R180 3.90 Rear End

[dhayes5]

I am looking at putting an '83 non-turbo (ZXB) 5-speed into my '72 240. Everything I read says to go with a 3.90 / R200 rear end with this tranny. However, I have found an R180 3.90 (seems to be rare) which would be a direct bolt in with no need to change the mustache bar etc. I do not plan to do anything radical to this car and think the R180 would be sufficient for the stock engine. Is $250 (includes shipping from California to NC) too much to pay for this? I know I can get an R200 for $100 but then I have to locate the mustache from a 280Z etc. etc. so by the time I get all the parts I may have $200 in it anyway. Is the R200 that much better for my application? Also, is the R200 any quieter than an R180?

[Royce]

I don't know that the R180 is any noiser than a R200. I think that if you are getting a lot of noise it is because you have a worn out diff, mount insulator or bushings. Either that or it is because you are using a solid mount insulator, like me, or poly bushings on the rear suspension pieces that transmit more driveline noise into the cockpit.

I don't think you "need" a R200 but I wouldn't want to have a R180 shipped across contry. It is just too heavy to ship back if you have some problem with it. I believe the 3.9 R180 would be from a 200SX, sorry don't know years, or a front diff from a Nissan 4x4 truck. I would try to find one close and depending on where you buy it should be between $60(pick & pull) - $175. If you do end up swapping to a R200 it really is not that big of a deal, okay it is a bit heavier, once you have all the right pieces. When I did mine 10 years ago I bought a cheap wrecked 280Z and swaped what I needed.

Hope it helps! Have fun!

[Ben]

I've put over 230HP through a stock (but rebuilt) 3.90 R180. That power is enough to bag the rears at 50mph on the 1st-2nd gearchange @ 6000rpm through the auto. No problems whatsoever. I've used the same combination in my ~220HP Skyline & split a spider gear while gently accelerating behind another vehicle. I turns out that the spider gear had been cracked for a long time (before I bought the car), so it was a matter of when, not if. The car now runs a 3.54 R180, with zero problems.

My 240Z will get a R180 with a Quaife LSD & I expect that to handle 400HP with no complaints.

[dhayes5]

Thanks for the input!

There was a web site I ran across a while back that showed what diff. came from what car. I remember the r180 being in the front of early '80s 4x4's and for a 6month period of 240sx production. I probably need to find that site.

[Marty Rogan]

Hey Dhayes,

I see from your tag line that you are running PU bushings with Tokicko shocks. Are those the non-adjustables? What springs are you using? How is the ride quality? I am thinking about going to PU's, but I am concerned withmaking the ride harsh.

I have the Tokicko non-adj and am thinking about going with the Stage 1 Euro Springs.

Thanks,

Marty

[2ManyZs]

Ben, I think you will find the R-180 won't hold up to 400hp. Up to 300 is about the limit from all that I have read. Anything above 300 and you are risking a failure. Especially if you put the extra strain on the stub axles with the Quaiffe. I don't think the ring or the pinion will take that amount of hp for very long. Check out the hybridz web site, I believe they have the most experience with Z's with that much hp and I think they will agree that 400 is too much for the R-180.

dhayes5, the 720 4x4 truck from 1/83 to 6/83 have the R-180 3:90 front diff. The 720 4x4 from 6/83 to 12/85 had a 4:11 as did the 200SX non turbo from 84-88. The 720 4x4 also had a 4:37 from 6/79 to 12/82 and a Long Bed 6/79 to 6/80 had a 4:62 fron diff.

IMO, if you are putting a ZX 5 speed in if you can get a 4:11 or 4:37 you may be more pleased with the rpms in overdrive on the highway while substantially increasing your acceleration in the lower gears. I believe I read somewhere that with the 5 speed and a 4:11 the overall gearing in overdrive is below 3:36 which is the stock diff. ratio. I can look for the write up if you need more info, I can't remember which magazine I read it in.

[dhayes5]

Marty,

I do have the same shocks you do, the Tokico non-adjustable (blue) gas shocks. With my current setup I did not notice as big a difference in ride harshness as I did in tighter suspension and better handling. My stock springs are dead though (see my post asking about stock ride height). I have ordered the stage i euro springs as well because I did not want to lower the car. Also, when I went from 195/70/14's to 205/55/16's my ride quality actually got smoother rather than harder -- not what I though would happen going to a lower profile tire. The panasport rims weigh less than the previous '70s mags. Maybe the lower unsprung weight helped.

Check your alignment after you put the PU bushings in. My RF caster was way out and my camber was out on all four corners. I hope the springs will help this. I think it will since all four corners of the car are at different heights.

If you have not done it already, the 4-piston upgrade is an easy upgrade and big imrovement to the stock brakes. I got mine from a local parts house ('80 Toyota 4x4 Truck). The only mod I had to make besides cutting the dust shields (very easy) was to get new rigid brake lines (also not too hard or expensive).

What do you have for exhaust?

2ManyZ's

I would love to see that article. If you can let me know what magazine etc. I might be able to get a copy at the liberary.

[2ManyZs]

I found the ,agazine it was in, it's the old Z Car magazine, Nov/Dec issue 1997. It is in the Ask Mr. Goodtech section, I will post the gear ratios in the Tech forum later today. This will give everyone a chance to look at it and perhaps answer a few questions for future users.

It list all the gear ratios for all the different transmissions, plus the overall gear ratios comparing a 280 5 speed with the Zx 5 speed.

[dhayes5]

When I find my 5-speed I want the 81-83ZX (ZXb) transmission. How do I tell if I have the right one if it is out of the car? Does anyone know what the identifying marks or numbers are they for this tranny?

Also, how hard (and expensive) is it to get parts (bearings, synchros and gears etc.) for these transmissions?

[SuDZ]

Originally posted by dhayes5

The only mod I had to make besides cutting the dust shields (very easy) was to get new rigid brake lines (also not too hard or expensive).

Where did you get the rigid brake lines?

SuDZ