Technical gearbox - wheels turning in neutral, normal?

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Technical gearbox - wheels turning in neutral, normal?

arc

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Had the car jacked up, drivers side wheel off, passenger side on the floor. engine running, car in neutral and the drivers side hub began rotating. is that normal. why would it do that?
 

arseofbox

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Its due to friction in the diff.

I think that because one shaft constantly moves (acting to partially pump oil around the system, the mainshaft may not be affected, but as the diff is much smaller and lighter it can be spun around with relative ease, causing the wheels to turn.

My 1242 does it, and did with the original 'box.

Its meant to happen :)
 

custard

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yup its normal.someone explained it to me once but i cant remeber.something to do with rotational forces or sumfink :eek:
 
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arc

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i always thought tho, neutral.. input shaft not in anyway connected to output shaft. and oil is only picked up by the gears splashing around in the oil, no pumps or owt?
 

HP

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arc said:
i always thought tho, neutral.. input shaft not in anyway connected to output shaft. and oil is only picked up by the gears splashing around in the oil, no pumps or owt?

The input shaft is turning, and gearbox oil is quite thick. It's literally just drag through the 'box that causes it - with the wheel on you can stop it by hand - if you're careful.
 

arseofbox

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The drag on the GB Oil is astounding...it must contribute fairly heavily to the power losses within the GB I think.

What I was getting as is the shaft rotation acting like a pump....not as a pump!!!
 

Hellcat

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arc said:
i always thought tho, neutral.. input shaft not in anyway connected to output shaft. and oil is only picked up by the gears splashing around in the oil, no pumps or owt?

As far as I have worked out the input and output shafts are always connected - all the gears are always meshed just the gears on the input shaft are not connected to the shaft - its the dogs that are connected to the shaft and splash the oil all over. The bearings are not perfectly frictionless though and can transfer some drive over when there is no load on the system i.e. when your wheel is up in the air.
 

rallycinq

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Hellcat said:
As far as I have worked out the input and output shafts are always connected - all the gears are always meshed just the gears on the input shaft are not connected to the shaft - its the dogs that are connected to the shaft and splash the oil all over. The bearings are not perfectly frictionless though and can transfer some drive over when there is no load on the system i.e. when your wheel is up in the air.

Go to top of t'class.

Perfect explanation of a gearbox.

Cheers

D
 
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arc

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hmmm.. dogs ? i'm gonna need some diagrams i think. i've never really looked into gearbags before
 

rallycinq

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arc said:
hmmm.. dogs ? i'm gonna need some diagrams i think. i've never really looked into gearbags before

Thay are a fairly scary concept until you get your head round the bit about the gears being in constant mesh, its the hubs that move. Then it becomes much clearer, I think.

Cheers

D
 
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arc

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yup, i've had a look around and it make sense now. I always though the selector moved the gears around. Now i see whats going on, and it all makes sense :)

cheers!
 
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