Jump to content

Photo

NA vs. NB Transmissions

- - - - -

  • Please log in to reply
13 replies to this topic

#1
bmarshall1

bmarshall1

    Member

  • Members
  • PipPipPip
  • 298 posts
  • Location:United States
  • Region:SW Florida
  • Car Year:1999
  • Car Number:23

Time for my monthly "This is probably a stupid question but I don't know the answer";  I have always thought that NB transmissions were stronger than the NA - maybe just the housing due to the additional webbing on the exterior.

 

My friend recently bought a trans for his 99 from the race shop and they sold him an NA stating it's basically the same but shifts smoother.

 

Any information anyone can share regarding the NA vs NB?



#2
Ron Alan

Ron Alan

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 3,732 posts
  • Location:Northern CA
  • Car Year:1995

"Strength" I believe may not be an accurate term. I think over time certain minor aspects were changed at the original source to improve functionality and eliminate certain things from happening(reverse at speed?). But I do not think the actual gears and main shaft have changed? And when a "rebuilder" has the unit apart they are changing wear items...Syncros, syncro springs, shift forks, roll pins, all seals, etc. All gears and probably shift hubs remain? The time and expense to replace all isn't practical. 

 

All that said...I think we are definitely beginning to reach life expectancy of 3rd gear which seems to blow up/fail at the highest rate. One of our local guys will replace 3rd gear for an additional rebuild cost but apparently Mazda is not able to keep stock of these. He said he bought every piece Mazda had awhile back and hasn't been able to get more(this was a conversation 2 months ago). I had 10 junkyard trannies 1 year ago and have none now. Getting harder to find easily. I wont hesitate to use either NA or NB. In the end It is a crap shoot on its life expectancy...and if you are a shitty shifter and running a Unsprung clutch disc good luck. Jim has always advocated a stock PP as well I believe. Eliminating the "shock" on these units is always a good thing!

 

I will gladly be corrected if anything here is not accurate...always learning!

 

For those trying to diagnose problems...if you suddenly begin missing shifts and/or grinding...check the easy things 1st! Pull the shifter and make sure the plastic bushing on the ball hasn't broken...also make sure your clutch slave cylinder has a good throw...barely disengaging the clutch will make it harder to shift(maybe air in line?)


Ron

RAmotorsports

 

Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#3
LarryKing

LarryKing

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 2,659 posts

Better call Saul.

 

I've always heard that NA and NB are essentially the same and that the NB supersedes the NA part no. I think I read that new gearboxes from Mazda are on back order.

 

My understanding is that the synchro snap rings are the weak link. Gearbox guru Mark Bennett first diagnosed this issue and had hardened snap rings manufactured to use in his "blueprinted" Miata transmissions. I believe Planet Miata and East Street subcontracted this technique (I may be wrong about that).


2017 - SMSE SEDiv ECR Champion
Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#4
bmarshall1

bmarshall1

    Member

  • Members
  • PipPipPip
  • 298 posts
  • Location:United States
  • Region:SW Florida
  • Car Year:1999
  • Car Number:23

Good points All.  maybe 'better' or 'reliable' is a better descriptor.  I have heard of the minor changes throughout the years as well as the snap ring issue.  I am pretty easy on shifts, on the other hand my race buddy does not rev match and will go through one every few years (at 4 races a year).  

 

Good to know NA or NB will get the job done.



#5
Steve Scheifler

Steve Scheifler

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 2,816 posts
Don’t take this as verified fact, but I believe there are one or more internal parts no longe available for the NA transmission, but those and certain related parts can be replaced together as a set. Sorry to be so vague but the point is that if certain parts need replacing in an NA box the rebuild will be more expensive than the same issue in the NB. Hopefully someone can supply the details.
Instigator - Made a topic or post that inspired other Broken record - You are starting to sound like a broken record.

#6
EMatoy

EMatoy

    Member

  • Members
  • PipPipPip
  • 103 posts
  • Region:Detroit
  • Car Year:1990
  • Car Number:73
This link below should answer some of your questions from 1.6 to 1.8 NA transmissions. Then from NA to NB there are more changes. A few are: NB shifter has 2 pins to locate it in the shift turret, NA has one. I do believe the synco setup from NA8 to NB is the same (NA6 had a single cone synchro for 2nd, later parts had a dual cone). Shafts are the same, gear size in 1.8 to NB is the same.

You can interchange single cone to dual cone parts but if swapping a single cone synchro to a double you have to swap the gear and synchro together.

I have had good luck with all generations of transmissions. It’s all in how you shift and the clutch disk of choice.

https://walter-motor...ion-differences
  • Steve Scheifler likes this

#7
Brandon

Brandon

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 765 posts
  • Location:North Jersey
  • Region:NNJR
  • Car Year:1996
  • Car Number:48SM

This link below should answer some of your questions from 1.6 to 1.8 NA transmissions. Then from NA to NB there are more changes. A few are: NB shifter has 2 pins to locate it in the shift turret, NA has one. I do believe the synco setup from NA8 to NB is the same (NA6 had a single cone synchro for 2nd, later parts had a dual cone). Shafts are the same, gear size in 1.8 to NB is the same.

You can interchange single cone to dual cone parts but if swapping a single cone synchro to a double you have to swap the gear and synchro together.

I have had good luck with all generations of transmissions. It’s all in how you shift and the clutch disk of choice.

https://walter-motor...ion-differences

 

What is the clutch disk of choice or is it dependent upon your shifting method? AKA - sprung disk + hamfist shifting is better than an unsprung disk? Or perhaps friction material (organic vs. ceramic/metallic)?

