12-28-2020, 02:44 PM
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#1
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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IMS center bolt
I am about to rr my clutch,RMS and ims. I am making my tooling and my question is does anyone know the thread and size of the center bolt on the original? I need to get the correct coupling nut for my puller.
Thanks, Dave
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Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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12-28-2020, 05:02 PM
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#2
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Registered User
Join Date: Oct 2018
Location: North Cali
Posts: 824
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Mine had an M8 1.0 mm center bolt, it`s a 1999 Boxster. I wouldn`t waste an original dual row bearing at such a low mileage though by pulling it out. Just a thought.
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12-28-2020, 06:08 PM
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#3
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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Thanks appreciate the quick response. I’m changing it with low miles mostly due to the clutch..... which leads to the RMS. Which leads to the IMS. I would prefer to remove the inner seal on the IMS bearing but there’s no way to remove without pulling on the inner race which is fine to get it out but not to reuse. Too much stress/damage unseen to comfortably trust it after that. I see videos of guys “tapping” on the inner race driving it in that last 16th inch possibly damaging the bearing. This is done on the way out. I went back and forth on leaving it completely can’t go that either.......
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Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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12-28-2020, 06:50 PM
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#4
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Registered User
Join Date: Sep 2018
Location: Laval QC
Posts: 830
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Quote:
Originally Posted by WhiteyII
... I would prefer to remove the inner seal on the IMS bearing but there’s no way to remove without pulling on the inner race which is fine to get it out but not to reuse. Too much stress/damage unseen to comfortably trust it after that. I see videos of guys “tapping” on the inner race driving it in that last 16th inch possibly damaging the bearing. This is done on the way out. I went back and forth on leaving it completely can’t go that either.......
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Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.
__________________
Grant
Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)
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12-28-2020, 07:34 PM
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#5
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Registered User
Join Date: Oct 2018
Location: North Cali
Posts: 824
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Quote:
Originally Posted by elgyqc
Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.
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I agree. Removing the inner seal wouldn`t make any further difference.
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12-29-2020, 03:35 AM
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#6
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Registered User
Join Date: Jan 2019
Location: PA
Posts: 1,686
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Quote:
Originally Posted by elgyqc
Why remove the inner seal? I removed the outer seal to allow engine oil lubrication and other than that left the original bearing as it was. The car has been running for 2 years since with no problems.
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Wouldn't the oil flow from the inside outward? Keeping the inner seal in blocks the oil flow. Maybe not completely, but it surely restricts it.
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2002 Boxster Base - Arctic Silver - Tiptronic
2010 Subaru Forester
1980 Ford C-8000 Custom Cab Emergency-One Fire Truck
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"I never lose. I either win or I learn." -Nelson Mandela
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12-29-2020, 04:20 AM
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#7
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Registered User
Join Date: Sep 2018
Location: Laval QC
Posts: 830
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Quote:
Originally Posted by piper6909
Wouldn't the oil flow from the inside outward? Keeping the inner seal in blocks the oil flow. Maybe not completely, but it surely restricts it.
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The inner seal side of the bearing is in the IM shaft, so the only oil on that side is oil that has passed through the bearing and is trapped in the shaft. The good stuff is on the outside.
The PCA videos with Jake Raby explain in detail what is happening with the IMSB.
__________________
Grant
Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)
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12-29-2020, 05:31 AM
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#8
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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So a couple questions, the really crappy oil that comes out when the bearing is pulled is there because of the inner seal causing stagnation or in other words because the inner seal doesn’t allow the oil to flow thru the bearing? Does the Retrofit LN bearing have an inner seal or does it let the oil flow thru or rely on immersion and splash?
I appreciate you guys and your knowledge.........
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Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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12-29-2020, 08:52 AM
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#9
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Registered User
Join Date: Oct 2018
Location: North Cali
Posts: 824
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Quote:
Originally Posted by WhiteyII
So a couple questions, the really crappy oil that comes out when the bearing is pulled is there because of the inner seal causing stagnation or in other words because the inner seal doesn’t allow the oil to flow thru the bearing? Does the Retrofit LN bearing have an inner seal or does it let the oil flow thru or rely on immersion and splash?
I appreciate you guys and your knowledge.........
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The original bearing is sealed with grease filled inside. IMS is a tube with about a liter of air trapped inside, since both ends are closed. When the engine warms up, pressure rises within IMS, and after a while air will leak through the bearing`s seals, creating vacuum when the engine cools down and the pressure drops. Eventually this will cause the oil to seep into the IMS, and will fill it, since the entire shaft is submerged in oil. Since it does not circulate so well, and you can`t drain it when replacing engine oil, it will become darker and crappy than the rest of the oil in your engine. So, if you just remove the outer seal, the bearing will get sufficient lubrication from outside. Somewhat depending on the oil level in your crankcase, it will get direct oil from being submerged, from splash, plus oil mist.
As far as I know the retrofit has no seals.
Last edited by Homeoboxter; 12-29-2020 at 09:02 AM.
