78 280z idle problem

[Jack Pearcy]

Also here’s a video of my car running with the fpr hose cut and the pump off

[chaseincats]

51 minutes ago, Jack Pearcy said:

I do have a new master cylinder, but I installed it a while ago, it may need to be bled again, as far as the pushrod goes do you mean use the original push rod? I still have it so it shouldn’t be an issue but right now it has the reproduction push rod in it

after swapping the master cylinder, did the clutch work at all w/o grinding?

[Jack Pearcy]

9 hours ago, chaseincats said:

after swapping the master cylinder, did the clutch work at all w/o grinding?

It didn’t work without grinding, it would go into every gear fine except for 1st and reverse but that was with the old clutch, now with the new one it’s doing the same thing but worse. I decided to test if the clutch was the culprit so I put it in reverse with the engine off and then started it with the clutch fully in and sure enough it just started driving.

[chaseincats]

3 hours ago, Jack Pearcy said:

It didn’t work without grinding, it would go into every gear fine except for 1st and reverse but that was with the old clutch, now with the new one it’s doing the same thing but worse. I decided to test if the clutch was the culprit so I put it in reverse with the engine off and then started it with the clutch fully in and sure enough it just started driving.

In that case ya, it's your clutch master cylinder's pusher.  Swap it out with the stock one you still have (I think you just need a pair of needle nose pliers that you can use to take off the snap-ring retainer clip).

[EuroDat]

When you changed the clutch. Did you compare the two pressure plates. There are basically four different heights available. The magical number between the flywheel and where the clutch fork contacts the collar is 92mm.

The collar must match the pressure plate. Very easy to mix them up when using aftermarket pressurs plates.

Measure the fork position in rest. From the front of the transmision bellhousing to the clutch fork should be around 115mm. If you measure 120-125 then the clutch fork will bind on the transmission housing before releasing the clutch.

 

Edited June 27, 2019 by EuroDat
Photo of clutch fork measurement

[Jack Pearcy]

1 hour ago, EuroDat said:

When you changed the clutch. Did you compare the two pressure plates. There are basically four different heights available. The magical number between the flywheel and where the clutch fork contacts the collar is 92mm.

The collar must match the pressure plate. Very easy to mix them up when using aftermarket pressurs plates.

Measure the fork position in rest. From the front of the transmision bellhousing to the clutch fork should be around 115mm. If you measure 120-125 then the clutch fork will bind on the transmission housing before releasing the clutch.

 

I didn’t compare the pressure plates but I did use the Nissan brand clutch and pressure plate replacements that are supposed to be oem quality

[EuroDat]

The problem is that the aftermaket industry doesn't really know the difference between all thedifferent models and pressure plates. 240Z up to 72, 240Z after 72, 260Z, 280Z and 280ZX up to 81, 280ZX after 81 and Maxima 810.

See attached photo's. Btw, They are not my photo's. Other people having similar issues.

[chaseincats]

2 hours ago, Jack Pearcy said:

I didn’t compare the pressure plates but I did use the Nissan brand clutch and pressure plate replacements that are supposed to be oem quality

The problem is with your new clutch master not slave cylinder's piston length.  Your clutch pedal is connected to a push rod (piston) which directly goes into your master cylinder.  The piston you have is (probably) too short which is in turn not able to push enough fluid through the clutch hydrolic system to fully actuate the clutch fork thus disengaging the clutch enough to change gears.

TL;DR: clutch master (not slave) piston length is most likely the item that isnt matching up to oem length.  Compare the oem one you have on hand.

[Jack Pearcy]

3 minutes ago, chaseincats said:

The problem is with your new clutch master not slave cylinder's piston length.  Your clutch pedal is connected to a push rod (piston) which directly goes into your master cylinder.  The piston you have is (probably) too short which is in turn not able to push enough fluid through the clutch hydrolic system to fully actuate the clutch fork thus disengaging the clutch enough to change gears.

TL;DR: clutch master (not slave) piston length is most likely the item that isnt matching up to oem length.  Compare the oem one you have on hand.

Okay that makes sense, I was only messing around with the slave cylinder because I assumed it would have the same effect, just would be easier to access

[chaseincats]

Just now, Jack Pearcy said:

Okay that makes sense, I was only messing around with the slave cylinder because I assumed it would have the same effect, just would be easier to access

totally understandable, let me know how it goes

[Patcon]

Just remember Chas (Eurodat) is one of the few resident transmission experts...

[EuroDat]

I thought the master cylinder was replaced earlier before the clutch and pressure plate was replaced. Now reading post #39 I agree.

My internet connection is not the quickest working out of a landcruiser or campsite and I scrolled past it.

Chaseincats has a good point. It looks like an incorrect master cylinder push-rod or adjustment. If it has the correct push-rod it should be adjusted according to fsm. See attachment.

.