Oil change after gearbox rebuild

snowdr

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I recently completed a full engine and gearbox rebuild, and have just carried out an oil change at 500 miles. I had fitted a gearbox drain plug with a magnet and was a bit concerned to find an oily "gunge" on the magnet, containing minute particles of metal. The gearbox is working perfectly, although there is a slight whine, (gearbox or primary drive?), noticeable only when pulling gently between about 2-3,000 revs, I think in all gears, although I’m not normally in 4th a those revs. I changed all bearings and bushes, together with new 1st and 2nd gear pinions, together with layshaft 4th. All parts were from AN.

Without the magnetic plug, the metal particles would certainly have gone unnoticed. Should I be worried, or is this to be expected as new components bed in? Photo of metal particles on kitchen towel below.
Oil change after gearbox rebuild

Thanks for your help.
 
I recently completed a full engine and gearbox rebuild, and have just carried out an oil change at 500 miles. I had fitted a gearbox drain plug with a magnet and was a bit concerned to find an oily "gunge" on the magnet, containing minute particles of metal. The gearbox is working perfectly, although there is a slight whine, (gearbox or primary drive?), noticeable only when pulling gently between about 2-3,000 revs, I think in all gears, although I’m not normally in 4th a those revs. I changed all bearings and bushes, together with new 1st and 2nd gear pinions, together with layshaft 4th. All parts were from AN.

Without the magnetic plug, the metal particles would certainly have gone unnoticed. Should I be worried, or is this to be expected as new components bed in? Photo of metal particles on kitchen towel below.
View attachment 115852
Thanks for your help.
Check both your primary and final drive tension. Either one can cause bushing/shaft problems and sludge.

The metal may not be a big deal since you changed two gears but change the oil again soon and see if it has gone away.

If you still have the sludge, go over it with a magnet slowly and then let it drain any oil off (maybe lightly warm it). There may actually be very little steel/iron metal there and the rest can be gearbox oil and bushing metal.

It may just be the picture causing the strange color - what gearbox oil are you using?
 
Thanks for the replies. I'm feeling more relaxed about it now, and another oil change in another 500 miles sounds prudent. Drive chains were just double checked and were OK. The oil was Millers ep80w90 GL4, but the refill is Castrol EP90, which is the oil that I normally use.
 
I put some yellow metal friendly penrite mild 110 but it says it is a replacement for 90 grade . Gearbox changes gear sweet as .

PENRITE
Mild EP Gear Oil is a SAE 110 extreme pressure automotive gear oil meeting the requirements of API GL-4 for moderate to high load applications.

Application​

Mild EP Gear Oil is designed for use in all steel gear sets in vintage and classic cars and trucks as well as rack and pinion steering systems of 1950' and 1960' vehicles.It is suitable for use in spiral bevel, worm and pre 1960 hypoid axles.

Mild EP Gear Oil is suitable for use in many gearboxes where a mild level of extreme pressure protection is required and in worm drive differentials used by early Peugeots.

Mild EP Gear Oil may be used where SAE 90 grades were originally specified (especially if the gearbox or diff is slightly worn) or SAE 140 oils were originally specified and the equipment is in good condition. It is also Ideal for use as an ISO 320 industrial gear oil.
 
I imagine the parts are just getting happy with themselves. I have started using redline MTL in my gearbox. That is an oil favored for use in vintage jaguar boxes and made my jag xk150 box shift much more smoothly than whatever was in it when I bought it. I rebuilt my box and after I turned the shift selector spring the right way, (Oops), my box is very tight and shifts quite nicely.
 
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