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Old 07-05-2019, 08:35 PM   #81
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100000 miles expressed in brush wear:



I decided the put the original brush set back as it`s one unit with the rectifier and the quality of the aftermarket version seems worse than the original. There`s still a lot of meat left in these brushes.



Done.




Last edited by Homeoboxter; 07-06-2019 at 06:48 PM.
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Old 07-06-2019, 04:35 PM   #82
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Very impressive work. Are you going to "nut and bolt" restore the whole car or just the engine and periphery?
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Old 07-06-2019, 06:47 PM   #83
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Very impressive work. Are you going to "nut and bolt" restore the whole car or just the engine and periphery?
Huh, I really hope I don`t have to touch anything else, but probably that`s a very naive assumption The rest of the car seems ok though, apart from the 11 years rest.
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Old 07-07-2019, 11:32 AM   #84
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Hi Markus,

No, I haven`t yet, but I was gonna drop it off at some machine shop to have it checked. Or I`ll just place it down on a glass table and meaure the gaps all around with a feeler gauge. I`m kind of far from that stage yet though.

Best,

Greg
Hi Greg,

first step is always to measure all parts, especially the cylinder heads. Because this is an full alloy engine you have to check for flatness, warps and if anything is straight.

You can check the head surface by using a steel ruler. Put the ruler on the head and put a torch behind the ruler so it shines in your direction. If you can see light come through between the head surface and the ruler, in general the head needs to be resurfaced.

Now it depends how much material needs to be machined from the head and if the head is warped in any way. Most time you can compensate with a thicker cylinder head seal, but if not the struggle begins, because than you have to reseat the valves, sometimes adjust the valve length and so on. Good thing on a M96 engine is that you can adjust the cam position / timing.

So before doing anything else first step is to do measurements and check if everything is straight.

Hope this is helpful.

Regards, Markus
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Old 07-08-2019, 02:32 PM   #85
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Hi Greg,

first step is always to measure all parts, especially the cylinder heads. Because this is an full alloy engine you have to check for flatness, warps and if anything is straight.

You can check the head surface by using a steel ruler. Put the ruler on the head and put a torch behind the ruler so it shines in your direction. If you can see light come through between the head surface and the ruler, in general the head needs to be resurfaced.

Now it depends how much material needs to be machined from the head and if the head is warped in any way. Most time you can compensate with a thicker cylinder head seal, but if not the struggle begins, because than you have to reseat the valves, sometimes adjust the valve length and so on. Good thing on a M96 engine is that you can adjust the cam position / timing.

So before doing anything else first step is to do measurements and check if everything is straight.

Hope this is helpful.

Regards, Markus
Hey Markus, thanks for the useful tips, I`ll do the measurements soon.

Best,

Greg
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Old 08-12-2019, 10:11 PM   #86
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At last I found some time to work a bit on the engine. As a replacement of the original dual row IMS bearing I decided to go with a roller bearing designed for higher speeds and higher radial load. For thrust control I`ve thrown in a simple ball bearing that I had machined to fit behind the roller. It`s a 2T scooter crankshaft bearing with C3 clearance to bear high temperatures.




Together they are just as wide as the original.



I had a groove machined on the outer ring to fit the original snap ring.



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Old 08-12-2019, 11:57 PM   #87
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The whole unit is submerged in oil normally that I think is sufficient for lubrication. However, oil has to find its way around the IMS that spins in the engine case.





Here`s a closer view. At high RPM and at certain viscosities much of the oil may be scattered off from the shaft due to centrifugal force. This may increase the chance that the bearing is not amply lubricated at all times.



Probably it`s overkill, but to overcome this possibility, I thought a bypass oil channel in the engine case could set the same oil level behind the IMS in all circumstances. So, after a few second hesitation I decided to drill an oil gallery in the engine case. There`s not much room here, so I fabricated a mini drill to do the job:



Engine case wall is pretty thick here, so there`s plenty of room for a little oil gallery.



In situ position. Horizontal lines indicate the oil level at min and max sign at the dipstick.



