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To follow on from the various clutch threads, does Freewheeling in a manual car cause any problems or issues to clutch / gearbox / engine?
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I though that you needed to keep the engine on to provide power to the steering, brakes etc.
I was told by a mechanic years back that the pistons didn't get the lubrication required if the car was in neutral.
Probably codswallop but it would be interesting to know.
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>> I was told by a mechanic years back that the pistons didn't get the lubrication
>> required if the car was in neutral.
So he thought a car didn't get any oil to the moving bits when waiting for the lights to turn green?
Was he a mechanic for very long?
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My DSG equipped petrol turbo has a freewheeling mode. Lift of the throttle and it will disengage the gear and revs drops to idle. It also stops fuelling two cylinders on light loads.
Not had a problem.... yet.
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Freewheeling in a RWD lorry (to exceed the limited speed on long downhill stretches*, for example) introduces unwelcome vibrations into the propshaft bearings; eventually leading to their failure and loss of drive.
Don't ask me how I know this.
*Known in some circles as "Scotsmans' top gear"
Last edited by: Dave_ on Sun 12 Feb 17 at 22:33
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My father and his mates used to call it 'silent fifth'...
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>> I though that you needed to keep the engine on to provide power to the
>> steering, brakes etc.
Correct, generally speaking.
>> I was told by a mechanic years back that the pistons didn't get the lubrication
>> required if the car was in neutral.
Fairly obviously not true, but it might be a very mangled version of a different truth. Many here will remember that the e.g. the Saab 96 and predecessors had a freewheel. It was selectable on mine by a t-handle on the bulkhead that, when pushed in IIRC, enabled the car to freewheel in gear. Off-throttle, the engine would be ticking over and providing no retardation at all.
I tried it once, and it was scary down a steep hill with the 1970s brakes so I never used it after that. Mine had a Ford-derived four stroke engine, but it was a hangover from when the cars were two strokes. A conventional two stroke gets minimal lubrication on the overrun as the oil is mixed in with the petrol but the throttle is shut so, to prevent excessive engine wear and possible seizure, Saab fitted the freewheel.
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I had a series of Rovers - 16,75,110 - with overdrive.. The ones with drum brakes (16/75) were scary in the Highlands using freewheel.. I stopped after one long descent with front drums red hot and smoke wisps entering the car - not at all pleasant . (The days of asbestos brake linings).
Totally unsuited to modern driving conditions - but great fun then. 25mpg? Must have used the freewheel.
Last edited by: madf on Mon 13 Feb 17 at 12:35
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>>>>
>> I tried it once, and it was scary down a steep hill with the 1970s
>> brakes so I never used it after that. Mine had a Ford-derived four stroke engine,
>> but it was a hangover from when the cars were two strokes. A conventional two
>> stroke gets minimal lubrication on the overrun as the oil is mixed in with the
>> petrol but the throttle is shut so, to prevent excessive engine wear and possible seizure,
>> Saab fitted the freewheel.
>>
It was not Ford derived;it was a genuine Ford engine.
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Fair enough. If I had said it was a Ford engine, no doubt somebody would have said it had a different sump or something.
It was a V4 Taunus engine (not the same as the UK Transit) IIRC, which I possibly don't. I liked it anyway, although people kept trying to tell me the head gaskets would go; they didn't.
Actually, as we are being pedantic, my Chambers dicky has "To conduct, draw, take, obtain, proceed or receive (from a source or origin)" as the first definition of derive, which seems to cover all possibilities. But I accept your correction:)
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>> Many here will remember that the e.g. the Saab 96 and predecessors had a
>> freewheel.>>
Ah - memories - I once had a SAAB 96 Monte Carlo, (q.v.).
A howling banshee of a two stroke and a wonderful handling car for its era.
It was HORRENDOUSLY costly to run: IIRC about 22mpg of petroil, which was, even at that time too much compared with a target of circa 30 mpg for its contemporaries.
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Freewheeling - zippy
