Good 240z engine/trans/diff combination?

[1984]

So I recently acquired a 1972 240z that has been sitting in a field for 20+ years.

 

Here's what I've identified:

-original L24 engine

-E31 cylinder head

-FS5W71B close ratio 5 speed transmission

-R200 differential with 3.7 ratio

 

The car has also been lowered. Any thoughts on this combination? 

 

I'll be posting on Z specific forums as well but I figured that I'd post here since I'm a member and there are some very knowledgeable people here.

Thanks!

 

 

[datzenmike]

Stock gears were 3.364 so a 3.70 is perfect for the change to the close ratio transmission.

[Icehouse]

Mine has a SR20DET.  I really like the combo in the Z.  

[1984]

10 hours ago, datzenmike said:

Stock gears were 3.364 so a 3.70 is perfect for the change to the close ratio transmission.

That's good to hear. I plugged the ratios into a rpm/mph calculator and it seemed to be pretty good. The real test will be a drive.

9 hours ago, Icehouse said:

Mine has a SR20DET.  I really like the combo in the Z.  

Congratulations! I bet yours has floor pans as well! Double bonus combo!

[datzenmike]

3.364 changed to a 3.70 is a 9.98% change in differential gearing.

 

First gear only for take offs, the stock 4 speed is 3.592 and going to the close ratio first of 3.062 is a 17% drop in RPMs so subtracting them there is only an over all 7.32% decrease¹ in RPMs in first gear.  At 2,000 in first this amounts to less than 150 RPMs.

 

Forth is always 1 to 1 so nothing to subtract and only the 9.98% increase in RPMs over a stock differential. In fourth at highway speeds, say 3,000 you are revving about 300 RPMs higher than fourth in the stock 4 speed and differential. In fifth (overdrive) at 3,000 RPMs this drops to 2,235 or 765 RPMs lower to save gas.

 

¹ Retaining the stock 3.364 differential and going to the close ratio 5 speed would have been a disaster for performance

 

 

[demo243]

A lot of unknowns on that engine- if it has been built up it could be solid as it is- definitely a possibility giving that someone did some work swapping out the trans and rear end along with suspension work.

 

If you are after more power then- no replacement for displacement! Find and L28 and build it up- can’t help you with the details as I’m still figuring those out myself- but the L28 in my Z feels pretty good!

[1984]

Here's a screenshot of speeds at 5000rpm. Just now figuring out how to post pictures so bear with me.

 

http://

 

As far as the engine goes, what I do know is that it ran well until the water pump went out. The previous owner noticed this while the engine was warming up in the driveway. For whatever reason they didn't replace the water pump and just let the car sit for a couple decades.  

 

The engine turned over easily by hand.

 

Here's a picture of the rear suspension. Anyone know how it's been lowered? 

 

http://

[demo243]

2 hours ago, 1984 said:

Here's a screenshot of speeds at 5000rpm. Just now figuring out how to post pictures so bear with me.

 

http://

 

As far as the engine goes, what I do know is that it ran well until the water pump went out. The previous owner noticed this while the engine was warming up in the driveway. For whatever reason they didn't replace the water pump and just let the car sit for a couple decades.  

 

The engine turned over easily by hand.

 

Here's a picture of the rear suspension. Anyone know how it's been lowered? 

 

http://

Everything looks pretty stock there- probably just some lowering springs 

 

Got any photos of it on the ground? Might help show how low it is.

[datzenmike]

 

Only the '80 280zx had the 0.773 OD 5th. You may have the '81-'83 transmission and its 0.745.

 

 

 

I thought the 240Z had finned aluminum drums?

[1984]

Oh so just the coils are shorter. Wouldn't the gas shock portion have to be shorter as well so they don't bottom out?

1 hour ago, demo243 said:

Everything looks pretty stock there- probably just some lowering springs 

 

Got any photos of it on the ground? Might help show how low it is.

There's some pictures. Those tires are 215/70 so 25.9".

 

[1984]

Yeah, I think it's from a 81-83 280zx. Must have been looking at the wrong part of the ratio chart. 

 

Those do look like cast iron brake drums. I'm guessing that they are just cheap replacements. I just did a quick search and aluminum drums are not only hard to get but they cost 4 times as much.

1 hour ago, datzenmike said:

 

Only the '80 280zx had the 0.773 OD 5th. You may have the '81-'83 transmission and its 0.745.

 

 

 

I thought the 240Z had finned aluminum drums?

 

[1984]

Here's some transmission pictures:

[datzenmike]

I can tell you that this transmission was made after '79 and it's from an EFI car. Could be from an 810 or Maxima but no reason to believe this. Probably from a ZX.

 

If the transmission was out put in 5th and turn the input shaft 20 times while counting the output.

 

If 24.5 turns it's the 0.773 5th

If just over 25 turns it's the 0.745

[demo243]

3 hours ago, 1984 said:

Oh so just the coils are shorter. Wouldn't the gas shock portion have to be shorter as well so they don't bottom out?

There's some pictures. Those tires are 215/70 so 25.9".

 

Nice find! That's a cool looking car.

