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Old 06-05-2019, 10:31 PM   #3
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box1993 is a jewel in the roughbox1993 is a jewel in the roughbox1993 is a jewel in the rough
Join Date: Nov 2014
Posts: 10
Default Re: Transmisson Backlash and AC Clutch

Originally Posted by fdryer View Post
There are cars with driveline slop but not to the extent of what you're experiencing. Are you sure its a driveline problem? Broken/worn engine mount(s)? Engine controls can produce similar symptoms. With 120k miles, what's the history of maintenance and parts replaced?

How do you know the ac clutch coil is open and the reason for the ac fuse blowing? The ac diode is used to absorb arcing in the ac relay contacts when ac is turned off. Diodes tend to short and blow fuses when ac is turned on. Look for this diode in the engine fuse panel, remove it and measure it for resistance with a multimeter. A diode acts as a choke for electrical voltage when a magnetic field collapses and generates a reverse voltage. This voltage can arc across the ac relay and burn contacts. Most ac diode failures occurs by creating a short and acts as a wire. A shorted diode usually blows the ac fuse when ac is turned on. A diode will measure resistance in one direction and when multimeter probes are reversed, resistance is higher. A faulty diode that's internally shorted will measure the same resistance in both directions like a wire.

Clutch coils have a very low resistance, between 2-3 ohms. Clutch coils have a built in thermal fuse to open when overheated above 450F, a possibility from a slipping clutch (rare). An internal short in the coil would either blow the main ac fuse or the internal thermal fuse. You can measure coil resistance.
Car has original pedal position sensor, it always bucked from early on(40k) and was suuuper sensitive in 1st gear because of how nonlinear the pedal tip in was. If you didnt have your foot steady on the floorpanel and on the pedal, you could inadvertently cause an unstable feedback loop of your foot slamming down and up as the car jerked forward and accelerated/decelerated over and over.

The jerking is getting much worse now, theres a noticable clunk feeling now.

Car has new coil, plugs, ICM, no check engine light currently. Always change oil. Im pretty anal about maintenance, but I did buy this car used looks like im 3rd owner, original was in chicago.
Someone could have been parking it against a wall and doing burnouts or brakestands the first 30k, I don't know.

Yep, AC clutch coil is an open circuit right now. Zero ohms at the connector terminals. I smelled fried resistor/eletrical components from the clutch the day it stopped working, so I'm assuming thermal fuse. Think magic smoke resistor smell

Shop said motor mounts are good, and I agree they look fine.rocked the car in gear, didnt notice engine move too much. Ill do a close inspection again.

I guess I can start with axle shafts and grease the new ones well/see what happens.
Do people ever put in thicker gear oil to help backlash if it is gear backlash?
The combination of aggressive electronic pedal tip-in, softer motor mounts and the backlash is no bueno at the moment

Last edited by box1993; 06-05-2019 at 10:40 PM.
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