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

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Discussion Overview

The discussion revolves around the implications of disconnecting the driveshaft from a transmission while revving the engine in drive. Participants explore the mechanical behavior of the transmission and engine under these conditions, including the role of the rear end speed sensor and the potential for using the engine and transmission as a power take-off (PTO) for a hydraulic pump.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant speculates that disconnecting the driveshaft will cause the transmission to not engage gears due to a speed input of 0 mph, leading to spinning at the tail of the transmission.
  • Another participant shares an experience with a failed rear end speed sensor, noting that the Check Engine light activated but the car continued to drive normally.
  • A participant discusses their intention to use the engine and transmission as a PTO to power a hydraulic pump, detailing specific RPM requirements and gear ratios for optimal performance.
  • One participant reports that after removing the driveshaft, both reverse and drive cause spinning at the tailshaft, but there are no brakes to stop the spinning, resulting in grinding noises when shifting gears.
  • Questions arise regarding the type of transmission (automatic or manual) and the nature of the grinding noise experienced during gear shifts without a driveshaft.

Areas of Agreement / Disagreement

Participants express various experiences and hypotheses regarding the behavior of the transmission and engine when the driveshaft is disconnected. There is no consensus on the outcomes or mechanics involved, and multiple competing views remain regarding the implications of this setup.

Contextual Notes

Participants mention the role of the rear end speed sensor and the potential for grinding noises during gear shifts, but there are unresolved questions about the exact mechanics and outcomes of disconnecting the driveshaft.

Who May Find This Useful

Individuals interested in automotive mechanics, particularly those exploring transmission behavior and power take-off applications, may find this discussion relevant.

Akita
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[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 .
 
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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.
 

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