hello,

i'm trying to chase a noise and to eliminate the gearbox from my enquiries i'd like to know if, whilst in neutral, the whole drivetrain is being moved by the wheels whilst the car is moving?

the 'how-stuff-works' article showed the output shaft would just spin but the gears attached would be moving at tickover from the engine but i've never been to convinced by hsw.

any clues would be great.

cheers

Yes the whole drivetrain rotates when car moving when in neutral. With the exception of reverse, all gears are constant mesh, but are free to rotate around the shafts until locked in place by the syncro hub, when you select a gear.

One thing to note, all torque through the drivetrain reverses direction while free-wheeling in neutral.

so effectively letting the car freewheel down hills (despite the control related issues) is not going to reduce the load on the transmission?

thanks for clearing that up. i had thought it was just the differential and the gearbox output shaft and none of the rest of the drivetrain that would be in motion during freewheeling.

cheers

toby

so effectively letting the car freewheel down hills (despite the control related issues) is not going to reduce the load on the transmission?

thanks for clearing that up. i had thought it was just the differential and the gearbox output shaft and none of the rest of the drivetrain that would be in motion during freewheeling.

cheers

toby

The torque through the box is greatly reduced if coasting in neutral or even with the clutch in. Under engine braking, the torque load is only slightly reduced.

Output shaft always turns in proportion to road speed. Input shaft will turn at engine idle speed in neutral. So if no gear selected, engine drives input shaft, wheels via differential drive output shaft.

Six speed box has an extra shaft just to make matters even more complex.

It's been a long time since I was a tech...so I'm not that up on modern gearbox design. Many automatic transmissions in cars and most modern motorcycles now have pressure fed oil to the bearings in the gearbox (in spite of being wet sump engine and gearbox design on nearly all bikes). Is oil pressure fed to bearings on manual transmission boxes in cars these days? Anyone know? If so, coasting may not be a good idea if input shaft speed driven.

Edited 27 March, 201016 yr by Estate Man

It's been a long time since I was a tech...so I'm not that up on modern gearbox design. Many automatic transmissions in cars and most modern motorcycles now have pressure fed oil to the bearings in the gearbox (in spite of being wet sump engine and gearbox design on nearly all bikes). Is oil pressure fed to bearings on manual transmission boxes in cars these days? Anyone know? If so, coasting may not be a good idea if input shaft speed driven.

Most modern boxes are simply splash and hope oil feed