Different Approach to DIY IMSB Retro / Parts and Pics
04-15-2013, 12:13 PM
#16
yawn. The bearing is never a problem until it is, and then its a very big problem. If you happen to be in the .5%, 1%, 5%, 10% whatever that has an IMS failure, then it probably doesn't matter much to you if the remaining 90%, 95%, 99%, 99.5% whatever percent are perfectly fine, does it?
If you are concerned about the value of your car, sell it and buy a 993. they seem to hold value.
If you are concerned about the value of your car, sell it and buy a 993. they seem to hold value.
OK maybe the value thing was a bit of a rant. 997's are depreciating like crazy too. The IMSB sigma doesn't help though.
Absolutely agree that it is a big problem if it goes and sucks when it happens to you. Its the mentality of chopping 3K off the price of a used 996 because it doesn't have an LN retrofit. Seeing these bearings pulled out time and time again with no issues is what I have a hard time getting my head around. Imre's had 200,000 miles on it and not close to failure!
I came from the 928 world with the 7 foot long timing belt and thrust bearing failures, both having catastrophic consequences. Lots of DIY maintenance info/parts out there on how to keep it from happening to you. I hope the 996 will be end up like that as well with more and more people working on them at home and developing alternatives.
04-15-2013, 04:25 PM
#20
RL Community Team
Rennlist Member
Rennlist Member
An approach I really like is user Feelyx's pressure-fed roller bearing (a poor-man's "Solution").
He had a great thread on it over on Pelican:
http://forums.pelicanparts.com/boxst...sign-idea.html
I think your choice of bearing should work out well KK. How did you extract the original? This is sometimes where trouble can happen, so detials of success stories are always good!
04-15-2013, 05:44 PM
#21
Rennlist Member
Bravo KK. I applaud your decision to take this approach. I had planned to do something similar with my car, but when my clutch suddenly crapped on me last October I needed to get the car back on the road so I had to just go for the LNE kit instead.
04-15-2013, 09:32 PM
#24
Rat Balls
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04-15-2013, 10:37 PM
#25
Drifting
Just a thought comes to mind when removing the seals. Is there any way for spent material from the chain tensioner shoes to find their way into the bearing? Could it be a possibility the seals were there to protect the ingress of foreign matter into the bearing, not just hold in the grease?
I have never been inside a 996 motor, but have worked on many DOHCs and others.
I have never been inside a 996 motor, but have worked on many DOHCs and others.
04-15-2013, 11:07 PM
#26
500 - thanks for the link http://forums.pelicanparts.com/boxst...sign-idea.html This was an interesting read, I had not seen that thread before. I definitely enjoyed the video of a valvetrain at 14,000 rpm.
There is a lot of speculation in that thread, I believe a lot of it would be addressed in the discovery documents for the lawsuit detailed in this thread https://rennlist.com/forums/996-foru...r-12-a-18.html Has anyone asked for these yet? It needs to be someone with a 2003 or 2004 and less than 130,000 miles.
KK - I agree with you that it is possible to find a quality bearing for less than $600. A fix like yours is something I have contemplated before. With respect to using a seal or not, did you consider using a shielded bearing?
There is a lot of speculation in that thread, I believe a lot of it would be addressed in the discovery documents for the lawsuit detailed in this thread https://rennlist.com/forums/996-foru...r-12-a-18.html Has anyone asked for these yet? It needs to be someone with a 2003 or 2004 and less than 130,000 miles.
KK - I agree with you that it is possible to find a quality bearing for less than $600. A fix like yours is something I have contemplated before. With respect to using a seal or not, did you consider using a shielded bearing?
04-15-2013, 11:56 PM
#27
Just a thought comes to mind when removing the seals. Is there any way for spent material from the chain tensioner shoes to find their way into the bearing? Could it be a possibility the seals were there to protect the ingress of foreign matter into the bearing, not just hold in the grease?
I have never been inside a 996 motor, but have worked on many DOHCs and others.
I have never been inside a 996 motor, but have worked on many DOHCs and others.
04-16-2013, 12:12 AM
#28
This thread is useless for any real long term reliability tests as long as KK is driving it(or not driving it a lot in this case). 
Thanks to KK, there is one more useless point that can be debated now, sealed vs open bearing. K I guess now I can expect JG dt40 to be used in threads with open bearing endorsements as well.
As someone said, what about any concerns from foreign debris contamination in the open design? It won't take too much to mess up a bearing. Lower mileage cars might fare better than high mileage cars as parts of the timing guides and other wear items within the engine could break off in higher mileage examples.
Thanks to KK, there is one more useless point that can be debated now, sealed vs open bearing. K I guess now I can expect JG dt40 to be used in threads with open bearing endorsements as well.
As someone said, what about any concerns from foreign debris contamination in the open design? It won't take too much to mess up a bearing. Lower mileage cars might fare better than high mileage cars as parts of the timing guides and other wear items within the engine could break off in higher mileage examples.
04-16-2013, 12:32 AM
#30
I shared the same concern after seeing pics of sumps with aluminum shavings from machining and brown bits from the guides. I had pulled my sump prior to this and it was spotless. I assume the risk is there if a guide comes apart but I would think the bearing is just as protected by the pickup screen and oil filter as any other internal part, so who knows. I think the bearing is more at risk to poor lubrication because of compromised seals. Remember, the LNE bearing is NOT SEALED on the flywheel side but has a seal on the tube side. So debri intrusion is not a concern of theirs. The Casper bearing is open on both sides but uses a "plug" in the tube. Personally I would worry about the "expansion plug" coming out or loose and touching the bearing. I don't agree with the point of sealing the tube.
I think I looked at every type of bearing I could that was a deep groove CH ball design, shielded included. I picked the closest I could find to mimic the LNE bearing, then simply removed the seals.
I think I looked at every type of bearing I could that was a deep groove CH ball design, shielded included. I picked the closest I could find to mimic the LNE bearing, then simply removed the seals.
But then again, you have the mindset that Porsche has used the wrong oil as well so maybe seeking an answer would be futile at best.
I'm not saying the open bearing is either better or worse but just trying to figure out why Porsche didn't do it with their vast knowledge and engineering resources.