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Old 07-27-2017, 08:22 AM   #1
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IMS - 2rs + freeze plug

All,

Starting a new thread so that the waters are clear.

Was originally going to go with an SKF Hybrid, later determined to be unsuitable, as discussed here:

IMS - Going with SKF hybrid

Came up with a theory that the grease washout in the IMS bearing was caused by the "lung effect:"

IMS - Going with SKF hybrid

So my new plan is as follows:

Acquire dead IMS shaft for testing. Plug the end with a freeze plug, measure that this causes no deformity of shaft. install a pressure gauge on the air space inside, then heat to 300 degrees, see how much pressure we get. Once I have that number, take compressed air and double it to make sure the freeze plug will hold.

then, discard test shaft and install pelican parts bearing, as supplied by Pelican, with the addition of a freeze plug on my vehicle in situ.

At 40k miles pull pelican parts bearing and verify that oil has not washed out the grease, at that time install suitable steel SKF, FAG, NSK bearing of high quality. Thereafter every clutch change.

why?

My theory is that Porsche got the spec of the bearing right, assuming no grease washout. The laws of physics tell me that the "lung effect" (discussed above) is the most likely reason oil and grease are getting exchanged in the bearing. So, if you stop this effect, the bearing Porsche specified will be more than suitable to get from clutch change to clutch change (100k or so miles)

So the permanent (in my mind) IMS method is:

1) install freeze plug in end of IMS shaft, install pelican bearing (uprated bolt is critical)
2) change bearing every time you change clutch (plain steel bearing is like $10, uprated bolt should last through as many clutches and bearings as an engine could go through.)

I am advocating that the IMS problem can be resolved for essentially $3. A freeze plug is the missing component. I have no financial incentive from Pelican Parts or the Freeze plug manufacturers, just a fellow hobbyist with a theory that I intend to prove to be correct.

$185 initial outlay, assuming you can borrow special tools, then an extra $10 every time you change the clutch is a LOT more palatable than thousands especially if it is just as effective at preventing catastrophic engine damage. I actually think a 2rs (double sealed) bearing without thermally caused oil intrusion will be more effective at preventing catastrophe as metal particles will be kept out of the bearing, allowing it to lead its full rated life EVEN IF you end up with metal particle or two in the oil.

If someone asked, I would say that the factory bearing with no freeze plug is highly suspect and should be changed, it almost certainly has oil washout, and is not to be trusted.

regards,

Silber
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Last edited by Silber; 07-27-2017 at 08:25 AM.
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Old 07-27-2017, 08:50 AM   #2
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Do we really need another thread on this?

Just buy the IMS Solution and be done with it.
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Old 07-27-2017, 08:52 AM   #3
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I second that.
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Old 07-27-2017, 09:03 AM   #4
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Originally Posted by algiorda View Post
Do we really need another thread on this?

Just buy the IMS Solution and be done with it.
Sorry, that is so expensive they won't even tell you how much it costs. Not going to spend that kind of money on an engine with 114k miles on it.

If you don't want to read my thread, just pass it by.

regards,

Silber
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Old 07-27-2017, 09:18 AM   #5
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Go for it Silber.

I went with a known IMS solution in my own car because I don't want to worry about it. However, I do enjoy reading these kind of experimental threads. You never know what you can learn.
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Old 07-27-2017, 10:23 AM   #6
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Hello Silber,

1. as said, there are 3 different IMS shafts available and they are different in detail.
2. you have underpressure in your crank case.
3. the simple freeze plug - in my opinion - can start moving. That is why i said come up with something more sophisticated.

Regards, Markus
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Old 07-27-2017, 11:32 AM   #7
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Quote:
Originally Posted by Silber View Post
Sorry, that is so expensive they won't even tell you how much it costs. Not going to spend that kind of money on an engine with 114k miles on it.

If you don't want to read my thread, just pass it by.

regards,

Silber
Hello Silber
I don't mind reading these type of thread's. I just had a thought about the grease in the bearing, would it not wash out anyway with the heat down there. I wouldn't have thought the grease would have been in there for long, unless it was some type of grease I dont know about. Just a thought.
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Old 07-27-2017, 01:09 PM   #8
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1. as said, there are 3 different IMS shafts available [B]and they are different in detail

The only part that would need to be the same would be the tube size for my test purposes. Would that be different on all 3?

2. you have underpressure in your crank case.

True, will have to account for that with my testing.

3. the simple freeze plug - in my opinion - can start moving. That is why i said come up with something more sophisticated.

I want to test just how hard it is to move a freeze plug in an IMS shaft, so am going to install one in a test shaft and try to get it to fail. Sometimes the simple solutions are the best, especially if when tested they hold up. I think any other solution will either be a) not as strong, or b) impossible to remove. Freeze plugs are time tested as very strong, and possible to remove.

Regards,

Silber
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Old 07-27-2017, 01:18 PM   #9
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Originally Posted by derfo View Post
Hello Silber
I don't mind reading these type of thread's. I just had a thought about the grease in the bearing, would it not wash out anyway with the heat down there. I wouldn't have thought the grease would have been in there for long, unless it was some type of grease I dont know about. Just a thought.

