What's new
What's new

Round dial backgear oil leak

Crazymonkey

Plastic
Joined
Nov 19, 2014
Location
Texas
Hey guys, i'm having issues with my round dial backgear leaking oil from behind the drive pulley. It doesn't leak immediately, but after a couple minutes of running, it starts slinging a decent amount of oil everywhere. I recently rebuilt the backgear and made an adapter plate to a marathon blackmax.
One thing i noticed that doesn't seem right, is the 13 thou of axial movement in the drive pulley with all the bolts tight. Is this normal?
The only other thing i can think of, is maybe i missed a gasket somewhere? I have one on the end of the pulley, and one that seals the bearing retaining plate (with the drain back hole).
Any ideas or comments would be appreciated. Thanks

20200111_213928388_iOS.jpg20200111_214853522_iOS.jpg20200111_201205411_iOS.jpg20200111_225153834_iOS.jpg
 
I'm sure you cleaned out the oil drain back port from outside the outer bearing, set the snap ring properly, and didn't cover it with a gasket, right?

Drain.jpg
 
I am going to go out on a limb, and suggest you are using normal radial bearings, not an angular contact pair.

MRC 209 SFF comes up as a radial bearing with a certain grease and a steel retainer.

The bearing pair should be an angular contact pair, which has no play. Using two radial bearings in this application would have on the order of 0.010-0.015 play, which matches what you say. Coincidentally I just posted about my results changing these very bearings, I would suggest perusing my post, and then deciding your best option for angular contacts.

reduction gearbox bearing set - 10EE

One other item, I bought the Monarch gasket for the bearing cap, and it covers the snap ring as well as the mating surface between the castings, possibly that helps with the leaking as well. I will say that I have had essentially no leaking from behind my pulley, even with the old bearings I just replaced.
 
I am going to go out on a limb, and suggest you are using normal radial bearings, not an angular contact pair.

MRC 209 SFF comes up as a radial bearing with a certain grease and a steel retainer. Additionally, the crimp in bearing shield shows that it is a radial bearing. Angular contacts do not use crimp in shields.

The bearing pair should be an angular contact pair, which has no play. Using two radial bearings in this application would have on the order of 0.010-0.015 play, which matches what you say. Coincidentally I just posted about my results changing these very bearings, I would suggest perusing my post, and then deciding your best option for angular contacts.

reduction gearbox bearing set - 10EE

One other item, I bought the Monarch gasket for the bearing cap, and it covers the snap ring as well as the mating surface between the castings, possibly that helps with the leaking as well. I will say that I have had essentially no leaking from behind my pulley, even with the old bearings I just replaced.


You are correct, i am not using angular contact bearings. The bearings i removed from the back gear were New Departure 3209. The front was a 47509V with seal and snap ring opposite from normal, and the rear was a normal New Departure 3209 open on both sides. From the New Departure handbook, these are "Single Row Radial - Type 3000". I have read some post about angular contact bearings being in the backgear, but those always seemd to be square dials. I was under the impression the round dial backgears came with normal radial bearings, and square dials came with angular contacts. Some one please correct me on this if I am wrong. I also believe these to be original as everything looked factory inside including the gaskets, and all New departure bearings.

Also, a note on the MRC 209SFFG bearing i put in there, i removed the rear shield and grease to make it the same configuration as the 47509V. It was hard to find an exact bearing that has a snap ring groove opposite of the normal side.

I am a little confused on what your saying with the gasket. The gasket i made goes underneath the snap ring like the one that was in there previously. Do you have a picture of the gasket you got from monarch?

20190307_234829380_iOS.jpg
 
you can see in my picture (also from a round dial) that it has the same bearings.

I'm thinking the AC bearings were from a newer iteration of the gearbox design.

As I recall I had a hard time sourcing one or more of those gearbox bearings (snap ring groove issues rings a bell) and had to remove a shield and clean them out and re-use them.
 
You are correct, with your information I should have prefaced my answer with "I have a square dial." I'm confused with the V suffix, the snap ring opposite normal side. Radial bearings are symmetrical, there is no preferential side, maybe the opposite side was relative to the side the shield is on.

Alright, going on the thought that round dial uses radial bearings, SKF and MRC seem to make a lot of C3 bearings, more clearance than normal. Maybe your bearings are C3 and that makes the difference between what you have and the original New Departure 3000 series.

Locate BB has 43209 bearings, I don't think the shield is necessary, the angular contacts don't have shields. Obviously the oil leaks past the shield anyway. For even more support you could use the full ball complement 1000 series, LocateBB has 41209 bearings as well. Additionally, Ebay is full of 6209 NR non C3 bearings from other manufacturers.

I wish this thread came up 2 days ago, I just put my gearbox back together. If your gasket is underneath the snap ring, then we have the same gasket. My original gasket was on top of the snap ring, not underneath. It was that way when I first took it apart, so I assumed that the proper way. My machine had obviously gone through many owners, I am sure yours the same. You could ask Steve at Monarch which way is proper. However, as I mentioned. I have never had leakage issues with my no shield angular contacts and the gasket on top of the snap ring.
 
