Transmission Noise in 3rd Gear - F4W71A

[Dave WM]

clutches and flywheels can get complicated.

you have the 225 and 240 mm versions, the smaller IIRC had 6 bolt holes for the pressure plate, the larger (2+2 and ZX) has nine holes so you have to have a matching flywheel and pressure plate. 

Next up is the throw out bearing, there are 3 diff lengths IIRC, not sure which goes where but you want it right so the pressure plate fingers are depressed correctly when you disengage the clutch. 

I am not even sure the pressure plates are the same within the 225 and 240 sizes, that is some may be taller than others. 

[Zed Head]

The zcarsource description is wrong on the clutch kit, turbo and 2+2 are the same parts.  Can't exclude one and include the other.  Edit - actually I see that what they did is to just add irrelevant information and leave out other relevant info.  It could be turbo, 2+2, or turbo 2+2.  All 240mm.

But you might have the right parts.  The pictures match.  Looks like the 240mm clutch setup.  The parts that you said are on the car look like 240mm also.  So, odds are you'll be fine.  92mm is the critical measurement.

https://zcarsource.com/transmission-service-kit-240z-260z-280z-72-78-new/

https://zcarsource.com/clutch-kit-260z-280z-280zx-300zx-74-83-non-turbo-2-2-81-86-turbo-new/

https://zcarsource.com/flywheel-manual-transmission-260z-280z-280zx-74-83-2-2-and-turbo-new/

 

 

Edited August 12, 2021 by Zed Head

[AnvilZ]

44 minutes ago, Dave WM said:

you have the 225 and 240 mm versions, the smaller IIRC had 6 bolt holes for the pressure plate, the larger (2+2 and ZX) has nine holes so you have to have a matching flywheel and pressure plate. 

 

17 minutes ago, Zed Head said:

The zcarsource description is wrong on the clutch kit, turbo and 2+2 are the same parts.  Can't exclude one and include the other.  But you might have the right parts.  The pictures match.  Looks like the 240mm clutch setup.  The parts that you said are on the car look like 240mm also.  So, odds are you'll be fine.  92mm is the critical measurement.

Thanks for the help, I just rolled under the car to check, I do have the 240mm setup because it has 9 bolts holding the pressure plate on. Sounds like from what you guys said this is fine to run on my car? I do intend to check the 92mm measurement before bolting the transmission back on, something I did not check the first time around. I know for a fact that I have the shorter Type A throwout bearing collar, have a hunch I will need to order one of the taller ones to hit that measurement.

[EuroDat]

I think Zed and Dave answered your questions, but just to add to trivia info.

The 240mm and 225mm are the same weight 23lbs in all the 240Z, 260Z and 280Z/ZX.

That is not the case for the 720 truck. It has a much heavier flywheel and a very wide ratio gearbox.

The 225mm clutch and pressure plate will work on the 240mm flywheel, but the 240mm clutch disc and pressure plate will not work on the 225mm flywheel.

Most parts suppliers have the later 280ZX 225mm or 240mm pressure plate and clutch disc, and I believe you will have trouble finding a 225mm flywheel. Most suppliers will give you a 240mm flywheel simply because it suits both sizes and is the same weight.

If your old pressure plate was the original type then you have the original 240Z throw out bearing collar and you will need to find one to suit the 280ZX pressure plate.

The bearing on the collar is the same dimmension through the 240Z to 300ZX.

[Zed Head]

56 minutes ago, EuroDat said:

The 225mm clutch and pressure plate will work on the 240mm flywheel,

I did not know this.  That, plus the equal weights, would explain why the manufacturers dropped the 225 only flywheel.  It's just not necessary.

I wonder why even call it a 240 mm flywheel.  Seems pointless.  7.5 mm extra friction surface diameter.

Edited August 13, 2021 by Zed Head

[AnvilZ]

@EuroDat thanks for the additional clarity, helps to clear things up a bit. I definitely have 240mm setup with the original shorter collar, it measures 34mm from the face of the bearing to the top of the ears. I removed my pressure plate today and measured the height on the forks, it is approximately 47.5mm. I was right around 10mm short on the 92 mm measurement from the ears to the face of the flywheel with the current collar, it looks like the 75-83 Z/ZX Coupe Non-Turbo collar should match up and get me very close to the 92mm. 

