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Poker2009
Österreich


Joined: 09 Sep 2009
Posts: 906
Location: London


PostPosted: Thu Jan 19, 2017 8:02 pm    Post subject: Reply with quote

From what I have read, the ceramic bearing is worse, and replacing a bearing in situ, is very risky and shouldn't really be done unless you have no choice.
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997.1 C2S, black, coupe, manual, Feb '05:
65k miles, tiny IMS bearing, Millers NT+ 10W50, driven above 3000 RPM.. original engine.
 
  
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Clanky
Österreich


Joined: 24 Aug 2012
Posts: 961
Location: Scotland

2007 Porsche 997 Turbo

PostPosted: Thu Jan 19, 2017 8:18 pm    Post subject: Reply with quote

If I had to do it, it would be replaced with an oil fed kit. I seems the only one guaranteed to remain lubricated.

Search youtube for the tests done on a bearing soaked in an oil bath & run up to speed. The centrifugal force throws out all the oil in the first second, proving that the idea of removing the seals from a replacement is not the way to go without some kind of forced lubrication.
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Poker2009
Österreich


Joined: 09 Sep 2009
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Location: London


PostPosted: Thu Jan 19, 2017 8:23 pm    Post subject: Reply with quote

Clanky wrote:
If I had to do it, it would be replaced with an oil fed kit. I seems the only one guaranteed to remain lubricated.

Search youtube for the tests done on a bearing soaked in an oil bath & run up to speed. The centrifugal force throws out all the oil in the first second, proving that the idea of removing the seals from a replacement is not the way to go without some kind of forced lubrication.


What nonsense
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Alex
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 16540
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Thu Jan 19, 2017 8:38 pm    Post subject: Reply with quote

+1!

Absolute nonsense
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Pops
Silverstone


Joined: 15 Jul 2016
Posts: 108
Location: West Sussex


PostPosted: Thu Jan 19, 2017 8:43 pm    Post subject: Reply with quote

I would go with Hartech's recommended solution as those guys know their stuff. Worth checking their website before taking the plunge.
 
  
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Thu Jan 19, 2017 9:13 pm    Post subject: Reply with quote

alex yates wrote:
Palladium wrote:
its outrageous that a recall wasn't put out on this problem, I cant believe the brand has remained undamaged through it all.


The failure figures would be too low to warrant a recall. That plus the fact that replacing ALL the bearings would bankrupt Porsche, it's far easier and cheaper for them to dish new engines out to those that failed under warranty.


The thing is, a soft recall to supply the £24 (sealess) IMSB whenever they cracked the gearbox/engine interface would have worked perfectly, and NOT bankrupted them.

The clutch needs changing anywhere from 30-50k miles and Porsche used to pop RMS seals like they were sweets.

There is no substitute: more like there was no excuse.

Mad
 
  
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DucatiRob
Kyalami


Joined: 22 Jul 2015
Posts: 1767
Location: Milton Keynes

2006 Porsche 997 Carrera 2S

PostPosted: Thu Jan 19, 2017 9:16 pm    Post subject: Reply with quote

alex yates wrote:
+1!

Absolute nonsense


Not so sure it is nonsense, all bearings need some form of constant lubrication but in my opinion it is overly complicated when just removing the seal does essentially the same job, plus no more moving parts required!

Gutted for the OP!
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30178
Location: Hertfordshire and Hampshire


PostPosted: Thu Jan 19, 2017 9:19 pm    Post subject: Reply with quote

I'm fully intending to replace mine:

GT4 on January 9th 2017 at 7:42pm wrote:
Hopefully the IMSB seals have been shredded by now, but if not, assuming I get there first, I'll fit a naked OEM IMSB when the clutch is done.
 
  
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Alex
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 16540
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Thu Jan 19, 2017 10:53 pm    Post subject: Reply with quote

DucatiRob wrote:
alex yates wrote:
+1!

Absolute nonsense


Not so sure it is nonsense, all bearings need some form of constant lubrication but in my opinion it is overly complicated when just removing the seal does essentially the same job, plus no more moving parts required!

Gutted for the OP!


The inside of a car engine is the equivalent of standing in a washing machine full of oil. The spray & vapour gets everywhere and the faster it spins - the more lubrication of all parts.
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krispe
Monza


Joined: 05 Feb 2014
Posts: 246
Location: Northampton


PostPosted: Fri Jan 20, 2017 12:15 am    Post subject: Reply with quote

Poker2009 wrote:
From what I have read, the ceramic bearing is worse, and replacing a bearing in situ, is very risky and shouldn't really be done unless you have no choice.


My plan was to fit the EPS Roller bearing when my clutch was due to be changed. I don't like the idea of the LN Ceramic braring. A friend had the LN fitted and it started to fail after 5k miles. He found swarf in the oil filter first so had the Bearing checked as a precaution and found it had begun to destroy itself. The ceramic ball bearings are harder than the steel bearing race and if the bearing was not perfectly aligned when fitted or the car is left standing for long periods, (and the bearing dries up), it can quickly wear out.

As my engine will now be rebuilt by Hartech I'll get them to fit the later IMS with the larger bearing.
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rob_p
Österreich


Joined: 20 Oct 2013
Posts: 967
Location: Leicester


PostPosted: Fri Jan 20, 2017 6:10 am    Post subject: Reply with quote

krispe wrote:
Poker2009 wrote:
From what I have read, the ceramic bearing is worse, and replacing a bearing in situ, is very risky and shouldn't really be done unless you have no choice.


