Zed Head

Did you mess with the vacuum advance hose? Maybe it's attached to the wrong port, getting full time vacuum. Try disconnecting it and see what happens.

I can't remember what 3rd gear looks like but I'm sure it's in the bucket. Let me know. Post a picture. Looking at the structure of the gear it wouldn't be surprising if it was a press-fit two-piece assembly. People say the whole gear needs replacing if the synchro is damaged, but maybe not. Maybe you can press it back together. If not, take it apart just to see what the innards look like.

I clicked the links and it just re-opened the thread. Not sure why. Here's an attempt at a fix. Edit - took out my links to shrink the page since cygnus fixed his.

I think I might have a new clue for you. It's one of those things we don't really think about, like getting the wrong collar for the throwout bearing. The engine is actually involved in locating the input shaft, through the pilot bushing in the crankshaft. Without that locating and support function the input shaft can **** and wobble inside its bearing. There's really nothing keeping its axis parallel to the other shafts without it. I remember thinking about that when I took a transmission apart years ago. The shaft is short and the power is transmitted through the coupling sleeve to the output shaft. But there's not a whole lot supporting it. It really looks all loose and disjointed when you ponder it. In short, your drill drive test procedure, while brilliant, may be flawed.

You should have made mention of the video. Would have looked sooner. Sounds terrible! I would use input, output, and counter- as the shaft designations. One possibility that might be possible is some sort of problem at the interface between the input shaft and the output shaft. The "direct drive" fourth gear path. Also, could it be possible that one of your coupling sleeves is partially engaged? Maybe a problem with a shift fork. Or maybe one of the inserts inside a coupling sleeve is out of place, maybe missing a spring or something. Spitballing...

Could you have cocked a bearing when installing? Maybe try the test with the front cover removed. Then you'll only really be using the adapter plate bearings, assuming that the front bearings aren't rubbing on something. Which you'll be able to see. Could also be a problem in the front cover. The nose can get bent or damaged.

Doesn't look terrible. Looks like maybe it had a collar of rust catching the edge of the piston, holding it in. I had a thought, that doesn't help you now but might someone else. I think that you could have blocked the brake line and the bleeder holes then filled the cavity with a low compressibility fluid, like water, oil or grease, and then pressed the other piston in with the C-clamp to generate pressure. Or popped it with a hammer. Just a thought about another way. If you pop it with a hammer you'd get a much faster pressure increase so leakage wouldn't be so significant. And the stuck piston would fly a lot farther when it came out.

The gear in the drawing could certainly go on backward. I have a vague memory of somebody mentioning that in a different thread. Might have been duragg over on Hybridz. He got so deep in to building his transmissions for 7000 RPM shifts that he was hand filing the synchro gears to perfection. Here's a EuroDat at, he probably has a thought. @EuroDat

Don't overlook the often overlooked ground circuit. Bad ground, bad sound.

That piece on the left in your picture is made of hard plastic. Is that what you're looking for?

This is not the site for you then, by a long shot. Try www.zcar.com you'll get more response.

Edit - this post is blunt, but true I think. No offense. You really do need to learn the details. You're in way over your head. You made it work, boost happens and it probably goes faster, but fine tuning requires detailed understanding. How about your boost controller? Maybe it's on the fritz. Without all of the details of your "turbo" system people can just throw out ideas. But you're not really processing the help you're getting. You just repeated my words back to me on my smog question, but didn't add any details. "FSM smog"? You're going to have to study up on how turbo engine management works, and keep cobbling away on your NA system. We'll throw ideas at you as you give more details though. Nothing good happens after 2 am.

Did you do the work, or buy it that way? There are people here who can add some ideas, but this is "classic" Zcars. com, not what you're running. I don't think that "aftermarket" heads exist for the L6 block, except for Derek's. If you bought one of those you should probably be on hybridz.org. But, back to the the basics - describe the engine details, and how it got that way. Are you running a ZX engine management, or a cobbled 77 EFI system? The stock Nissan turbo, or "aftermarket"? "Smog" means what? Hoses not understood or actual systems described in the Emissions chapter of the FSM? We know a lot about the Nissan made stuff, but once somebody gets in and starts tweaking, it can get weird.

Is your BCDD still attached? They are known for causing idle speed problems. You should put your car and engine details in the first post or your sig. Not clear what you're working with. It might be a 1977 (right?, not 1997) car, but the engine could be a transplant. Plus you have an AFR gauge, which implies that you've done some modifications.

Is it an automatic transmission? With a manual you can just push the clutch pedal. Engine RPM is controlled mainly by air allowed in to the intake manifold. You might have some kind of intake system leak. Automatics have some vacuum actuated mechanisms, that can cause problems.

My 76 has done the same thing in the past. It's either the fluid heating up and expanding or the water pump collapsing the lower hose, reducing overall system volume. The coolant reservoir level will only drop as the engine cools off and a vacuum is created in the coolant system, pulling coolant through the tube attached to the radiator neck. The radiator cap needs to be one designed to work with the reservoir, not an old 1950's cap. And it needs to be working correctly. If the radiator is full now you know there are no air pockets in it. Put the cap on and leave it. Make sure that the hose from the radiator fill neck to the reservoir is tightly sealed at both ends and has no pinholes, otherwise the system will suck in air instead of coolant from the reservoir as it cools down.

Looks good. Worst case, the brass fails (unlikely) and you have to find a steel replacement.

Here's my 1/76 build date car horns. Crusty, no signs of letters. L brackets, "standing" on tabs.

zcardept's ad says it's a high tone horn. And it has an H on it. Might be a clue, don't know.

Can you push the piston in farther, to break the bond? Easier to push it in mechanically first. Once it's loose it probably won't take much to pop it out.

So the horns are the same, but the brackets are different...? The brackets should still be in Saint's car. A picture will show.

zcardepot says that 76-78 used the same horn. https://www.ebay.com/itm/Datsun-1976-78-280Z-Horn-High-Tone-OEM-Genuine-NEW-680/222686611201?hash=item33d9280701:g:OlMAAOSwY45UTt1-&vxp=mtr Here's a 78 - http://forums.hybridz.org/topic/124393-78-280z-project-wps30/ Forgot to say, if you take a picture of what you have it might give someone the initiative to do the same for you.

Describing the problem helps understand it, is what I tell people often. Had to follow my own advice. I found a decent Remy "Gold" unit with about 3/4 left in the brushes, good resistance A to F, and smooth quiet bearings. Had a coupon, only $22 outlaid, with a $7 year-long return period extension. Got some sun, saw a bald eagle harassing the flocks of geese at the wildlife refuge next door...overall, a nice day in the wrecking yard. Got it home and installed and all is back to normal, had 14.5 volts at idle. Then found a couple of places on eBay that sell rebuild kits. $30 for bearings, slip rings, regulator and brushes. I might swap the Ford regulator for the kit's and maybe keep the Ford bearings, depending on quality. But I should be ready for the next go-round, whenever it happens. A good rainy weather project.

There's a drawing in the FSM.

Alright, that was something different. Back to our regular schedule... Thanks for the help. Sunny and 65 out here, so I'll probably go test wrecking yard alternators now that I know what to look for. The good remans cost over $150 at the parts stores.