Daft things that Non Blondes do too.

[PeteH]

When you are towing, the propshaft is turning the gears, in much the same way as when being driven, As a gearbox relies on splash lubrication, then provided there is sufficient quantity of oil in the `box no harm will occur, Hundreds of thousands of miles every year are covered by those who do, including myself. With the events that do occur unrelated to the towing, more often forgetting to put the `box in Neutral, or more likely, leaving the handbrake engaged!. The U-S Tacoma, was an Auto too, the difference there was that with the Transfer box put into neutral all the rest rotated without any prospect of damage to the Gearbox, as it and the Engine where not in the "loop". Even the likes of semi Auto`s, basically auto clutch, including my P-107 are flat towed regularly and for hundreds of miles too without any issue`s.

Slush box auto`s are a different thing altogether. That is a no no-no. DSG `boxes are not advised, although some have been towed without problems, it depends on the design, with some US dealers even fitting approved specialist "kits" to allow it.

Pete

[steveo]

My old Marlin kit car had had a new gearbox fitted by the previous owner after he towed it home after having a fuel pump fail, turns out the box has a oil pump inside & runs dry if it is towed (Rover V8 with 5 speed manual box) expensive mistake!

[johny]

26 minutes ago, PeteH said:

When you are towing, the propshaft is turning the gears, in much the same way as when being driven, As a gearbox relies on splash lubrication, then provided there is sufficient quantity of oil in the `box no harm will occur,

Well its actually a bit different to drive our gearboxes from the prop end because although its true the mainshaft will spin there will be limited splash lubrication as none of the forward gears on it will turn. They are held stationary along with the input shaft and laygear so there could be a lack of lubrication especially for the tip bearing and gear sleeves...

[NonMember]

12 hours ago, PeteH said:

When you are towing, the propshaft is turning the gears,

No, it's not. Not on a Triumph box, anyway. The propshaft is ONLY spinning the mainshaft. None of the selector hubs are engaged but the gears are all in mesh with the input shaft, which is held stationary by the clutch and engine. That means the layshaft isn't rotating and there is NO splash lubrication.

The situation is probably less bad on a car with overdrive, because the OD oil pump will be operating and some splash will occur from the pressure release.

[johny]

8 minutes ago, NonMember said:

No, it's not. Not on a Triumph box, anyway. The propshaft is ONLY spinning the mainshaft. None of the selector hubs are engaged but the gears are all in mesh with the input shaft, which is held stationary by the clutch and engine. That means the layshaft isn't rotating and there is NO splash lubrication.

yes the only remedy I can see is to wedge the clutch pedal down and put the gearbox in 4th gear. That would ensure everthing is spinning in the gearbox and more closely replicate the normal driving situation but of course could lead to disaster😨

[Pete Lewis]

on some Renault trucks in the 90s with the B9/18 spd gearbox we fitted a tap in the clutch pipe so to tow you engaged a high gear pressed the clutch, locked it with the tap so 

on towing the gear train still operated the oil pump and kept it all safe 

its not a new idea 

Pete

[PeteH]

There is obviously some disagreement about this. And I appreciate there are a limted number of vehicles not suitable. But in my case, I am happy with over 25years, and many thousands of miles flat towing a variety of vehicles. Hundreds of others have done it too. In the USA, virtually all R-V users, especially the larger ones, Flat tow, and there is a large pool of vehicles that have been proven over many thousand miles, some even with "auto" boxes. The minority vehicle damage has mostly been down to operator error, not faults with the transmission.

11 hours ago, NonMember said:

No, it's not. Not on a Triumph box, anyway.

My 13/60 box is out at the moment, well has been since 2015!. I`ll take a look and check on that, as I am considering prepping the Herald for flat tow. Thanks for the heads up! it`s appreciated.👍.

Pete

[johny]

I think even though the lube in a towed gearbox isnt as designed it doesnt usually cause a problem because the components arent under load😊 

[NonMember]

The lack of load means that it's not going to suffer in a hurry. I think the Green Flag man who decided to get a flatbed to recover my Toledo over a distance of ten miles was probably being over-cautious. However, I don't think I'd want to flat-tow a Herald or Toledo over long distances because the mainshaft tip bearing will dry out and reveal its weakness.

[Pete Lewis]

my experience in gearbox manuafacture is  rotating shafts are more of a spin drier  

what oil !!!!

sorry i remain very cautious

Pete

[johny]

without load there should be minimal contact so the tip bearing being a needle roller should be ok. However if towed for a long distance Id be more worried about the stationary gear sleeves running dry and seizing on the spinning mainshaft....