Clutch fork throw

[rcv]

I’m nearing the end of my veeery long rebuild project on my L24 and I finally bolted on my original F4W71A.  I’m using the original throw out collar and fork, but installed this new clutch kit from zcarsource: link.

When pressing on the slave cylinder side of the fork, I was just expecting to feel a nice gradual resistance as the TO bearing engaged the pressure plate. Unfortunately I feel absolutely nothing until almost the end of travel. I can’t imagine that small amount of travel is going to be able to get enough leverage to actually disengage the clutch. Any ideas what I could have done wrong?  
 

Here’s a video of me fiddling with the fork to show what I mean: 

 

[EuroDat]

If you pull the clutch fork back until the throw out bearing touches the pressure plate fingers and then measure the distance away from the front of the bell housing, you should measure about 115mm give or take a couple of mm.

If you read more, then you probably have a mis match pressure plate / throw out bearing collar.

If you measure the height of the pressure plate and throw out bearing, they should add up to 92mm. You will need to dismantle the transmission for that.

 

Edited July 3, 2020 by EuroDat

[rcv]

Yeah looks like I read closer to 150mm. Possibly this pressure plate isn’t right for my setup? I could have sworn I checked the height and it was the same as the old one. I’ll pull the transmission off and check again. 

I’m really hoping I don’t need to get another pressure plate as I already had this one balanced with my flywheel. 
 

 

Edited July 3, 2020 by rcv

[EuroDat]

150mm is way to much. It's an easy misstake and happens a lot. The aftermarket industry make one type of pressure plate, but in the S30 series Zeds they had 4 different heights over the years.

Each type had its own matching collar. The bearing and fork have the same dimensions.

 

Edited July 3, 2020 by EuroDat

[EuroDat]

If you order the collar, it should be the matching collar for the pressure plate. Unfortunately most parts stores don't know this and do not offer the option with the collar.

[rcv]

Got it, I’m betting I have the “Type A 4 Speed” collar but the plate is meant for “Type B”. If that’s the case, any reason I can’t just buy a type B collar and drop it in? Are the forks any different between the A and B?

[EuroDat]

Yep. The type b is probably what you need. Always good to check what you have now first and then go buy the correct height collar. You should check it in the shop before buying it. It you bug it from the shop where you bought the pressure plate. They should be able to supply you with the corrdct collar.

I think they supply the prsssure plate and collar are for the Type B transmission for the 280ZX mobel. It fits all S30 models, just need the collar to match.

Edited July 3, 2020 by EuroDat

[rcv]

Hmm the height of the spring fingers looks really similar between my old clutch setup and the new. It’s hard to get a great reading, and the new one is bolted/compressed against the flywheel but still, they seem really close. 
 

Is it possible I screwed up the install of the fork/TO somehow?

(sorry about the image rotation - I’m posting from my phone and it’s not obeying the EXIF data I guess)

Edited July 3, 2020 by rcv

[rcv]

Actually it looks like I mismeasured the setup on the engine. I was measuring to the bolt pocket on the flywheel which is ~10mm deeper than the friction surface. That means that I almost certainly need the longer collar. Damn I was really hoping to drop the engine in over the long weekend. Ah well. Thanks for the help!

[rcv]

So after looking online at part shops, I'm even more confused.  The total height of my collar is ~46mm with the height from the rear to the bearing of ~27mm so it definitely seems like the "Type A" collar in the picture above.  Looking online, it seems like everyone is listing this same part as the only "70-74" throwout collar:

• Z Car Depot: 1.86" (47mm) total height
• MSA: 1 3/4" (44mm) total height, 28.6mm from base to bearing
• Datsun Garage: 1 3/4" (44mm) total height, 28.6mm from base to bearing
• Z Car Source: No dimensions listed

These all seem to be the same as the part I already have. 

@EuroDat - in this thread from 7 years ago (wow!) you mention that the collar from the F4W71As has a bearing to fork mating surface distance of 16mm, and the B's have one that measure 29mm.  My transmission is an A, and I measure 16mm on my collar from the bearing to the ears so seems consistent.  What I don't get is that there were way more F4W71B transmissions made than the A's, but every store online seems to be selling the A collars.  What am I missing here?

Does anyone have the flywheel-to-finger measurement of a pressure plate + clutch disk that works with any of the collars listed above?

It bugs me that I can't make sense of this, but is there any reason this 55mm long 75-83 collar wouldn't just work for me?

 

[Zed Head]

4 hours ago, EuroDat said:

.

 

This picture is confusing because the measurements shown are only valuable for comparing between them, and because the type of transmission, either type A or B or number of gears, is irrelevant.  It's just a bad illustration.  The measure that has value is not shown, from the surface of the bearing to the surface of the ears.  Even the aftermarket guys are confused about the sleeves/collars, every one of them shows a worthless dimension.

I would forget about "A" collars and "B" collars.  Figure out a way to get the distance from the surface of your pressure plates springs (where the TO bearing contacts them) to the flywheel (which you almost did, but never finished) and post that up.  Someone out here probably has the collar you need, and knows how to get the measurement that will add up to 92 mm, and will send it for a few dollars.

[rcv]

With my new pressure plate back on the bench, the distance from the bench top to the tips of the springs is ~44mm. 

 

I’m assuming that 92mm is from the flywheel to the ears of the collar, right?

That would mean that I need a collar where the spring-side of the bearing to the fork-side of the ears measures 92 - 44 = 48mm right? Does anyone out there have one they’d be willing to part with?

Just as a check, I zero’d my calipers at the ears and took a measurement on the old plate, and I got 91mm:

 

Edited July 4, 2020 by rcv