R51/3 crankshaft endplay?

alkis
Posts: 13
Joined: Thu Mar 28, 2013 9:50 am

R51/3 crankshaft endplay?

Post by alkis »

Hi to all

I am rebuilding a friend's R51/3 that destroyed its connecting rods. I am trying to find the crankshaft axial permissible play inside the crankcase but the workshop manual does not state it. Do any of you kind fellows happen to know it?
Thanks in advance
Alkis

User avatar
Micha
Posts: 531
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 crankshaft endplay?

Post by Micha »

Is this what you need?
Attachments
end play.JPG
Michael Steinmann
R51/3 1952
Engine Nr. 529466

User avatar
Micha
Posts: 531
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel

Re: R51/3 crankshaft endplay?

Post by Micha »

And here is a link to the workshop manual:
http://salispartsusa.com/parts/wp-conte ... -tools.pdf
There's also the stuff regarding con-rods etc.
Michael Steinmann
R51/3 1952
Engine Nr. 529466

alkis
Posts: 13
Joined: Thu Mar 28, 2013 9:50 am

Re: R51/3 crankshaft endplay?

Post by alkis »

English is not my native language so i may misunderstand it but the abstract from the manual that you posted , i think, talks about the desired distance of the oil slinger ring to the crankshaft distancing ring that fits after the oil slinger.
It is strange that BMW does not state the correct endplay of the crankshaft since they are very thorough with the gearbox shafts endplay. They do not even have shims with different thicknesses for the crankshaft..
Any way thank you very much for taking the time to answer me.

User avatar
schrader7032
Posts: 7682
Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX

Re: R51/3 crankshaft endplay?

Post by schrader7032 »

I was looking for something in the Barrington /2 manual for something similar but couldn't find it...same in the BMW workshop manual. But I'll offer this number... I was tracking down some vibrations on my R69S and called Vech. I was told that if I were to put a dial indicator on the front of the crankshaft, the value of 0.002" fore/aft movement would be acceptable. I guess I would check the movement out by actuating the clutch and watch for movement. Also, I might have to lightly tap the nose of the crankshaft to the rear and repeat the clutch actuation.

Not your bike, but I suspect that something in this ball park is what you're looking for.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

User avatar
bm68andreas
Posts: 29
Joined: Thu Jan 01, 2015 3:21 pm

Re: R51/3 crankshaft endplay?

Post by bm68andreas »

Alkis dear friend where do you live in Greece?
I have a tip for you where you can send your crank for rebuild,.....
He knows all the details about BMW's cranks...
saluti Andreas
[iKONTOGIANIS][/i]

alkis
Posts: 13
Joined: Thu Mar 28, 2013 9:50 am

Re: R51/3 crankshaft endplay?

Post by alkis »

Two thou of an inch seems reasonable i guess. Thanks for the info!
Andreas, I live in Patras and i have sent the crankshaft to Panagakis machine shop. It is a local machine shop that i have worked with in various occasions and have always been satisfied. Who are you proposing ?

User avatar
bm68andreas
Posts: 29
Joined: Thu Jan 01, 2015 3:21 pm

Re: R51/3 crankshaft endplay?

Post by bm68andreas »

I think is better to send it to Michalis at N.Kosmos
he has more experience..
call me ..6942805221.
have a nice day
[iKONTOGIANIS][/i]

User avatar
caker
Posts: 143
Joined: Sat Nov 12, 2011 10:49 pm
Location: Haddonfield, NJ, USA

Re: R51/3 crankshaft endplay?

Post by caker »

All things being equally mounted, I'd think it would only depend on the clearance spec of the main bearings used - the axial play in the main bearings - at most.

Like a "6004" has no noticeable axial movement between the inner and outer race, whereas a "6004-C3" you can feel it with your fingers.

C0 up front, C3 in back, as I was recently mentored.

-Chris

User avatar
malmac
Posts: 502
Joined: Sun Jun 29, 2014 2:10 am
Location: Toowoomba, Australia.

Re: R51/3 crankshaft endplay?

Post by malmac »

caker wrote:
Thu Jun 17, 2021 9:15 pm
All things being equally mounted, I'd think it would only depend on the clearance spec of the main bearings used - the axial play in the main bearings - at most.

Like a "6004" has no noticeable axial movement between the inner and outer race, whereas a "6004-C3" you can feel it with your fingers.

C0 up front, C3 in back, as I was recently mentored.

-Chris
Chris

I think you are on the right track. Not sure if this helps.
When doing a crank positioning which has plain bearings, there has to be shims to position the crank forward and aft and to set a suitable amount of end float.
However when the crank is using roller bearings then the end float is, as Chris states, determined by the clearance specs for the specific bearing used.
The positioning of the roller cranks is still important and shims are used to correctly position the crank in the crankcase in respect to oil slingers and centering the conrods in the barrels.

Hopefully this will assist or perhaps just seem to make even more questions.

Mal
mal - R69s
Toowoomba- Australia

Post Reply