Help wanted with camshaft bearings

[CJH]

Can somebody help me with the subtleties of different camshaft bearings? I'm finally getting around to starting the reassembly of my 2.1 project engine. I started this a few years ago - it was meant to be a winter project, but for various reasons I've had to put it aside, but now I'm finally in a position to finish it. I've started sorting through all the parts today. Along the way I seem to have accumulated three sets of camshaft bearings, but I can't remember why, and now I'm not sure which set to use. They're all slightly different.

My engine case is stamped as an early DJ, and both halves of the case seem to be machined to take a thrust bearing at the gear end. The first bearing set I have, and which I've been using for various test assemblies and for timing the camshaft, is a Kolbenschmidt set. Only one of the gear end shells is a thrust bearing - the other one has a locating tab but no thrust surfaces. The shells for the flywheel end don't match - one is narrower than all the others, but one seems to be the same width as the two middle shells:


The second set I have is a Mahle set. This one also has only a single thrust bearing, but the two shells for the flywheel end are both narrow:


The third set is one that's in a 'VW Original Classic Parts' bag, and appears to be a VW Group part. The two gear end shells are both thrust bearings, and seem to have a soft grey coating on the bearing surfaces, including the thrust surfaces. There is no locating tab in either thrust bearing. The two flywheel end shells are both narrow, and neither they nor the middle shells have this soft grey surface:


So should I be using two thrust bearings, or doesn't it matter? Is there any significance to the differing widths of the flywheel end shells (I suspect the wider one will interfere with the core plug)? Is there something special about the soft grey bearing surface? If I use the set with the two thrust bearings, what stops them rotating in the case - do I need to punch a 'tab' into one of them to match the recess in the case?

[CJH]

Well I think the Kolbenschmidt set that I've been using must have had a packing error - having checked I'm now certain that the wide shell at the flywheel end will interfere with the core plug at that end. So I'll use one of the other two sets.

I checked my Bentley manual, but I'm still none the wiser as to whether both the gear end shells should be thrust bearings. The camshaft will be properly located even if only one of them is a thrust bearing, but I don't understand why some sets have one thrust bearing and some two.

In the sets I have that have a single thrust bearing the other shell has a tab that fits into a notch in the case. This is enough to stop both shells from rotating. But in the set that I have with two thrust bearings neither shell has a notch, so I can't see what prevents them from spinning in the case.

[bigherb]

Essentially the camshaft bearings are the same as the type 1 Aircooled engines which only used one thrust bearing
Type 1 Aircooled and early 1.9 WBX used the Aircooled one thrust bearing set. Std size bearing set part number 111 198 541
Type 4 Aircooled used two thrust bearings set 021 198 541
Later 1.9 and the 2.1 WBX used two thrust bearings set 025 198 541

Locating tabs. Type 1 only had a tab on one side of the crankcase for the thrust bearing shells.
Type 4 IIRC only had one tab, WBX?

[CJH]

Thanks Bigherb - my VAG double thrust set is labelled with that 025 198 541 part number, so I'm inclined to go with that set, despite it not having a locating tab on either of the thrust bearings.

I've just dug out the shells that were in the engine when I rescued it from a scrapyard - they're a single thrust Kolbenschmidt set, but the engine had had a rebuild already I think (there's a '*' character stamped next to the engine code), so they may not have been original.

You say that 'later 1.9 and the 2.1 WBX' used the double thrust set - is that *all* 2.1 WBXs?

I guess my only concern in using the double thrust bearings is whether a case that was designed specifically to use them had some other way to locate them and stop them spinning. I'm puzzled why my case would have both halves machined to take thrust bearings, as well as a recess for a tab on one side - it's as though single and double thrust sets are interchangeable. Maybe I'm worrying for nothing about the bearings spinning.

[itchyfeet]

All late WBX use double afaik, this is what I fitted to my 2.1
https://www.brickwerks.co.uk/t3-parts/e ... hrust.html" onclick="window.open(this.href);return false;


this is for early WBX, says for 2.1s which is confusing because I didn't think they did a 2.1 in the early case

https://www.brickwerks.co.uk/t3-parts/e ... t-all.html" onclick="window.open(this.href);return false;

[CJH]

Thanks Itchyfeet - yes that early set is the Kolbenschmidt set that I have that has (in my case) the wrong shell for the flywheel end.

My 2.1 case is evidently from early in the production run - engine code DJ001991 - so if there's such a thing as an 'early 2.1', then mine's probably one of those. But it's definitely been machined to take a thrust bearing on both sides.

I did a little bit of googling, and double thrust bearings seem to be specified for higher performance engines, i.e. with more resistance to the cam turning, caused by stiffer valve springs for instance. But there also doesn't seem to be a problem with the shells spinning, despite the lack of a locating tab.

Looking in Bentley, for the 1983-1985 WBX there's a label pointing to the thrust bearing with the caption 'Tabs must engage in recess'. For the 1986 onwards WBX, the label points to the middle bearing and says 'notches fit to each other' - there's nothing about notches for the thrust bearings.

[silverbullet]

I got your pm CHris so here's what I have found:

There were "crossover" 2.1 cases (suffix B, rather scratchy hand-engraved letter on the mould tooling, but no diagonal web across the alternator mouting) but they were thin shell bearings and double thrust.

The flywheel end cam bearing should be narrower than the middle one, otherwise you will block off the oil drain.

The OEM double thrust bearings didn't have an anti-rotation tab, the last ones I had from BW did have a tag so I had to reach for a small file.

Personally I would fit the VW ones as first choice. I have used the Glyco Type 1 double thrust ones in my own 2.5

[CJH]

Thanks Ian

There were "crossover" 2.1 cases (suffix B, rather scratchy hand-engraved letter on the mould tooling, but no diagonal web across the alternator mouting) but they were thin shell bearings and double thrust.

My case has no diagonal web, but the 'B' suffix is nice and neat like the rest of the part number. But I think you're saying the double thrust bearings were the same even on those crossover cases. Given that VW evidently felt that the tabs weren't necessary and no other anti-rotation device was built into the later cases, then I'll go with the VW set as you suggest. I test-fitted the double thrust bearing into the opposite (right) side of the case, and it seems to be a tighter fit than on the 'assembly' (left) half of the case, so maybe that helps to stop it spinning. Thanks again.