280z 5-speed into a 240?

[Zed Head]

They came through well.  Looks like an R180.   Pretty crusty but it's a dry crust. 

I don't know how solid the FSM data is.  An R180 from an 810 would swap over though, from Terrapin's chart.  Regardless, if you're sure it's 3.7, it probably is.

[Garm]

Yeah I need to clean that. I only did what I needed to change the fluids (which were awful) 

[munters]

One thing to add.

Outside us

diff 3.7

5 gear first 2.9 and fifth 0.83 I think

[siteunseen]

R180 on the left, R200 on the right.

https://www.lainefamily.com/240Z_V8_Conversion-files/240Z_Conversion_Differential_Driveshaft.htm

[Garm]

^ THAT is great, thank you

 

[EuroDat]

On 5/16/2019 at 6:27 PM, Garm said:

Understood, thanks. I am starting with a 280z motor in the car, I think that simplifies things. I've read a few places it's a straight bolt on, even re-using the 240 shifter. 

And no, I don't want weeks worth of downtime trying to figure out something or fabricate something; I'd rather be out driving it!

Things to consider if you don't want to spend a lot of time working on the car and still want a 5 speed.

Look for a 5 speed out of a 280Z or a 280ZX 2+2. They are both "wide ratio" FS5W71B transmissions. It will give you a first gear that is fairly close to your 4 speed. Still high, but close.

The 280ZX Coupe "close ratio" FS5W71B will feel like you skipped first gear and started off is second. Try that with your 4 speed and see how it feels to start off in second gear.

The next step would be to look for any 240Z, 260Z or a the 280Z after 77 with an automatic transmission. They have a 3.545:1 R180 diff and it is a direct replacement for you 3.364:1 R180. The 5th gear will still be taller than the original 4th, improving highway fuel economy, and give you better off the mark performance.

They are the quick and easy mods.

I can post an excel file on the ratios later when I am home if you want them.

If you go "close ratio" then you will want to change the diff to something like the R200 3.7:1 or 3.9:1, but that is a more involved mod.

[Dave WM]

I have the 3.54 on the close ratio, and yes there is a bit more finesse required starting off. Not a lot but noticeable. living in flat land makes it a non issue, if you were in hill country and found yourself stopped on a uphill grade it may make it more of a problem. Up side is you can stay in 1st a bit longer. The CR trans I pulled was setup for a 3.7 based on the speedo gear that was in it.

if you are in a lot of stop and go traffic it may be an issue. IMHO you should drive it as is for a while, you may find it not needed at all.

 

[EuroDat]

Here is a simple excel file that shows the different speeds per transmission/diff ratio.

Calculate ratios 01.xlsx