What happesn if you disconnect the driveshaft and rev the engine in Drive?

  • Context: Automotive 
  • Thread starter Thread starter Akita
  • Start date Start date
  • Tags Tags
    Drive Engine Rev
Click For Summary
SUMMARY

Disconnecting the driveshaft from the transmission while revving the engine in drive results in the transmission spinning without engaging gears, leading to grinding noises when attempting to shift. The rear end speed sensor plays a critical role in this scenario, as it can prevent the transmission from engaging properly when the speed input is zero. The user is utilizing a 7.3 Powerstroke engine with an E40D transmission to power a hydraulic pump, aiming to optimize performance by altering shifts and maintaining specific RPMs. The absence of a driveshaft causes the transmission to spin freely, creating potential damage if not managed correctly.

PREREQUISITES
  • Understanding of automatic transmission mechanics
  • Familiarity with rear end speed sensors and their functions
  • Knowledge of engine RPM management and gear ratios
  • Experience with hydraulic pump operation and requirements
NEXT STEPS
  • Research the function and troubleshooting of rear end speed sensors
  • Learn about automatic transmission behavior without a driveshaft
  • Investigate optimal gear ratios for hydraulic pump efficiency
  • Explore methods for safely testing engine RPMs without a driveshaft
USEFUL FOR

This discussion is beneficial for automotive engineers, mechanics, and DIY enthusiasts interested in transmission behavior, hydraulic systems, and performance optimization of vehicles, particularly those using Ford Powerstroke engines.

Akita
Messages
8
Reaction score
1
[Moderator note: This thread was moved from a HW forum. Hence the template. But it doesn't sound like homework.]

1. Homework Statement
What will happen if i disconnect driveshaft from transmission and rev engine in drive?

Homework Equations


Rear end speed sensor could be play some role in this ?

The Attempt at a Solution


Googled some.My guess is that based on speed input 0 mph ,transmission will override "drive" state and won't engage gears and spin at the tail of trans .
 
Last edited by a moderator:
Engineering news on Phys.org
I had that rear end speed sensor fail in one of my cars. The Check Engine light came on, but the car drove normally.
 
anorlunda said:
I had that rear end speed sensor fail in one of my cars. The Check Engine light came on, but the car drove normally.
im trying to use my engine and transmission as PTO to power hydraulic pump,engine in first 2 gears lowering ratio 2.70 and 1.70 depend on gear rpm range comes 500-800rpm ,pump needs 1800rpm or 3000 if i go gear type to achieve max performance.I want to alter shifts and rev engine up to 2500rpm with 1:1 or 4th gear 0.87 ratio to maximize fuel efficiency,at 2500 it gets 200hp,pump needs only 100hp so it will be wast of fuel.engine is 7.3 powerstroke,e40d trans
 
anorlunda said:
I had that rear end speed sensor fail in one of my cars. The Check Engine light came on, but the car drove normally.
i'll check it out now physically,will get back later today :D
 
took off driveshaft,both reverse and drive spins at tailshaft.but problem is there's no brakes to stop spinning in either direction and it grinds trans inside every time i switch gears.Now i have to figure out at what gear transmission spins at 1500,2000,2500 rpms.
 
What are you trying to accomplish?
 
Is the transmission auto or stick shift?
What do you mean "grinds the trans..."?
 
anorlunda said:
What are you trying to accomplish?
im trying to use my engine and transmission as PTO to power hydraulic pump
AZFIREBALL said:
Is the transmission auto or stick shift?
What do you mean "grinds the trans..."?
shifting from either D or R to any other positions forces grinding as there no driveshaft and I am assuming inertia keeps trans spinning ,so it made ugly noise until i turned off engine 3 secs later.
 

Similar threads

Torque Reaction Force of Transmission and Drivetrain
  • · Replies 10 ·
Replies
10
Views
14K