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Hey gang, I’m new here and not to sure how this works but I need some advice. I took on a 1978 280z project car a couple months ago and after a lot of time and money finally have it running. Now I have what sounds like the pinion bearing going in my differential. First and second gear there is a clicking but at higher speed I don’t hear it. I was gonna drop the diff and rebuild it but I wanna do it all in one go because it’s my daily. I don’t know all the seals, bearings, etc; and was wondering what all I had to replace in it. If anyone could give me a list that would be super! any other advice would also be great 🙂
 

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Buy a second differential, either swap it or have the spare rebuilt professionally (the setup charge will be what the shims cost from nissan alone!)

Pick your ratio now and get it. I'm partial to 3.7 and 3.9's for stock engines. 3.9 if you have an early 5 speed, 4.11 if you have a later ZX one... 3.7 is perfect for the four speed and was what the world got.
 

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Buy a second differential, either swap it or have the spare rebuilt professionally (the setup charge will be what the shims cost from nissan alone!)

Pick your ratio now and get it. I'm partial to 3.7 and 3.9's for stock engines. 3.9 if you have an early 5 speed, 4.11 if you have a later ZX one... 3.7 is perfect for the four speed and was what the world got.
first check the u joints
 

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Buy a second differential, either swap it or have the spare rebuilt professionally (the setup charge will be what the shims cost from nissan alone!)

Pick your ratio now and get it. I'm partial to 3.7 and 3.9's for stock engines. 3.9 if you have an early 5 speed, 4.11 if you have a later ZX one... 3.7 is perfect for the four speed and was what the world got.

He's right you know. I have an early 5 sp with a 3.9 and an extra 3.54 laying around.
 

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If I may follow the sidetrack another step, I would note that the business of diff ratios is pretty much a matter of personal taste.

For example, having long ago shed the Boy Racer syndrome (especially around city streets), I have come, with much experience, to appreciate the value of "legs" for open road work. In such cases, a tall diff has numerous advantages, especially with the native torque of a sweet straight six. Even the mountains of the West have failed to occasion a downshift at road speeds, and the paybacks of middle revs and good mileage while making time are their own reward (not to mention the enhancement of longer engine life).

So, it depends on what you like; tearing around stopsign to stoplite, or comfy cruising for hundreds of miles at a time.

$.02 from the peanut gallery.
 

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I don't know about boy racer syndrome but I can tell you the ONLY difference in ANY of the ratios in terms of "long legs"on the stock engine is ZERO! The 3.90 will get you to 125 faster than 3.36 and do it all day long same as the 3.36 with or without a five speed! Same for the 3.7...

And they all pull between 22-27 on the freeway with SU's, depending on the speed you will be going. You gotta work into triple digits to get less than 20mpg on the highway.

I've pulled 17,000 mile road trips in my 3.90 car, driving with two drivers 36 hours straight...
As well as 15,000 mile road trips in my 3.70 car, driving for entire tank fulls at top speed in the middle of the night...

These aren't small block Chevies, they don't need nor like to run at 2,000 at highway speeds. It's bad for their bearings, if nothing else!

These engines are designed to run at 3,000 to 4,000 all day long and love it. Not overheat (the 3.9 was running at close to 4,000 rpms towing a trailer up the Palm Springs Grade with three people in it and 110F and was nowhere near even getting warm much less overheating!)

Use the revs the engine has to give you. If you want to run at 2,000 and shift at 3,000, get yourself a diesel Jetta!
 

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Mr.D:

Google "boy racer syndrome"; you might find someone you know well...

That's certainly an interesting concept of gearing and mathematics you have there. Makes one wonder why manufacturers have bothered to offer a plethora of ratios between 2.xx and 4.xx over the last hundred years. You do understand that for a given rev, top speed goes down as diff ratios go up, right? And isn't the real issue in this scenario, torque and not horsepower? And isn't maximum torque most often developed in the low to middle rev range?

And that old canard about "it loves to rev", the battle cry of adolescent fantasies, deep pockets, and frequent rebuilds (see, "boy racer", above). True, some engines tolerate that kind of abuse better than others, but none "love" it. Have you never wondered why racing engines of various stripes see very frequent rebuilds? Those mechanics must not be as smart as you about such things, eh?