 

Thanks for the further clarity and the link to that vendor too. I will be checking in on them once they return to normal operation.


Bona fide - A bonafide Spec Miata driver

#8
Jamz14

Jamz14

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 1,310 posts
  • Location:California
Bigger issue might be the pressure plate used. Don't understand why people run the ACT plate. I suppose it is because it is a "race" plate. Their special 130hp motors must be overwhelmingly their stock plates designed to handle.......130hp+. Or maybe they just like that shitty feel out of 1st gear and the shock it sends through the drive train. Or maybe they are faster with it.
Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Sponsor / Advertiser - Site sponsor / advertiser... support these guys! Novel Approach - When a paragraph simply won't do... Make it Rain - Made Paypal donation of $100+ Bona fide - A bonafide Spec Miata driver

#9
Bench Racer

Bench Racer

    Different strokes for different folks : )

  • Members
  • PipPipPipPipPip
  • 5,508 posts
  • Location:Wauwatosa, WI
  • Region:Milwaukee
  • Car Year:1990
  • Car Number:14

Seems the reason for your pressure plate post is to Troll those who claim to have 130 plus HP. :bigsquaregrin:

 

Or maybe some people use a springless pressure plate because it was recommended by a noted/trusted Spec Miata racer.   


Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#10
Steve Scheifler

Steve Scheifler

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 2,816 posts
I’ve never run a spring disk because those springs represent a significant failure risk. A stock plate and pretty much any of the popular 3-4 puck unsprung disks is a great combination.
Instigator - Made a topic or post that inspired other Broken record - You are starting to sound like a broken record.

#11
Jamz14

Jamz14

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 1,310 posts
  • Location:California
No, it was to point out that we make no significant hp or torque whether you have a special motor or not that requires an aftermarket PP. The stock PP with any of the ACT disks make a wonderful combination. To point out that just because the rules say you can doesn't mean you should . To think for yourself instead of listening to know it alls like you and I Bench.

Yes I scoff at the notion of 130hp. That's because it ain't happening legally or with a properly reporting dyno. But whether I scoff at it or not doesn't matter. That is the new number. Doesn't matter if I believe it or not, 130 hp doesn't require an ACT competition PP unless you enjoy tearing up your gear.
Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Sponsor / Advertiser - Site sponsor / advertiser... support these guys! Novel Approach - When a paragraph simply won't do... Make it Rain - Made Paypal donation of $100+ Bona fide - A bonafide Spec Miata driver

#12
EMatoy

EMatoy

    Member

  • Members
  • PipPipPip
  • 103 posts
  • Region:Detroit
  • Car Year:1990
  • Car Number:73

What is the clutch disk of choice or is it dependent upon your shifting method? AKA - sprung disk + hamfist shifting is better than an unsprung disk? Or perhaps friction material (organic vs. ceramic/metallic)?

Thanks for the further clarity and the link to that vendor too. I will be checking in on them once they return to normal operation.


In my SM it’s a sprung 4 puck disc. In my champcar it’s a stock disc (the race discs can’t handle it long term the springs break and come out). All have the ACT pressure plate - mainly to keep it common and since I have them. I feel it’s totally unnecessary in an SM. If anyone else raced my SM it would also get a stock plate to handle the poor shifting that most do. If you made drivers spend time shifting unsynchronized transmissions they would likely break way less parts.

#13
Bench Racer

Bench Racer

    Different strokes for different folks : )

  • Members
  • PipPipPipPipPip
  • 5,508 posts
  • Location:Wauwatosa, WI
  • Region:Milwaukee
  • Car Year:1990
  • Car Number:14

 If you made drivers spend time shifting unsynchronized transmissions they would likely break way less parts.

 

The devil made me respond to this ^ comment. If Spec Miata drivers were in Karts their would be a whole lot more respect shown while on

track.  :yep:


Broken record - You are starting to sound like a broken record. Donor - Made PayPal donation Bona fide - A bonafide Spec Miata driver

#14
Jim Drago

Jim Drago

    East Street Racing / 2 Time National Champion

  • Administrators
  • 6,566 posts
  • Location:Memphis, Tn
  • Region:Mid South
  • Car Year:2005
  • Car Number:2

No, it was to point out that we make no significant hp or torque whether you have a special motor or not that requires an aftermarket PP. The stock PP with any of the ACT disks make a wonderful combination. To point out that just because the rules say you can doesn't mean you should . To think for yourself instead of listening to know it alls like you and I Bench.

ahh we agree.. been running stock PP for 15 years with 3 puck unsprung disc
 

Yes I scoff at the notion of 130hp. That's because it ain't happening legally or with a properly reporting dyno. But whether I scoff at it or not doesn't matter. That is the new number. Doesn't matter if I believe it or not, 130 hp doesn't require an ACT competition PP unless you enjoy tearing up your gear.


Maybe not out there.. getting ready to ship one that way, maybe they will let you dyno:) But I agree, 140 doesnt require more PP either imo and they say I have 150 for years and I never used anything but stock :)

East Street Auto Parts
Jim@Eaststreet.com
800 700 9080

NASA Champs Winner - NASA Champs Winner Hoosier Super Tour points Champion - Hoosier Super Tour points Champion ARRC Champion - Won the ARRC Race in a Spec Miata Series Champ - Won a points based series in a Spec Miata BFG Supertour Winner - Majors Winner - Circuit of the Americas Winner - We have a Winnah! - Won their 1st race... Congratulations! June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner June Sprints winner  - June Sprints winner SCCA National Champion - Won SCCA Runoffs at Road America SCCA National Champion - Won SCCA Runoffs at Road America




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users