duowing

I'm wondering, is there a spped limiter or something on my car? The digital dash readout seemed to stop at 85, and I wasn't sure if I was continuing to go faster or not. Is it just something with the autos?

Heat Rave R

On the later 280ZX's, even the analog gauge clusters only went up to about 80mph. So I suspect that's "normal" for your digital dash as well.

duowing

So essentially I am going faster, I just don't know how fast, is there anyway to make the digital dash read past that?

NismoPick

the digi dash just goes to 85mph, no way around it that I know of.... but just because it says "85" you can still go faster... just look @ ya tach... if the tach continues to go up... you are continuing to accelerate

hoov100

you could always swap out the digi dash and put in some sorta aftermarket speedo.

NismoPick

or the 79 "130 mph" analog speedo

domsgarage

The digital on my 85zx went well past 100!

jfairladyz

Let your mind be your speedometer. If don't feel your adrenaline rushing then you're going slow. If you start to feel your adrenaline pumping then you're going fast Thats all that matters in my book. Besides, what good is a speedo over 85 anyway. At that point you're speeding anyways, right? So anything after that can be based on the adrenaline method described above.

NismoPick

which was a 300zx... not a 280zx

duowing

yea, I get you jfairladyz, although it would be nice to know how fast I'm going sometimes, just so I can tell people of my stupidity. Eventually I'm gonna switch to the 5-Speed, which I imagine will allow the car to go faster having 5 gears and all, or be better set up for it and put in the analog dash. Just something about that needle going up is so much better than watching the damn numbers.

By the way, about how fast can you go in a 2+2 auto? I know it only has 3 gears as opposed to 5, does that kind of limit your top speed?

NismoPick

duowing: I want you to play around w/ this web page and report back on what you've learned (no... it's not a trick):
http://www.geocities.com/z_design_studio/

duowing

I've been looking at it, and I guess I'm just not good with this stuff. I can't figure out exactly what it's telling me. It's showing me the gear ratios and what not for the 5-Speed, but isn't the automatic transmission alot different?

NismoPick

yes... all the tranny options are manuals, but do a quick search on the net (or if someone already knows, feel free to post it) to find the gear ratios on the auto trans, then plug them in to the boxes on that page. use your mouse to roll thru the graph.

duowing

Well here's what I've found: http://zhome.com/ZCMnL/tech/GearRatios.html

Auto non-turbo 87-89:

1st - 2.458
2nd - 1.458
3rd - 1.000

Looking at it, the 280ZX would be essentially slower, but still not too bad for an auto. This really makes me impatient to drop that 5-speed in my Z.

007max

hey thats pretty cool, thanks for the link, i really hate my 80mph speedometer

figured out that i got up to 110mph trying to keep up with my friend who was driving his '90 300zx, unfortionately he kept accelerating for quite a bit further after i reached that speed

FubarI33t

I don't know how fast the 2+2 auto's run due to I have never drove mine. I am swtiching a few things around. droping auto trany. putting in a 5 speed, droping the 3.54 rear gear. puting in a 3.90 rear.

lww

Depending on your wheel/tire size, if they're stock, based on the gearing and a stock Nissan 81-83 NA 5 speed, it'll do 152mph at 6000 rpm.

Unfortunately, in stock form, it doesn't have the power to get there.

With the 5 speed, realistically, top speed will probably be in the 120 to low 130 mph range when the car was new or if the motor is running as good as new.

With the automatic it's theoretically 125 mph with the auto and 3.545 rear-end at 6000 rpm. This is probably achievable with a stock motor in new condition.

One with use that's not as good as new will probably be in the 110 to 115 range depending on how much TLC it needs.

I've seen some that would barely hit 100 mph and it was scary even to watch!

The moral of this story is, top speed is a useless measurement. You can do it safely in very few places and even then, you won't be impressed by the results unless you make a LOT of changes/upgrades to the car and the motor / suspension are in top condition.

I would be much more impressed in a car that can do 0-60 in short order and handle the corners like it's on rails. This is 'realistic' fun and the kind I like!

duowing

Is there anyway to modify the digital dash though, so that it will read past 85? I know it's set up so that it won't read past 85. I imagine there's gotta be something just blocking it from reading over that.

NismoPick

hit the MPH / KPH button...

Other than that... there's not really any way around the 85mph max, unless ya play w/ the electronics. Duowing: you could be the first to discover the way around it! Go forth and conquer!

FubarI33t

If you knew computer's. And what lang the chip is programed to. You could reprogram it to go higher. Does a Z have a data port?

jfairladyz

The speedo readout should have it's own drivers. But most likely you could get different drivers and display (capable of a triple digit readout) and use an adjustable regulater to tune it to work with your speed sensor. Hardest part would be calibrating it to the right speed. You could splice off of the existing sensor and have someone calibrate it on the fly while comparing it the stocker. Of course over 85 you'd have to rely on some other means to verify if it were still displaying accurate speed.

Of course there are two far easier methods to go about accomplishing the triple digit speedo. One would be to hack out a 300zx digi dash and steal the speedo display and driver and the speed sensor. Then transplant these to your existing dash.

Or switch over to analog, which would be a cake job considering a little rewiring isn't rocket science to you. Get yourself an analog cluster. Verify if you'll need different sensors or not. Most likely you'll atleast need to get the speedo cable. And wire everything up. It's that easy.

NismoPick

Needed parts for the digi to analog swap:
-analog gauges & entire dash wiring harness

Quite an easy job. At the dash wiring harness hub (at the passenger door, under the dash) all the connections are the same for digi & analog dashes.

With the dashes out... swap the gauge clusters & wiring harnesses. Yada yada yada... that is it!

I have personally completed that task. Total time: ~4 hours (give or take an hour).

I propose that 1000000000000 times over trying to figure out how to override the digi speedo.

duowing

Now do you use the analog from the 280ZX, because I thought the analog's only went up to 80 mph, or are you using a different speedo as well? I'd probably look into swapping to analog when I do the 5-Speed swap. One thing I was wondering. What exactly is required to do the 5-Speed swap and where can all of this be purchased and how much might I be looking at to do the tranny swap, how much might I be looking at to do the digital to analog swap?

NismoPick

the 79 280zx's came w/ a 130mph speedo... but I believe the rear diff was also a 3.7:1 ratio, so you'll need the tranny speedo cog to keep the right speed ratio for the speedometer.

for your 5 speed swap... I think it's been covered plenty in other recent threads... look through the technical section on here.
https://www.zdriver.com/forum/forumdisplay.php?f=79

Also... I think you will get to know junk yards pretty well, as they will get to know you, in the search for parts.

jfairladyz

If they don't know you're name at the local junk yard, then you must not own a Z I spent the first year and a half of owning my Z in junkyards. Constantly trying to source parts. I scored a 130mph speedo in a junk yard as well as most of the parts on my car Scouring different yards weekly until I found the parts I needed. Now that I don't have any pick n pulls near here (1, with no Z's as of yet) it's just weird not being able to cruise to the yard to find some rare parts.