EuroDat

As I said, digging up memories from 33 years ago working in an automatic transmission shop. We use to do an "upgrade" in the commodores. It was a simple heavier spring set in the valve body. You could get these transmissions to churp the tyres going to second gear with a bit of tweaking in the valve body. Normally the converter will just touch the flex plate or maybe a couple of mm off. 1/8" is getting close to maximum, but it should pull together. I don't think the 3mm is a problem. The 23mm covertor to flexplate when the transmission is fitted is a problem. The convertoer has two prongs to drive the oil pump. Can you measure them they should be about 20mm if my memory serves me correctly? 23mm will mean if you get it to bolt up to the flexplate, the pump will disengage.

1/8" of an inch is ok. Normally they just touch or have a couple of mm. You mentioned the transmissions turns with the engine. You should be able to turn the converter by hand using fingers or a screwdriver to line up the bolt hole to the flex plate. If you can't get the converter to turn without turning the engine then the center section on the convertor is probably not lined up with the back of the crankshaft and not entering the crankshaft. How did you fit the transmission. Did you use the bellhousing bolts to pull it in or did it push up by hand? It's been a long time since I seen one of these in pieces, and that was in a VL commodore. Memory is fading. Can you post some photos of the convertor.

That doesn't sound right at all. Can you remove the converter from the transmission and test fit it to the flex plate. I think there might be something going on there. It should slide onto the bolts. Make sure when you refit the converter to the transmission to turn slowly while gently pressing it into the pump. The two prongs wil click into the notchss and you will feel the converter slide in. Btw: In Australia you could buy a performance upgrade kit for the 4N71B transmission, which is basically the 3N71B with a lockable sprag clutch. They used the RB30 engine with the 4N71B in the Holden VL commodores in 1985.

Looking at your photo of the clutch disc and pilot bearing. It doesn't look like it's lined up enough to get the input shaft to slide into the pilot bearing. I would try to line up the disc a little more. Feel around the outside of the disc and check if it is centered on the pressure plate. You can do that at three positions through the pressure plate cover. You need to get it within 1/2 mm. DON'T pull the transmission into position with the bolts. You could damage something. Just jiggle the back of the transmission it around and push. It should slide in.

That is a very neat drawing indeed. WOW When I did my "caveman style" sketch I was going through the montions and not expecting anything like this. Hey, if the darn thing worked with those measurements you took on the original clutch, it will work fine with the 125mm mearuement. I know for a fact the clutch will fully disengage with 15mm on the 71B, but it was very close to the floor and badly adjusted. If everything was adjusted correctly it should have hit the bell housing. Who knows what was going on. Time to move on.

Hi Kelly, I mentioned going through the tests in the EFI book. The one I linked you in the pm conversation. Have you done these tests? Could you share the results? It would help a lot if we have the information to go on.

I would stick with the original bushes where possible for a street car. If you go with PU, be carefull with PU components on the front compression rods. They are known to break due to the extra stiffness. People literally burn these old bushes out. Must like breathing in toxic fumes. I have had a lot of sucess by grabbing the center bush with a pair of vice grips, heating only the outside metal and twisting the inner bush. It will let go eventually and you can pull it straight out with very little mess and fumes.

Don't worry. You are not the first and certainly not the last. If you play with your datsun long enough you, you will be here again asking questions. Most of us have been through it. If you can identify any reason for the problem, then I would try the washers behind the pivot ball. Like Kars said, you have an adjustable push rod and if needed you can make a longer one easy enough. Your biggest concern is binding on the back of the bellhousing when you disengage the clutch. Maybe check the collar next time you have the transmission of the engine. Make sure it doesn't come too far off the tube and jam.

Zed Head has a point. I also have another question. When you fitted the transmission to the engine, did the bell housing mate up the the engine or did you pull it in with the bolts? You should be able to push it all the way without any mechanical assistance. That could indicate the collar is jamming on the tube and pushing on the pressure plate. I would not think it could result in so much fork travel without disengaging the clutch. That doesn't seem to be the case when you tested it with the drive shaft.

I took some measurements of my spare transmission to give you something to go on. I can't see why the 92mm rule would not apply for the 71A, you kind of proved it with the old clutch although we don't know if it was the same as, or the original clutch. The position of the fork in relation to the front of the bell housing is the same on the 71A/B/C. I also did some checking on my transmission. When I position the fork at 135mm, there is very little room behind +/- 15mm. Not enough to fully depress a correctly adjusted clutch pedal. Everything being equal, your old clutch will be further forward due to the thinner disc. The diaphragm in the pressure plate has a fulcrum of about 5 to 1. So 0.5mm woulf move the diaphragm fingers about 2.5mm and the clutch fork about 4.5mm give or take a couple tenths of a mm. Mind you, that is going out from a situation with a pddal box having little wear and correctly adjusted. A clutch will easily disengage with 15mm clutch fork movement. It will be low in the pedal movement. Another thing to note. When I push the fork all the way back the collar almost slips over the end of the support tube. That is not good. See photos.

