02-13-2018, 10:33 AM
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#1
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Registered User
Join Date: Mar 2013
Location: Scotland
Posts: 82
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Yeah it's superb, t just takes all the guess work out of it.
Measuring 13mm inside he crank etc is just about impossible. This does it for you.
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02-14-2018, 03:49 AM
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#2
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Registered User
Join Date: Mar 2013
Location: Scotland
Posts: 82
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One thing that I found quite strange about the IMSB is the centre stud.
I'm sure you have all figured this out many years ago and it's weakness has been mentioned on this thread already but I find it hard to believe that that stud (M8) is all that is supporting the rear end of the IMS which is driving the cams.
Well I know the bearing is but that is being supported by that stud/bush and the flange is fixing the stud to the engine ( which is very secure).
I suppose by increasing the diameter of the stud you have to decrease the thickness of the flange internal busing part as there is only the same amount of space inside the bearing.
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02-14-2018, 07:42 AM
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#3
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,648
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Quote:
Originally Posted by Troutman
One thing that I found quite strange about the IMSB is the centre stud.
I'm sure you have all figured this out many years ago and it's weakness has been mentioned on this thread already but I find it hard to believe that that stud (M8) is all that is supporting the rear end of the IMS which is driving the cams.
Well I know the bearing is but that is being supported by that stud/bush and the flange is fixing the stud to the engine ( which is very secure).
I suppose by increasing the diameter of the stud you have to decrease the thickness of the flange internal busing part as there is only the same amount of space inside the bearing.
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There are three major flaws in the factory center bolt:
1. There is a rather severe under cut in it to accommodate an O-ring seal; when they break, they tend to break at this undercut.
2.The material of construction, it is mild steel.
3.It needed to be larger in diameter.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
Last edited by JFP in PA; 02-18-2018 at 01:46 PM.
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02-18-2018, 10:11 AM
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#4
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Registered User
Join Date: Apr 2016
Location: SE Michigan
Posts: 496
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Quote:
Originally Posted by JFP in PA
There are three major flaws in the factory center bolt:
1. There is a rather severe under cut in it to accommodate an O-ring seal; when they break, they tend to break at this undercut.
2.The material of construction, it is mild steel.
3.It need to be larger in diameter.
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Does this poorly designed factory bolt take any part of the bearing failure?
__________________
1997 Boxster arctic silver/ red, XNE riveted mahogany/ leather steering wheel & 917-style wood shift knob, Ben’s short shifter, PSE, 996 TB, UDP, stereo/ center console delete, hardtop and speedster humps, daily driver rain or shine or snow!
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02-18-2018, 01:44 PM
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#5
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,648
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Quote:
Originally Posted by Boxstard
Does this poorly designed factory bolt take any part of the bearing failure?
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Yes. Sometimes when the bolt fails, the IMS bearing can move off axis, timing chain(s) jump, and you get piston to valve contact related failure. The IMS bearing itself is still relatively OK except for the bolt failure. Other times, the bearing itself is tearing up, possibly causing the bolt failure; so it can go either way.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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02-18-2018, 03:07 PM
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#6
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Registered User
Join Date: Apr 2016
Location: SE Michigan
Posts: 496
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Quote:
Originally Posted by JFP in PA
Yes. Sometimes when the bolt fails, the IMS bearing can move off axis, timing chain(s) jump, and you get piston to valve contact related failure. The IMS bearing itself is still relatively OK except for the bolt failure. Other times, the bearing itself is tearing up, possibly causing the bolt failure; so it can go either way.
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Interesting... sorry one more question, this tapered bolt is common for factory dual- and single-row bearings? If so, obviously bearing design itself accounts for the failure more I guess.
__________________
1997 Boxster arctic silver/ red, XNE riveted mahogany/ leather steering wheel & 917-style wood shift knob, Ben’s short shifter, PSE, 996 TB, UDP, stereo/ center console delete, hardtop and speedster humps, daily driver rain or shine or snow!
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02-19-2018, 01:22 PM
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#7
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Registered User
Join Date: Feb 2005
Location: It's a kind of magic.....
Posts: 6,648
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Quote:
Originally Posted by Boxstard
Interesting... sorry one more question, this tapered bolt is common for factory dual- and single-row bearings? If so, obviously bearing design itself accounts for the failure more I guess.
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Both the OEM single and dual rows use similar center bolts, but they are not exactly the same due to the bearing depth differences.
__________________
“Anything really new is invented only in one’s youth. Later, one becomes more experienced, more famous – and more stupid.” - Albert Einstein
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