Clutch Damper

Dealing with all subsystems specific to the diesel powered Datsun-Nissan 720 pickup trucks.

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Clutch Damper


Post by mikej678 »

On the hydraulic clutch damper which port goes to the master cylinder & which goes to the slave? When I removed it from the truck I didn't label them.

What is the damper for? The gas engines for that year didn't have them(per FSM), but my 95 XE V6 did. What would happen if I didn't use it?

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Re: Clutch Damper


Post by philip »

The FSM description suggests this vibration dampener device is there to soften vibrations (chattering) that may transmit to the pedal while the clutch is being released. Problem is the device also adds in an inch or so of pedal travel before the clutch actually begins to release.

In fact, the gasoline powered 720 trucks DID have the clutch dampener too. I have seen them in junk yard trucks. Yeah, I know the FSM implies only the diesels had them.

Under the square cover is a rubber disc. Over time, this disc compresses which in turn allows the piston behind it to move too much as the clutch release is operated. The effect is you will have to push the pedal a bit further before clutch release begins even though you have correct mechanical freeplay at the pedal.


Notice there is NO clearance between the disc and the piston nor the disc and the square metal plate cover.

Rather than removing the device, replace the rubber disc with a couple of plastic drain plug washers. Remember, you still need to be able to reinstall the square cover. You will find as I did that the clutch engage/disengage range is further from the floor than before. I prefer it this way. :wink:
Last edited by philip 14 years ago, edited 3 times in total.
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1982 Datsun 720KC SD-22

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Post by ffdjm »

Thanks for the tip. When I replaced the original engine in my 720 pickup, the (used) replacement engine came with a clutch, which got installed along with the engine. I was barely able to disengage the clutch. I finally figured out that the springs on the replacement clutch were stronger than my old clutch and caused the rubber cushion in the damper to compress all the way before the piston in the slave cylinder began to move.


1981 Datsun 720 diesel pickup
1990 Nissan UD 2000 cabover dump
Case 450C dozer
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