It is a strange problem you have and I can't think of anything else but the flywheel. Is it the same flywheel you had on the old clutch? If you want to test the clutch, that is simple. Just remove the rubber boot and use a crowbar in the space between the fork and bellhousing. Use a small piece of wood between the crowbar and fork at the slave cylinder rod position. Depending on the size block of wood, you should get a full stroke with little effort. Be carefull the crowbar doesn't slip, fly out and hit your knee. Don't ask If you do use the washers on the pivot ball, don't go more than 4mm. You want enough thread over to provide support. The only other thing I can think of to correct the fork position is the make a spacer ring between the collar and throw out bearing at position of the arrow. I wouldn't go any more than 4mm. If you do one of these two modifications than 4mm will move the fork approximatly 7.5mm forward at the slave cylinder rod. Do both mods and you would move the fork 15mm forward. Try the washers and see if you get 25mm movement with the crowbar before the fork hits the back of the bellhousing. You can always make a pushrod to suit.

While we are on the subject. The figure CL-16 shows the stroke at 35mm. That is the maximum stroke of the slave cylinder, not the operating stroke which should be max 25mm with all adjustments done correctly.

Yes. That 12mm travel is not enough. You need about 15 - 20mm normally depending how fine the clutch pedel is adjusted. 12mm the clutch pedel most probably will not reach the floor before the fork bottoms out. I was thinking about a thicker than normal clutch disc, but I have never seen that happen. Always a first though.

Yes, try the new fork. If thet doen't help much then it must be the flywheel or something with the thrust bearing in the crank that holds the crank shaft in place. One other measurement you can take is the distance from the bell housing to the throwout bearing. Set the fork up at the 115mm mark and use a straight edge other the bell housing next to the input shaft. With your collar, the measurement you should read is 66 to 67mm from straight edge to throwout bearing. If you get that, then the problem is not in the pivot ball or fork. Normally the fork to bell housing distance should be in the 112 to 118 area. 124mm might be ok, but I think I would be putting two 2mm thick washers behind the spring washer on the pivot ball. That 4mm will get you about 7mm on the fork end and get you in the zone.

That is not the original pivot ball. Looks like one out of the RB engined cars, Skyline R32 etc. P/N:30537-RS581 Yours should look like this. The pivot you have is correct. Part number: 30537-21010 You should measure 26mm from shoulder to top of ball. Btw: If you want to buy that pivot ball, you could try this to compensate for not reaching the 91mm measurement. You can use a couple of ID: 10mm washers on the pivot ball thread to extend the pivot ball. That and a spacer ring behind the thrust bearing to increase the length of the collar/throw out bearing combination. To do the thrust bearing you will need to remove the bearing and machine a ring. This is fixing symtoms, not what is causing them, but it could get you on your way. In the last two photos are my spare fork, throwout bearing and pivot out of a 300ZX. The throw out bearing/collar measure 42mm. That would mean a pressure plate on the bench would need to be 50mm. The 300ZX plus a lot of other datsuns/nissans with the F*71A B C transmissions use the same pivot ball.

I think I would remove the pressure plate and set it up on the bench with the throwout bearing collar. Start doing the math. Measure it all again. You need the 91-92mm measurement. I see you had 86mm. I'm not sure how you measured it, but if you use the same procedure you used on the old pressure plate/collar combination 91mm then something is still not right. The clutch fork ratio is 120/65. The slave cylinder rod moves 1.85mm to 1mm throw out bearing movement. 92-86 = 6mm. 6 x1.85 = 11mm. You are measuring 135mm. 135 -11 =124. Still a long way off the 115mm bell housing to clutch fork measurement. The 115 is approximate and depends on clutch disc wear. A new clutch could be up around 118mm. Is the flywheel surfaced. Could that be where you are loosing a couple of mm? If you do go ahead with the fork in the 135mm position, there is a good chance your clutch pedal will bottom out before the pedal reaches the floor and the clutch may not be fully disengaged. The other problem you will have is your slave cylinder travel will runout and pop the rubber cup out of the cylinder. You will need to make a longer rod for the slave cylinder the prevent that from happening.

I made a pdf with a lot of this info 4 or 5 years ago. I'll have a look for it and see if it needs updating and upload it to the tech section. It had all the clutch part numbers and most of the dimensions.

You should to do the measurements with the pressureplate off the flywheel. On a flat workbench is fine. Place the throw out bearing with collar on the pressure plate fingers and measure the height from the clutch fork tabs to bench top. If the pressure plate is fitted and compressed it will have a different height.

Funny, I wrote almost the same thing 7 years ago? Unfortunately a lot of people measure these collars in a why that makes no sense now. The most important measurement is the 92mm from the flywheel surface of the pressure plate to the contact point for the clutch fork. Those collar measurements you see 32, 42, 38 and 41 are not very handy to you because they measure the total length from the throwout bearing shoulder. They measure past the tab for the clutch fork.You can figure out what you need with some calculating and refering to the one you have. You can measure your pressure plate with the throwout bearing and collar and see how far off 92mm you are. Note the difference between your measurement and 92mm. Then measure your collar like in the photo with 32, 42, 38 and 41mm. Example: If you measure 82mm. That is 10mm short. Then measure your collar at 32mm. You will need the 42mm collar. Most aftermarket clutchs are based on the 75-83 280Z ZX couple clutches with that pressure plate. ALL this information is related to the pressure plate height. The picture of all the different collars I posted is very old and explained where all these different heights came from. The problem these days is there are so many Zeds running around with non original clutches and therefore no real relation to the A, B etc trnasmissions.

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.

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.

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.

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.

What about the steering column coupling. That has been NLA for years, 10 years at least. Trying to find a NOS or near new condition example is like trying to find a wholly mammoth. http://www.carpartsmanual.com/datsun/Z-1969-1978/steering/steering-column/28

M6x1.0 bolts. IIRC You will only get 4 or 5 turns into the pulley before it bottoms out against the timing chain cover.