DUE TO MY NEGLECT & STUPIDITY, I WAS FORCED TO REPLACE THE REAR END ON MY 49,SERIES 62 4 DOOR CAD. CAR HAS HYDRO. AND THIS WAS A FACT. INSTLD 3.36. I REPLACED IT WITH A 3.77 TO 1 AXLE WHICH FACT. INTLD WITH A STANDARD TRANS. MY QUESTION IS THIS:
AT 60 MPH, WHAT SHOULD THE RPMs BE FOR THE DIF. AXLES? I WILL SAY THAT WITH THE 3.77 MY CAR RUNS WITH RENEWED VIGOR OVER THE 3.36.
I HAVE NOTICED THAT THE RPMs MUST BE UP BECAUSE I CAN HEAR IT.
THANX FOR THE HELP
FRANK STAGNITTO,13539
02-26-05
Frank, IF my math is correct,in the past when the engine was turn 2000RPM, now at the same road-speed, the engine is turn at 2082 RPM.
Not much defference, but enough to notice.
Your speedometer is off some, also.
The way I figure it is: 3.77-3.36=.41X2000RPM=82.000RPM (I picked 2000RPM just for s***s and grins).(it could have been any RPM) With the old diff.,the Drive Line had to only turn 3.36 times for each time the axle made one turn. Now, the DL has to turn 3.77 times for one turn of the axle.
Good Luck, and happy motorin, Jim
Frank,
The difference in the RPM is proportional to the axle ratios. For any given road speed your new axle causes the engine to turn 3.77 times for each 3.36 times it turned with the old axle. Therefore when you engine with the old axle was turning 2000 RPMs for a give speed, the new axle requires an engine RPM of 2244 for the same road speed. ( 3.77 / 3.36 x 2000) = 2244
HTH,
Ralph
RALPH,
THANX FOR THE FEED BACK. I BETTER UNDERSTAND NOW.
FRANK
HI JIM,
THANX FOR THE REPLY AND HELP. I CAN BETTER UNSERSTAND THIS THING NOW. IN THE END, I EXPECT HIGHER RPM & A BIT OF HIGHERE FUEL USAGE.
FRANK