I especially liked the part about how low revs are bad for the bearings; a novel notion indeed. As is the comparison of V-8s (all possessed of second and third order harmonics issues) and straight sixes, which have the best first, second, and third order harmonics of any cylinder configuration (save V-12s, of course). This fact just might explain why the recent rebuild of my Z's 200k mi, low rev engine revealed a crank, rods, cam, and valves and guides that were all still within "Std." specs. and provided over 60lb. of oil pressure.

Mileage? There's that old math bugaboo again; the direct relationship between revs and mileage seems to be well understood by any expert one could name. Hint: the lower the revs per mile, the better the mileage. You can look it up.

I admit that you lost me with the anecdotes about long trips; are you saying that one can only do such things with numerically high diff ratios and screaming engines, or that you enjoy driving irresponsibly in adverse conditions? I wonder, over 15K mi., do you think flooring it to road speed saved you much time in the process, or did it just make you feel fast?

And the Jetta thing.... very witty, I'm sure. Actually, around town, my usual shift point is around 2.5k rpm; city streets are no place for grownups to play "racer".

So I hope you'll see why I might think you missed the point of this intellectual exercise. My point is that if one gets his jollys from zooming around city streets, scaring old ladies and endangering kids, I s'pose short diffs are just the thing (of course, "pointless" comes in to play here, as most any econobox or faketruck today will outrun most any 20 or 30 yr. old car). But if you like road trips and love your car, there is no substitute for "legs" on the open highway.

Again, its an issue of personal taste, but its been my experience that real Road Warriors love tall diffs, tall tires, and overdrives (Leycock de Normanville forever... those Brits are a clever lot).

Just another $.04 from the peanut gallery...
 

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Mr.D:

Google "boy racer syndrome"; you might find someone you know well...

That's certainly an interesting concept of gearing and mathematics you have there. Makes one wonder why manufacturers have bothered to offer a plethora of ratios between 2.xx and 4.xx over the last hundred years. You do understand that for a given rev, top speed goes down as diff ratios go up, right? And isn't the real issue in this scenario, torque and not horsepower? And isn't maximum torque most often developed in the low to middle rev range?

And that old canard about "it loves to rev", the battle cry of adolescent fantasies, deep pockets, and frequent rebuilds (see, "boy racer", above). True, some engines tolerate that kind of abuse better than others, but none "love" it. Have you never wondered why racing engines of various stripes see very frequent rebuilds? Those mechanics must not be as smart as you about such things, eh?

I especially liked the part about how low revs are bad for the bearings; a novel notion indeed. As is the comparison of V-8s (all possessed of second and third order harmonics issues) and straight sixes, which have the best first, second, and third order harmonics of any cylinder configuration (save V-12s, of course). This fact just might explain why the recent rebuild of my Z's 200k mi, low rev engine revealed a crank, rods, cam, and valves and guides that were all still within "Std." specs. and provided over 60lb. of oil pressure.

Mileage? There's that old math bugaboo again; the direct relationship between revs and mileage seems to be well understood by any expert one could name. Hint: the lower the revs per mile, the better the mileage. You can look it up.

I admit that you lost me with the anecdotes about long trips; are you saying that one can only do such things with numerically high diff ratios and screaming engines, or that you enjoy driving irresponsibly in adverse conditions? I wonder, over 15K mi., do you think flooring it to road speed saved you much time in the process, or did it just make you feel fast?

And the Jetta thing.... very witty, I'm sure. Actually, around town, my usual shift point is around 2.5k rpm; city streets are no place for grownups to play "racer".

So I hope you'll see why I might think you missed the point of this intellectual exercise. My point is that if one gets his jollys from zooming around city streets, scaring old ladies and endangering kids, I s'pose short diffs are just the thing (of course, "pointless" comes in to play here, as most any econobox or faketruck today will outrun most any 20 or 30 yr. old car). But if you like road trips and love your car, there is no substitute for "legs" on the open highway.

Again, its an issue of personal taste, but its been my experience that real Road Warriors love tall diffs, tall tires, and overdrives (Leycock de Normanville forever... those Brits are a clever lot).

Just another $.04 from the peanut gallery...

