Different Approach to DIY IMSB Retro / Parts and Pics
04-26-2013, 08:38 AM
#47
Burning Brakes
My point was that the shaft was clearly not designed to house oil. I agree that the videos I've seen some had oil in it some significant, and usually nasty. Normally those were failed bearings or clearly worn, the few threads about preventative replacement had none or insignificant, but of course there is no hard or controlled data. So I would suggest that the amount of oil is directly proportional to the health of the seals in the bearing. Like I said, i think an open on oil side CH bearing makes the most sense, & I like the idea of a sealed cap over the shaft end. I'm not raining on your parade. Fully open might make the most sense, the lessor of the low cost evils if you will, but as a mechanical engineer, I can just say it reeks of potential problems. Your fear that the cap may cause problems seems far less likely than the issues I brought up, and both JR & Casper who have many more engines undee their belt than all of us agree with that. If you think they know their stuff regarding other points of the M96, why on earth would you think that you are right about this one point and they missed it? Sorry, but it makes little sense is all I'm saying.
04-26-2013, 12:19 PM
#49
Captain Obvious
Super User
Super User
Mine had a good amount of oil in the shaft and the bearing looked normal. I've installed the CH bearing with the seals on and put 400ml of engine oil in the tube. The way I figured that if/when the seals start leaking, there will be oil to keep the bearing lubricated for a while. It's an experiment, just like Krazy's project. The more people try different things the better it is.
04-26-2013, 04:30 PM
#51
Good that your trying something different, but don't big up yourselves that the Porsche engineers are stressed about any garage experts out there.
Their interest in 996 IMS bearing fixes evaporated around 2006, by then they are onto the next gen engine without it.
I like this forum, but this IMS fixation is beginning to wear thin
Their interest in 996 IMS bearing fixes evaporated around 2006, by then they are onto the next gen engine without it.
I like this forum, but this IMS fixation is beginning to wear thin
04-26-2013, 05:29 PM
#53
2nd Gear
Join Date: May 2011
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys, (hopefully) *future* 996 owner here, I'm curious of this: anyone hear of IMS failures that happen after taking preemptive action on the IMSB? Seems like something I haven't ever heard about since most IMSB threads seem go: "Got it done, and I'm good to go, now"
Is the IMSB a wear item similar to the clutch, suspension components or anything else that wears out with use? Or is it like engine (main) bearings that *hopefully* last as long as possible
By the way I like the idea of the open bearing. The only way I see it not working would be if anything unwanted gets in it
Is the IMSB a wear item similar to the clutch, suspension components or anything else that wears out with use? Or is it like engine (main) bearings that *hopefully* last as long as possible
By the way I like the idea of the open bearing. The only way I see it not working would be if anything unwanted gets in it
04-26-2013, 08:14 PM
#54
Burning Brakes
I was serious too, not baiting or provoking a reaction. I'm sorry that people are sick of IMSB discussions. I belong to the camp of "If you don't like them, then don't read them." I can easily say I'm sick of the "Look at my car with 19" wheels" threads too..I just don't read them. Constructive discussion is what is required, not insults and degrading name calling.
For one, I agree that the seal removed and bearing open on both sides would promote more flow through of oil through the bearing. How much and whether this has any value is debateable. Again, I'm not making waves or preaching. I only want to explain that only in theory, is theory proof of what occurs in reality. In reality, we know that the greased sealed steel bearing has lasted in (pick a number) close to 95% of the M96 engines, and 5% resulted in failure. If grease wash out was such a sure thing, then the failure would be much higher. In theory many are assuming that it is the grease wash out that has caused the failure. In reality, no one knows for sure. It is not worth anyones time to analyze the bearings (except maybe to JR) as it is moot to most whether it was the seals that failed, which then caused the wash out, or a slow wash out of the grease that caused the seals to fail, then the bearing. However, if the seals are the problem, and a better longer lasting seal, in a better smoother bearing could be used, then the issue is closer to being solved, inexpensively. The amount of grease in a sealed bearing is actually pretty small, typically less than 30% of the free space. Most, if not all, (I know of none that aren't, but that is not anything remotely definitive) ball bearing and race bearings are designed to be used with grease, not oil, as even in an oil bath, the ***** and races wear at an accelerated rate. So all those IMSBs that have lasted 75k miles, must still have grease of some kind in them. Ergo, better grease retention, means longer life. You can never assume that an oiled ball bearing will have no wear, or last as long as a greased bearing. They don't. But for sure, an oiled bearing will outlast an unoiled one. That is what I meant by the lessor of evils.
