Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Bevel box rebuild

I am using a laser temp gun, I measure the temp as soon as I bring it home from a drive. I have also done it a few times where leave out the interior panels and run it to see the difference in the pinion housing on temp. When my bearings went out on the pinion the temp was 240+ on the pinion housing.

Wow that is hot !
I have one of these cheap fridge sensors fitted. For �3 I consider it disposable , and cant be highly accurate , but I dont think it needs to be. I pushed the thermocouple into an electrical spade tag clamped by one of the bbox mounting bolts , ran the cable down the transmission tunnel and out near the gear level , so have a real time view of the temp. The blurb says it will go up to 110 - if it goes higher and self destructs, at that temp there is something very wrong with the box.
I also have one fixed to the oil tank under the bonnet, with the display on the dash, to get a real time view of engine oil temp.

http://www.ebay.co.uk/itm/FOR-FRIDGE-FREEZER-REFRIGERATOR-DIGITAL-LCD-THERMOMETER-TEMPRATURE-MEASUREMENT/171337562066?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140328180637%26meid%3Dacd90c4552844619aa8f6ecb31020948%26pid%3D100009%26rk%3D2%26rkt%3D10%26sd%3D281083965381

Bwitched.
Can you inform us how your bevel box is doing ? Is it still quite ? And how many miles you did with it now ?
Looks to me that your solution is the only way to solve this problem. But who can do it for us ????

More informations about Bearings 'bevel box?

Along with the chassis work, compensator, rear wheel bearings and various other small jobs, I was also going to get Esprit Competition in Aubagne, France to drain and refill the bevel box with Redline High Shock 75W250. Sadly due to a very serious family illness of the owner of Esprit Competition, it is closed for the time being and I suspect very unlikely to be back in action before I leave France (and my M3W in storage) at the end of the month.

Having spoken to Marcassus Sport in Toulouse (the parent company for Morgan activities of Esprit Competition), they said no harm in leaving all this until I get back to France next spring but if I am going to continue to be driving the M3W for the next three weeks, he recommended changing the bevel box oil from the original Morgan filling to Redline. The person I spoke to there (british guy) said he has had two bevel boxes seize on his M3W already on the Autoroutes.

My question is: what is the fill capacity of a 2012 bevel box in imp. pints or litres? I have been searching for this info and cannot find it anywhere.

I'm adding to this old thread (which I found really helpful when mucking with the BB) rather than start yet another one about the bevel box.

While my BB was out for a clean and service I learned a few things:

Having decided to drill/tap the box for a top fill plug, I decided the right way to do this was to remove the side cover and drive sprocket before the work began to ensure any swarf was fully cleaned out. The side cover has a large diameter, though surprisingly thin, O-ring, so no gasket to disturb or sealer needed. Removing the cover (via the small internal hex screws) also removes the crown wheel and carrier (spool) and no critical settings are disrupted in the process.

I was surprised at how much gear oil remained in the BB even after being drained hot after a good run (I use a lift with the car level). Probably only a few ounces, and it appeared to have been hiding in the front pinion area. This suggests that having the nose of the vehicle elevated somewhat while draining is a good idea. Bwitched above noted his front housing had a somewhat obstructed opening to the front bearing area, though mine looked fine. I was relieved to see there was no evidence of abnormal wear, and the two short duration "flushing" stints with normal gear oil I had done left the interior very clean indeed. These days I run the Redline 75W250 Heavy Shockproof oil, the pink stuff.

As the right side port (where the breather is on my car) was 3/8" BSPP, I elected to make the new top plug hole the same so I could move the breather there. Later I decided to add a remote fill hose to the shock top area via a BSP to AN8 fitting with the breather mounted on the hose end.

I have seen photos on the forum of remote filler hoses being connected to the right side port. After having the BB open, I believe this could be a bad idea, unless you are very careful about how much oil you are adding. That right side port (center of bottom photo) is not open directly to the BB interior. Rather it opens into the center of the hollow spool shaft (top of top photo below) which carries the crown wheel and bearings. This hollow shaft has only two 5mm or so diametrically opposed holes in it (top photo again). Trying to fill via the right side port would likely take quite awhile as oil would only flow through the lowest one of those two holes or perhaps through the roller bearings themselves. If one is relying on oil coming out of the right side as a "full" indication, you could easily be fooled into thinking it was full when you had only a few ounces in there. So I would recommend using the original level plug for verification, or filling with a measured amount of oil.

For reference, with the BB set up level on the bench and being dead empty, I measured the gear oil capacity at about 10 U.S. ounces (about 300ml) by pouring gear oil slowly in the new top port with the rear fill/level plug removed. I will probably experiment with larger amounts of oil next season to measure sound and temperature changes with more oil, but am some what concerned about getting the oil level at or above the seal level as these seals are generally not designed to be fully immersed and are likely to seep oil when immersed, as others have noted.

Finally, I was surprised to see a thread repair insert in the main housing (bottom photo), as it certainly appeared as if the BB had never before been removed from the vehicle.

All good info Steve.

I am with you, the top fill is where it should and measure the oil going into the bb.

Thanks for the information Steve, all useful stuff to know. I will be interested to hear what you find with the different oil levels. I am reluctant to over fill the BB because of the possibility of leaks from the seals, as you mention. It may well cause higher temperatures with the increased internal friction. I know more about helicopter gearboxes than cars and overfilling them usually leads to high temperatures. I have tried to improve cooling airflow to my BB with a NACA duct directing air to the pinion area, not sure if it has made much difference as it still screams after 20 minutes at motorway speeds. Soundproofing the bulkhead made a big difference but thats not a good engineering solution.

While your BB is on the bench it may be worth replacing the pinion seal. The one fitted as standard is a Nitrile type and doesn't have a high temperature classification, only about 80c from memory. Several pinion seals have leaked. A higher temperature class (200c) and better quality is a Viton R23 double lip seal (55x42x8mm) but check the size before ordering a new one as I am told there are two different sizes possible. I have replaced one pinion seal by marking the nut position before removal to get the same position on refit, it worked well. The nut is a LH thread.

The wealth of knowledge on this Forum is fantastic👍

interesting the thread insert. It suggests that someone mucked it up at the factory and threw in a repair.