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Taxelson

75 z, want to swap my 4 speed for a 5 speed, best option?

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I just bought a 1975 280z with a tired engine and 4 speed transmission, I want to swap a 5 speed, what is the easiest and best option for this transmission swap. This is my second z, had a 1976 z 25 years ago when I was just out of high school, got a good deal on it, but she is tired. As a second topic, I know I will need to rebuild this engine, any advice on what to use. It's not a daily driver, just fun on the weekends, don't need gas mileage, just fun, thanks.

Troy

Edited by Taxelson

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Congrats on your purchase. It's always nice to see another classic on the road. I believe you can swap out a 5 speed all the way up to '83. As for your rebuild, it really depends if you want it stock or mix and match heads, use FI or carbs etc..

PMG

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If you are going to rebuild it yourself switch to flat top Pistons for higher compression and a little more pep. But if you're going to have some one rebuild it for you go with either Datsun Spirit or Robello Racing.

Sent from my iPhone using Tapatalk

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If you don't care about MPG then why swap to a 5-speed? Anyway, like Pmg said any 77-83 Z 5-speed will bolt right up. The T5 is probably different but those rare and harder to find.

 

You can probably get some new ITM flat top pistons or a used set from an 82-83 280ZX. That's probably your biggest bang for the buck performance wise for the engine.

 

Chuck

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First, state your goals. Why do you want a 5 speed? Is it to reduce RPMs at freeway cruising speeds? 

 

Second, how do you know your engine needs to be rebuilt? Is it burning oil? What is the compression like? Have you adjusted the valves lately? Is your fuel system in good repair?

If it does need a rebuild, what are you looking for? (Again, state your goals.) Datsun Spirit and Rebello are pretty expensive if all you're looking for is a nice cruising experience.

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Short answer on the transmission would be: Close ratio 71B with a 3.7 or 3.9 transmission. There are a lot of variables, like highway use or just cruising around town which will influence your decision.

 

Im running a 82 280ZX 5 speed with a 3.7 diff from a 300ZX. The combi works well, but finding a close ratio 71B in good condition is getting harder. Another option is the 71C.

 

Here is a snap short of some data I have on the combinations. Based on my 280Z.

post-25317-0-46799000-1446483003_thumb.j

post-25317-0-66530200-1446483021_thumb.j

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Thanks everyone, I'll look for a 5 speed, maybe I'll get lucky and find the flat top Pistons from the 82-83 zx as well. Any other thoughts welcome.

Troy

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My goal is to have a good cruiser at highway speed with solid acceleration 0-60, any thoughts on engine rebuild are welcome. Yes it burns oil, and smells of oil while driving.

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Same story with me, I had a '76 in high school.  25 years later I found one just like it on craigslist.  Sold my motorcycle before I had the "big one".  Now I have three Zs in my garage.  :)

 

Get this book and I guarantee you can rebuild it yourself if you have some tools.  I'd never rebuilt a car motor before, lurked around on this forum followed the book word for word and it turned out fantastic.  When I ran into something I wasn't sure about I'd ask for help on here, politely, and always got it figured out.  There's guys on here daily that are the original owners of early 70's cars.  It's amazing how much information is available on these little cars.  Every problem has been fixed 100s of times by these guys.

 

http://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine/dp/1931128030 

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Find an 80-83 280ZX with a good engine and 5 speed and swap them in.  Use your intake and exhaust manifolds.  That would be the most cost-effective way to get there, I think.  Keep your old engine for "building" if you decide you want more performance.  You'll have a DD and an engine project to work on.

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Mud,

Thanks, that link didn't work, what's the name of the book, I'll get it ASAP. I'm on the hunt for an 5 speed. I think part of the reason I'm looking at a 5 speed, the car I bought has 14" wheels, maybe it would be a more comfortable RPM at cruising speed with some 16" wheels, right? I think I'll buy the rims, tires first, then see how comfortable the cruising speed is. Sound good everyone

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You can change cruising speed with a different differential.

 

On that topic though, be aware that 1975 has an odd bolt pattern on the differential.  So if you do swap differentials, you'll need to get a 76-78 propeller shaft (center driveshaft).  Or swap pinion flanges.

 

On the wheels - it's tire diameter that matters.  A "normal" 14 wheel can have the same diameter as a 16" wheel with a low profile tire.  http://www.discounttire.com/dtcs/infoTireMath.do

 

On transmissions - many people focus on cruise but they should really focus on 1st gear.  

Edited by Zed Head

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Mud,

Thanks, that link didn't work, what's the name of the book, I'll get it ASAP. I'm on the hunt for an 5 speed. I think part of the reason I'm looking at a 5 speed, the car I bought has 14" wheels, maybe it would be a more comfortable RPM at cruising speed with some 16" wheels, right? I think I'll buy the rims, tires first, then see how comfortable the cruising speed is. Sound good everyone

Try this link: http://www.amazon.com/Rebuild-Your-Nissan-Datsun-Engine/dp/1931128030/ref=sr_1_1?ie=UTF8&qid=1446502999&sr=8-1&keywords=how+to+rebuild+your+nissan+ohc

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