Without looking at the detailed assembley of the IMS, bearing, flange, etc design, dynamically, I, as an engineer, know not to assume that oil in the tube is definitively caused by travel through the bearing seals. Could be around the bearing seals, or some other path. Again, we have people assuming that in theory more oil flow is all that is required. Where is the reality check, or proof of the pudding? If you and Imo000 are willing to use your engines to provide such data, that is great. Most of us clearly don't say things like "Im looking forward to the next tear-down to check my new CH bearing." !! I applaud the labor and time you are putting in to all this. It will not be wasted, I am sure. My first choice, as I stated, would be to use a far better sealed, greased, CH bearing, if a ball bearing design was to be used, and like you, treat it as a wear item. The added life from the increased durability of the CH bearing would greatly stack the odds in my favor of no failure that way. Since the seals in a true sealed bearing hold grease in, and oil out, since they are not under pressure, I would expect a long useful life. IF I didn't want to pony up the cash for The Solution, which is a far better, well, solution.
The question of debris in an open bearing has been mentioned. Any debris is catastrophic for any ball bearing design. Less so, for a full ceramic bearing because the races and bearings are harder, smoother and truer, so debris can not get to where it can do as much damage, compared to the softer, wider tolerance steel bearings and races. The CH naturally does fall in between the two. Again, a sealed bearing would have far less chance of any debris entry, and one side open CH, less chance than a both sides open bearing. So there are your hazards. If you are just aware of these items, then you can be prepared for their possible outcomes.
For one, I agree that the seal removed and bearing open on both sides would promote more flow through of oil through the bearing. How much and whether this has any value is debateable. Again, I'm not making waves or preaching. I only want to explain that only in theory, is theory proof of what occurs in reality. In reality, we know that the greased sealed steel bearing has lasted in (pick a number) close to 95% of the M96 engines, and 5% resulted in failure. If grease wash out was such a sure thing, then the failure would be much higher. In theory many are assuming that it is the grease wash out that has caused the failure. In reality, no one knows for sure. It is not worth anyones time to analyze the bearings (except maybe to JR) as it is moot to most whether it was the seals that failed, which then caused the wash out, or a slow wash out of the grease that caused the seals to fail, then the bearing. However, if the seals are the problem, and a better longer lasting seal, in a better smoother bearing could be used, then the issue is closer to being solved, inexpensively. The amount of grease in a sealed bearing is actually pretty small, typically less than 30% of the free space. Most, if not all, (I know of none that aren't, but that is not anything remotely definitive) ball bearing and race bearings are designed to be used with grease, not oil, as even in an oil bath, the ***** and races wear at an accelerated rate. So all those IMSBs that have lasted 75k miles, must still have grease of some kind in them. Ergo, better grease retention, means longer life. You can never assume that an oiled ball bearing will have no wear, or last as long as a greased bearing. They don't. But for sure, an oiled bearing will outlast an unoiled one. That is what I meant by the lessor of evils.
Without looking at the detailed assembley of the IMS, bearing, flange, etc design, dynamically, I, as an engineer, know not to assume that oil in the tube is definitively caused by travel through the bearing seals. Could be around the bearing seals, or some other path. Again, we have people assuming that in theory more oil flow is all that is required. Where is the reality check, or proof of the pudding? If you and Imo000 are willing to use your engines to provide such data, that is great. Most of us clearly don't say things like "Im looking forward to the next tear-down to check my new CH bearing." !! I applaud the labor and time you are putting in to all this. It will not be wasted, I am sure. My first choice, as I stated, would be to use a far better sealed, greased, CH bearing, if a ball bearing design was to be used, and like you, treat it as a wear item. The added life from the increased durability of the CH bearing would greatly stack the odds in my favor of no failure that way. Since the seals in a true sealed bearing hold grease in, and oil out, since they are not under pressure, I would expect a long useful life. IF I didn't want to pony up the cash for The Solution, which is a far better, well, solution.
The question of debris in an open bearing has been mentioned. Any debris is catastrophic for any ball bearing design. Less so, for a full ceramic bearing because the races and bearings are harder, smoother and truer, so debris can not get to where it can do as much damage, compared to the softer, wider tolerance steel bearings and races. The CH naturally does fall in between the two. Again, a sealed bearing would have far less chance of any debris entry, and one side open CH, less chance than a both sides open bearing. So there are your hazards. If you are just aware of these items, then you can be prepared for their possible outcomes.
