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 Post subject: Transmission swap
PostPosted: Wed Jan 11, 2017 11:10 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
Hello,

I'm planning on swapping a rebuilt 5 speed transmission into my 260z this year, and the transmission that I'm buying doesn't have the original shifter with it. I'm assuming I can use my 4 speed shifter, is that correct?

Also I'll be leaving my clutch and flywheel alone, so I believe that means my throwout bearing and clutch fork need to be reused from the 4 speed trans as well.

Any other tips or potential problems I should be aware of?

Thank you!

Jay


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 10:19 am 
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Joined: Fri Dec 25, 2015 7:39 pm
Posts: 449
Location: Long Island, N.Y.
Yo Frank. Yo Paul. This question is/should be an easy one for you guys to advise Jay on. Do I remember you saying, Frank, that the 5th gear on these trannys were a little weak? 8)

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1985 300ZX- GLL Dark Pewter Metallic - Survivor


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 5:00 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
No, Paul knew that. I beat mine mercilessly.

Of interest here is that the early (240Z) 4-spd and the (280Z) 5 spd boxes present the shift lever at slightly different places, so the 240 owner would have to slightly elongate the slot in his floor to allow the 5spd lever to poke up thru it, and then he might also find some knuckle-busting clearance problems btwn the stick and the dash in 1st/3d/5th gear. Bryan Little resolved this by installing Vinny Bedini's nifty 'short shifter' kit. That allowed plenty of room for the stick and made each shift quicker. A good deal until MSA "discovered" Vinny's idea, patented as their own and began charging double for it.

Please note that I specify *240Z* to *280Z* gearbox swaps. This might not apply to 260s, depending on what gearbox they have. The 240Zs use two slightly different manual 4-spd boxes (a "71-a" and a "71-b"), but honestly, I've never paid attention to what box the 260s came with! Jay might get away with no modifications at all.

Whenever you have the engine or gearbox out, CHANGE THE THROWOUT BEARING. They can look fine, act fine, sound fine and still be within the final few hundred miles of their lifespan. How do I know this? Because while my engine was pulled and being rebuilt, I looked at my throwout bearing almost daily. It had worked just fine up to that point and my Little Voice said, "Hey, if it ain't broke...." So I didn't replace it. Put the engine back in and within 300 miles it began singing to me. Within another 300 miles it was crying and making it "difficult" to shift smoothly. But I wasn't about to spend another $800 to replace a $35 part so I waited another year until my L28 engine was ready and THEN changed out the bearing. You couldn't turn it with both hands by then. So I saved $35 for about 2yrs during which time my Z hated me. Stupid, stupid, STUPID.

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1970 240Z


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 7:07 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
Thank you for the replies guys.

Frank, I'm surprised your bearing didn't catastrophically fail from pushing it that long..... It must have been screaming!

Mine has only 600 or so miles on it, as does the clutch and pressure plate..... so I do plan to reuse it. Ill be installing it though, so if it fails I'm out time mostly. And I get to tell myself "you should have listened to Frank!"

Vinny Bedini is who I'm buying my transmission from, it is a rebuild that he just completed and I cannot wait to pick it up! Interesting story about Vinnys shifter mod too.

Brian Littles website is what originally led me to this club!


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 7:09 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
Also I'm hoping to get away with doing this without having to modify anything.


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 7:51 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
Vinny excels at engine rebuilds and gearbox rebuilds. He stands behind his work 100%.
You will never be sorry for buying one of his gearboxes. He's been rebuilding them for more than 40yrs.

Bryan Little has forgotten more about the Z car than I will ever learn. I stole his Z for a week once while he was on vacation and he has re-worked every single system on the car to 95% competition strength. It's almost too hot for the street, but he tones the exhaust down and makes it sound like a pussycat. His 4:11 rear gears makes it take off like a rocket (the first and only 4:11 Z I've driven) and it's safer to start the car in 2nd gear.

