Towing RWD Manual Tranny Trucks.

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--with the rear wheels down. Any time a two company tows a medium duty truck with the rear wheels down, the tow truck driver disconnects the rear driveshaft. Would it not be easier, for short tows of under a few miles, to leave the driveshaft in place, engage top gear, and depress the clutch pedal all the way with a pedal depressor? Countershaft turns and tranny internals get lubricated. The clutch release bearing is very beefy on these trucks and should be able to handle the clutch load for about fifteen minutes.

Sure beats lying under the truck by the side of a busy highway disconnecting the driveshaft.
 
I would assume they are trying to not damage their customer's gear as much as possible. There is no liability when you pull the driveshaft.

What happens if the release bearing is on it's last legs and that does it in? The off chance the depressor is not set correctly or gets knocked off? Different procedures for manuals v autos? An excellent way for an inexperienced employee to cause catastrophic damage.
 
Disconnecting the driveshaft is quick and removes any possibility of damage if your scenario goes wrong.
 
Broadly speaking it's about distance to be towed; if it's short (a few miles) it's OK to tow in Neutral Gear, clutch engaged. If the distance is for any distance, say, beyond 5 miles or so, disconnect the driveshaft.

I would guess that the owner's manual for the towed vehicle almost certainly addresses the issue, refer to it and follow the recommendations.
 
Why is it bad to tow in neutral gear? I never heard of such a thing as towing in neutral might cause damage to a red vehicle. What will happen for extended towing?
 
No, any one who drives a manual DOES NOT know this.

When the counter shaft rotates the gears on the counter shaft, which are submerged in oil, transfer the oil to the mating gears on the output shaft and this oil lubricates the gears and the bearings on the output shaft. In neutral none of the gears on the output shaft are locked on to the output shaft, so none of the gears are turning and there is no oil reaching the output shaft. So we have the output shaft turning with no lubrication if the truck is being towed. I would not like to tow a vehicle any more than a kilometre with no oil being fed to the output shaft.

Here is a quote from the Owners Manual of my Sierra RWD pickup truck "Two wheel drive vehicles should not be towed with all four wheels on the ground. Two wheel drive transmissions have no provisions for internal lubrication while being towed."

With 4WD and the transfer case in neutral, the tranny output shaft is not turning and the truck can be towed.

To add to my original post, the release bearing is not rotating if the engine is not rotating, so there is no concern about damage to the release bearing if the truck is towed with the clutch pedal depressed.
 
Does transmission fluid leak out when the driveshaft is removed, and front of vehicle raised up?
 
In the specific case I was discussing - medium duty trucks - no, because the driveshafts are multipiece, there are three or even four shafts coupled together and the rearmost shaft, which is being disconnected, just slides out of the stand alone slip joint which has grease in it.

It would be an issue with my Sierra pickup where the one-piece shaft slides into the rear of the transmission. With light duty vehicles they do not bother disconnecting driveshafts, they use tow dollies if necessary. Now, with more rollback tow trucks, they just load the entire vehicle on to the tow truck.
 


This is from the video Shannow posted in the Synchromesh Explained thread. This picture should help understand how the output shaft is lubricated.
 
So does that mean driving a 2wd rwd car in neutral with the clutch disengaged is in principal the same thing as towing in neutral?
 
Originally Posted By: Kurtatron
So does that mean driving a 2wd rwd car in neutral with the clutch disengaged is in principal the same thing as towing in neutral?

Basically, yes. However that's not really an issue, as it takes several miles of towing before any damage occurs, and you would never drive for several miles in neutral with the clutch disengaged.
 
Originally Posted By: KrisZ
What would anyone use neutral and keep the clutch disengaged at the same time?

Exactly. Like I said, not a concern...
 
I have a 2005 Chevy 1500 with the New venture 3500 in it,great tranny, no clue about towing it,when I moved It went on a u-haul trailer,they said no to towing with wheels on the ground(dolly)
 
Originally Posted By: andyd
Wabbout pumping an extra qt or 2 in to raise the lube


It's not getting flung anywhere by anything. Some transmissions have a little "dipper" that provides some splash lube, and this is mentioned in owners manuals. Saturn s-series come to mind.

My w123 automatic allows limited all-down towing (to a service garage, reads the manual) but its ancient automatic trans also has a rear pump. It even allows roll-starting!
 
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