The seal is supposed to keep the grease in and other stuff out. Even heated liquefied grease should stay in there to some extent. I just wonder why when these are taken apart there is no grease, only oil.

It seems like there has to be some factor other than simple heat that would remove all the grease and substitute oil. Air expands and contracts with heat, this creates pressure in a sealed system, or movement of fluids/gasses in a system with a leak. I think the bearing seals are that leak and the action of the air pulls oil through the bearing over and over washing the grease completely away. Remove the air reservoir and (hopefully) the problem is solved.

I could well be wrong, but most analysis of the IMS looks at the grease washout as a given, and tries to solve the problem from there by throwing fancy bearings at it. I want to go back one step and solve the grease washout problem so the fancy bearing is not needed.

regards,

Silber
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Old 07-27-2017, 05:01 PM   #10
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Quote:
Originally Posted by Silber View Post
The seal is supposed to keep the grease in and other stuff out. Even heated liquefied grease should stay in there to some extent. I just wonder why when these are taken apart there is no grease, only oil.

It seems like there has to be some factor other than simple heat that would remove all the grease and substitute oil. Air expands and contracts with heat, this creates pressure in a sealed system, or movement of fluids/gasses in a system with a leak. I think the bearing seals are that leak and the action of the air pulls oil through the bearing over and over washing the grease completely away. Remove the air reservoir and (hopefully) the problem is solved.

I could well be wrong, but most analysis of the IMS looks at the grease washout as a given, and tries to solve the problem from there by throwing fancy bearings at it. I want to go back one step and solve the grease washout problem so the fancy bearing is not needed.

regards,

Silber
Hello Silber
I don't think you can remove the air reservoir from a bearing. They are never fully packed with grease, for a number of reasons.
If you look to the other end of the IMS shaft what do you see, a simple plain bearing. Never any problems at that end. Personally I think a plain bearing is the way to go, oil fed of course. I know as well as most there is one on the market
but wouldn't be a big deal for an engineer with a lathe to make one.
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Old 07-28-2017, 01:59 AM   #11
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Quote:
Originally Posted by Silber View Post
The seal is supposed to keep the grease in and other stuff out. Even heated liquefied grease should stay in there to some extent. I just wonder why when these are taken apart there is no grease, only oil.

It seems like there has to be some factor other than simple heat that would remove all the grease and substitute oil. Air expands and contracts with heat, this creates pressure in a sealed system, or movement of fluids/gasses in a system with a leak. I think the bearing seals are that leak and the action of the air pulls oil through the bearing over and over washing the grease completely away. Remove the air reservoir and (hopefully) the problem is solved.

I could well be wrong, but most analysis of the IMS looks at the grease washout as a given, and tries to solve the problem from there by throwing fancy bearings at it. I want to go back one step and solve the grease washout problem so the fancy bearing is not needed.

regards,

Silber
The grease is washed out.

If you don't understand why read the SKF brochure i've linked in the other thread. Especially the part with the sealings, contamination, lifetime and so on. OK over all it's 300 pages, but than you'll understand bearings a little more.

The IMS tubes are different in detail, because the used bearings are different. Some have circlip grooves, some not. Also some are for 3 chain and some are for 5 chain engines.

Regards, Markus
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Old 07-28-2017, 05:53 AM   #12
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Originally Posted by Smallblock454 View Post
The grease is washed out.

If you don't understand why read the SKF brochure i've linked in the other thread. Especially the part with the sealings, contamination, lifetime and so on. OK over all it's 300 pages, but than you'll understand bearings a little more.

The IMS tubes are different in detail, because the used bearings are different. Some have circlip grooves, some not. Also some are for 3 chain and some are for 5 chain engines.

Regards, Markus
Markus, all of the tubes have clip groves cut in them, just in different places and of different sizes depending upon which style bearing is used.
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Old 07-28-2017, 07:39 AM   #13
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Originally Posted by derfo View Post
Hello Silber
I don't think you can remove the air reservoir from a bearing. They are never fully packed with grease,.
By air reservoir i meant all the air in the ims tube, it is acting as a reservoir of air that sucks oil through the bearing, i believe.

Regards,

Silber
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Old 07-28-2017, 07:55 AM   #14
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Originally Posted by Smallblock454 View Post
The grease is washed out.
The IMS tubes are different in detail, because the used bearings are different. Some have circlip grooves, some not. Also some are for 3 chain and some are for 5 chain engines.
I am just going to test the freeze plug, so will never install a bearing or chain, will never go in an engine. I believe the tube dimensions are common to all styles of shaft.

regards,

Silber
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Old 07-28-2017, 09:58 AM   #15
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Silber says this is his personal experiment. He is not evangelizing use of his freeze plug. And if you have been around the M96 as long as I have you will have read prior discussion(and rejection) of the freeze plug + ball bearing idea by an expert(not me- although I was the one who asked that specific question).
Let's try to help Silber ? it is like a Jake Raby destruction test without all the instruments and dyno
The Freeze plug dimensions and material choice.
1. How do you define Interference fit?give the 0.0000"
2.Why use plug material with a different coefficient of expansion ?
3. Use Bearing Seal ? High temp Epoxy?
I do hope no destruction occurs !

