[TR] Flat towing a TR3

Sun Oct 29 11:24:30 MDT 2023

It is the layshaft gears that are partially submerged in the oil.  If they are spinning they will fling oil all around the transmission case keeping everything lubricated.  It the engine is not turning the gears are not turning.  Hence, smoked bushings.  

If, however, the transmission is equipped with an overdrive unit, the ring gear, the planetary gears and carrier are all spinning and those are also partially submerged.  They will fling oil about the inside of the OD unit and since the OD and the transmission share lubricant and there are passages between the two some of that oil will find its way to the mainshaft and MAY provide enough lubrication to save it.  
I say MAY since I have not tested this and I am not inclined to do so, but one hears anecdotes of those who have flat towed a car with no issues.  I must ask was this car equipped with overdrive?

Dave 

    On Saturday, October 28, 2023 at 11:25:03 PM CDT, Tony Drews <tony at tonydrews.com> wrote:  

Spinning the differential unloaded cause no issues.  Spinning the output shaft of the transmission while it's in neutral provides no lubrication within the transmission and will nuke applicable bearings / bushings.  When the car is in gear, oil is being flung about the transmission, in neutral that's not the case.  That's why you need to disconnect the driveshaft before towing with the rear wheels on the ground.

Regards, Tony Drews

 On 10/28/2023 5:58 PM, Frank Fisher wrote:

  enlighten me as to why one would have to disconnect the driveshaft.  
  inquiring minds need to know 
  Frank 

      On Saturday, October 28, 2023 at 11:11:09 AM PDT, Kinderlehrer <kinderlehrer at comcast.net> wrote:  

Hardy Prentiss used to flat tow his TR3 behind a Jaguar E-type all over the country. He did disconnect the driveshaft before towing.

Bob

From: Triumphs [mailto:triumphs-bounces at autox.team.net] On Behalf Of Philip Ethier
 Sent: Saturday, October 28, 2023 8:37 AM
 To: Art McEwen
 Cc: triumphs at autox.team.net
 Subject: Re: [TR] Flat towing a TR3

I fried a MKII Cortina bearing by flat-towing.

On the other hand, a SAAB 96 was no problema, just put the car in Freewheel.

On Thu, Mar 28, 2019 at 9:06 PM Art McEwen <amcewen2 at cogeco.ca> wrote:

I read somewhere where this wasn't possible without disconnecting the driveshaft due to, I think, a bearing in the gearbox or O/D that doesn't get lubricated without the gearbox in gear.   But I've also read reports of Kas Kasner and his contemporaries routinely flat towing to the race track.    Which is true?  Both?  Neither?  Or is Kas forgetting he used to disconnect the driveshaft at the end of the weekend?

I've seen several MGBs (different gearbox design?) and MX5s being flat towed behind RVs, I know the MX5 manual says it's a no-no.

Just wondering.

Art '60 TR3A.

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