I had one other idea while I was considering bearing availability, although not directly applicable to the current situation. A double row angular contact similar to the spindle rear bearing could be used, along with a spacer to take up the difference between the double row bearing width and the dual single row stack width. LocateBB does have a snap ring 45209 bearings available. I had considered using one of these if I had not been able to find a snap ring pair.
 
You are correct, with your information I should have prefaced my answer with "I have a square dial." I'm confused with the V suffix, the snap ring opposite normal side. Radial bearings are symmetrical, there is no preferential side, maybe the opposite side was relative to the side the shield is on.

Alright, going on the thought that round dial uses radial bearings, SKF and MRC seem to make a lot of C3 bearings, more clearance than normal. Maybe your bearings are C3 and that makes the difference between what you have and the original New Departure 3000 series.

Locate BB has 43209 bearings, I don't think the shield is necessary, the angular contacts don't have shields. Obviously the oil leaks past the shield anyway. For even more support you could use the full ball complement 1000 series, LocateBB has 41209 bearings as well. Additionally, Ebay is full of 6209 NR non C3 bearings from other manufacturers.

I wish this thread came up 2 days ago, I just put my gearbox back together. If your gasket is underneath the snap ring, then we have the same gasket. My original gasket was on top of the snap ring, not underneath. It was that way when I first took it apart, so I assumed that the proper way. My machine had obviously gone through many owners, I am sure yours the same. You could ask Steve at Monarch which way is proper. However, as I mentioned. I have never had leakage issues with my no shield angular contacts and the gasket on top of the snap ring.

Yes, the V suffix for NDH bearings mean "SNAP RING LOCATED ON OPPOSITE SIDE FROM STANDARD." You are correct, the snap ring side doesnt matter if there isnt any shields or seals, but in this case there was a shield on the factory bearing.

The original New Departure 3000 series bearings (as well as all other New Departure bearings had a standard precision rating of ABEC 1, unless marked on the bearing. The MRC bearing i chose is also an ABEC 1 for that reason. Unfortunetly i cant find anything about radial or axial clearance in the NDH handbook, but the MRC is a class C0, which is tighter then a C3. For these reasons, i think the bearing is a good replacement for the original. While i'm sure an angular contact pair or full ball compliment bearings would be better, i don't think the bearings are my issue, or necessary when i already have these new bearings installed with less then an hour of run time. I appreciate your thoughts on the matter, and hopefully it will help someone in the future source backgear replacement bearings.
 
So i decided to install a gasket between the thrust washer/spacer and the bearing retaining plate tonight, and the leak stopped! I ran for over 30 minutes with no leaks. While i'm excited it doesn't leak anymore, I don't understand why mine needs a gasket, when others don't. Is this a normal gasket i should of had in from the beginning? Or will it hurt anything being in there?

20200115_003412474_iOS.jpg
 
The C0 bearings are definitely precision bearings. In picture 4 of your original post it shows a gasket between the end cap and the pulley shaft. The square dial doesn’t have that gasket since the pulley shaft is not hollow. Is it possible that that gasket was slightly too thick and the end cap wasn’t tightening down against the pulley all the way?
 
I suppose its possible, but only a couple thou. The gasket i took out was pretty close to the 1/64 gasket i put in (0.0156"), and i tightened those four bolts holding the cap on as much as i felt comfortable just incase that was the problem.
The gasket I put in between the thrust washer and the bearing retaining cap is still holding up, so i think i will just continue running like this and keep an eye on it
 
Not sure what is up....

You called it a spacer. I believe Monarch calls it a deflector. I call it a flinger. That spacer is for flinging the oil that works its way through the bearings outward so it runs back through the port on the bottom. Maybe there was too much oil making its way through the bearings, maybe the ID of the flinger was letting oil pass to the outside of the finger and now the gasket paper is helping that, maybe there was too much oil in the gearbox, maybe I'm crazy, IDK

Glad to hear its not running out now though!
 
I have been out of town, got home and looked at my parts diagram of probably square dial MG era, which looks the same as the round dial since both use the larger Reliance motor. Kind of hard to tell, but looking with a magnifying glass it does look like the gasket is behind the snap ring, and it definitely does not show a gasket for the front cap. Since it seems like the source of the problem was the pulley not being sufficiently tightened against the oil slinger/bearing stack, maybe a previous owner improperly put the front cap gasket in, and with a new unsqueezed gasket there was too much stack width to get the pulley tight enough. As an experiment maybe take the front cap gasket out and your new spacer gasket out and see if there is still no play.

If it works you could make a delrin plug with an an o ring to seal the hole in the pulley shaft against oil exfiltration and keep no gasket under the cap. I made similar plugs for the bearing recesses in my ELSR casting rather than using the cast iron plugs, so that I can get to the bearings easily for greasing.
 








 
Back
Top