Previous Thread
Next Thread
Print Thread
How to tell B and RB cranks apart without tools?? #2553376
09/22/18 09:17 PM
09/22/18 09:17 PM
Joined: Mar 2006
Posts: 1,229
In The Hills
J
jughed Offline OP
pro stock
jughed  Offline OP
pro stock
J

Joined: Mar 2006
Posts: 1,229
In The Hills
Is there an easy method of ID'ing B and RB crankshafts? I can't tell them apart by eye, and don't have the proper measuring tools.

Thanks for any help.

Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2553380
09/22/18 09:36 PM
09/22/18 09:36 PM
Joined: Jan 2003
Posts: 2,655
western PA
M
mopar4ya Offline
master
mopar4ya  Offline
master
M

Joined: Jan 2003
Posts: 2,655
western PA
Yes, by the casting numbers.

Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2553475
09/23/18 02:31 AM
09/23/18 02:31 AM
Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
moparmarks Offline
I Live Here
moparmarks  Offline
I Live Here

Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
You don't have a tape measure?


72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
Moparmarks Parts & Restorations
Desert Mopar Metal
Grand Jct. CO
970-261-7039
http://moparmark.com/
motormangj@gmail.com
Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2553520
09/23/18 09:06 AM
09/23/18 09:06 AM
Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline
master
gregsdart  Offline
master

Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
The main bearing journals are smaller on the B cranks. RBs are 2.750, Bs are 2.675? An RB crank will have a circumference of 8.639 inch, or 8 5/8 plus a touch.


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: How to tell B and RB cranks apart without tools?? [Re: gregsdart] #2553622
09/23/18 01:54 PM
09/23/18 01:54 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
R
RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
R

Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
^^^ cut a strip of paper & measure the circumference then divide Pi into that for the journal diameters Greg posted.


live every 24 hour block of time like it's your last day on earth
Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2553667
09/23/18 03:31 PM
09/23/18 03:31 PM
Joined: Jan 2003
Posts: 8,016
Polson, MT
DoctorDiff Offline
master
DoctorDiff  Offline
master

Joined: Jan 2003
Posts: 8,016
Polson, MT
You don't have to measure anything.

If the rear main bearing journal is almost the same diameter as the rear main seal journal, you have an RB crank.

If the main bearing journal is noticeably smaller, you have a B crank.

Re: How to tell B and RB cranks apart without tools?? [Re: DoctorDiff] #2553738
09/23/18 05:52 PM
09/23/18 05:52 PM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
R
RapidRobert Offline
Circle Track
RapidRobert  Offline
Circle Track
R

Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
That's too easy! Thanks Doc.


live every 24 hour block of time like it's your last day on earth
Re: How to tell B and RB cranks apart without tools?? [Re: DoctorDiff] #2553755
09/23/18 06:21 PM
09/23/18 06:21 PM
Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline
master
gregsdart  Offline
master

Joined: Jan 2003
Posts: 9,963
Frostbitefalls MN (Rocky&Bullw...
Originally Posted By DoctorDiff
You don't have to measure anything.

If the rear main bearing journal is almost the same diameter as the rear main seal journal, you have an RB crank.

If the main bearing journal is noticeably smaller, you have a B crank.

Like homer would say,, Doh,,,,!!!!!


8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
Re: How to tell B and RB cranks apart without tools?? [Re: DoctorDiff] #2553913
09/24/18 12:16 AM
09/24/18 12:16 AM
Joined: Mar 2006
Posts: 1,229
In The Hills
J
jughed Offline OP
pro stock
jughed  Offline OP
pro stock
J

Joined: Mar 2006
Posts: 1,229
In The Hills
Originally Posted By gregsdart
The main bearing journals are smaller on the B cranks. RBs are 2.750, Bs are 2.675? An RB crank will have a circumference of 8.639 inch, or 8 5/8 plus a touch.


Originally Posted By DoctorDiff
You don't have to measure anything.

If the rear main bearing journal is almost the same diameter as the rear main seal journal, you have an RB crank.

