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| | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | I have a '59 Apache 3200 that I installed a th350 in. I thought I saw a link to a RPM calculator based on tire size and gear ratio; however, after searching, I have been unable to find that link again, leading me to think I spent too much time in the garage smelling gasoline. If anybody can help, it would be greatly appreciated. Thanks.
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | | | | Joined: Oct 2002 Posts: 4,066 Bolter | | Bolter Joined: Oct 2002 Posts: 4,066 |
Redryder pixMy HotrodA veteran - whether active duty, retired, national guard, or reserve - is someone who, at one point in his or her life, wrote a blank check made payable to The 'United States of America', for an amount of "up to and including my life."I am fighting cancer and I am winning the fight | Pain is part of life; misery is an option. | | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | | | | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | Thanks for the reply. Now I guess I am Cornfused????? To figure out the rearend ratio I spun the rear tire and counted the revolutions on the drive shaft and I come up with 1 revolution of the tire causes 2 revolutions of the drive shaft. So this would be a 2:1 gear ratio?
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | | | | Joined: Oct 2002 Posts: 4,066 Bolter | | Bolter Joined: Oct 2002 Posts: 4,066 | I would think your rear end gear would still be the same prior
to your installation of the 350
Redryder pixMy HotrodA veteran - whether active duty, retired, national guard, or reserve - is someone who, at one point in his or her life, wrote a blank check made payable to The 'United States of America', for an amount of "up to and including my life."I am fighting cancer and I am winning the fight | Pain is part of life; misery is an option. | | | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | yes. the trans swap did not change the rearend ratio. I am trying to determine rpm at 60mph to see if the motor will be struggling at highway speeds or lugging driving in town.
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | | | | Joined: Oct 2002 Posts: 4,066 Bolter | | Bolter Joined: Oct 2002 Posts: 4,066 | what did you have before, did you change engines too..
Redryder pixMy HotrodA veteran - whether active duty, retired, national guard, or reserve - is someone who, at one point in his or her life, wrote a blank check made payable to The 'United States of America', for an amount of "up to and including my life."I am fighting cancer and I am winning the fight | Pain is part of life; misery is an option. | | | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | the motor is a L6 235 with 3 on the tree. I removed the original manual trans and installed a TH350 automatic. From what I have been reading this rear end would probably give me 3000+ RPM @ 60mph which would be undesirable. So I wanted to see (with a calculator) what I could expect and using the 2:1 gear ratio in the RPM calculator it says I can expect 1500 RPM at 60 MPH which also sounds undesirable. Isnt a 2:1 ratio odd for a 59 Apache 3200?
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | | | | Joined: Jul 2001 Posts: 3,887 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Jul 2001 Posts: 3,887 | you do not have a 2:1. the thing wouldn't be able to get out of it's own way - the stock rear would be 3.9:1, which is what your check shows [double what you thought] ... if you want to lower your highway RPM, either spring $1000 for the 3.38 rear gear set and installation kit, or go to a 700R4 overdrive automatic
Bill | | | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | Squeeze, Thanks for the clarification. Thats what I thought too about it not moving at all. Where did I mess up with the calculation? tire spins once and drive shaft spins twice then whats the magical step I left out  I appreciate your time.
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | | | | Joined: Feb 2004 Posts: 29,844 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,844 | Did you have only one wheel jacked up? If so, the spider gears in the differential change the apparent ratio. The only accurate way to check it is to roll the vehicle in a straight line with both tires on the ground and count the turns of the driveshaft. I'll bet you get nearly 4 turns of the driveshaft to one turn of the wheels unless the rear end has been modified. You'll need an overdrive trans like a 700R4 to get the RPM down to a manageable level, or put in a 3.55:1 gearset.
Jerry
Last edited by Hotrod Lincoln; 08/05/2011 3:14 AM.
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| | | | | Joined: Jul 2001 Posts: 3,887 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Jul 2001 Posts: 3,887 | keep one wheel on the ground, turn the other wheel two complete rotations, count the driveshaft revs - it's pretty hard to tell 2 rev from 1.95 [or 4 from 3.9 either really], so knowing the possibilities helps, the 59 might have had a 3.38 from the factory, that's when the option started, but the standard with a stick shift was 3.90 and with the OD it was 4.11
Bill | | | | | Joined: Jul 2010 Posts: 127 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2010 Posts: 127 | Ha that was my mistake  I was only turning one wheel. As for the OD trans.....well I'm messing around with tire diameter. It looks like if I use a 16" rims with 285-70-16 tires 1 will end up around 2500RPM at 60MPH. since this is a toolin around truck for My 17 yo daughter I doubt it will see much highway driving. Perhaps later on we will look at a 700r4, but for now the budget dictates the TH350 (the price was FREE) Thanks everyone for the help it is always appreciated. If anyone would like to add to this I could alway use the schoolin"
Last edited by Village_Idiot; 08/05/2011 3:32 AM.
Jessica's TruckThe true definition of insanity: To do the same thing the same way repeatedly and expect a different result each time. | | |
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