04-26-2013, 10:55 PM
#55
Captain Obvious
Super User
Super User
Well said! One of the reasons I left the seals on is that if the original non HC double row lasted 200Kmiles then a hybrid should last as long but probably longer and the seals will protect it from any metal contamination too. Mine is a double row so it is much stronger to start with so my extra protection was to replace it with a hybrid. I'm not the type that looks forward to the next teardown as I've done enough of those (non 996 related) that I cherish when things work well and last a long time. My first option was to leave the old bearing in. Second to replace it with a standard double row. Third a double row hybrid and the last option was to develop a bearing just like the solution. I don't have the money to risk and develop the Solution type of simple bearing (had the whole thing drawn out by a fellow RL-er) so settled with a double row hybrid. Rod and I (mainly Rod) came up with the idea of a simple oil fed bearing before JR released any details. This shows you that different people can come up with the same thing at the same time. 
05-01-2013, 08:51 AM
#57
First -my compliments to krazyk for a well thought out diy .Second on the discussion of bearings and oiling .Most if not all two stroke outboard motors use a ball bearing for the crankshaft main bearings .Lubrication is either direct oil feed or oil mixed with gas . Since a boat motor is always under load you could infer it's a tough environment .If the ball bearings work there and they do I fail to see why an open bearing won't work on an IMS .
05-01-2013, 08:28 PM
#59
Burning Brakes
Honestly, more superb photography. REALLY nice job.
Please don't compare a bearing used in a 2 stroke outboard motor to one used in Porsche engine. We have enough threads where members think we are insane already, and the joke possiblities are endless.
KK, please, I never said your decision was a huge mistake. And like so many have posted all over the forum, there are what, a hundred thousand M96 and variants that have never had an IMSB issue with the original bearing, so perhaps the "improved" one from Pelican may be so much better, or jsut a , that it is all that is needed and the whole IMSB debacle would never have happened, or to so many fewer as to be considered a margin of error. And I thought I quite plainly spelled it out, NO ONE REALLY KNOWS! We DO know that if the bearing fails it is a trashed engine and a huge bill, and that is what this is all about. DOing what you can to try to avoid it, completely. I applaud that. For sure the flow of oil in to and out of the tube would increase the oil flow through the bearing, which you, personally are trying to do. With that increased flow is the increased chance of debris, vs one sided or no sided access. Is not that clear? Is debris a potential issue. Sure it is. Is it one you should worry about. I doubt it. No more than JR points out anyone should worry about debris causing a clogging in an oil channel and a hot spot or worn bearing journal being the result. ANYTHING can happen. All you can do is try to minimize any negative potentials. You absolutely MAY have the best solution. I dunno. Worth a shot. All I did was throw in my observations and express a point of view, based on my mechanical engineering experience with bearing and lubrication, and infrmation gleaned off of the manufacturers and professional sites. It's your car, take it or leave it. Food for thought. Whatever.
Please don't compare a bearing used in a 2 stroke outboard motor to one used in Porsche engine. We have enough threads where members think we are insane already, and the joke possiblities are endless.
KK, please, I never said your decision was a huge mistake. And like so many have posted all over the forum, there are what, a hundred thousand M96 and variants that have never had an IMSB issue with the original bearing, so perhaps the "improved" one from Pelican may be so much better, or jsut a , that it is all that is needed and the whole IMSB debacle would never have happened, or to so many fewer as to be considered a margin of error. And I thought I quite plainly spelled it out, NO ONE REALLY KNOWS! We DO know that if the bearing fails it is a trashed engine and a huge bill, and that is what this is all about. DOing what you can to try to avoid it, completely. I applaud that. For sure the flow of oil in to and out of the tube would increase the oil flow through the bearing, which you, personally are trying to do. With that increased flow is the increased chance of debris, vs one sided or no sided access. Is not that clear? Is debris a potential issue. Sure it is. Is it one you should worry about. I doubt it. No more than JR points out anyone should worry about debris causing a clogging in an oil channel and a hot spot or worn bearing journal being the result. ANYTHING can happen. All you can do is try to minimize any negative potentials. You absolutely MAY have the best solution. I dunno. Worth a shot. All I did was throw in my observations and express a point of view, based on my mechanical engineering experience with bearing and lubrication, and infrmation gleaned off of the manufacturers and professional sites. It's your car, take it or leave it. Food for thought. Whatever.
05-01-2013, 08:32 PM
#60
Good job KK and thanks for the update and photos. Are you also converting to or already using Flat6 spin-on full filtration filter?Just thought that would further reduce the debri concern, if any.