Datsun Roadster Forum-311s.org

Currently running the stock 3.9 diff combined with 195/65 R14 tires. (Tire diameter pretty darn close to stock diameter)

Thinking of possibly switching over to a 3.7 diff on my 1600 with a 4 speed, I'm but reluctant if there is problem with diving in the hills or mountains.

(Found the gear calculator in the wiki, so I'll get on idea of rpm change.)

I'm curious what the owners that are currently running the 1600/4spd 3.7 diff set are experiencing in drive-ability on different road grades.
Comments anyone?

Cheers
Ray B.

Its a nice combination. Corrects a bit for the VW ratio 1st gear and drops the highway revs. You won't be winning stoplight drag races, but definitely makes the 4speed more highway friendly. Give it a try, you will probably like it.

I have recommended this a bunch of times to 1600 owners. Nissan got the gear ratios backwards, both cars are better off trading differentials. Also everyone that has done this has been happy with the change.
Dave

david premo wrote: ↑Thu May 21, 2020 9:42 pm I have recommended this a bunch of times to 1600 owners. Nissan got the gear ratios backwards, both cars are better off trading differentials. Also everyone that has done this has been happy with the change.
Dave

Well of course since I have now had both my 3.9s overhauled. I'm putting a 5 speed in the one, maybe both.

Yeah all manuf's gear too low ratio diff it to keep the cars driving .very fast and racy gets more tickets &crashes then its too $$$to insure to drive
3 .7 still to low 3.54 or even 3.0 is what I want
Steep hills arent fun on a any stick real quick
3.7 s are not easy to find Id bet , most likely came on flat terrain states AZ. FLA.

3.7 came stock in 2L.

redroadster wrote: ↑Fri May 22, 2020 6:05 am 3.7 s are not easy to find Id bet , most likely came on flat terrain states AZ. FLA.

Better not bet too much on that: 3.7 was the stock ratio for 2000s delivered to USA, and show up regularly on eBay.

https://www.ebay.com/itm/Datsun-Roadste ... SwarNevUv9

Jon

"Its a nice combination. "
x4

As JT says.
I've recommended it myself. Did it on my old 1600. Never a problem.
Most likely you will hardly notice except for a couple hundred rpm down on the highway, maybe less (on stock size tires or near stock). In the lower gears you will hardly notice it at all.

Count me in too! It's nice if you want more "relaxed" cruising rpms...no noticeable deficits otherwise.
I will add that 1600s with the stock 3.9 just sing along at "high rpms" on the freeway...personally never had a problem with it.

Also... the R16/3.9/5-speed combo is great.

jhayden wrote: ↑Fri May 22, 2020 8:14 am

redroadster wrote: ↑Fri May 22, 2020 6:05 am 3.7 s are not easy to find Id bet , most likely came on flat terrain states AZ. FLA.

Better not bet too much on that: 3.7 was the stock ratio for 2000s delivered to USA, and show up regularly on eBay.

https://www.ebay.com/itm/Datsun-Roadste ... SwarNevUv9

Jon

Maybe just here ...in the last 12 years of searching CL
I remember 2 or 3 2 L 311s. .unless it was in the 7500 up range ..I searched for 2 yrs looking for mine found only 1 that was worn out as hell for 3800$

Alvin wrote: ↑Fri May 22, 2020 9:00 pm Count me in too! It's nice if you want more "relaxed" cruising rpms...no noticeable deficits otherwise.
I will add that 1600s with the stock 3.9 just sing along at "high rpms" on the freeway...personally never had a problem with it.

Also... the R16/3.9/5-speed combo is great.

Agreed:
I had the 4 speed 3.9 and drove it across country no problems, but the drone does get too you after5-6 hours. The entire time, my buddy and I would comment on how nice it would be to have a 5-speed and the car really seemed to need it. I REALLY would have enjoyed the lower noise of a 5 speed. So, I now have the H20/3.9/5-speed and agree, it is a great combo.

I just added3.7 To my 1970 1600 last month. I love it. I notice it on the freeway. It’s a fantastic upgrade. I still have the original 4 speed in it.

I was just up at Mike Young's place, and he had a beautiful 1600 / 4 speed car with the 3.7 rear in it. He says it's the best combo. With the 3.38 1st gear, it's still quick from a stop, but you get a little rpm relief on the freeway. Apparently there was a 3.5 rear in the 810 wagon that add also fits.

I swapped a 3.9 into my 69 2000 on the recommendation of Dave Premo when I switched to Solexes. I like the combo. I have my original 3.7 sitting in my garage if anyone is interested. I hope to be in the bay area in a couple of months so can get it to California.