wbx 1.9 in MV case

[klucz]

Hey everyone. I've been battling with a wbx 1.9 rebuild for a while and have found that my DH case is in borderline condition. Now I'm considering picking up a 2.1 core to build on. Before I spend the money and drag it home I wanted to ask if anyone knows if there are any issues with building a 1.9 in an MV case. I'm pretty sure I remember hearing that 1.9's were built in the later style case through the end of production in Germany but just not imported to North America. Reason I'm considering doing this is because my old pistons, cylinders, rods and crank appear to be in pretty good shape. I will re-check everything for sure but am wondering what my options are. Maybe I'll stumble onto a nice 2.1 and bail on the 1.9 completely, but if I can save some dough that would be good too.

Thanks

Paul
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84 Westy 4spd sold

[D Clymer]

Hi Paul,

There are really only three differences between the early and late cases.

A. The early case uses a one piece #1 main bearing while the late case uses a #1 bearing with the thrust washers separated from the bearing.

B. The late case has an extra threaded boss for the second oil pressure switch on the 86-91 oil pressure system.

C. The late case has slightly more internal clearance for longer strokes.

The pistons and cylinders are the same dimensions for both the 1.9 and the 2.1. The 1.9 just has the wrist pin holes lower and a shallower dish. So fitting the pistons and cylinders from the 1.9 into the 2.1 case is no problem.

The 1.9 crank has a 7mm shorter throw than the 2.1 crank. This presents no problems, so the crank should drop right in.

However, while I've rebuilt quite a few 2.1s, I've actually never had a 1.9 apart. So there are a couple of critical details I'm not positive about. First of all, I'm not positive that the 1.9 has the same dimensions at the #1 bearing and that the thrust surface is machined the same as the 2.1 crank. I am almost positive it is, but I don't want to go and state that something is a simple drop in and then have it turn out to not be. The other area of question I have is that the dimensions of the #1 and #2 journals on the 1.9 crank appear to be slightly different than those of the 2.1. (Chart in the Bentley manual.) We're talking just a few thousandths, but I'm wondering which bearing set you'd use.

I know one way to get this right would be to send the crank out to DPR and have them machine the mains for .010" under the standard 2.1 crank dimensions. Then you'd use the .010" main bearing set for a 2.1 and everything would be perfect.

So the answer to your question is probably a simple yes. It will work. But I would clarify those two points (#1 thrust surface and #1/#2 bearing diameter compatibility) first. Of course the other possibility is that you get a 2.1 core and it also has a nice crank and good pistons and cylinders. I think in that case I would just rebuild the 1.9 rods (if needed) and use the 2.1 parts. There's certainly nothing wrong with an extra 200cc.

Keep in mind also that the cam is different between the 1.9 and the 2.1. The 1.9 cam has lower lift and duration. Given the choice, I'd use the 2.1 cam on either displacement combo.

And yes, they did keep building the 1.9 in europe right through the end of German production in 1990. The later 1.9s were built in the late style case. We know the late case as a 2.1 case here because the changes to the case coincided with the release of the 2.1 engine, but in the ROW the smaller displacement engine continued but with the changes noted for the 2.1.

Hope this helps.

David

[crazyvwvanman]

Replacing the 1.9 case with a 2.1 case is explicitly covered in the Bentley.
Page 13.57

Mark

[klucz]

Thanks for your replies David and crazy.

David - This 1.9 is the only wbx I've ever been into so your insight is very appreciated. I see in Bentley that bearing #2 size is different, but #1, 3 & 4 are the same. The difference in the thrust bearing is one of the main reasons why I'm considering this. I'd definitely want to use a 2.1 bearing set because of the better design and availibility. Your points about possible differences in bearing size and thrust surface is exactly the kind of information I'm looking for.

crazy - Thanks for the heads up. I've seen the bit in Bentley and you have to admit that there isn't a whole lot there.

One thing I should probably mention is that I have a blue dot 1.9 crank that's within spec. That's not saying a whole lot though I know, not until you have the new bearings torqued down in the case and check clearances. From what I've gathered only blue dot bearing sets are available, and only the later 2.1 sets are available in off sizes. So those seem to be some major limiting factors.

Another thing I noticed in Bentley is that bearings 1 and 2 are numbered differently on the 1.9 and 2.1. On the 1.9 #1 is the first one from the flywheel and #2 is the split shell in the next position over. But on the 2.1 the first bearing from the fw is labeled #2 and the split shell next over is #1. And if that's the case then according to the journal sizes listed in Bentley that would mean that journals 1 & 2 are different by about 5 mm on a 1.9 and 2.1. Or is there maybe a mistake there?

This is all uncharted territory for me so sorry if I'm way off on something.
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84 Westy 4spd sold

[klucz]

That's just silly what I said about there being 5 mm difference between 1.9 and 2.1 crank journals. The info in Bentley cited by crazy above proves that. It must just be a typo in Bentley. Thanks again for your replies and info.
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84 Westy 4spd sold

[D Clymer]

[klucz]

Thanks for pointing that out.
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84 Westy 4spd sold

[stevey88]

Then why don't just make it a 2.1 if you are buying a 2.1 core? Will the digijet works with a 2.1? I understand the DJ engine uses the Digijet.
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Steve

[klucz]

At this point I just want to build a tight motor, either 1.9 or 2.1. I already have some good 1.9 parts so that seems to be an option. If I find a 2.1 in good condition then we'll see about that. I'm learning as I go and there's still lots of stuff that I don't know about.

AFAIK US spec DigiJet will work fine on a 2.1. DJ engines use a different version of DigiJet with a different harness and ECU.
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84 Westy 4spd sold

[RGS Paul]

DPR Machine will sell you a crank with whatever stroke you want.

Rocky Jennings has nice piston and cylinder sets, he also can build you a nice set of rods.

Drop in a Type 1 hydraulic cam.

Keep the DJ fuel injection.

Add a oil cooler.

Drive in happiness for the next 300k mi.

What I'd do at any rate. Probably come out cheaper then a GoWesty kit too, and it would be all new parts ('cept the crank).

Paul
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'87 Syncro 7-Pass. Adventure Touring Vehicle
"Simplicate, then add lightness." Colin Chapman

[klucz]

This is my first rebuild and I would consider a good running stockish motor to be a major success. I'm shooting for price and quality, speed will have to wait. But if I were to sink a lot of change into a wbxer at this point and time I think I'd just get in line at Vanistan.
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84 Westy 4spd sold

[klucz]

I just wanted to add a couple of things regarding some of the earlier comments.