Zed Head

I should have looked at more pictures. There's a Nissan FS5C71B 5-speed gearbox in the link below. Might have parts and know some potential buyers. Kind of far away though. http://lescollinsracing.com/transmission/gearbox

By the way, it doesn't seem that your rebuild kit will work, so that question might be answered. And your rebuild guy now knows more arcane Datsun transmission stuff.

So is the consensus growing that this is a Nissan Competition 5 speed with the tail shaft converted to slip-yoke? Still need the ratios to be more informed. Thanks for the puzzle. Found some more links. http://www.datsunroadster.com/PIC_PAGES/PARTS_INFO_PAGES/synchro_info.htm Doesn't look like a Roadster box - http://www.datsunroadster.us/PIC_PAGES/PARTS_INFO_PAGES/transmission_types.htm Here's a Comp box for sale, with the flanged tail - http://510forsale.blogspot.com/2009/11/1969-datsun-pl-510-road-race-car-for.html

Cool. I missed that one too. Doesn't look like the "case cover" is threaded. Looks crimped, so probably not unassemblable.

Found this today. Posted the larger picture in a different thread. Page EC-21 1972. Percolation is a bad thing, I think.

A timely post, re the Panama problems. I looked back to where I found a drawing of the thermostat placement and find also that Nissan has a check procedure. Made a copy. It's in the 1972 FSM, page EC-21. I didn't find anything in 1973 though, and the Parts Manual shows it as disappearing in June of 1972. Maybe that's Build date.

Found some old CZC.com threads on the steel Porsche-style, and actual Porsche factory, synchro topic. Haven't figured out if it's just the synchro/baulk ring or if you need the gear/cone that goes with it too. Steel and brass might not be interchangeable. It looks, though, that the gear ratios might tell if you have a Competition transmission. The ratios can be pretty tight 1st to 5th. Might not even be suitable for the way you plan to drive. Here's one example, not sure if they're all like this. 2.906 / 1.902 / 1.308 / 1.0 / 0.864. 2.906 would need something like a 3.9 diff, which would make the .864 5th a 3.37 overall. Compared to a .864 with a 3.54...3.06. Just playing around in your thread. Good luck.

They look like steel on my computer. A brush with some Scocthbrite would remove any tarnish. But they'll be out and on the bench soon anyway. The outer part of the teeth is thicker also in the pictures, both here and my ratsun link. Almost like tops have been machined down. Pretty sure I saw a post from JMortensen about machining Porsche steel synchros to fit the Datsun transmissions. Don't know where Datsun gets their steel synchros. It's an interesting puzzle.

Still weird that your guy couldn't tell steel from brass. Oh well. Note the conversation on the Competition transmissions in that link and the different ratios. John Coffey probably knows what you have there. Might reply if you sent him a message.

Groovy! Looks like steel, not "black fiber" (who coined that term anyway?). Found an old thread with pictures. Edit - modified the link so that it can be opened. something weird gonging on. Change the space between community and ratsun to a . community ratsun.net/topic/51601-5-speed-id-help/page-2

The thing I circled? It shows up in the pre June 1972 diagram. Looks a lot smaller though. #38 http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-240z-260z/manifold/to-jun-72

C'mon Bart, haven't you seen the problems that other people have had. Are you implying that they're all idiots? One good, many bad. It's simple calculation of the odds.

Hot. http://www.weather.com/weather/tenday/l/Panama+City+Panama+PMXX0004:1:PM

A few more pictures showing how the carb heating just might, maybe, who knows, be part of the problem. Even if it's not though, it's so easy to eliminate it as a potential cause. Eliminate the simple stuff and you're left with a better focus. No thermostat in the carb heating line, coupled with attachment to a high velocity return to the water pump inlet, pulling water through the manifolds, could lead to excess heat at the carbs. As noted in the FSM, "deterioration" can occur with too much heating.

They're probably following this thread and don't want to open a new can of worms. He hasn't fixed the most basic problems yet. Getting in to the carbs would just add to the chaos.

I meant the the thermostat in the picture I posted, at the carburetor heating line.

What about proper coolant line connections and the thermostat? Too easy?

Probably means that your brakes need bleeding. The light indicates a pressure imbalance between the front and back brake systems. The thing with the wire connected to it is the pressure switch.

It should read the same. The speedometer drive gears in the transmissions are the same so the cable will be spinning at the same speed. On the other hand though, some 240Z gauges are not the same size as 280Z, I think. Not sure which. But if you can get it in the dash and the cable connected it should be as accurate as the 240Z gauge. Forgot to say, the fonts are probably different. A no-no for the purist.

Tried to find more on the topic and went in a big circle back to myself (!) and others. It's down near the bottom of the page (this is why we need post numbers Mike). And here's the picture and description from the FSM. I would check for that thermostat first, and block the line at the back of the cylinder head. That should give proper flow and control, for cooling and carbs.

Also, it may be that the way you have those hoses connected runs the hot water through the carburetor heating plates. I think that there's supposed to be another thermostat in that line to the carbs, but don't really know the system. But, being in Panama, I think that you could block both of those lines and improve cooling for the engine and avoid overheating the carbs. That might be the whole problem right there, you're overheating the carburetors. Hopefully one of the carb experts will chime in. If I'm off-base feel free to send a torpedo.

It must be tough down there to find someone who knows these cars. You said that the radiator works fine "while running the car". And overheating when stopped is more likely to be an air flow issue. But I do see that you have the coolant hose looped back to the water pump inlet. This will allow the coolant to flow back to the pump without passing through the head or through the radiator. Try blocking that path before doing anything. No guarantees but it's cheap and easy and will help cooling.

I saw a post on another forum a little while ago from a guy who got hit in his Z. His belts looked in good shape but snapped on impact. He bashed his face and nose on his steering wheel and looked pretty messed up. The polymers used in the belts are susceptible to degradation from sunlight. They can look fine but actually be severely weakened. If there are any vendors out there who want to develop a new product, bolt-in replacement belts would be an easy sell, I think. We're all surrounded by SUV's and distracted drivers these days, plus many have grown accustomed to having an air bag in their other cars.

So you do have a small amount of heat buildup. Still doesn't really explain your problem, but might be a factor. Here's something easy to look at that might be significant, especially since you're in Panama and probably don't use your heater - are the heater core coolant lines from the back of the head blocked off or are they looped back to the water pump, from the head? Or are they connected properly to the heater core? Looping the line back to the pump inlet (bypassing the heater core) can cause overheating, in a perfectly fine cooling system. And, still wondering about fuel pressure, and the return lines for your fuel supply system. Important.

Euro gives good advice. Replace the hose too, it's probably aged. The one thing not said, that we're all hoping isn't the case, is a too-tall collar. But, a later clutch kit would use a later clutch fork and slave cylinder, so odds are that's the way to go. You could try cutting the slave cylinder rod down first. It should come out with the rubber boot.