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What's an IMS bearing?

johnoscar

Trainee
Joined
22 Apr 2013
Messages
60
So just read the post on here about IMS bearing failure and basically crapped my pants, so got the service history out for my car and can see two things, first in 2010, Specialist charge to strip gearbox and fit new pinion/input shaft bearings £880 the second in 2011, specialist charge to strip gearbox and replace the tail shaft bearing- dress first gear as requested £475. Are either of these two jobs the IMS bearing? If not should I be crapping my pants?????
 
The consensus is that the IMS failure rate is about 5% of cars sold.So,unless you are really unlucky,you'll be fine. Forums tend to be frequented by owners who've had a problem, so the numbers look much much worse than they really are. I'm not technically educated enough to know if any of the work you're car has had done relate to the IMS bearing.I'm sure someone will be along in a minute who can put you straight.Enjoy your car.
 
johnoscar said:
So just read the post on here about IMS bearing failure and basically crapped my pants, so got the service history out for my car and can see two things, first in 2010, Specialist charge to strip gearbox and fit new pinion/input shaft bearings £880 the second in 2011, specialist charge to strip gearbox and replace the tail shaft bearing- dress first gear as requested £475. Are either of these two jobs the IMS bearing? If not should I be crapping my pants?????

No, the IMS is the Intermediate Shaft bearing/seal. It's supposed to be sealed for life but often it leaks all its grease out & then it can wear but without any symptoms. Eventually it drops some or all of its balls, the shaft is no longer supported & the chain which drives it & subsequently the cams jumps a tooth and then valves meet pistons.

Conventional wisdom is it is worth replacing the bearing with the uprated LN kit if you are dropping the gearbox &/or replacing the clutch.
 
The intermediate main shaft (IMS) bearing has nothing to do with the gearbox so I am afraid you are in there with the rest of us hoping we are not the 1 in 20!

The IMS is part of the system which enables the opening and closing of valves relative to the pistons, this in itself is not an issue under normal conditions, the problem comes when the bearing breaks up and the swarf rampages around the engine damaging everything it comes across which in turn can lead to the cam chains breaking or jumping teeth causing valves to hit pistons creating a bill which may be beyond economical repair.

Gently driven low mileage manual cars seem to suffer the most based on the knowledge accrued over the last few years of reading this website and the fact that I have convinced myself that a high mileage tiptronic which is driven as it was designed to be driven should increase the odds to more like 1 in a 100 if I apply high level man maths!.
 
Shurv said:
Forums tend to be frequented by owners who've had a problem, so the numbers look much much worse than they really are. I'm not technically educated enough to know if any of the work you're car has

You know, you are right, from an outsiders point of view the 996 forum seems dominated with IMS and Bore Scoring threads, to the point (if I was trying to decide a model to by) it would 100% rule that model out. the topic never drops down the board without another one starting. In fact my mate Rob was actually looking at going from 964 to 996 and ruled out the idea entirely on reading this stuff.
:nooo:

Sure it's only five percent bad, but where is the other 95% good. I mean if one in twenty people told you that you had bad breath, would the fact everyone else said nothing be enough?

You guys should do yourselves and your cars a favour and start a 'Who has not had an IMS failure?' thread, fill your pages with happy IMS stories of the 95% (I think?) of owners that have run their car for thousands of miles and many years with no problems at all. Make it a bar chart with more than one line on it.

Strike some sort of balance?
:dont know:
 
clarkycat said:
You guys should do yourselves and your cars a favour and start a 'Who has not had an IMS failure?' thread, fill your pages with happy IMS stories of the 95% (I think?) of owners that have run their car for thousands of miles and many years with no problems at all. Make it a bar chart with more than one line on it.

Strike some sort of balance?
:dont know:

A couple of years ago a thread was started to do exactly that.

Sadly, after a very short time, one of the most ardent activists suffered a catastrophic IMS bearing failure and everyone stopped adding to the list as they didn't want to tempt fate. :sad:

Rather than start a new thread interested parties might just want to add to this one.

>> http://911uk.com/viewtopic.php?t=61268&start=60&postdays=0&postorder=asc&highlight=

EDIT/PS

In fact I'm going to bump it up the board and ask the contributors to give us an update.
 
Preventive replacement is considered cost effective during a clutch change as the gear box would be split and saves on labour costs, but if the bearing fails it send its broken components throughout the engine, and in some cases the rebuild cost may be more than the vehicles market value. I'm not TOO worried about mine, but it is in my thoughts, and I am budgeting for an upgraded IMS when I change my clutch next year . Prevention being much more cost effective than rebuilding an engine. Research it and come to your own conclusions, or drive and enjoy your car, fingers crossed you are not in the 5%.
Scott.
 

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