Wrecker towing & driveshaft disconnect

This lubrication source issue is what makes some manual transmissions non towable also. It can work out that when the engine is not running, not enough of the internals are spinning in the lubricant, to splash lube onto the parts that are being spun by the driveshaft.
Some manuals can be towed after the lube is worked through the transmission/transaxle. Our Frontier is approved to tow, but the manual requires idling the engine in Neutral halfway through the day. I'm sure it's to spin that section of the manual transmission that's dipping lube onto the rest of it. Sounds like what Honda wants for the automatic in CR-V: Stop and Oil'Er Up.

Thanks guys!

I figured that it might have something to do with the engine having to be spinning .... whether or not it's actually being called on to supply drive torque .... which it doesn't when holding back the vehicle on downgrades - but it is of course spinning then.

Indeed, the pump that provides pressure to operate the clutches and other hydraulic components, is also the very necessary lubricant pump for bearings, the wet clutches, thrust washers/bearings, gears, etc. All of this is driven by the torque converter's outer housing where it engages with the pump. if the motor is turning, the pump is turning, even if the input shaft is NOT turning (sitting at a traffic light in drive for example, the input shaft is not rotating). With the engine off, the transmission has no lubrication or cooling. It was the 1960's since a transmission was built with a rear pump driven by the driveshaft. You could actually push start those vehicles!

Charles

Phil, The pump in the transmission runs off of the input shaft. Even though the tranny is in neutral, there are still many parts turning and the pump isn't pumping to provide lubrication.

Our 2005 E450 chassis has the Ford 5R110W 5/6-speed computer controlled transmission in it with a TOW/HAUL mode in which (with this mode engaged) the transmission automatically downshifts for you when going down hill.

When doing this downshifting, the vehicle's rear drive wheels are of course at times forcing relatively high transmission and engine spin speeds - driven from the "wrong end" of the transmission -> from the driveshaft end instead of the engine end. I assume the transmission is getting great fluid flows during these times due to everything spinning well inside the transmission.

Can some explain to me why "towing" an RV with this type of transmission - that is designed to also supply heavy downhill vehicle braking for long runs - can get ruined from being towed with all tires down ... especially when the transmission is in neutral while being towed??

I can understand problems with earlier transmissions that aren't designed to provide extensive downhill vehicle braking .... but why is there any concern with transmissions designed to provide automatic downhill braking?

carringb wrote:
It can be done. GS does have contracts with Landoll operators:

I know it can be done, I just find it surprising they would use an expensive rig like that semi when they can tow a C with a medium duty wrecker. I was envisioning putting a large C on a rollback truck. It would be close to 15' tall.

It depends on how many of what height the OVERPASSES are on the trip behind the wrecker!

I would NOT SETTLE for a rebuild of your transmission.

INSIST upon installation of a remanufactured transmission - with a hard-copy written guarrantee that you can carry along with you in your RV. Your might want to add in a little of your own money, too, and - if available - have them install a heavy duty version of the transmission from the remanufacturing supplier.

"You can 't have too rugged of a transmission - just one that maybe you can't afford."

I watched a rollback haul my dad's Chevy K2500 with 9ft TC. Weight wise it was not bad, but it looked kind of scary and top heavy!!

rjstractor wrote:

Baja Man wrote:
curious.....why wasn't a flat bed dispatched? IU was recently towed due to a tire blowout and they sent a flatbed.

They put your 31' long, almost 12' high motorhome on a flatbed? Impressive!

Not as big, but here is a B+ on a rollback.



Saw the pic just the other day on another RV forum. If not going far or fast and driver is careful..........

Charles