Last edited by Gelbster; 07-28-2017 at 10:19 AM.
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Old 07-28-2017, 10:42 AM   #16
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I expect that Silber has already seen this thread. It runs for about 250 posts and addresses some similar questions. Post #52 actually has a freeze plug in the diagram. It's worth browsing through if you are interested in this topic.

Another IMS bearing thread
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Old 07-28-2017, 11:10 AM   #17
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I expect that Silber has already seen this thread. It runs for about 250 posts and addresses some similar questions. Post #52 actually has a freeze plug in the diagram. It's worth browsing through if you are interested in this topic.

Another IMS bearing thread
I had not seen this link, about halfway through reading it, came upon this:

Another IMS bearing thread

had not considered the pressure disassembling IMS shaft. Will have to think that one through. At first blush, I don't think the pressures will be high enough, but need to test exactly how high the pressures might be experimentally.

EDIT: the last two posts in the thread seem to indicate the IMS Solution uses a "blanking plate" to block air/oil from the ims shaft tube. Sounds very similar to what a freeze plug does, and would indicate that pressure inside the shaft is not an issue.

All I want to do is make the Porsche bearing last as long as a clutch does reliably. May not be possible. Nothing in that thread rules out that a plug might help the situation, however.
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Last edited by Silber; 07-28-2017 at 11:21 AM.
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Old 07-28-2017, 11:27 AM   #18
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Originally Posted by Gelbster View Post
The Freeze plug dimensions and material choice.
1. How do you define Interference fit?give the 0.0000"
2.Why use plug material with a different coefficient of expansion ?
3. Use Bearing Seal ? High temp Epoxy?
I do hope no destruction occurs !

1) Freeze plugs commercially available would seem to be .3mm or .01 inch interference. However since they are sheet metal there will be some deformation.

2) I have changed my mind on this, I think steel plug will hold better and be less prone to impacting anything.

3) am hoping that without the air in the IMS shaft to pressurize and depressurize the bearing, a standard 2RS seal will be enough to make the bearing last as long as a clutch reliably. Pelican parts bearing is rated at 40k, plan to pull it at that time to verify if there is any grease left or it all washed out.

The only real risk I am taking is that a freeze plug will cause my engine to explode. I can rule a lot of that out with destructive testing on a dead IMS shaft. I believe there is a previously sold ims retrofit that used a freeze plug, anyone know more about this?
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Last edited by Silber; 07-28-2017 at 11:31 AM.
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Old 07-28-2017, 11:45 AM   #19
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I appreciate your willingness to experiment and freely share your results. I wish you best of luck and be safe.

I get where your coming from financially. My car has 133K miles and, at 17 years old, the last nine of which have been mine, I've of the opinion that the car owes me nothing. That being said, if I'm still the owner when the car needs a clutch, I'll replace the bearing.

My math is kind of like this....
Current value of car: $7.5K
Value as a roller (worst case):$2.5K
Spending $1500-$2,000 to just go ahead and replace the bearing seems like very expensive insurance.

Please understand that I'm all for the bearing change with a clutch. I sleep well at night not worrying about this thing although I do find the discussions worth reading.
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Old 07-28-2017, 02:51 PM   #20
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OK, let's talk about the expansion of air.

And sorry i have to calculate in the metric system, because i'm too stupid to do it in the imperial system.

If we have 1 litre of air = 1000 cm3 and we heat it up 10 degree celsius it will expand 37 cm3 with every 10 degree celsius more.

So lets say the ims shaft has a volume of 1 litre (i'm retty shure it's more) and we heat it up from 0 degree celsius to 200 degree celsius as a max, value (i would say the max. should be between 120 and 150 degree celsius in the IMS area). So calculate worst case 200 degree celsius and that would mean we have an expansion of 740 cm3.

p1 = 10^5 Pa
V1 = 0.1m^3
T1 = 0° = 273K
V2 = 0.174m^3
T2 = 200° = 473K
p2 = ?

p2 =

p1 * V1 * T2 | 10^5 Pa * 0,1 m^3 * 473 K | 4730000 | 99574 Pa
--------------- = -------------------------------- = ---------- =
T1 * V2 | 273 K * 0,174 m^3 | 47,502 |

99574 Pa = 0,99574 Bar = 14,4 PSI

To compare that. The recommended 986 front tyre pressure is 2.0 Bar.

Atmospheric pressure will be set as a constant of 1 Bar at normal ground.

Additionally in a crank case we have a low pressure system. That means we have negative pressure. And that means we are below 1 Bar atmospheric pressure.

Next would be to calculate the right volume for the IMS tube so you can calculate the right pressure at a given temperature.

Personally i think that would be a lot of atmospheric pressure for a simple freeze plug in a rotating and vibrating IMS tube. Also i suspect the volume in an IMS tube is much higher. And remember the freeze plug has to stay in place and you have to prevent additional unbalancing.

Regards, Markus

PS: i don't know if there is any way to show the formula in a better way. If i open it in the editor it looks good. But if i click save it looks goofy.


Last edited by Smallblock454; 07-28-2017 at 02:54 PM.
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