Towing a MGB

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Towing a MGB

Post by chadders » Mon Jan 06, 2020 9:08 am

As not everything I believe is necessarily true I thought I'd contact the MGOC about this.

This is the reply from Roger Parker, the authority on MGBs:

"Gearbox lubrication is by splashed oil only so towing towing means there is the same splash but an added advantage of no heat generation from transmitting engine torque.

Overdrive lubrication is also by splash but with some pressurised oil that is generated by the oil pump driven by a cam on the third motion shaft The main purpose of the 400 to 420 psi oil pressure generated though is to operate the overdrive clutch and move it from the spring held position for direct drive into the overdrive engaged position and hold it there against the constant spring pressure and see the drive not passing through the overdrive gears to give the lower engine speed for the same road speed.

During towing the propshaft will still turn and as direct drive is always engaged in the OD this means that the third motion shaft will also turn so the OD oil pump will also be working and circulating oil as it does when the car is being driven and the OD is in direct drive.

Generally it is only manual gearboxes and auto gearboxes that have oil pumps that will not be operating during towing that can see damage if towed over long distances. The MG RV8’s 5 speed LT77 (SD1) and later cars R380 5 speed gearboxes (also fitted to very many V8 conversions)are examples of manual boxes that suffer from this towing restriction."
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