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1970 240Z


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 Post subject: Re: Transmission swap
PostPosted: Thu Jan 12, 2017 8:30 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
That is actually what Vinny told me, he said he's been doing transmissions for decades and engines for a very long time as well. I'm looking forward to meeting him in person.

Bryan's Z is a favorite of mine, and I'm looking forward to meeting him and his Z hopefully too! I will occasionally watch his YouTube video of the 7k rpm shifts just to hear it go..... What a fun car that must be!

A friend of mine has a 260z with 4:11 gears and it is quite a fun car to drive. I'm planning on adding 3.90 gears to mine, I'm hoping it has a similar effect! His has a larger cam than mine, stiffer clutch too. It's entertaining for sure.


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 Post subject: Re: Transmission swap
PostPosted: Fri Jan 13, 2017 11:13 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
OK, I just learned the 260 and the 280 use the same bellhousing, case and tailshaft, so you shouldn't have any clearance problems anywhere with the transmission body itself. I *ASSUME* (oh, oh) that means they shift from the same place and the stick *should* pop up right thru the same place. The only difference btwn them are the 3rd gear ratios and the extra (5th) gear. That should mean you can use your own old shifter. I guess you got lucky! :mrgreen:

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1970 240Z


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 Post subject: Re: Transmission swap
PostPosted: Sat Jan 14, 2017 9:26 am 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
That's great news Frank! Thank you for looking into that for me.

Jay


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 Post subject: Re: Transmission swap
PostPosted: Mon Jan 16, 2017 9:34 am 
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Joined: Wed Jul 23, 2008 2:38 pm
Posts: 3098
Location: rhode island
Just make sure you use the correct throw out bearing sleeve. There's a short and long one, you want the long one to the best of my knowledge, but double check that. Also, as for shift rods, there are straight ones and curved ones to solve any location issues. All the transmissions will swap to any engine, any Z from 70-83, 4 and 5 speed There are two 4 speeds and the older one, the shifter I think was located in a different location, or the hole was in a different spot on the first Z's but all workable. There are two 5 speed, the early one with 2 ears on the tail shaft is a 4 speed converted to a 5 speed via the factory and has per say a weak link there, but it's Japanese metal and I haven't broke mine yet, but not going to push it either. The later 5 speed found in the 81-83 280zx non-turbos is an actual built 5-speed and just stronger than the early ones, and has one ear on the tail shaft. Gear ratios at significantly different, and the later is called a close ratio mostly because of the gearing between 2nd and 3rd and has like a granny first. From my personal experience I think it's better to use a 3.9 or 4.11 with the later 5 speed.


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 Post subject: Re: Transmission swap
PostPosted: Mon Jan 16, 2017 9:54 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
Thank you Paul!

I'm going to have to give my 4 speed shifter a try first I guess as it's all that I have.

I just bought a 3.9 differential today which I'm very excited about, and the transmission is the early model which I am aware has the shared 4/5 gear piece that creates a weak link. I'm not planning on really hammering it so I think I'll be fine, I'm hoping the gearing will work out ok and result in an overall quicker car. I'm not unhappy with my 4speed gearing but i think highway driving would be unpleasant with the 3.9 and 4th gear only. That's my main motivation for the swap.


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 Post subject: Re: Transmission swap
PostPosted: Mon Jan 16, 2017 10:30 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
My stock 2.4L with the "71-a" gearbox and 3.9 differential gave me 124mph, floored on level road. It would NOT do 125, altho I know a few tricks today which might have given me 125 and maybe more back then (or I could have simply driven it off a high cliff). I also averaged 28 mpg on two of my cross-country trips, while the car was loaded with everything I owned. When empty I could still out-drag a '55Chevy w/4bbl, lots of 350 Corvettes and 280Zs up to about 75mph, at which point they just began walking away from me. The car demonstrated a heart-stopping performance against a 275GTB/4 Ferrari once which seared itself into my memory forever (we were both over 100mph in a tunnel :shock: ). The car was a good performer until it ran out of breath above 6500rpm.

