Ratios of NISMO 5-speeds?

[ZMunkey]

Does anyone from "way back in the day" know what the available ratios were for a NISMO 5-speed tranny for the 70-73 Z cars? I just bought a 73 240 Z racecar and it came with a Nismo 5-speed for a spare. The serial number is listed as NMCD 2#. Any help would be appreciated. Much thanks, photos coming soon!

Eric aka ZMunkey

[2ManyZs]

Here's the list of the tranmission ratios that were available. I don't have anything that will tell me which trans you might have given the serial number.

Perhaps Alan T. might have something that will decipher the serial number....

[ZMunkey]

I was told that it was a "close ratio" model... I dunno what good it would do me if I were to auto-x the car like I want to do... that and driver's events at tracks like Willow Springs and Phoenix International or Firebird International. If I stick w/ the 240Z trans and look for a 3.70 or 3.90 rear end, then my acceleration will be faster (than the stock 3.64 rear end). That's what's needed for auto-x work! Anyone else agree with this statement?

Eric aka ZMunkey

[HS30-H]

Hi Eric,

Congratulations on your new race car. Hope you do well with it.

2ManyZ's posted the list of the names for the different "B" box ( 'Bent Stick' FS5C71-B option box ) transmissions and their ratios - which you should copy and file away for future reference. That's useful data.

I think that the spare box you have is the "Option 2" Direct Drive ( fifth gear is 1:1 ratio - ie. not overdrive ) and the shift pattern is the 'Dogleg' first ( first gear is all the way over to the left and back, and reverse is all the way over to the left and forward, leaving second, third, fourth and fifth in the conventional 'H' gate pattern ). Does that make sense? If it doesn't then I'm not explaining properly!

The idea of the 1:1 Direct Drive top gear is that in a pure race car you don't really need an overdriven top gear at all - as long as your Final Drive ratio and driven tyre size are correctly matched to the max revs that you want to turn.

The idea of the 'Dogleg' shift pattern is that when racing you very rarely need first gear, and the 'H' pattern gate of the remaining 4 forward gears makes it a lot less likely that you will 'wrong slot' and ruin the transmission ( or worse..... ).

Sorry if you already know the above, but you might not.

Coincidentally, I've been using an "Option 2" box on my car for a while now ( even though its not a race car ) and rowing it along in the gears is real fun. Its just that first-to-second shift that takes a moment longer. Its mated to a 3.9 R200 with LSD, and my rear tyre size is 225 / 60-14 at the moment. I don't find that too frantic for my engine, although prolonged high-speed cruising on the Motorways here in the UK ( max legal speed 70mph ) can be tiring. To be honest, a final drive ratio of 4.1 or 4.375 would also be OK for me ( a lot more interesting around the backroads and occasional circuit drives ).

For your AutoX and track work, I think it would be fun for you to try the Option 2 box for a while. If you have good engine power then a 3.7 or 3.9 rear end ratio might be OK. If you are limited for torque ( like me ) then a numerically higher diff ratio might be more suited to it. Depends on your tyre size of course.

If you want to turn the Option 2 box into funds to use elsewhere on the car, then you could sell it for quite a few dollars. You might be pleasantly surprised!

Good luck,

Alan T.

[Royce]

The other thing to consider is what class you plan to run in if you plan to compete. For example, I don't think many SCCA classes would allow you to use anything other than stock. Always best to check the rule book, if that applies, to make sure you can run what you want to run. Even the dog leg first gear trans would probably be an issue for some classes.

[ZMunkey]

Classification... Hmmmmm... I'm pretty sure that the way this car is built and stripped, I'm going to be in whatever the highest class is... basics are as follows:

1. 8 gallon fuel cell

2. fully stripped car

3. full rollcage, welded and braced to rear strut towers, no dash, connected to firewall and flooring and directly to seat

4. modified engine (not original) w/cam/ weber carbs, recurved electronic distributor, MOPAR "Orange" box and Accell coil, 6-into-1 header, 2.5 to 3" exhaust, no muffler (currently but will add one soon)

5. no alternator, running relocated marine deep-cycle battery in hatch area

6. enlarged radiator

7. coil-over front suspension, a-arm bump-steer adapters, koni shocks (non-adjust)

8. rear coil-over springs on stock mounts, koni shocks (non-adjust)

9. 4-speed tranny (stock 73 240?)

10. Stock rear end (73 240 3.54? R-180?)

11. two sets of rims, one Toyota Celica Supra 14x8 w/Kumho V700s, one set 14x7 Slotted mags w/ BFG street tires for practice runs (and for sliding around!)

No ignition switch, but a master kill switch on the passenger side, switches for fuel, ign, fan, and a big ol' "start" button

Its a pretty cool car but I think the jetting on the carbs isn't right. The guy didn't know much about webers and had no adjustment gear to even read the settings. He just stuck the largest jet in the kit into the secondary jet! I'm pretty certain the carb is running rich at idle, lean in the primary and very rich in the secondary... I don't know anything about webers, but I'll be buying a book and tuning equipment from Motorsports soon.

