m20 crank sprocket, on m52 crank need to modify or should slip on?

[kickinindian]

so like the title states should the m20 timing belt sprocket slide onto the m52b28 keyway after the crank spacer or does it need to be modified i kinda held it up to each other today and it looks like the sprocket side is too small

[digger]

should basically slip on to get it started then go all the way with some effort you can use the bolt to screw it in from memory, no need to modify the gear itslef.

make sure the mating surfaces are immaculate, no dents etc that will score the surface

usually use a puller to remove it so its not a sloppy fit that can usually be done by hand

[kickinindian]

thanks digger! and i use the m20b25 crank bolt and conical washer/spacer too?

so it would be oil seal spacer>sprocket>conical washer>crank bolt. correct?

[redlightpete]

You'll need to cut the stepped section off the conical washer because the crank snout is a little too long. Also the m20 crank bolt is too long. The m52b28 one is shorter and works.

[kickinindian]

damn it i bought the crank without the bolt could i cut my m20 one down and that would work?

[digger]

a unmolested bolt is about $20 or less from other places if you get stuck

http://www.pelicanparts.com/catalog/SuperCat/0278/BMW_0278_ENGMAN_pg1.htm

i thought the m20 one was too short but could be wrong. m20 on LHS one i used for S52 crank on the right

[redlightpete]

Maybe I'm remembering the bolt length backwards. Just make sure you have a reasonable amount of thread engagement and that you're not running out of thread depth before you fully clamp the parts together.

[digger]

updated pic to the correct one

[kickinindian]

okay so i will have to get the m52 one then oh well good to know

[MR 325]

Yes you will need the 24v crank bolt and you will need to machine the washer down to sit correctly.

[kickinindian]

putting this here for later

m52 crank bolt #11211720633

[16vCorey]

Yep, you have to use the M52 bolt. I didn't have to do anything to the washer when I built my M20B28, so I'm not sure what that's about.

[MR 325]

Yep, you have to use the M52 bolt. I didn't have to do anything to the washer when I built my M20B28, so I'm not sure what that's about.

It will work without modifying the washer but it won't sit currently.

What crank spacer did you use?

[mikerob97]

I am looking for information on where to buy the proper cranksshaft spacer and properly machined washer - does anyone know where I might find one?

Thanks in advance for any help.

[abit]

here is info about washer machining down: (as far as I remember, I even took more than 1,25mm off, by using the same crank spacer as he)

http://www.msportster.co.uk/m20b28-engine-build/nggallery/page/8

spacer dimensions: