Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 M3W Bevel Box Lubrication

My 2012 M3W arrived with grease filled bevel box.

I replaced that with redline heavy gear oil after numerous times of filling running and draining to get almost all the black grease out.

The whine (must have straight cut gears in the bevel box) is really getting under my skin so am thinking of injecting some synthetic grease in there to hopefully quieten down that whine.

If it was filled with grease only, so a mixture of grease and heavy gear oil should not be an issue.

Anyone done this or has any opinions?

Rather than grease, it was probably filled with a gear oil plus a particularly incompatible additive that was used in some of the early M3W bevel boxes that could cause the oil to effectively congeal in the box. An early instruction from the factory was to get rid of this mixture as soon as possible. As for filling with actual grease I don't know if anyone has tried it but have doubts about how well it would lubricate the bearings.

The gear set in the BB does NOT use straight cut gears. They are the same as any other automotive differential.



I would not recommend grease of any type. I believe that the very early M3W's had a gear oil of sorts, but with the additive it turned very dark and thick. Some of the guys had to flush it out with fuel oil several times to get it cleaned out.

The problem with grease is that it will develop voids and you can lose contact of the grease with the inner bearings etc.

I believe that I was the original recommender of the Redline Heavy Shock Oil for the BB. It has been used in many Harleys to calm down the straight cut trans gear noise in 5th gear and is highly recommended within the motorcycling community.

Some here did have a slight drop in noise with it, but I believe the consensus now is that if your BB is noisy, it will always be noisy. The NEW M3W's tend to quiet down after a few thousand miles or so, but others are quiet from the get go.

There has been some discussion on lapping of the ring and pinion gears in an effort to "smooth" the teeth to quiet down the BB. Short of a total replacement, the lapping may be your best bet at this time. Even with a new replacement, I believe it's still a hit or miss as to whether you end up with a quiet of noisy BB.

Good luck with your BB.

Mine was originally filled with the black goo, even after 2 dealer services it had not been flushed out or topped up. So much for changing it at every service.

This is why I do my own servicing now.

I took the drain plug out and NOTHING came out so I left a drain pan underneath for a day or two and got about a spoonful of black gloop out.

So I flushed the BB out with diesel twice, then cheap engine oil, then re-filled with Millers EP140.

Thankfully no damage done to the internals.

I'm now on the third fill with the Millers and after a summers driving it comes out pretty clean.

Thank you guys, I bought mine used with just under 3K miles on it from a Morgan dealer.
If I buy used I always service fully not matter what I am told about servicing.
The BB was one of the items so I took the drain plug out expecting to see oil coming out and absolutely nothing. Pushed my finger in and it was covered with what appeared to be black grease.
I called the dealer and he said yes the early ones were filled with grease. I said I was going to use heavy gear oil instead and he was in full agreement.
That followed numerous oil fills followed by runs and drains.
It is quiet until it gets hot and then sings.
Unfortunately that others me a lot, so maybe I should avoid downhill twisties in the Morgan and take the Vanderhall Venice instead.

Don't worry Areg, flush it out properly then fill with a good heavy gear oil, I fill mine up to the orange breather on the side and it has become quieter with milage.

About 7000 miles it used to scream its head off, now at 13000 its the quietest it has ever been just a little noisy between 50-60 mph after a long run in hot weather.

Avoid down-hill twisties 😱 but that's what it's made for.

Everyone I've talked to has had to do the same as yourself fully flush out the old oil/grease from the bevel box then service with EP140 regularly. (I get my one done twice a year along with the engine oils) and I've averaged 5000 miles /year. Not as many as some I know but then it's only taken out at weekends and the occasional run to Grindlewald.

Service regularly and use it for what it's designed for - having fun. (As well as working out where every new rattle is stemming from)

LOL
As well as working out where every new rattle is stemming from.

Dab, a little old, retired with enough toys so I get about 500 miles a year on the Morgan. Will not live long enough for 13K
But I am going to try two different heavy gear oils and see.

Just ordered a bump steer elimination kit from my dealer who is 500 miles away. With the new retro wood steering wheel driving can get painful.

I just replaced the Mobil1 Syn oil in the bevel box with Redline Heavy Shockproof oil. Substantial improvement. Hopefully I can live with it and not end up resorting to the oil used for Model A Ford transmissions which is heavier.
I had the Mobil 1 in the box for 1500 miles and there was absolutely no deposit on the drain plug magnet.
I have also had history with the Redline. I had it in my BMW R1200C for over 50,000 miles.