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steve21757 08-22-2009 18:27:29 75.23.47.155 32581 Report to Moderator	I am going to install a new rearend with air bag suspension on my B-61 mack.I have a 9 speed overdrive duplex tranny.Does anyone know the formula for figuring out your speed if you know your gear ratio of your trans,ratio of your rearend, and your rpm.I'm trying to decide what ratio to put in the truck to comfortly run 60 to 65 mph preferably 65 with aload of nomore than 25000 lbs on my gooseneck.Your help is greatly needed. THANKS STEVE. P.S i am leaning towards 4.11? [Reply]  [Send Email]
steve21757 08-23-2009 06:42:45 68.92.125.19 32586 Report to Moderator	Re: B-61 MACK HELP in reply to steve21757, 08-22-2009 18:27:29   russ were you figuring the mph at max rpm of engine which is 2100 or less?I havefound a 3.90 rearend, how much faster would that be?THANK YOU SO VERY MUCH FOR YOUR HELP.   [Reply]  [Send Email]
russ springerr 08-25-2009 05:33:07 67.151.214.3 32600 Report to Moderator	Re: B-61 MACK HELP in reply to steve21757, 08-23-2009 06:42:45   390 will give you another 6-8 miles per hour.if you are just going to pull tractors with it you are better off with a 390 russ   [Reply]  [No Email]
russ springerr 08-23-2009 05:20:50 67.151.214.3 32585 Report to Moderator	Re: B-61 MACK HELP in reply to steve21757, 08-22-2009 18:27:29   depending on the size of your tires if you have 20' 411 SHOULD RUN ABOUT68 IF YOU HAVE 22: SHOULD RUN ABOUT 72   [Reply]  [Send Email]
russ springerr 08-23-2009 05:20:41 67.151.214.3 32584 Report to Moderator	Re: B-61 MACK HELP in reply to steve21757, 08-22-2009 18:27:29   depending on the size of your tires if you have 20' 411 SHOULD RUN ABOUT68 IF YOU HAVE 22: SHOULD RUN ABOUT 72   [Reply]  [Send Email]