What IMS bearing have you fitted? 3.4 C2

[Marky911]

Those of you who have had a new IMS bearing fitted to your 3.4s, could you please tell me what bearing you fitted and where you bought it please?

Also did it come as a kit with end cover or did you buy just the bearing? If so did you get the cover from Porsche?

This video from Pedro's garage shows well the issues and I'm pretty impressed with the direct oil feed bearing.

http://youtu.be/hzUq2DFpeKw

However I'm happy to fit a traditional style un-fed bearing as I'll only be doing 2-3k miles a year so even if I change it every 20k miles that'll be 7-10 years time.

So let me know what you've all been fitting please so I can decide.

I've seen the SKF bearing for £25 or so but has anyone actually fitted it? I'm guessing it's the wrong width so needs a spacer to take up the shortfall? Also it comes back to where do I get the cover from if I source just the bearing?

One final thing, I'm aware of some scaremongering suggesting that they shouldn't be pulled in situ. I'm not convinced.
One of the arguments is that it pulls on the chains, yet the bearing pullers I've seen simply anchor against another part of IMS shaft. They aren't fixed onto something else in turn yanking away at the shaft and chains. It's a bearing and a hole for said bearing. Not rocket science.

I'm a precision engineer producing subsea oil and gas components including bearing housings etc so do have an understanding of them to an extent.
I don't want an argument about whether I should change it, I would just like to hear what bearings you've been fitting, so let keep it friendly.

Thanks!

 

[Chris_in_the_UK]

Paging Alex Yates, Alex Yates to the forum please!

 

[Marky911]

Ha, why's that then?

I seen him link to the SKF one in another thread. I think I can see a spacer in the pic though. That's how I guessed (rightly or wrongly) the bearing is slightly undersize width wise?

Anyway I await Alex's input then.

 

[Alex]

Question 1 - Why do you want to change it? Is it broken?

Question 2 - How can you ensure the shaft, which once the cover plate is removed is only really held in place by the chains, will stay exactly static in its floating position whilst you 'wind' the original bearing out?

Question 3 - How can a precision Engineer take the 'Pedro video' seriously?

:?

 

[Marky911]

1) Because it's a very inexpensive way of future proofing my engine for the next 20k miles. No mine isn't broken. If it was I'd be asking the best way to spend the £8k-£10k on fixing my catastrophic engine failure?

2) I can't guarantee it remains totally static but I'm so sure it'll be fine, by the number of people who've had them changed and the number of respected Indys that are prepared to change them, Hartech not included, who incidentally I rate, but also get sick of seeing people get shot down if they dare not to agree with Hartech.
I'm yet to find a single thread stating "Changed IMS bearing, engine has gone bang". Which versus the "My IMS has gone bang" threads is enough to make me make my own decision.

3) So you don't agree with any of the principals in the video? That's fine. To each his own and all that. :thumb:

So what's your story Alex? In no way being arsey there by the way. Are you a Mechanic, Indy, had an IMS swapped and it went bang? Genuinely interested if you can give some cast iron info on it.

I know the chances of it happening are slim but I can't see how spending a few hundred pounds to eliminate the possibility for a good few years is a bad idea.

 

[Chris_in_the_UK]

General rule of thumb with IMS is if it's ok and you are not in there for another reason (clutch or RMS leak) then leave well alone.

Swapping them in situ (except the uprated later version) is possible - with care and knowledge and patience. If it's in good condition then just remove the seal. Make no mistake, the risk of damage and problems by swapping in situ represents a risk. Harlech, 9e and a few others will not physically do it themselves.

Pedro has no real proper engineering qualifications (according to his website) and whilst he has a following, I am not one of them nor would I ever be but I find his ramblings entertaining.

 

[Marky911]

Yep I know what you're saying Chris and that's totally fair enough. There are going to be people who feel happier leaving well alone and those other people who figure the risks presented by swapping the bearing are minimal enough to make it the option they'd rather go with.
My cars original engine was scrapped by IMS failure at 55k miles. Someone may have told the owner at the time "If it's still working, leave well alone".

Like I said in my first post I don't want to argue, especially with you regulars, as intend to be on here quite a bit. :thumb:

I'm yet to discuss with my Indy who has fitted bizzilions of them to boxsters and 911s and has never had one back due to failure. I'm sure he mentioned a while ago you can no longer get the original double row bearing from Porsche.
I'll discuss my options with him by the looks of it. I presumed there'd be a few people on here who'd done it, but maybe not.

 

[Alex]

I'm a Toolmaker by trade but have always done most of my own spannering, weather permitting. I have a 3.4 with 104k on the clock. Last month I had a new clutch fitted, so whilst I had access, I checked the condition of the bearing (perfect) and removed the outer seal so the bearing is now lubricated by the engine oil. I have read many, many threads on IMS bearing failures, causes of, replacements, so called upgrades and so on and believe I've educated myself to the level I'm happy with.

Some advice from me from the knowledge I've gained over the past 2 years (and the past 30 years working in Engineering and Manufacturing environments):

The dual row bearing used in the 3.4 engine IMHO has been the most success with regards to failure rates.
Check your bearing when you have chance and if it's fine, remove the outer seal for future lubrication and leave well alone.
Do not replace a good known bearing with ANY other bearing, that until it's expired it's infant mortality lifespan, can not be classed as a solution to the bearing you already have fitted.
Porsche will never replace a bearing in situ and will only supply the full assembly - reason being - the only way to guarantee an IMS assembly is assembled correctly with everything pressed together square, etc. is to do it off line.
I bet 90% of these 'specialists' will always tell you - they only do things the documented Porsche method and wouldn't do it any other way.............until they can make a few extra quid by pulling and pressing bearings in situ.
The weak link with the IMS is not only the bearing, but also the spigot that is pressed into the internal diameter of the bearing and clamped to the cover plate. If you do go down the route of breaking up a perfectly good set-up to fit an unknown that will probably have the same odds of survival as what was already in, then make sure you at least fit a bigger threaded diameter spigot.