Oil should easily reach the stationary center parts of the IMSB unit via this hole.



The oil gallery actively contributes to the better lubrication of the IMSB as well: the spinning sprocket generates a high oil pressure in its cavity that forces oil into the gallery and thus the back of the IMS.



Oil within the IMS gets depleted via this small hole drilled on the sprocket.

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Old 08-13-2019, 02:07 AM   #88
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It’s always great to see people try new things. Can’t say I agree with using two different bearings (as an engineer, I see many issues with this...a larger roller bearing seems better to me as thrust forces in this application should be minimal), but I am interested to see how your oil gallery works out.

Of course, it will take at least a few years and tens of thousands of miles, plus pulling the bearings for inspection for a definitive answer, but I hope to be around for that.

Very innovative. I will be watching with interest.
I hope your theory pans out

Last edited by particlewave; 08-13-2019 at 02:12 AM.
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Old 08-13-2019, 08:30 AM   #89
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Itís always great to see people try new things. Canít say I agree with using two different bearings (as an engineer, I see many issues with this...a larger roller bearing seems better to me as thrust forces in this application should be minimal), but I am interested to see how your oil gallery works out.

Of course, it will take at least a few years and tens of thousands of miles, plus pulling the bearings for inspection for a definitive answer, but I hope to be around for that.

Very innovative. I will be watching with interest.
I hope your theory pans out
Thanks! I think I will have to replace the DMF in about 5-10k miles, so I`ll have a chance to inspect the bearings as well. Hopefully it won`t fall apart before that
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Old 01-08-2020, 11:03 PM   #90
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Everlasting boxster project: I haven`t touched the thing for a while, and now instead of progressing forward, I took a step back and split the crankshaft bearing housing to take a peek into the main bearings. Luckily they all are in fantastic condition. Maybe I`ll check the clearances with plastigauge just in case, but there`s no apparent sign of wear.
Here are a some pictures:










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Old 01-11-2020, 04:02 PM   #91
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Back to work!

Glad to see an update. I was wondering what was going on.
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Old 01-14-2020, 04:49 PM   #92
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Yeah, every project is getting delayed since the little one arrived. Hopefully the Boxster will run at least when he gets the license Thanks for keeping track of the progress!

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Glad to see an update. I was wondering what was going on.
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Old 01-14-2020, 08:27 PM   #93
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Crank issues

Update: I was a bit too optimistic last time when I said everything inside the crank bearing housing was in perfect condition. I lifted off the crankshaft and took a second look. I discovered a few things:

1) The most shocking is this by far:




I assume this piece was already missing in the factory, otherwise I can`t really see how it could have escaped from here without getting jammed in between the journal and the bearing. Must have been a late Friday session on the assembly line when this got through quality control. Actually, if it was just fine for 100k miles, I might as well put it back, right?

2) I still could find pieces from the plastic chain tensioner pad that fell apart. This little thingy is a real pain in the butt. Make sure you replace yours in time! Makes a lot more sense to replace these regularly than any IMS update.



3) One of the thrust washers seems a bit more worn than it should be. Looks like it got mixed with some plastic from somewhere, or just burnt, I don`t know.




The other one, that`s not pushed by the crank when the clutch is being operated, seems brand new.



4) When the casing was machined, these ugly burrs should`ve been removed I guess. They come off easily and can cause damage anywhere they get to. German precision, where did you go?




More to come once I received the parts.
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Old 01-15-2020, 05:47 PM   #94
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...4) When the casing was machined, these ugly burrs should`ve been removed I guess. They come off easily and can cause damage anywhere they get to. German precision, where did you go?
...



I interviewed for a position at Mercedes Benz Vans last year (its a local production facility). One of the interviewers said "Perfection is an unobtainable goal; we just do the best we can." LOL
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Old 01-16-2020, 03:10 PM   #95
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I interviewed for a position at Mercedes Benz Vans last year (its a local production facility). One of the interviewers said "Perfection is an unobtainable goal; we just do the best we can." LOL
So I assume you didn`t take the job

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