Bearings..

[craigieeb]

I'm about to get a seat of main/crankshaft bearings for the M50..

I've got the old ones here, but the part number cant be found on either realoem or bmw fans,
I'm sure there standard in size as the production date on them is 01-91
and i dont think the crank has ever been out let alone have a re-grind,

what would people suggest?



If you cant see the number,
it's 1717523 then underneath is
524/525

[Simon13]

M50 uses the same shells of M20's and lots of other bmw engines if the mains are 60mm and big end 45mm

I'd not worry some stock M50 shells in the correct size will do

[craigieeb]

Yeah, I noticed they were the same as the M20,

I was just curious why the part number's didnt show up anywhere
normally realoem/bm fans tell you if they have been replaced with part number xxx
but nothing of the sort came up.

just got me a bit curious

[HairyScreech]

Sometimes obsolete numbers don't show up, I have had a real head scratcher with some z3 bits recently due to obsolete numbers.

As Si says, m20 and m50 shells are pretty much interchangeable but I notice there you have a double tang bearing, I can never remember which is the old type but the M20 used 2 different shells, double tang and single tang. Ones hard to get and can be a pain in the arse.

[craigieeb]

Good spot!!

If my memory serves, my old M20 had a single tab/tang, I think

But knowing my luck, it'll be the "double tang" bearings that will be hard to find

I have just seen these, while typing this lol

http://www.ebay.co.uk/itm/271129090424? ... EBIDX%3AIT

they look to be the same, whether it's just a generic picture or not... is a different question

[craigieeb]

Hmmm
just to add to my confusion lol

I've checked my spare M50 n/vanos block, (the main one is getting a boring)
but on this one, the block has a single "tang" and the caps are double

[HairyScreech]

http://www.r3vlimited.com/board/showthread.php?t=256117

There you go.

I think I have both styles kicking about so will have a poke tonight.

From what I can see there may be several ways around this if you have an early 360 oiling block.

It's worth noting that despite the internet hearsay that 360 oiling is better it is not, here's Mahle's take on it.

http://www.vandervell.co.uk/images/slid ... forman.pdf

[craigieeb]

Some good info there fella

I've just ordered a set of standard size kolbenschmidt
I made sure they had the double and single tab's/tangs..


(pic of actual bearings)

and after reading the loss of efficiency/performance/power even, in the 360 grove bearings,
I just went with the norm