Good luck
:thumb:

 

[Chris_in_the_UK]

Yep, double row is an odd one - it is possible to fit a spacer.

If you are hell bent on it then avoid the LN ceramic malarky and the roller bearing options. A good old decent quality bearing would be my choice (without seals).

I would doubt the 'bazillions' quote for the number fitted though - which Indy?

 

[Niall996]

Paging Alex Yates, Alex Yates to the forum please!

:lol:

 

[Marky911]

Good info Alex. Much appreciated.

Does flipping the seal open on the outer side (the side you can access from flywheel side) actually get much oil in that area? I've only seen photos so far so am struggling to picture it.

So you don't believe the spinning bearing will force oil away rather than take it in? As per "that" video. :grin:

The threaded spigot is definitely something I've read very little on. So is it that the spigot is screwed into the end plate/cover? I'd presumed it would be machined as one piece?
If so are you saying the old standard spigot should be removed then the thread opened up and a larger thread machined in for an updated spigot to be fitted? If so where does the larger threaded spigot come from?

Excuse all the questions but it sounds like you've done all the reading up I'll have to so if you don't mind me picking your brains. Sounds like inspection is the way to go first then.
I've mentioned before on another thread though my luck with cars is terrible. If something can happen it will happen on me. Snapped head studs on my old 70s 911, and again on my 964T, etc etc. So I understand the risks with any 911 but it would be nice to not have to rebuild the engine for a couple of years.

 

[Marky911]

Yep, double row is an odd one - it is possible to fit a spacer.

If you are hell bent on it then avoid the LN ceramic malarky and the roller bearing options. A good old decent quality bearing would be my choice (without seals).

I would doubt the 'bazillions' quote for the number fitted though - which Indy?

The bazillions quote was my little tongue in cheek take on it. He's done loads and loads though and used to just fit the standard bearing with seal flipped up.
Not sure I should mention him as he prefers to stay out of Internet discussions so I don't want anyone to be able to cast doubt over his name. Well respected though and not in the business of doing things just to make money. I'm guaranteed an honest opinion from him. Great lad.

Yes I've read the LN ones have been failing too. That's why I thought that pedro vid is onto something. Basically you can put whatever bearing you want in there but it's not a bearing problem, it's a lubrication problem, hence the direct oil feed.

 

[Chris_in_the_UK]

No worries - I respect your reluctance to name, but I suspect I know who you are referring to.

Heard mixed reviews - always good to shop around and not keep ones eggs in the same basket.

 

[Niall996]

Marky, I've been down a few thread cul de sacs on this one and I've found there to be a huge amount of disagreement about the right approach floating around the internet, and also among indie, magazines, specialists. Porsche retailers etc.

But from what I can gather, if there is one area of consensus it is that the early 3.4 is considerably less prone to IMS than the later 3.6 engine. And that if it's running fine today it's probably going to run fine until any number of other long life issues come to bear. In other words, something else will get your engine as all engines are 'got' ultimately. Your IMS bearing won't be the part to go. And all you need to do, to be absolutely certain, is to check the bearing now. If it's fine, then it's de facto fine. It's working. It's being lubricated. It hasn't degraded. It's doing it's job perfectly well. The issue has not affected that car. If you find that there are tell take signs of wear and degradation THEN look for a fix. And that's a whole other story.

The advise to pull of the seals if they are actually even still there has been rigorously put forward but I'm not qualified to comment on it. I know Alex and others advocate it and I think Hartech as well. But it's all a bit if a blur...

But it makes perfect sense to me. If your bearing is fine, then there's nothing to worry about. Whatever caused the ones to go that did go, is not relevant. Your engine is one of the 95% that are perfect. If there is a problem and you catch it on time, i.e. if your one of the 5%, THEN you move into solution mode.

 

[poppopbangbang]

I've had a look at mine today. Dual row, 1999 MY C4 with just shy of 300K miles on it. I was planning to change it but there is no point. The oil seal wasn't much of a seal anymore so it's been fed engine oil for who knows how long anyway.

The dual row bearings have nearly twice the load capacity of the single row bearing and in reality don't fail unless you are really, really unlucky. I think the failure rate is something like 0.6% for dual row at 100K miles vs 8% for single row.

Steel ball bearings operating within their load rating either fail in very short order or run forever.... unless they are ceramic bearings, I've used ceramic silicon nitride and zirconia based ceramic bearings in motorsport applications (e.g. clutch basket bearings on gearbox front covers) and whilst they offer advantages in weight and friction they are not stronger than steel bearings despite what people think (hardness is not strength) and are prone to developing play from the ultra hard ceramics running against the steel race if the lubrication supply is not controlled accurately. In an application like the IMS bearing play becomes failure quite quickly. To give an example we used to life the ceramic bearings carrying the clutch basket in one of our F1s at 500KM, these days we use steel in the same application and the oldest has 2200KM on it and is still going strong.

My vote if it's a dual row just leave it alone.