Crankshaft Bearings

[G Dicko]

Hi All
I have had reason to completely strip and rebuild my 1946 500cc model 18 engine. The drive side of the crankshaft has 2 ball race bearings and 2 spacer washers between them and the timing side has a 2 piece roller bearing and bronze bush. This is the correct original set up as far as I know.
Now for the problems, I noticed before removing the engine that there was over a mm (0.040") of side movement in crankshaft? After splitting the cases I found the timing side stub shaft was worn were the roller bearing sits and the bearing is badly worn.
The stub shaft is available but not the bearing. I personally can't see why it can't have a ball race bearing on both sides like modern engine's have ? Also a ball race bearing would be 1/2" wide and should take out the side play because the original roller bearing is 0.450" wide. Obviously I would have to carefully check that it wasn't to tight because I understand that it would need a few thou of side clearance.
Could someone please advise me on this.

Many thanks
Glen

[G Dicko]

Hi All
As I had no reply or advice about the crank roller bearing issue I assume no one has experienced the same problem, so I thought I would share how I resolved it to help anyone who may have the issue in the future.
First, I spoke to an incredibly helpful guy named John at "workshop 14" (advertised in the Jampot mag) John told me that AJS did a modification and stopped using the Roller bearing in the later years of production. Instead they used a longer crank case bush with a big top had that replaces the inner bearing race (you still need the roller bearing outer race). This bush was available from from "AMC classic spares" (also advised in the Jampot mag) as was the timing pinion that I was struggling to get. I thought I was going to have to get a pinion gear specialty made. AMC classic spares was very helpful and 2 days later I received both parts needed for the rebuild.
Speaking as a retired engineer/ machinist I can tell you that both parts were absolutely perfect and well made to good tollerances.

Thanks to John at Workshop 14 and AMS classic spares I can now start the rebuild

All the best
Glen

[Allen_F]

Easier to rebuild an engine thasn post a pic in this weired arrangment. Notice the lack of manual for your model.

51 flywheel assembly.PNG

[Allen_F]

1 being reply to post.

add pic.PNG

[dave16mct]

Manual here:
http://archives.jampot.dk/book/Owners_m ... Manual.pdf
Dave.

[SPRIDDLER]

I've already written up how to post photos (with screen shots) as it's a frequently asked question. It's in the 'Frequently Asked Questions' (FAQ) forum under the topic title: 'How to post photos on the forums'.

It's also here:

viewtopic.php?f=19&t=27956&p=237049&hil ... os#p237049