Back then 2400rpm gave me 71mph. I still use that same 3.9 R180 today, altho I now run a siamesed F54 L28 and a 280ZX 5-spd. Now 2300 rpm gives me 73-75mph in 5th. In some ways my original 4spd was quicker than the ZX 5spd is, but as you said, it screams for another gear on the highway so that 0.864:1 overdrive 5th gear make a world of difference.

A 260 has a longer stroke (more torque) and a higher rev-limit than my 240 had (about 8 grand instead of 7), so your numbers should be better than my original 240 if you install a 3.90.

(Vinny is good at setting load, gear clearance and backlash in differentials, too).

Talk to Vinny, Paul or Bryan Little about what color speedometer drive gear you will want for your 3.9 pumpkin. (Actually, Bryan's website might have a section about that.....?)

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1970 240Z


Last edited by Frank T on Wed Jan 18, 2017 12:39 pm, edited 10 times in total.

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 Post subject: Re: Transmission swap
PostPosted: Mon Jan 16, 2017 10:59 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
Right ~ I found it.
In Bryan's Datsun Z Garage website homepage, you can scroll down to the link about gear ratios. That gives you a complete comparison of all the gear ratios in each gear of each transmission. Then, if you press ENGINE MODS (steering wheel and speedometer gauge), you can scroll down and it shows your 3.9:1 differential requires a "white" (19 tooth) speedometer drive gear.

If you sell or store your original 260 differential, be a sport and place your stock speedo gear in a sandwich bag wired to the tailshaft. The next owner might not even be aware he has to change it.

Incidentally, you actually said you were hoping to build your 260 to be "quicker" (not faster) by swapping in a 280 gearbox. That didn't happen for me; I got higher top speed but slightly slower acceleration. Nobody would have been disappointed by it, unless they remembered how quick the car was with the original "71-a" gearbox. It just wasn't quite as quick with the 5spd as it was with the old 4spd. Now that I've replaced the L24 with the tricked-out L28 and the ZX 5spd, the acceleration is back to (at least) as quick as it was 40yrs ago, but I also have the relaxing 5th gear for the highway. In fact, the L28 has the same stroke as your 260 has, so I can actually start the car in 2nd gear and use all that torque to pull away at low revs, like an old Austin Healey. I spend most of my life in 2nd and 3rd, with 4th for boulevard travel. 5th gear is only useful for highways over 60mph.

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1970 240Z


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 Post subject: Re: Transmission swap
PostPosted: Tue Jan 17, 2017 12:07 am 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 12863
Location: CT
Oh, by the way:

My throwout bearing failed with only about 2,000 miles on it, but it was about 22yrs old. My car (like yours) had been stored for many moons and started about twice a month. It's not just mileage; old is old. I won't belabor this point, but $25-30 is a really low insurance policy.

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1970 240Z


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 Post subject: Re: Transmission swap
PostPosted: Tue Jan 17, 2017 8:58 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 265
Alright already Frank........


........... I'll replace the throwout bearing when I do the swap! :mrgreen:

I'm surprised that your car felt slower when you swapped transmissions. From the chart on Bryan's website I can see the ratios for each gear are a few tenths less aggressive....but you also mated it up to a 3.90 final drive....it should have been noticeably quicker I'd say. That's surprising to me. Looking the ratios over I am thinking that I'll probably be quite happy with the 280a trans, each gear is just a bit milder than the corresponding gear from my current 4 speed but I'll have more gear in the back to make up for it.

Idk, seems like it will work out good. It's going to be fun trying it out anyway!

I plan to order a speedo gear from the Z store soon too. No worries on throwing anything away, I keep all the original stuff together. I have no desire to sell it either, this old girl is stuck with me for life! :wink:

Your Z sounds like a fun one to me Frank, I hope to see it this summer!


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