in a corner in order to get round safely. The key is concentrating on the steering and avoiding violent shifts in balance. With practice it is possible to steer the car "on the brakes" around a corner. If I hadn’t had this very ably demonstrated to me I would never have thought it possible but with practice I was just about there myself. Hope this is of some use to someone.
Talking about driving technique when someone’s lost it does seem a bit crass but it is useful to think about it as it could happen to any of us and we might not all walk away. I think it almost impossible for anyone other than Mark to work out precisely what happened. But engine braking in itself is not a major problem, the problem is a sudden change in braking force when turning i.e. letting the clutch out too quickly/without balancing the revs.
Reading this forum I too had the doctrine of "never engine brake" beaten in to me and I now think it is a risky doctrine to follow. As a general rule it is fine but it can cause more problems than it solves. For example, going around a bend and having to lift off due to an unforeseen problem etc. In my early days driving the Griff, this situation terrified me with thoughts of spinning. At Oulton Park I did spin through not lifting off in a corner and as a result went wide over a curb and lost control. I learnt on an airfield driving course that it is not only possible but positively safe to lift off in a corner in order to get round safely. The key is concentrating on the steering and avoiding violent shifts in balance. With practice it is possible to steer the car "on the brakes" around a corner. If I hadn’t had this very ably demonstrated to me I would never have thought it possible but with practice I was just about there myself. Hope this is of some use to someone.
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