If the main bearing journal is noticeably smaller, you have a B crank.


Thank you both!!

that is what i wanted to know.
...and who keeps a tape measure in their pocket at all times??

Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2553975
09/24/18 09:22 AM
09/24/18 09:22 AM
Joined: May 2005
Posts: 4,679
Florida
BDW Online content
master
BDW  Online Content
master

Joined: May 2005
Posts: 4,679
Florida
Ron Jeremy?

Re: How to tell B and RB cranks apart without tools?? [Re: jughed] #2554002
09/24/18 11:02 AM
09/24/18 11:02 AM
Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
moparmarks Offline
I Live Here
moparmarks  Offline
I Live Here

Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
..and who keeps a tape measure in their pocket at all times??
Well that would be me, and Ron I guess


72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
Moparmarks Parts & Restorations
Desert Mopar Metal
Grand Jct. CO
970-261-7039
http://moparmark.com/
motormangj@gmail.com
Re: How to tell B and RB cranks apart without tools?? [Re: moparmarks] #2554029
09/24/18 12:12 PM
09/24/18 12:12 PM
Joined: Jan 2003
Posts: 43,458
Round Lake Beach, Illinoisy
Rhinodart Offline
Rhinotruck
Rhinodart  Offline
Rhinotruck

Joined: Jan 2003
Posts: 43,458
Round Lake Beach, Illinoisy
You two are almost twins, I know I don't look anything like the hedgehog... biggrin

100_0092.JPG
Last edited by Rhinodart; 09/24/18 12:16 PM.

The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!
Re: How to tell B and RB cranks apart without tools?? [Re: moparmarks] #2554065
09/24/18 01:38 PM
09/24/18 01:38 PM
Joined: Sep 2003
Posts: 19,237
north of coder
moparx Offline
"Butt Crack Bob"
moparx  Offline
"Butt Crack Bob"

Joined: Sep 2003
Posts: 19,237
north of coder
Originally Posted By moparmarks
..and who keeps a tape measure in their pocket at all times??
Well that would be me, and Ron I guess


and i as well. a 10ft stanley "mini tape" has resided in my pocket at all times for 40 some years or more. they get replaced when the 0-3" or so numbers wear off. [just say it and get it over with ! biggrin]
beer

Re: How to tell B and RB cranks apart without tools?? [Re: Rhinodart] #2554067
09/24/18 01:45 PM
09/24/18 01:45 PM
Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
moparmarks Offline
I Live Here
moparmarks  Offline
I Live Here

Joined: Nov 2003
Posts: 12,493
Western Colorado High Desert
Originally Posted By Rhinodart
You two are almost twins, I know I don't look anything like the hedgehog... biggrin


We are twins where it counts. whistling


72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
Moparmarks Parts & Restorations
Desert Mopar Metal
Grand Jct. CO
970-261-7039
http://moparmark.com/
motormangj@gmail.com
Re: How to tell B and RB cranks apart without tools?? [Re: moparmarks] #2554265
09/24/18 10:39 PM
09/24/18 10:39 PM
Joined: Jan 2003
Posts: 43,458
Round Lake Beach, Illinoisy
Rhinodart Offline
Rhinotruck
Rhinodart  Offline
Rhinotruck

Joined: Jan 2003
Posts: 43,458
Round Lake Beach, Illinoisy
haha I must admit you do have the best bacon though... drool


The funny thing about science is that if you change one miniscule parameter you change the entire outcome to the way you want it.

JB Rhinehart, Realist

A-Body's RULE!
Re: How to tell B and RB cranks apart without tools?? [Re: Rhinodart] #2554531
09/25/18 03:54 PM
09/25/18 03:54 PM
Joined: Jan 2003
Posts: 16,376
D
dogdays Offline
I Live Here
dogdays  Offline
I Live Here
D

Joined: Jan 2003
Posts: 16,376
Chrysler engineers thought in fractions. The RB is 2 3/4, the B is 2 5/8.

R.







Powered by UBB.threads™ PHP Forum Software 7.7.1