240sx Trans Clutch Drive Issues - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

JGP · 08-10-2023, 07:03 AM

Hello,

Need the communities help in diagnosing an issue I have with my manual s13 Ka24e. The car will not shift into gear without stalling and grinding gears. However, when I removed the driveshaft, the car will easily shift into gear and no stalling. I have replaced the master cylinder, reinstalled clutch countless times, replaced slave cylinder, bled lines etc.

Thoughts?

Thanks Everyone!

AKADriver · 08-10-2023, 07:24 AM

Have someone press the clutch pedal while watching the movement of the slave cylinder and clutch fork to make sure that the slave cylinder starts pushing the fork basically as soon as the pedal is pressed. If not, then the pedal could be out of adjustment, pedal bracket could be cracked, or the hydraulics are still bad/not fully bled. Is the damper loop still in place? If so this can take a few tries to fully bleed out.

Pull back the fork boot and see if you can make sure the fork is correctly pushing the throwout bearing sleeve through its full range of motion. Make sure the fork is not bent or cracked and the fork pivot ball is not broken.

JGP · 08-10-2023, 07:39 AM

Thanks for responding. What do you mean damper loop? Any explanation why the car would shift into gear while running with the driveshaft off?

However, I will double check the fork etc. Last I checked everything seem to be in good order, no cracks etc.

AKADriver · 08-10-2023, 11:06 AM

The damper loop is a pair of junction blocks with a bleeder valve and long loop of hardline attached to the passenger side frame rail in a stock 240SX that's attached in between the hardline that goes over the firewall and the rubber line to the slave. It's very common to just eliminate it even back when these cars were still pretty new because it made bleeding the clutch a pain. It's supposed to damp clutch chatter or something. I have no idea. RHD cars often didn't have it. Yours was probably eliminated by a previous owner.

With the driveshaft off the synchros are doing the work of speeding up/slowing down the output shaft to match the input shaft when you change gear even though the clutch is not fully disengaged. With the driveshaft in the momentum of the car prevents the transmission internals from matching speeds and it grinds.

JGP · 08-10-2023, 01:34 PM

Thanks for the explanation. Yeah those dampers were removed with the 5 speed swap.

Thursday7 · 08-18-2023, 10:57 AM

Quote:

Originally Posted by JGP

5 speed swap.

Bingo. Sounds like the auto pilot bushing was not replaced with a manual one. This will certainly cause clutch release issues if it wasn't changed.

JGP · 08-18-2023, 11:25 AM

Quote:

Originally Posted by Thursday7

Bingo. Sounds like the auto pilot bushing was not replaced with a manual one. This will certainly cause clutch release issues if it wasn't changed.

Thank you for the info. Im pretty sure I swapped in the new pilot bushing however it's probably worth checking. Im basically a pro at swapping out the trans now.

Thanks Everyone!

08-10-2023, 07:03 AM	#1
JGP Join Date: Nov 2012 Location: So Cal Age: 36 Posts: 39 Trader Rating: (1) Feedback Score: 1 reviews	240sx Trans Clutch Drive Issues Hello, Need the communities help in diagnosing an issue I have with my manual s13 Ka24e. The car will not shift into gear without stalling and grinding gears. However, when I removed the driveshaft, the car will easily shift into gear and no stalling. I have replaced the master cylinder, reinstalled clutch countless times, replaced slave cylinder, bled lines etc. Thoughts? Thanks Everyone!

08-10-2023, 07:24 AM	#2
AKADriver Post Whore! Join Date: May 2002 Location: Springfield, VA Age: 42 Posts: 3,475 Trader Rating: (1) Feedback Score: 1 reviews	Have someone press the clutch pedal while watching the movement of the slave cylinder and clutch fork to make sure that the slave cylinder starts pushing the fork basically as soon as the pedal is pressed. If not, then the pedal could be out of adjustment, pedal bracket could be cracked, or the hydraulics are still bad/not fully bled. Is the damper loop still in place? If so this can take a few tries to fully bleed out. Pull back the fork boot and see if you can make sure the fork is correctly pushing the throwout bearing sleeve through its full range of motion. Make sure the fork is not bent or cracked and the fork pivot ball is not broken.

08-10-2023, 07:39 AM	#3
JGP Join Date: Nov 2012 Location: So Cal Age: 36 Posts: 39 Trader Rating: (1) Feedback Score: 1 reviews	Thanks for responding. What do you mean damper loop? Any explanation why the car would shift into gear while running with the driveshaft off? However, I will double check the fork etc. Last I checked everything seem to be in good order, no cracks etc.

08-10-2023, 11:06 AM	#4
AKADriver Post Whore! Join Date: May 2002 Location: Springfield, VA Age: 42 Posts: 3,475 Trader Rating: (1) Feedback Score: 1 reviews	The damper loop is a pair of junction blocks with a bleeder valve and long loop of hardline attached to the passenger side frame rail in a stock 240SX that's attached in between the hardline that goes over the firewall and the rubber line to the slave. It's very common to just eliminate it even back when these cars were still pretty new because it made bleeding the clutch a pain. It's supposed to damp clutch chatter or something. I have no idea. RHD cars often didn't have it. Yours was probably eliminated by a previous owner. With the driveshaft off the synchros are doing the work of speeding up/slowing down the output shaft to match the input shaft when you change gear even though the clutch is not fully disengaged. With the driveshaft in the momentum of the car prevents the transmission internals from matching speeds and it grinds.

08-10-2023, 01:34 PM	#5
JGP Join Date: Nov 2012 Location: So Cal Age: 36 Posts: 39 Trader Rating: (1) Feedback Score: 1 reviews	Thanks for the explanation. Yeah those dampers were removed with the 5 speed swap.