My plan was to fit the EPS Roller bearing when my clutch was due to be changed. I don't like the idea of the LN Ceramic braring. A friend had the LN fitted and it started to fail after 5k miles. He found swarf in the oil filter first so had the Bearing checked as a precaution and found it had begun to destroy itself. The ceramic ball bearings are harder than the steel bearing race and if the bearing was not perfectly aligned when fitted or the car is left standing for long periods, (and the bearing dries up), it can quickly wear out.

As my engine will now be rebuilt by Hartech I'll get them to fit the later IMS with the larger bearing.


Sorry to hear this! I had mine done at hartech - fully recommend for peace of mind.
One thing to think about.... I sourced a used ims (larger bearing) shaft from eBay and got Grant to fit that - they checked they were happy with it first and they were fine with this solution. I paid something like £250 and they are about £1,000 from Porsche - it was a decent saving.
Other than that I just went with everything else recommended.

Good luck with it!
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bazhart
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Joined: 20 May 2009
Posts: 958
Location: Bolton Lancashire


PostPosted: Fri Jan 20, 2017 10:02 am    Post subject: Reply with quote

Just for clarity Clanky - a ball bearing does not require a pressure feed (indeed it would not benefit it but overfill the void if ever the seals were good enough to hold a pressure feed).

Ball bearings are designed for either entrapped grease or a small amount of splash oil.

These start out with grease but then due to temperature and the relatively poor sealing qualities of the seals - it gradually gets hot, becomes fluid and runs out of the seal.

If the bearing when fitted was tight or had high spots - initially small particles of worn metal mix with the entrapped grease to form a sort of grinding paste - wearing the whole bearing.

When the grease has run out a very small amount of oil splashes back in - usually sufficient to run the bearing for the rest of the engines life - but sometimes not - hence eventual failure.

If the bearing survives long enough for the seals to wear enough to allow sufficient oil to splash in - then as long as they were not too worn n the initial grease filled stage - they often then last almost indefinitely - hence the general advice - if it has lasted say over 80K probably just remove the seal and leave it alone.

Replacing the bearing in situ can damage the chain, the plastic runner tracks and also result in "pick up" when pressing the bearing into the tight hole that distorts it.

Ceramic bearings do not like shock loading and a view of the "RollRing" video demonstrates the apptly named "clanking" that goes on.

The centre of the bearing remains stationary while it is the outside that rotates - so the centre cannot spin out oil.

The chain sprocket (or gear for a Hivo example) is much bigger diameter than the outside of the bearing and the chain runs up to around 40mph in a chain bath and as a result the forces splashing oil around the proximity of the bearing from those sources well exceed any spin-out from the actually bearing - negating the value of the video you mentioned.

The bearing track retains oil in t he bottom so it is always lubricated on start up and thereafter.

This explains the advice on here to preferably just remove the seal.

If you have to replace it in situ some special tooling can minimise the potential risk of damage.

Baz
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Delanor
Nürburgring


Joined: 01 Oct 2016
Posts: 435
Location: The land of the big cat!


PostPosted: Fri Jan 20, 2017 11:34 am    Post subject: Reply with quote

As there were several different IMS bearings fitted from `98 on are they all suspect for failure from the first design?

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Alfaian
Imola


Joined: 12 Mar 2014
Posts: 825
Location: S.wales


PostPosted: Fri Jan 20, 2017 1:14 pm    Post subject: Reply with quote

Well put baz; question for you- mines an early 2005 3.8 S with the smaller bearing and it's parked on my driveway which is fairly steep with the nose facing down. Am I right in thinking the ims bearing is swathed in luxurious millers 10w50 nano while it's parked up?

Just a thought and thanks in advance

Thumb
 
  
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Alex
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 16540
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Jan 20, 2017 1:16 pm    Post subject: Reply with quote

Its submerged in oil when parked on the flat so deffo will be nose down.
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Alfaian
Imola


Joined: 12 Mar 2014
Posts: 825
Location: S.wales


PostPosted: Fri Jan 20, 2017 1:37 pm    Post subject: Reply with quote

alex yates wrote:
Its submerged in oil when parked on the flat so deffo will be nose down.

Thumb ssk going in tomorrow bud. Will report back Cool
 
  
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Palladium
Indianapolis


Joined: 01 Nov 2015
Posts: 2496



PostPosted: Fri Jan 20, 2017 1:42 pm    Post subject: Reply with quote

do all cars have these ims bearings, not just Porsche?

I would say yes, if so, its even more of a disgrace that such a basic component was so bollocks.
 
  
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Alfaian
Imola


Joined: 12 Mar 2014
Posts: 825
Location: S.wales


PostPosted: Fri Jan 20, 2017 1:58 pm    Post subject: Reply with quote

Palladium wrote:
do all cars have these ims bearings, not just Porsche?

I would say yes, if so, its even more of a disgrace that such a basic component was so bollocks.


Only porsches flat 6 I believe
 
  
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Alex
Le Mans
Le Mans


Joined: 06 Mar 2014
Posts: 16540
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Jan 20, 2017 2:02 pm    Post subject: Reply with quote

No they don't. Most have their cams driven off the crank. I thinkthe reason porsche did it was to reduce chain wear, etc. as it can be geared down and run slower, although I always thought it was due to the boxer design flat 6 engine.
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bazhart
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Joined: 20 May 2009
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PostPosted: Fri Jan 20, 2017 2:43 pm    Post subject: Reply with quote

It also results in a physically smaller cam box sprocket and saves space which is desperately needed when you have two cylinder heads opposed and big tyres to squeeze in.

It reduces the speed of the oil pump as well (although that may not be a good thing).

Ball bearings usually retain oil in the carriers for a long time after running but even if parked up - the ball track in the IMS bearing is a groove internally in the vertical plane so the groove will always have some oil in it whatever way the car is parked and the oil splash is generated before the engine even fires up - so no need to worry about parking angles etc.

Baz
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