5 speed with 3.54 rear gears

[Rich1]

It appears that a lot of 240z are now running an 81-83zx transmission with 3.9 or 4.11 gearing.

I was looking at doing this as well--until I came across the May 2008 Classic Motorsports article on their 240z drivetrain swap. They used a 81-83zx 5speed transmission with 3.54 gearing.

There appears to be some advantages to this appoach:

1. It looks like a straight swap--it's an R180 (instead of R200), so you wouldn't need the Zx mustache bar, etc

2. Lighter weight differential

I realize that the R200 is a stonger differential--I will be running a rebuilt/ lightly modified L24 motor.

Is anybody on the Z boards running a 3.54 diff?

Thanks..

Edited September 14, 2009 by Rich1

[kenz240z]

I've got an L28 and 5-speed out of an '82 ZX in my '73 240Z. I swapped the 3.54 (my car originally had an automatic) with a 3.90 R180 from an early '80's Datsun 4X4 pickup. The side flanges are different on the truck. Fortunately, the flanges from the 3.54 will bolt on. I found the 3.90 R180 at a local pick-n-pull salvage yard. A friend of mine found a 4.11 R180 from a Nissan 200SX. Here's a helpful link: http://atlanticz.ca/zclub/techtips/differential/index.htm

[jmortensen]

81-83 trans has taller gearing and is less well suited to the 3.54 rear gears. The earlier 5 speeds were basically the same as the 4 speeds but had a shorter overdrive, and they were better suited to the 3.54, although they still had a big gap between 2nd and 3rd gear. The 280ZX 5 speed N/A came with a 3.90, and there was a reason for it. I would go with 3.90 or 4.11 gears for a modded street car. You can get a 4.11 R180 pretty easily out of a 240SX. They require an easy modification described here:

http://forums.hybridz.org/showthread.php?t=114798

[Bruce Palmer]

Unless you're putting out some serious torque, fifth (~25% over) will be worthless on anything other than flat ground and you'll be rowing back and forth between 4th and 5th just to keep the RPMs in a usable range.

[240jetjoc]

I have a stock 1972 with 3.36 gears and a 1981 5-speed. It handles the taller 1st gear without problems. My car cruises effortlessly at 50mph or more in fifth gear. It will accelerate up rather steep hills in 5th gear without a hitch, even the coast range here in Oregon. Fuel economy is excellent. Would a 3.54 or lower ratio be better? Probably. Is it necessary? Not in my experience. Beandip has ridden in my car on several occasions and can verify my comments. The L24 has plenty of torque for a 2300 pound Z, even with the 81-83 5-speed.

Edited September 14, 2009 by 240jetjoc

[=Enigma=]

1. It looks like a straight swap--it's an R180 (instead of R200), so you wouldn't need the Zx mustache bar, etc

Just for clarification, the ZX does not have a mustache bar, only a small rear mount bracket. As correctly pointed out, the later style mustache bar is only needed when using an R200 in the S30 chassis.

[beandip]

I have a stock 1972 with 3.36 gears and a 1981 5-speed. It handles the taller 1st gear without problems. My car cruises effortlessly at 50mph or more in fifth gear. It will accelerate up rather steep hills in 5th gear without a hitch, even the coast range here in Oregon. Fuel economy is excellent. Would a 3.54 or lower ratio be better? Probably. Is it necessary? Not in my experience. Beandip has ridden in my car on several occasions and can verify my comments. The L24 has plenty of torque for a 2300 pound Z, even with the 81-83 5-speed.

I do agree, it depends on what you want the Z for. Drag racing go with the 3.90s or 4.11s but if you want a great street driver I would keep the 3.54s I have a automatic which has the same ratio as the 4 speed in top gear. I was running 3.90s and the car off the line was strong. But now I have gone back to 3.54 and the Z is now a pleasure to drive. I don't have my Z for drag racing or track use. I belong to a Z Club and we cruise all over he west coast with our twisting hwy and mountains. Spirited driving for sure and the gearing is great now. So it depends on what you expect from your Z. I say keep the 3.54s give them a try and see what you think for your kind of driving. You can always change later.

Gary

[rdefabri]

I am running a 5-speed with (allegedly) a 4.11 R180. I say "allegedly" as I haven't confirmed...my suspicion is that it's a 3.90 since acceleration is nice, but not off the charts. However, I did take a spin in another board member's Rebello stroker car, and while his was quicker, I didn't think my car was that much slower.

I pull about 3,000 rpm in 5th at 60 mph FWIW. 4th and 5th barely have a difference, so to the points made previously, you may want to stick with the 3.54

[kenz240z]

For those who are considering a 3.9 or 4.11 diffy, swapping in a R180 truck diffy is simple & straightforward. In the photo with the two diffys, the stock 3.54 is on the left and the truck 3.90 is on the right. It is the front diffy out of a early '80's Datsun 4X4 (K embossed on the top). The next two photos show the side flanges. The one on the left is from the stock 3.54 and the one on the right is from the truck 3.90. Note that both flanges use a bolt through the middle to attach to the diffy. So, it is a simple matter of removing the flanges from the truck diffy and bolting on the flanges from the stock diffy. No buttons to swap between diffys and the stock mustache bar & half-shafts do not need to be changed out.

My '73 has a L28 and 5-speed out of an '82 ZX and a truck 3.90 R180. The '82 ZX had a R200 3.90, so I've essentially got the '82 ZX drive train in my 240Z, although I did replace the fuel injection with SU carbies. My Z is a mountain cruiser, not a track car and not a drag car. I live in Colorado and cruise the twisty mountain roads with fellow Z car owners who enjoy spirited driving. Uphill acceleration is good and I'm getting 20-21 MPG. Probably better on the highway, but I haven't done enough highway driving to figure out the mpg...

[Rich1]

Thanks for the insights..

Adam--thanks for the correction on the moustache bar.

Kenny-thanks for the info on the truck diff swap--which looks easier than a R200 swap.

Anyone know how much is lost in off the line acceleration between running 3.54 and a 3.9?

For those running an R200 diff, do you have an handling issues--like the ones mentioned on John Coffey's Betamotorport's site?

Rich