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Checking bearing sizes and crank assembly

Posted by Jon Gilbert on 8 October, 2012

I’ve had a bit more time to spend on the 1500 rebuild which meant I could measure the bearing saddles in the case halves and the surfaces on the crank. Knowing these numbers means I can order the correct bearings. My replacement case seemed to have been bored at some point (although it didn’t look like it had) and the crank from The VW Engine Company had been reground to get the surfaces all lovely smooth, so I ordered the appropriate sizes.

When they arrived I gave them all a trial fit. They seemed to be ever-so-slightly tight but they did go in to their saddles with a light push.

Once I was happy with these I was able to build up the bearing stack on my crank. This required the use of the kitchen oven (much to my wife’s horror) to get the gears hot enough to slide onto the crank. These gears won’t go on without heat as they are a super tight fit. Some people uses a blow torch to heat them up and then tap them home. But, my work bench is made of wood. The shed is made of wood too and I really didn’t want to start a bonfire. So the oven is the best bet and ours goes up to 300 degrees Celsius.
I left the gears in there for 20 minutes and made sure the crank was very cold by putting some ice packs around it. I popped the first bearing on, making sure the dowel pin hole was facing the right way (very VERY important) followed by the cam gear, which slid on easily. Next up you need to slide on the spacer before getting the brass distributor drive gear out of the oven and sliding that snug up agains the spacer.
At this point the crank was roasting hot, so I took a break with a nice cup of tea.
Once cooled, I managed to get the circlip on, slid on the other bearing followed by the oil slinger and finally the woodruff key.

So that’s another stage of my engine rebuild complete and I have to say I rather enjoyed it.

UPDATE Jan 2013: Those ever-so-tight bearings proved to be a pain in the back side. It turns out that my vernier gauge was inacurate and the case had never been bored. The tight bearings caused the crank to bind when the case was tightened up. This meant I had to take it all apart again and start from the beggining. Yes that means the crank had to be taken apart too! The upside is that the saddles were fine but this of course meant I had to buy a new set of bearings. I’ll blog about it soon but the thing to take away from this is triple check your measurements and triple check them again!

Engine bearing for a 1500 single port VW Beetle engine

Here is one of the engine bearings fitted into a case half

VW Beetle 69mm crank assembly

I trial fitted the bearings too. When fitting these properly it is wise to apply some lubrication to prevent wear when turning the engine over for the first time. I use cam lube.

Cam and distributer drive gears from a VW type 1 engine

I heated the gears in the oven to 300 degrees Celsius so I could slide them onto the crank shaft. I’ve tried this at 250 degrees before and still had to tap the gears home. 300 degrees made a huge difference with no tapping required.

VW type 1 engine parts

Masking tape was used to protect the crank shaft from the circlip. It is a tight fit and can easily score the bearing surface.

Complete crank shaft from a VW Beetle engine

Here you can see the gears and bearings in place, complete with the oil slinger washer and woodruff key. Apparently this is known as the bearing stack.
The order to put them on goes from right to left: Number 3 main bearing, cam gear, spacer, brass dizzy gear, circlip, number 4 bearing, oil slinger and woodruff key.

Main bearing ona VW Beetle type 1 69mm crank

Don’t forget to pop the number 1 main bearing on the flywheel end of the crank. And remember to check where the dowel pin hole is located in the case half other wise you’ll have major problems when it comes to assembling the case.