WBX-Unknown

[937carrera]

I have finally found the specs for the one piece main bearing I knew it would be somewhere on the internet

After searching for bearing specs for KS, Mahle and Glyco I decided to use VW classic to see if the information was there. It was, but the data was a little too rounded for my liking, but I now had part numbers rather than NLA

One piece bearing https://www.volkswagen-classic-parts.de ... 82d97.html "26" mm

Three piece bearing https://www.volkswagen-classic-parts.de ... b7f4e.html "20" mm excluding thrust washers. We already knew this was 19.8mm

I then dropped the part number into a site that had popped up before, though these are oversize, the bearing length remains the same at 25.96mm https://e-shop.eoltas.lt/en/74181630-KOLBENSCHMIDT/

So my one piece bearing has worn 0.07mm while itchys had only worn 0.04mm. I'm happy now that I will be able to get the endfloat back into spec and not have to use three maximum thickness shims

I still want to figure out why there is a dimension difference between the two bearings, but that's just satisfying my intellectual curiosity. My technical German has improved again

[itchyfeet]

Sorry my untrained eye does not see anything wrong where am I looking?

Con rod first. Remember axial play at 0.4mm is within spec so that isn't causing the side load

[937carrera]

Look at the shell between about 11 o clock and 1 o clock. There's a dark curved line with a lighter colour to the shell above, compared to the rest of the shell.

That's where the bearing is more polished & worn, and where the additional side play at the small end is coming from.

[itchyfeet]

oh hes I see that now thought it was a relflecton.
is that typical of a bent rod then?

[937carrera]

Maybe...

Typical would see the same wear on the diagonally opposite shell, which there isn't.

I think I need to take a closer look at the little end of that piston / con rod and see if there is any sign of uneven wear there

[itchyfeet]

checked piston/rod/ pin weights?

[937carrera]

No, not yet, a bent rod weighs the same as a straight one.......Or are you thinking a heavy piston causing torsional stresses on the crank.

It's very difficult to bend a crank and type 4 / WBX ones are pretty strong

[itchyfeet]

No I was just stabbing in the dark, perhaps an unbalanced piston/rod/pin can cause wear if you found that one was different you might do some more research on it.

Remind me it's not reground is it, wasn't there talk of grinding marks on that journal, can't remember?

[937carrera]

The journal specs were a couple of pages ago, the crank is completely standard, almost as new except for main number 4, couple of minor marks on rod number 2 cylinder which I'm OK with now

I put the spec sheet up a couple of pages ago, you must have been enjoying your hols that day

[itchyfeet]

I put the spec sheet up a couple of pages ago, you must have been enjoying your hols that day

yep on me holls and on a mobile, I may have mentioned that the pics are slow to load so all you see is the text for about 15 minuites if you can even be bothered to wait that long

[937carrera]

Sorry about that, here's another....

Early case alternator bracket



I've just weighed the rotating assemblies, set out as rod + piston, rod being rod+ shell bearings, piston being piston+gudgeon pin+1 circlip:

1. 569+549 = 1118
2. 568+546 = 1115
3. 567+549 = 1114
4. 567+551 = 1118

They look pretty good, but the kitchen scales I used aren't giving consistent results, so these values were the result of a number of weighings, being sure to repeat the positioning on the scale. They are all as pulled from the case, no cleaning, so this was the actual rotating mass, ignoring oil in the rod.

[itchyfeet]

Its not that then.
Personally I wouldn't worry as you are fitting new shells

[itchyfeet]

I still want to figure out why there is a dimension difference between the two bearings, but that's just satisfying my intellectual curiosity.

I know
The answer is staring you in the face, let's see if you can work it out before I can get into the shed and get the money shot.

[itchyfeet]

The answer is they are not different they can't be, it's the assumption that the thrust washers touch the bearing thats wrong, they don't they are held clear by the casing.

P1100438 by Paul_Barr, on Flickr

[bigbadbob76]

Doh!
Obvious now aint it.