[Zed Head]

Just a follow-up for confirmation.  What's being said is that the two outer holes of each set of three holes on a 240, are equidistant around the perimeter of the flywheel and match the 225 plate bolt pattern.  And the locating pins are the same.  Has this been confirmed?  I had both in my garage and never tried a 225 plate on a 240 flywheel.

And, you could even use a 240 pressure plate on a 225 disc and 225 flywheel.  The excess pressure plate would just hang over the edge of the disc.  And, you could let excess 240 disc hang outside of 225 parts.  

All these years and turns out all of the parts are interchangeable.

[AnvilZ]

@EuroDat another question for you in the ongoing rebuild saga, item #18 below is some type of shim or spacer that goes under the counter shaft bearing in the adapter plate:

 

I am coming up empty on any information on the OEM thickness for this shim, it is NLA. Do you happen to have one to compare or know offhand? I am pretty sure the one in place currently is not OEM, and neither is the bearing sitting on top of it (item 16), looks like a cheap replacement. Item 17 at the other end of the counter shaft on my transmission is a Nachi bearing which is probably the OEM bearing, I am replacing both with new Nachi bearings. Just want to make sure the shim is the correct thickness, mine is a rough cut piece of aluminum with measurements O.D. - 51.5mm, I.D. 34.2mm and thickness 2.65mm. 

Picture of the bearing and shim:

 

Also, if it helps anyone in the future the countershaft bearings are listed as NLA but with a little digging I found the Nachi replacements:

Item 16: Nachi 6205 C3 Open Bearing (25mmx52mmx15mm)

Item 17: Nachi 6304 C3 Open Bearing (20mmx52mmx15mm)

[EuroDat]

That shim is for the cluster shaft end play. The 71B is slightly different but the priciple is the same. See attachment for the 71B set up.

You shouldn't need to adjust the shim thickness after replacing the bearings. It becomes critical when you change the cluster shaft of the transmission housing. The cluster shaft and housing have tolerances and the shim compensates for this. The bearings on the other hand are precision machined parts and don't have those tolerance issues.

It does not hurt to check. The bearing should have a small amount of end clearance. Ball bearings should not be pre-loaded. They are not designed for high axial tension like a tapered roller bearing.

 

[AnvilZ]

3 hours ago, EuroDat said:

You shouldn't need to adjust the shim thickness after replacing the bearings. It becomes critical when you change the cluster shaft of the transmission housing. The cluster shaft and housing have tolerances and the shim compensates for this. The bearings on the other hand are precision machined parts and don't have those tolerance issues.

That is my concern with this non-OEM adapter plate shim that seems to be in my transmission, I am worried the shim not being original might not be properly compensating for the shaft and housing tolerances. Could also be throwing off measurement "A" in your post for the end float. I also did not have a front shim at all when I disassembled my transmission, can't recall if I mentioned that earlier. I found a picture of the same adapter plate shim in my Haynes Manual, the I.D. looks much larger, which seems to support my theory that my current shim was something installed during a rebuild:

Wondering if I can "reverse engineer" the thickness by installing the counter shaft without an adapter plate shim and subtracting out the recommended range for end float from measurement "A" above. Any better suggestions come to mind?

[AnvilZ]

On 8/16/2021 at 5:46 PM, AnvilZ said:

@EuroDat another question for you in the ongoing rebuild saga, item #18 below is some type of shim or spacer that goes under the counter shaft bearing in the adapter plate:

@EuroDat correction on this post, #19 is the item I was referring to as the shim between the countershaft bearing and the adapter plate, the non-OEM aluminum spacer I showed in my picture was #19, not #18. I was looking at the countershaft backwards in the diagram, sorry for the confusion. 

[EuroDat]

4 hours ago, AnvilZ said:

@EuroDat correction on this post, #19 is the item I was referring to as the shim between the countershaft bearing and the adapter plate, the non-OEM aluminum spacer I showed in my picture was #19, not #18. I was looking at the countershaft backwards in the diagram, sorry for the confusion. 

Pos#19 is not in the later 71B versions. Pos#18 (Pos#6 in the 71B 4 speed, see attachment) is used to correct the tolerances in the transmission housing.

Pos#19 is designed to remove any axial movement between the adapter plate and the adapter plate bearing. I don't know why they chose this method to remove end play. The point to all of it is the bearing should fit neat in the adapter plate housing without any forward / backward movement.