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| | | | Joined: Sep 2004 Posts: 117 Member | | Member Joined: Sep 2004 Posts: 117 | I was wondering what would happen to my gearing if I swapped the old granny 4 speed for a turbo 400 automatic. I can't remember if a straight drive rear end is geared lower or higher than an auto trans rear.
Anyone have any ideas? | | | | | Joined: Sep 2004 Posts: 117 Member | | Member Joined: Sep 2004 Posts: 117 | My pump drives off the crankshaft, so there is no probs with a PTO | | | | | Joined: Nov 2004 Posts: 7 Junior Member | | Junior Member Joined: Nov 2004 Posts: 7 | REAR ENDS WITH AN AUTOMATIC ARE HIGHER THAT WHY WITH A LOCK UP TORQUE CONVERTER IT ACTS LIKE AN OVERDRIVE
Richard Laszchuk
| | | | | Joined: May 2000 Posts: 424 Shop Shark | | Shop Shark Joined: May 2000 Posts: 424 | If you are just swapping trannys, both will be 1:1 in high gear. | | | | | Joined: Feb 2004 Posts: 29,774 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,774 | Due to the built-in slip in a torque converter, your engine speed will be 10% higher at the same road speed with an automatic. A lockup clutch will bring the speed back down to the same as high gear in the standard trans. Rear ends for an automatic trans are generally higher-geared, to take advantage of the torque multiplication of a converter on breakaway. For instance, my 58 Chevy sedan had a 3.55:1 rear end when it came out with a 3-speed, and the standard rear end for the Powerglide that year was a 3.36:1.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Sep 2004 Posts: 117 Member | | Member Joined: Sep 2004 Posts: 117 | I'm not sure the lock-up converter would stand pulling a load. only reason I was going to swap is that the old 4 speed jumps out of 1st gear and is noisy in reverse. | | | | | Joined: Dec 2003 Posts: 1,144 'Bolter | | 'Bolter Joined: Dec 2003 Posts: 1,144 | Rebuild the current transmission or find matching replacement. It's lasted this long and with proper care new clutch and pressure plate will give you many more years service.plus you avoid shadetree engineering to make the auto fit and work. | | | | | Joined: Sep 2004 Posts: 117 Member | | Member Joined: Sep 2004 Posts: 117 | I'm gonna take your advice and rebuild it. | | |
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