Eric

[ZMunkey]

I went to this transmission ratio calculator:

http://www.geocities.com/z_design_studio/

which does show some of the competition boxes that were available. I don't know if I have the "close ratio w/od" box or the "Option 2" box like you've suggested. I'm thinking like you though, that NMCD 2# means "option 2" and that its got a 1:1 5 gear...

If I mainly want to do auto-x and driver's track day events and not actual road racing, wouldn't I want the shorter 1st gear found in the factory 4 speed? Expecially if I'm turning the 3.364 factory R-180 diff?

Oh, if I use the competition 5 speed and the 3.364 rear end, I can pull to 60mph at 6156 RPM! That would be a complete auto-x in just one gear (mainly)... If I use the factory 4 speed then 2nd gear is the same as first gear in the NISMO box (60 mph at 6170) and I have a shorter first gear for launching...

Does anyone know if I need a different driveshaft to install the NISMO box? I was told that I didn't... that it was the same length as the original 4 speed.

Eric aka ZMunkey

[Zedrally]

Originally posted by ZMunkey

. I'm thinking like you though, that NMCD 2# means "option 2" and that its got a 1:1 5 gear...

Hi,

It's easy to find out if it is 1:1 in fifth.

Simply put it into 5th gear and count the number of time the shaft turns.

I really don't need to add if the input shaft is turned 1 revolution and the output is the same then you have that 1:1 5th, do I?

Likewise you can do the same for all the other gears and then compare the raio with whats in the book. {Wouldn't mind betting thats the Close Ratio Option 2 box, you lucky lucky person}.

[ZMunkey]

'simply put it in 5th gear'

Easier said than done... its not in the car! How do I shift this bad boy?

Why would I be a lucky lucky person to have this tranny? From what I can see on the tranny calculator, I *could* run auto-x events in 1st gear all the way out to 63 mph with my stock 3.364 rear end... BUT, that's *identical* to 2nd gear in my factory tranny with the 3.364 rear end! Where's the benefit in that (other than having 3 more gears to play with before I'm in 5th at 1:1 rather than just 1 gear before 4th-1:1)? Am I making sense?

A really BAD Z in a magazine was equipped with the factory 4 speed and 3.90 R-200 rear end and had finished 5th and 7th at SCCA auto-x nationals on two different occasions... His motor was built similar to mine, only with triple Webers instead of duals (and 30 years of development time because he bought it new!). It was really wicked!

Now on a road course I can see the benefit... 1st locked out to the left (like the old Porsche trans) and 4 higher gears ending in 1:1 with 2nd being only slightly taller than 1st in order to make it useful for cornering.

Sounds like, for what I need to do, that I need to sell this trans and get a 3.90 R-200 and other related parts I need to make this car nicer...

Eric aka ZMunkey

[ZMunkey]

If anyone's interested, rather than just cash, I have a laundry list I need for this car:

Hood with hinges

front bumper and early 70-72 mounts

rear hatch w/glass and seal

front windshield seal

body seals for left and right doors

rear hatch body seal

a gallon of decent white paint (or heck, just about any color in a gallon quantity) I'd love to paint the car bright yellow, but that paint's just too expensive for me)

Toyota truck front brake calipers (4 piston)

I have to make this car a little more "stock" in order not to be thrown into a class I can't win... My front bumper is mangled... the front hood is dented and converted to 4 pin retention rather than two pins and hinges, which I'd rather have.

Other other items are pretty self-explanatory...

You can reach me via email or at work daily at 760-922-7121, just ask for Eric. I'm in Southern California and can deliver.

Eric aka ZMunkey

[Zedrally]

Originally posted by ZMunkey

'simply put it in 5th gear'

Easier said than done... its not in the car! How do I shift this bad boy?

Why would I be a lucky lucky person to have this tranny? From what I can see on the tranny calculator, I *could* run auto-x events in 1st gear all the way out to 63 mph with my stock 3.364 rear end... BUT, that's *identical* to 2nd gear in my factory tranny with the 3.364 rear end! Where's the benefit in that (other than having 3 more gears to play with before I'm in 5th at 1:1 rather than just 1 gear before 4th-1:1)? Am I making sense?

Eric aka ZMunkey

Eric, it all depends on your use.

Obviously, it's not the tranny you want to run, shame you're not in Aus, otherwise I'd be tempted to make you an offer. It's ideal for my use [Rally], unfortunately the freight would be prohibitive.

As to how to shift it, get a shifter from another trans, and yes you do make perfect sense, you may as well stay with a stock trans.

Mike

[ZMunkey]

Well, I'm sure I can take this trans to 1 track day and sell it to someone. There's always someone looking for Nismo gear and there's a lot of these Zs still being raced here in the US.

ZMunkey