Hi

I want to go back to original rear diff. That include to instal a R180 instead of my R200.

I bought the car with the R200.

I´ve found an R180 but the gear ratio says 3.545(3911) and comes from a Automatic.

I have a 5 speed transmission so will that make problems for me?

My car is a 240Z, 1973. I´m not racing just cruising.

No problem, the 3.54 rear end will give you a little more go, faster off the line but not much compared to the stock 3.36 ratio.

Thanks Grannyknot and have a nice day.

2 hours ago, Jarnved said:

Thanks Grannyknot and have a nice day.

What's driving the return to R180? Most people want to go the other way...

I ran the stock R180 3.36 behind my L28ET for years before my kids shamed (badgered) me into swapping to an R200. Personally, both me and my turbo motor were just fine with the R180 but it made the kids happy for some reason... You NEED an R200 = Internet Wisdom.

I guess the reasons I would favor the R200:

Nissan evidently found it to be a good idea to go to the larger ring gear. (wear?, strength?)

Obviously it should be stouter, but I don't really thrash my cars like that anymore.

My #1 reason would be there seem to be a lot more ratios available in the R200. Especially if you go to an R200 out of a more modern car in a hybrid z type manner. Potentially R200 ring and pinions might be available also if you had a really precise ratio need...

10 hours ago, Jarnved said:

Hi

I want to go back to original rear diff. That include to instal a R180 instead of my R200.

I bought the car with the R200.

I´ve found an R180 but the gear ratio says 3.545(3911) and comes from a Automatic.

I have a 5 speed transmission so will that make problems for me?

My car is a 240Z, 1973. I´m not racing just cruising.

That looks to be a great combo you have of 3.54 and 5 speed.

I have a 5 speed and both 3.9 and 4.11 R180's.

I am thinking of going the route of a 3.54 myself.

I am running too many RPM's on the highway for my liking.

I am swapping my whining 3:36 for a 3:54 as we speak. I am currently running a 5 speed and can't wait to relieve myself of the whining and the somewhat better performance. I realize that it's not going to be dramatic, but I am not going to be autocrossing the car either. 3:70 is what I would have preferred, but I'll be happy enough if the decelleration whine is gone...!

15 hours ago, Patcon said:

What's driving the return to R180? Most people want to go the other way...

I want my car to be original.

2 hours ago, Jarnved said:

I want my car to be original.

Did it originally come with the 5-Speed...? My '73 did not. If I had to do the restoration over, I would have left the original 4-Speed intact as well as the original engine. I would never sell either, so I can still swap both back in for a true "numbers matching" car. Until then, I will drive it and enjoy it.

Edited August 22, 20231 yr by Tirnipgreen

50 minutes ago, Tirnipgreen said:

Did it originally come with the 5-Speed...? My '73 did not

Jarnved is in Denmark, In europe we had the 240z with original 5 speed gearbox!  (Fs5C71 A or later B )  I once had a 240z original Dutch car (Netherlands) and it had the orig 5 speed standard. (Fs5C71B) That gearbox (and diff! 3,9:1 ) is now under my usa spec 240z. (got the orig parts as spares on the attic)