The only time that I used 90W oil in my overdrive transmission was by mistake. 75W-90 might rate similarly to a 20W-50 engine oil, on viscosity alone. I would concede that a multigrade EP, e.g. Obviously, if you've use EP90 for ever and it's not harmed your 'box then one cannot argue, but if not, perhaps worth sticking to the spec.ĮP 90 might 'look' like a 50 weight engine oil at 100 deg C but it will be very viscous at lower temps - see the chart.
#Laycock overdrive number series#
Somewhere I read an article where they had tested a series of oils and the 'correct' 20W/50 gave a 400psi pressure downstream of the n/r valve and with EP90 it rose to 700psi and resulted in the cone clutch being jammed as it was driven with excessive force. I understand the issue can be that the Laycock OD as in the 4-cyl car can be sensitive to oil weight and with EP90 can give rise to higher pressures than desired. All very interesting stuff.Īs an aside I've just acquired a Myford ML7 lathe and, would you believe it, there is the same sort of discussion on their blogs, i.e., which oil is best for the headstock bearings!!! Ah hem!! Maybe Quantum should have pursued their experiments with EP80, or some of the multigrades as well. Read the June 2005 topic of the month in this link from :Īccording to Quantum Mechanics I have been lucky with my previous OD units, but there again I haven't seen the problems associated with using detergent oils either! The chart Nigel has donated seems to suggest EP85 roughly corresponds to 40W engine oil and EP80 to between 25 and 38W. The numbers are not strict as such and cover a range RAYīut isn't EP 90 the same viscosity as 40W engine oil? I've used EP 90 in all my previous 1800 B's,all O/D,and never had a problem. They cause trouble by making the oil foam and slowing down the operation of the OD's internal operating components. The detergent additives, of regular engine oil, aren't needed in your transmission as there is no combustion taking place. The use of non-detergent 30w oil has been proven to work the best with these OD transmissions. Freeing it up requires a good whack with a large hammer. When used in a standard OD, the pressure reaches extremely high numbers and can cause the OD cone to lock against the braking ring. This is why BL recommended using 90W gear oil. The OD used in the V8 application used much heavier return springs than those used in the standard B OD. Changed to Penrite gearoil 30, NO further problems in 6000 miles GT V8 had overdrive, why would you think gear oil would be an issue? Gear oil for GEARS, yes, not NOT for overdrive cones surely?!! After all MG specified it for the V8 box which was more or less a 1800 box. If you are in any doubt use gear oil, straight EP90. Has anyone used the Millers Classic MINI oil - which claims to be designed for engine applications which share oil with the 'box and therefore appears a better choice for the MGB O/D gearbox? MG MGB Technical - Gearbox oil (for 'bos with Laycock O/D) I see the spec for the 'box is the same as the engine - namely 20W/50.
0 kommentar(er)
