Automatic trasmission and rear axel

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SUMMARY

The discussion centers on optimizing the rear axle ratio for a V8 350 carburated motor paired with a TH700R4 automatic transmission. The current rear axle has a gear crown with 42 grooves, which is causing performance issues at high speeds. A steeper axle ratio, such as 4:56, can improve acceleration but will limit top speed compared to a shallower ratio like 3:23. For automatic lock-up and overdrive functionality, further adjustments are necessary to ensure they operate seamlessly.

PREREQUISITES
  • Understanding of V8 engine performance characteristics
  • Knowledge of TH700R4 automatic transmission operation
  • Familiarity with rear axle gear ratios and their impact on vehicle dynamics
  • Basic automotive electrical systems for lock-up and overdrive control
NEXT STEPS
  • Research the effects of different rear axle gear ratios on acceleration and top speed
  • Learn about TH700R4 transmission tuning for improved performance
  • Investigate automatic lock-up and overdrive mechanisms in automatic transmissions
  • Explore performance modifications for V8 engines to enhance high-speed capabilities
USEFUL FOR

Automotive enthusiasts, performance tuners, and mechanics looking to optimize vehicle acceleration and high-speed performance in V8-powered cars.

omaremanuels
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i have a v8 350 carburated vortec motor and a automatic trasmission th700r4 4 speed , i want to know which one rear axel i get more displacement when the car to go in high speed, because with the actual rear axel it feeling forced, the rear axel have a gear crown inside 42 grooves. and i want to know how to do to the lock up or overdrive works in automatic way.

o_emanuels@yahoo.com thanks for help


spanish
tengo un motor v8 350 carburado montado en un malibu 81 con una trasmision th700r4 4 velocidades pero en alta velocidad se queda con falta de desplazamiento debido al diferencial trasero, arranca con mucha potencia pero en alta se queda, yo quisiera mas desplazamiento en alta, mas desarrollo, la corona interna del diferencial tiene 42 ranuras. y tambien quisiera saber como hago para que el lock up o overdrive trabaje de forma automatica

o_emanuels@yahoo.com gracias por la ayuda
 
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Welcome to PF, Omar. Unfortunately, your wording is very difficult for me to understand. And despite having Spanish blood, I can't communicate in that language.
If I understand correctly, the response is that the steeper that axle ratio is, the faster you will accelerate. A shallow ratio will give slower acceleration, but a higher top end.
For example:
If your car (even with that itty-bitty baby motor :biggrin: ) can run 13 seconds and top out at 100 mph in a quarter mile and continue on to 120 mph in the long run with 3:23 gears, swapping down to a 4:56 axle might give you 11.5 at 110 mph in the quarter, but your top speed will be only that 110 mph.
Those are just 'for instance' figures, not something that I worked out mathematically. Still, that's the essence of how the axle ratio affects performance.
You should really have a conversation with Stingray about this.
 
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