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Swapping 280Z 4 speed to 5 speed. Parts needed?


MOTORHEAD427

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Hi there.

I have a `73 240Z with original block and 4speed tranny.

I`ve recently started the restoration and replaced everything you could imagine except for the engine and the tranny. I`ve got 45 mm triple Webers, 6 barrel ceramic coated headers, msd electronic ignition, new heavy duty radiator, distributor new manual and electric fuel pumps, brake master cylinder, clutch etc etc.

I also replaced the bushings, engine mounts etc. The problem is as you would have guessed is the transmission.

I want to replace the stock tranny with a 280Z 5 speed transmission and I want to keep the original engine. My question is, what else should I get with the transmission and what kind of a rear end should I get for better performance?

All help is much appreciated and thank you in advance.

ERIC

P.S.: I`m located near Pasadena, CA. If you have a 5 speed transmission for sale in Los Angeles, Orange County area, I`ll come and pick it up.

Turk240z.jpg

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The 280Z 5-speed is going to be tricky to find. I would search for a five speed from a 280ZX...they are plentiful and cheap. One thing to consider though is the possibility of upgrading to a 240SX transmission. as the 280ZX trans' become harder to find the 240SX transmission should be the next wave of readily available transmissions. A quick search should give you some info on the 240SX swap if you lean that way.

 

check out this link for a rough idea of what certain combos of transmissions and rear ends will yield performance wise:

 

http://www.geocities.com/z_design_studio/

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What I`ve been told by many people is that, the only perfect fit 5 speed tranny would be from a Non Turbo 280Z. You`re talking about 240SX. That sounds like a lot of work.

 

ERIC

 

well, there was never a turbo 280Z. and the 280Z 5 speeds were a factory option and very hard to find. the 280ZX 5 speeds are everywhere, produced from 79-83, they made tons of them, and you should be able to easily pick one up from the local junkyard for a nominal price. the turbo 280ZX transmission will be a bit harder to find, cost more money, and be harder to fit. the turbo transmission is a BW T5.

 

the 240SX transmission is more work that the 280ZX turbo T5, and more money too, but if you plan on going turbo in your car in the future, or really abuse your car than it might be worth the extra time and expense up front so you dont end up swapping transmissions again on your next big upgrade. of course if you plan on keeping your car non turbo, and you dont treat it too bad, the 280ZX NA transmission should work fine, and is a direct bolt in.

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Guest 280ZForce

you can easily pick up a 79-83 280zx 5 speed here in so cal..they are usually all over. i think there was a couple in the JY i saw over the weekend even.

 

Should be able to pick 1 up from a local seller for around $150-$200, and from a jy for $50-$100.

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Wrong:

he 77-81 5 speeds are almost just the 4 speeds with the extra gear and are considered "wide ratio".

 

The 82-83 5 speeds were designed as 5 speeds from the get go and are considered "close ratio".

 

If I remember correctly, ANY L series tranny will bolt up to any L series engine. The only differences are tranny or driveshaft length. If you get the transmission from a 2+2 the driveshaft will be longer, and if I remember correctly there are some oddball trannies that are a different length (though rarer then most).

 

If you want the 82-83 5 speed, I think it would be a straight swap using your driveshaft, as these later cares have an R200 and a different flange.

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I would suggest you replace the diff when you install the 5 speed. A 3.90, 4.11, or 4.38 diff would go best with those carbs, lower is better but it kinda depends on how much rpms you can tolerate on the freeway. I'd try to find a 4.11 or a 4.38 if I were you, but I'm probably on the aggressive side of what is acceptable.

 

NA ZX trans has closer gear ratios and will suit your triple setup much better than the T5 or 240SX swaps suggested, or the 280Z 5 speed for that matter.

 

When you buy the trans get the collar for the throwout bearing that it came with, and get a 280ZX pressure plate as well! The 4 speed pressure plate and throwout bearing collar is a different length and won't work. The rest of the stuff (flywheel, throwout fork, clutch disk, driveshaft) are all interchangeable.

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The 77-81 5 speeds are almost just the 4 speeds with the extra gear and are considered "wide ratio".

 

The 82-83 5 speeds were designed as 5 speeds from the get go and are considered "close ratio".

This is not correct. The 77-79 trans are wide ratio. The 80 trans is the first year of the close ratio and has a .773 OD which actually makes it the closest ratio of all of them. The 81-83 has a .745 OD, making it slightly wider ratio than the 80.

 

Ratios and other helpful stuff here: http://www.geocities.com/z_design_studio/

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Thank you, thank you, thank you!!!!!

Great info!

I tried to change the title myself after having realized it wasn`t descriptive at all but I was not allowed to do so. Thank you for doing it for me, it helped a lot!...(BTW, title should have been Swapping 240Z 4 speed to 5 speed. Thanks anyways Jon)

Now I know exactly what to do.

This is the most informative Z site on the net.

 

ERIC

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We just took out our 3.90 open rear and 5 speed and put in a 4.38 LSD and 4 speed with the 3.55 1st gear ratio. Its night and day difference on acceleration through the gears now. Its now a road race car and a stop light to stop light terror (even more so than before). we dont need any 5th gear for what we use it for.

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Actually there is less of a 2-3 gap ratio now for us running this 4 speed vs the 77 280z 5 speed we had in it before. (3.549/2.197/1.42 vs 3.321/2.077/1.308). Very close actually between the 2 cept for 1st gear which we like really low to get us our hard launches for drag racing. Dont even notice rpm hurting wide ratio drops when shifting at 7500 with a 4.38 rear it winds up so fast anyway.

 

Agreed the zx 5 speed has the better 2-3 ratio. I just dont have one ready to throw in but had quite a few 4 speeds laying around so went with what we had as we want a very low 1st.

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Ah, I see. I bet you'd notice another nice improvement going to the ZX 5 speed.

 

I looked around for 2 months for a decent zx 5 speed but never came across one for sale. Started on a 240sx conversion but it never materialized on the other end.

 

Gotta use whats available....

 

All this will be mute when the LS6 goes in next spring.

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