Re: R 10 Overdrive

Posted by Peter Packard On 2013/1/27 18:48:31

Tom is correct in that the oil in the overdrive section has a higher fill level and seeps into the front of the trans within a few days. If parked downhill this could severely deplete the oil level the OD Section. It is also true that it takes a reasonable driving distance for the oil fron the front to get to the back section to replenish the OD level, particularly with thick oil and flat running. The front gearbox oil is thrown up onto a rail cast into the side of the box and makes its way to the rear of the box. However this usually only occurs reliably in the lower gear ratios and if you are using SAE 140 grade oil it will not throw much up until the oil heats up.
Personally I deliberately run my gearbox level overfull and it works. I always remove the front plug and, if oil flows out as it should, I immediately replace the filler plug. I then remove the OD section filler plug and fill until oil overflows and replace the plug immediately.
I know that I am running the front gearbox section overfull but it will have no ill effect and provides a measure of drought proofing to the OD section of the gearbox. I use a GL 90 mild EP Trans oil and have never had a problem, even towing heavy car trailers on 90-100F days. I always check the od level before a big trip and it takes 10 minutes. The R6 in my 38 Richards Six cost me $1 but the gearboxes are much more expensive now and must be taken care of. Oil is cheap OD gearboxes are not. PT