Duel Row Bearing Consensus ?

[southernstar]

Interesting analysis, Fat mike. However, we can't lose sight of the fact that some people are literally losing sleep or at least, losing enjoyment of their cars because they are perpetually listening for suspicious noises and suspecting the worst. What value do you put on lost sleep/enjoyment of your car?

IMO this really is a personal choice and, let's face it, some people are more risk-averse than others. In any event, these discussions and the failure rates reported to Porsche should at least provide some assistance to some people in making a rational decision on the issue. And Essex, your reasons are not purely emotional, but rational. You obviously intend to keep your car for a long time and in those circumstances, as Perfectlap points out, it makes much more sense to spend money now to replace the clutch/upgrade the bearing, rather than wait.

Brad

[Johnny Danger]

"JD if he is under any illusion that he won't get corn holed on the re-sale of the Dangermobile".


That's an understatement. I'd be prepared to get it cornstalk and all !

[Dave S.]

I just had my single row 2003 IMSB replaced yesterday with 25k miles on the odometer. Bearing (and seal) was in perfect condition when removed, so maybe I was just paranoid. The cost including LN Engineering ceramic bearing, clutch and RMS was only $2386.00 plus tax.
I did however see a whole box of wasted IMS bearings and shafts at the independent shop I went to. Some were double row. I don't have any idea of how many miles were on them. Just sayin...

[Perfectlap]

I don't look at it relative to the current value..if I did I would have been dumping a car that is still both a head-turner and track/autox performer long ago. Due to excessive supply the current value of your Porsche will always be low. but the costs to enjoy these cars will never scale down with depreciation and of course there is no escaping the high cost of Porsche maintenance. So ANY significant repair cost is a bad financial decision unless you find that mint Porsche from the little old lady in Pasadena. And personally, selling my Boxster S for current value would require that I spend more to gain comparable performance / feedback and bar-setting in its category. So I'm not really gaining anything that way either and I'm still facing the same mass produced depreciation.

[manolo]

Originally Posted by Johnny Danger

I'm in similar situation wherein my vehicle only has 20k original miles.

As little as you drive that car, would you even notice if the IMSB failed?

[southernstar]

Dave S., that's an excellent price - one that is about $600.00 to $1100.00 less than I have been quoted. Did that include an LN bearing and a complete clutch kit? And JD, with about 2000 miles a year (and I am assuming annual oil changes before putting her back on the road in the spring), I suspect your IMS bearing is looking as good as the rest of the dangermobile!

Brad

[Johnny Danger]

Originally Posted by manolo

As little as you drive that car, would you even notice if the IMSB failed?

The windows wouldn't go down right ?

[southernstar]

The windows will, but the hottie in your picture probably wouldn't when she finds herself stranded road-side in a car with a smoking pool of oil beneath it!

Brad

[thom4782]

My 2 cents.

I believe that IMS bearings fail when lubrication becomes inadequate due to a leaking flywheel side seal. If my belief is correct, I can only guess that dual row bearings failed less often than single row bearings because the dual row seals were better due to either design, manufacturer or assembly.

In any event, perspective is important. With single row bearings, replacement is like buying insurance against a 1 in 10 possibility of a very costly failure. The so-called insurance premium is roughly $1700 to replace the IMSB. The risk is approximately $5000 to $10,000 to replace a failed engine. Seems like a high premium to me. The probability weighted risk drops to between $500 and $1000 (10% failure probability x $5000 to $10000 engine replacement costs. So in the sterile world of probabilities, its a $1700 premium to avoid a $500 to $1000 loss.

With a double row bearing, the odds of failure improve to 1 in 100. Given the difference in odds, a IMS dual row bearing replacement is an even higher premium to pay compared to the single row bearing situation. This is because the cost to replace the IMSB is the same, but the probability weighted risk drops to 1 % of $50 to $100. Like all cases with insurance, the probability weighted numbers mean little if your engine dies due to an IMSB failure.

So this brings me to my answer to JDs question. I might replace a single row bearing as a preventative maintenance measure. I would only replace a dual row bearing at the time of clutch replacement with one exception. I would replace dual row bearings in cars with low annual miles or infrequent oil changes. These latter conditions allow increase oil contamination and degrades the seals more quickly.

Hope this helps.