 

The short answer is yes- ideally the struts should be shortened and use shorter inserts in order to keep the shock travel. But... there were a number of aftermarket lowering spring kits available- and still available. The majority of which were more then likely just slapped on. It does look like those tires have a good bit of sidewall which will make the car look lower too. 

 

Here is a shot of my car sitting on a 15x8 wheel with a 225/45 tire-- note the huge gap! but with a bigger tire it would look lower. 



Still those springs look to have fewer coils then the ones on my car which lead me to believe it would sit lower in its travel and therefore lower the car. 

Could run it as it is if you don't have any issues with it bottoming out.

Edited November 27, 2023 by demo243

[1984]

I agree. I read a post you made here about the close ratio transmission from the Maxima, which is a possibility, but it's more likely that it came from a 280zx. Especially since the previous owner said that the previous owner said that some parts came from a 280. 

[1984]

I wish I would have saved this car sooner. While in highschool a friend drove it but when he went away for college he left it at his parents house. The water pump went out around this time and has just been sitting since. I assumed they had gotten rid of it until I saw it about a month ago.

 

So anyway, I know a little bit about it's history and could possibly learn more. They said that the previous owner lowered it, who they are still in close contact with. 

 

I do know that they drove it as it is for years. I'll inspect things a little closer but I didn't notice any rubbing on the tires or anything else. And I'll have to pull a strut out for inspection. Thanks for your input, I hadn't thought about a chopped coil.

 

Oh and good looking car. Did you black out the trim? If so, how'd you do it?

14 hours ago, demo243 said:

Nice find! That's a cool looking car.

 

The short answer is yes- ideally the struts should be shortened and use shorter inserts in order to keep the shock travel. But... there were a number of aftermarket lowering spring kits available- and still available. The majority of which were more then likely just slapped on. It does look like those tires have a good bit of sidewall which will make the car look lower too. 

 

Here is a shot of my car sitting on a 15x8 wheel with a 225/45 tire-- note the huge gap! but with a bigger tire it would look lower. 



Still those springs look to have fewer coils then the ones on my car which lead me to believe it would sit lower in its travel and therefore lower the car. 

Could run it as it is if you don't have any issues with it bottoming out.

 

 

[demo243]

Thanks- that’s her “good” side… driver door is a bit beat up, and over all has a poor failing oxidized silver paint- but that kinda gives it a rough and tumble look. Most the stainless trim is actually pretty still there- just shadowed I guess, but does have a black rubber windshield gasket. Kinda going for a grey/black look right now.

 

Better late then never for saving it! Hopefully it doesn’t give you too much trouble.

 

I look forward to seeing your progress!

[1984]

So I cleaned up the valve cover and head a little bit in preparation to take the valve cover off (first time taking a valve cover off any engine). 

I had read that the camshaft oil spray bar is destined to fail on the early L24 engines and sure enough it has. 

 

See pictures below.

 

The short section of the spray bar on the radiator side of the engine is missing and I'm wondering where it might be. Did it fall into the timing chain void? I drained the oil and fished around through the drain plug with a magnet to no avail. Also went down the timing chain void with the magnet.

 

My amateur eyes saw no damage to any of the springs or cams. But the spray bar is beyond repair and is not well designed so I plan to fabricate a new one that is failsafe. 

 

My question is: where did that 2-3" section of tubing from the camshaft oil spray bar end up? I'm a ways away from cranking the engine but I'd really like to find the missing piece. 

 

 

 

 

[datzenmike]

Likely down at the bottom of the timing chain cover. With luck it made it safely into the oil pan. Looks like large brake line. Probably could cobble something up. Pinch the end closed, tack it on and have a couple of holes like the rest to spray oil on the cam.

 

If that end is off the spray bar all the oil will just gush out there. There will be a lot less for the rest of the cam lobes.

 

On the L series four cylinders, the cam is hollow and each lobe has an oil hole on it

[yenpit]

On 11/26/2023 at 2:45 PM, datzenmike said:

 

Only the '80 280zx had the 0.773 OD 5th. You may have the '81-'83 transmission and its 0.745.

 

 

 

I thought the 240Z had finned aluminum drums?

 

All of the 240Z's had finned ALUMINUM drums from the factory, but they were discontinued in the aftermarket years ago.  I believe all of the aftermarket are now finned CAST IRON 😒

[yenpit]

On 11/26/2023 at 4:56 PM, 1984 said:

Here's some transmission pictures:

 

Single forked ear on bottom left of tail housing & speedo pinion bolt at 6 o'clock is the 5th ratio .745 5spd..............that is a good one!

[yenpit]

On 12/2/2023 at 10:14 PM, datzenmike said:

Likely down at the bottom of the timing chain cover. With luck it made it safely into the oil pan. Looks like large brake line. Probably could cobble something up. Pinch the end closed, tack it on and have a couple of holes like the rest to spray oil on the cam.

 

If that end is off the spray bar all the oil will just gush out there. There will be a lot less for the rest of the cam lobes.

 

On the L series four cylinders, the cam is hollow and each lobe has an oil hole on it

 

Rebello has a custom made oil spray bar, that is pretty much fail safe.  We use them on our vintage race engines.