Oh dude, there is so much wrong in what you've said....FFS!
First, have you understood there is NO top speed difference in ANY of the Stock Engines with ANY of the stock gearing from 3.08 to 4.38? The car is drag limited, it's going to go 125 mph. Period.

These aren't Chevy V8's and applying their design input to them is a an exercise in stupidity beyond the pale! A 5.7 revs half as much as a 2.8 to make the same torque/power. Period. This is why the L-Series was designed with high silicon blocks and rings designed to wear not the bores. That said, there are plenty going on 300,000 miles without overhaul. My L28 in the 76 started life in a 3,90 differential car and lived there for 225,000 miles, it then went into my lighter 76 and has gone another 125,000 miles. Still going strong. 175# Compression across the board. No need for frequent overhauls because "Racing Engines" rev to 8000+ not a mere 4,000 like designed for an L-Series at highway speeds.

If you're going to prattle, prattle cogently. You said nothing of import or applicable. We're not talking about racing cars here, we're not talking about highly stressed engines *unless you lug the **** out of them and overload the bearings*! With the speeds legal in the USA there is absolutely NO NEED for a 3.36 differential, it's lugging the engine as most people don't understand how to drive and keep the engine in it's powerband and keep up proper engine speed for coolant flow and oil flow. They're not Chevy V8's that float the valves at 4,000 or slightly higher. They run just fine there.... It's not 'boy racing' by a longshot. Climb a hill in the proper gear for once, you will be amazed. I guess 60's Era Splitwindow VW Microbusses were all owned by 'boy racers' who continually ran their engines at 4,000 rpms to just keep up with traffic. Ever do a tach check on an B110? Theyre pumping 4K+ at 70 mph on the freeway and still giving you 40+ mpg!

What I discussed was STOCK RATIOS available in STOCK VEHICLES outside the USA. The USA had decontented, sponge-sprung low cost of entry cheap vehicles for sale because Datsun was a cheap car company. Period. Everywhere else the cars got decent gearing to better employ the powerband of the engine by drivers who understood how to drive small displacement engined vehicles, and didn't start out in Truck Engine'd Behemoths with turning circles comparable to the Exxon Valdez.

"Rebuilding" an engine at 200K and finding everything to spec inside and nothing worn? Who's the one incompetent to comment here again? Seems like you missed the mark and listened to one toooo many V8 Experts on the internet that swear 100,000 miles is the limit of engine reliable operation before overhaul becomes 'mandatory'....

I don't think this was an intellectual exercise whatsoever...just spewing of worn inapplicable myths. Comfy Cruising at 85mph in West Texas is done just fine at 4000 rpms and a 4.11 same as with a 3.9, or 3,7... They will all give you mileage in the mid-high 20's you won't break 30 by a longshot with a 3.36 or a 3.08...total B.S. won't happen not with an L28 and carbs!

Again, with the speeds that are legal in the USA, and given there is no impact on top speed whatsoever in the ratios being discussed iwth a stock engine, the lower you go, the faster you get there and there are no maintenance issues, no longevity issues, etc. Saying so is pure ignorant bullsh*t! They're all available worldwide from the factory, they all follow the same OEM durability longevity envelope. Period.
 

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Oh and I think driving From Tawas Michigan to Riverside California a distance of 3,950KM in a total time elapsed from start to finish of just over 30 elapsed hours wasn't 'fast' by any sense of the word...but it DID save time being that it was done in less than a day and a half and it's "supposed to take" 3 to 4 days elapsed time.

That was in a bone-stock 76 Fairlady Z 2+2 with L28, Early 5 Speed, and 4.11 Gears. That's a STOCK combination my man. No 'boy racers' want a 2/2! IN FACT if the 2/2 in question would have been my 77 Fairlady, it would have been done with the STOCK 4.38 Gears in the rear end. Educate yourself, my man, you're off the mark on how these vehicles are designed to work.

If you want tall tires and high gears, buy a Corvette...and if you haven't noticed, this isn't a damned Corvette Forum!
 

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A "short" diff in an L-Series ANYTHING starts at 4.62.... and 20" tall tires. Maybe 4.44 if you can find the R190...

You realize the DIESELS ran the same 3.36 Final Drive and 0.76 Overdrive Fifth?

Yeah, tell me more how that's 'desirable' in a gasoline engine with half the torque! Riiiiiiiight!
 
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