[southernstar]

Thom, there is no direct correlation between oil contamination and lower mileage, especially if the car is driven is for more extended runs, rather than the short, in-town, stop and go daliy trips that many higher mileage cars are regularaly subjected to (let face it, that does tend to contaminate the oil). For vehicles that are winter-stored (as Johnny's seems to be), it is of course important to change the oil each spring before putting the car on the road. My car is driven largely as described for about 4-5000 miles a year before winter storage, followed by an oil/filter change each spring when she is put back on the road. I have a magnetic drain plug and also cut open the filter to check for particulate matter. Simply put, the oil that is drained out each spring looks virtually indistinguishable from new.

My BMW X3 is driven year round and not only gets much higher annual mileage, but a higher percentage of its trips are of the stop and go variety. The factory recommends oil changes every 25,000 km (about 15,000 miles) and I can assure you, when it goes that long the oil looks quite dirty in comparison. I would far rather have a lower mileage car that has had its oil changed every 5000 miles at most, than a higher mileage daily driver that has had its oil changed according to Porsche's recommended schedule!

Brad

[southernstar]

Hey JD, I just noticed that you have entitled the thread 'duel', rather than dual. After reading the disparity in opinions (and considering the fact the dangerman no doubt regularly engages in duels), I am beginning to understand why!

Brad

[Johnny Danger]

Originally Posted by southernstar

Hey JD, I just noticed that you have entitled the thread 'duel', rather than dual. After reading the disparity in opinions (and considering the fact the dangerman no doubt regularly engages in duels), I am beginning to understand why!

Brad

Must have been a Freudian slip ?

[thom4782]

Brad:

You described it well. Contaminated oil is root of the problem in my opinion. I agree that your comment abot low mile cars with frequent oil changes, especially after winter or many months storage. Thanks for clarifying my explanation.

Thom

[thom4782]

Revised - duplicate submittal

[EssexPorsche]

Thom,
It's not about the money, it's not about the price tag( sorry got all a bit Jessie J there)
You can't price the pleasure these cars bring nor can you evaluate peaceful sleep.

People can post all the maths they like but if you are a risk averse guy and love your 986 ... It's irrelevant .

As I said before the whole subject is emotive and very much a personal perspective.
There is no right are wrong. There are informed opinions, there are no doubt biased opinions, there is for sure plenty of hear say. All anyone has to do is reconcile their own course of action with themselves. Whether that be the wife or the wallet who cares.

It's easy for me to say because I made my choices based on who I am and what my car means to me.

No wonder the prices of 986s is @rsing out if all people read is this stuff when looking to buy.

Come on guys, we all know what's what now. Make your choices, pony up or pipe down so we can get back to the fun stuff!

[ccjazz]

No intentions of derailing the thread, but.....regarding oil changes and their importance to IMSB health.

Summers here are not as long as some of you are accustomed to, which explains the low mileage on my car. I've done the last 2 oil changes in spring after winter storage. I was thinking about moving my oil changes to fall before putting it away for the winter to have clean/fresh oil in it while in hibernation.

So, what would you recommend is the best schedule, spring or fall changes?

I will likely average 2-3000 mi/year.

[Johnny Danger]

Originally Posted by ccjazz

No intentions of derailing the thread, but.....regarding oil changes and their importance to IMSB health.

Summers here are not as long as some of you are accustomed to, which explains the low mileage on my car. I've done the last 2 oil changes in spring after winter storage. I was thinking about moving my oil changes to fall before putting it away for the winter to have clean/fresh oil in it while in hibernation.

So, what would you recommend is the best schedule, spring or fall changes?

I will likely average 2-3000 mi/year.

What ever happened to the concept that synthetic oils were good for thousands of miles ?

[thom4782]

For most people, it is about the money. They worry - not because their 986 will be a total write off if the engine grenades due to an IMSB failure - but because they might have to fork out $2oK in the worst case to buy a Raby engine and have it installed in their Boxsters to get their cars back on the road.

[springer123]

I have a 1999 Base model but the engine was replaced by a Porsche dealer under warranty in 2003. In 2011 I had the clutch, RMS, and IMS cover replaced. The part number for the IMS shaft base was P996-105-017-02. According to jb92563's post, this is the cover for a dual row bearing? I've heard different statements. Some say I could have either a dual row or single row bearing, but most likely it's a single row because the engine was replaced in 2003. Is there anyway the cover I have could be used on a single row bearing or do I have the dual row?

[clickman]

I change my oil before putting the car to bed in the fall. I don't like leaving the engine guts sitting in the acids and other crap generated during my spirited driving season...