the seal slips on the outer race - why this design?
the seal slips on the outer race - why this design?
(OP)
Application - Rear wheel bearing 1989 Porsche 911
Original SKF bearing was a dual row angle contact ball bearing. PN 305988 42mmx80mmx42mm The seal slips on the inner race.
I got a "replacement" FAG 527243CA - the seal slips on the OUTER race. In other words the seal is moving. My question is why do they do this? What application indicates having the seal move with the inner race?
In this application debris can build in the tight area next to the moving seal - therefore I think this is not a good application of the outer slip type seal.
Please comment if you can.
Thanks,
-Henry
Original SKF bearing was a dual row angle contact ball bearing. PN 305988 42mmx80mmx42mm The seal slips on the inner race.
I got a "replacement" FAG 527243CA - the seal slips on the OUTER race. In other words the seal is moving. My question is why do they do this? What application indicates having the seal move with the inner race?
In this application debris can build in the tight area next to the moving seal - therefore I think this is not a good application of the outer slip type seal.
Please comment if you can.
Thanks,
-Henry





RE: the seal slips on the outer race - why this design?
... It might be to let centrifugal force energize the seal lip, or to let any accumulated liquid, e.g. water, to bleed out.
If the replacement doesn't last 20 years, you can sue FAG.
Mike Halloran
Pembroke Pines, FL, USA
RE: the seal slips on the outer race - why this design?
good thinking re. possible functions of seal running on the outside race..
1 - the wheel many times doesn't spin very fast... so likely the rotation would generate fairly low forces
2 - I don't think any water would get in the bearing.. if it did I'd likely have failure before it would drain out
I'm currently contending that this is a mis application for this bearing. I'll try call FAG on Monday and see if I can get an application engineer on the phone.
The main concern is the seal running in debris. I just thought of something... with the seal running on the outside it would have to seal against a pool of water.. whereas if it spun on the inner race it would only have to deal with splash.
Thanks,
-Henry
RE: the seal slips on the outer race - why this design?
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RE: the seal slips on the outer race - why this design?
thanks, seems like the link covered face sheilds in general. I'm thinking that the lip sliding on the outer race is not good for this app. I'll try and remember to post here if I can get to FAG and ask about this...
In any case I think I have to pull the bearing out because a used a bit of grease to slide it in and it probably now has this grease pushed up against the sliding seal.. in a short time I suspect this will pick up all sorts of grit and eat away at the seal.. not to speak of the water that can sit back there.
-Henry
RE: the seal slips on the outer race - why this design?
RE: the seal slips on the outer race - why this design?
Russell Giuliano
RE: the seal slips on the outer race - why this design?
my current conclusion is that the seal is the wrong part for this bearing or somehow the seal has a manufacturing defect..
re. 89 Porsche - if you google around you find that 42x80x42 bearings are used on many vehicles, BMW, MB, Porsche, Crysler/etc. - but yes still I guess not a huge demand. Yes, I agree not a Chinese knockoff.
This is not a flinger app. so I think I'm still solid in questioning that I can't get the seal to slip on the inner ring.
RE: the seal slips on the outer race - why this design?
I'd stop worrying about it unless it gives trouble.
Mike Halloran
Pembroke Pines, FL, USA
RE: the seal slips on the outer race - why this design?
I already bought a new nice SKF bearing this moring.. the seal runs nicely on the inner ring..
If we find out the root cause on with this... I'll post here.
PS: my mechanic looked at some of his FAG bearings this morning... they had the same issue... the SKF bearings that we've checked do not have the issue.
re. stop worrying about it... I don't want to be driving to the track 200 miles away and have the rear bearings go out.. so while I have the car up in the air, might as well put the proper good part in there..that's my approach.
RE: the seal slips on the outer race - why this design?
Russell Giuliano
RE: the seal slips on the outer race - why this design?
yes, I was thinking of doing just that. But still the seal needs to "lock" on the outside ring and slide on the inside ring.. I'll let you know what I find and post another picture.
-Henry
RE: the seal slips on the outer race - why this design?
I took off a seal and discovered something...
There is another sealing system under it.
The outside ring is lightly sealed with the red seal but looks to be heavily sealed by the black seal underneath.
See pictures...
you should see a angle view of the bearing with top seal off and the black seal part below...
also included a picture of the back side of "front" seal.
RE: the seal slips on the outer race - why this design?
RE: the seal slips on the outer race - why this design?
Your configuration appears to have the out shield acting a landing area for the inner seal and acting as a slinger to keep contaminants out off the lip.
I have been looking for information about a shield that we used that fit on the shaft and ran against the face of the outer bearing race. This arrangement kept all contaminants of the inner shield
It looks like your bearing got a little hot.
RE: the seal slips on the outer race - why this design?
yes, I think it works as you say.
the only remaining question/issue is that where the outer part of the shield runs near the outer ring...I have contamination and the ledge the bearing is pushed against is close to the moving seal..
stay tuned as I get more info.
thanks for the comment
RE: the seal slips on the outer race - why this design?
Just for information.
Look at the type D seal. It appears that in your case they rotated the lip 90 deg. and had it running against the an added outer shield instead of the inner race. This arrangement is probably due to bearing size.
http://www.dynaroll.com/catalog/pag009.htm
RE: the seal slips on the outer race - why this design?
http://ww
Russell Giuliano
RE: the seal slips on the outer race - why this design?
I'm probably over thinking this, I've been know to do that.
Take a look at this tread, it has a Visio picture showing that the seal runs very close to the mounting structure and there is a place for debris to build up... this is why I like the conventional seal configuration.
http:
RE: the seal slips on the outer race - why this design?
I would say that the FAG is a SUPERIOR seal design as it has an outer flinger and an inner contact seal. I would prefer this design to the standard bearing seal. I'd pop that outer seal back on and install it!
Russell Giuliano
RE: the seal slips on the outer race - why this design?
site. This could be a decided advantage on certain gear boxes.
This design would also tend to prevent debris from contacting the edge of the lip seal, not so in the D type seal. This would do the same a the add on shield we used to prevent debris from contacting the seal lip and migrating to the rubbing surface.
RE: the seal slips on the outer race - why this design?
if it wasn't for the debris/possible rubbing concern you are probably correct... my concerns could be not an issue but at least I would say it was reasonable to question it expecially since it is different than OEM. There is probably a chance the FAG is superior.. but I don't know the other specs. on it like ball tolerance/what type of grease/etc.
Since the company will take back 2 FAG's (one was installed and they know that) I'm going that route and installing the conventional "D" seal SKF.
-Henry