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12-29-2020, 06:32 PM
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#10
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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Thank you Homeoboxster, to my surprise the retro kit showed up today and it has one seal, the inner. As of now I think I’m going to inspect in place removing the outer seal, if I have any doubts I’ll replace. I’m having no luck finding the m8 x 1.0 coupling nut for the puller. I contacted LN for a source and was told that they are going to start loaning tooling (2021) for free with purchase from them. I bought from Amazon so as far as tooling I’m SOL but the kit was $200 less expensive and according to Amazon returnable thru 1/31.
Thanks for the help and loan of your knowledge.
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Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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12-29-2020, 07:18 PM
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#11
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Registered User
Join Date: Sep 2018
Location: Laval QC
Posts: 830
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Quote:
Originally Posted by WhiteyII
... As of now I think I’m going to inspect in place removing the outer seal, if I have any doubts I’ll replace. I’m having no luck finding the m8 x 1.0 coupling nut for the puller.
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A wise course to take IMHO. If eventually you do want to change the bearing see the videos on Youtube by Ben Burner. He made or improvised all the tools necessary, for almost nothing.
https://www.youtube.com/watch?v=UJ5WwbgQejs
From there you can link to his complete series of IMS bearing replacement videos.
__________________
Grant
Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)
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12-30-2020, 12:41 PM
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#12
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Registered User
Join Date: Aug 2005
Location: Sanford NC
Posts: 2,573
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Tool kits are often offer in for sale forums.
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12-30-2020, 03:42 PM
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#13
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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Thanks Mike, I got the puller/tools figured out, bought the correct tap and drill bit from Amazon delivered next day. Bought a 1/4” coupling nut, drilled and rethreaded to m8x1.0, same for the puller rod..... and red loctited matching bolt in the rod.I’ll let you know
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Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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12-30-2020, 05:35 PM
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#14
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Registered User
Join Date: Oct 2018
Location: North Cali
Posts: 824
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Quote:
Originally Posted by WhiteyII
Thanks Mike, I got the puller/tools figured out, bought the correct tap and drill bit from Amazon delivered next day. Bought a 1/4” coupling nut, drilled and rethreaded to m8x1.0, same for the puller rod..... and red loctited matching bolt in the rod.I’ll let you know
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Just now that you spent so much time and effort on making a tool don`t feel obligated to use it
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01-06-2021, 05:47 PM
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#15
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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__________________
Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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01-06-2021, 06:11 PM
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#16
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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Anybody know why you’re not supposed to use compressed air to blow the dust out
On your dual mass flywheel and no solvents “brakeclean”?
__________________
Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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01-07-2021, 04:43 AM
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#17
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Registered User
Join Date: Sep 2018
Location: Laval QC
Posts: 830
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Quote:
Originally Posted by WhiteyII
I went in to my 23,250 mile 1998 Box and as the pictures show the dual row bearing was on its way. I pulled the seal on the bearing and found the bearing cage was broken but still in place and the balls just starting to go but races looked good...
I know I'll be flamed, but I think I'm going to put it back together. I ordered a LN spin on filter and mag drain plug. I have a filter cutter so I'll change the oil at 50 miles first and inspect the filter, then 500 and then 1000mi. Your thoughts........

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Very interesting. Seems to be the perfect example of IMSB failure in a car that has not been driven enough. I inspected the IMSB on a 2000 Boxster with 115,000 miles on it, I pulled the outer seal and verified the bearing, it was fine. I put a new o-ring on the flange and put it back on, it has been running ever since without problems.
Was there any grease left in the bearing... or oil?
I find your course of action reasonable. With the bearing seals in place it seems to me that very little metal would be circulating.
__________________
Grant
Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)
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01-07-2021, 05:45 AM
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#18
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Registered User
Join Date: Apr 2017
Location: Crown King and Sun City, AZ
Posts: 66
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No there was no grease whatsoever. Hey my tooling worked great..........
__________________
Dave
1998 Boxster
1978 R100RS BMW Motorcycle 140K, 1 owner
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01-07-2021, 09:40 AM
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#19
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Registered User
Join Date: Oct 2018
Location: North Cali
Posts: 824
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Quote:
Originally Posted by WhiteyII
I went in to my 23,250 mile 1998 Box and as the pictures show the dual row bearing was on its way. I pulled the seal on the bearing and found the bearing cage was broken but still in place
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Are you saying you found the cage like this after removing the seal? Looks like a perfect cut.
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01-07-2021, 01:50 PM
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#20
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Registered User
Join Date: Sep 2018
Location: Laval QC
Posts: 830
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Today I pulled the IMSB flange off the engine that I bought on ebay last Juin (and that just arrived after being stuck at the border) and the bearing is perfect. I removed the outer seal to check it out... turns smoothly and there is no play. Unless closer inspection reveals something I will put a new o-ring on the flange and button it up. The engine is supposed to have just under 99,000 miles on it.
__________________
Grant
Arctic Silver 2000 Boxster S - bought with a broken engine, back on the road with the engine replaced
Green 2000 Boxster 5-speed and 1978 928 auto
1987 924S 5-speed (Sold) - Blue 2000 Boxster 5 spd (Sold)
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