6 speed and 3.6 speedo gear for NA
 

I am looking at swapping a 6 speed and 3.6 into my NA. I have read several threads about simply swapping over the mechanical speedo gear from the NA 5 speed if you are keeping the same rear ratio. Since I am swapping the 3.6 diff as well I will need to change the speedo gear. I am not 100% sure what all will be needed to get my mechanical speedo to read right wit the 3.6 gearing.

From the following thread it looks like I can assemble what I need based on the parts listed below. Wouldn't it be possible to just get the correct gear and make the needed speedo assembly based on the NA and NB parts I have from the 6 speed and 5 speed?
It would be great if someone would make a sticky for 6 speed swaps so lazy people can find all the info in one place! :winner: The awesome stickies we have in other sections really spoil you.

https://www.miataturbo.net/general-m...ver-%2A-41362/

1011-17-442A - This is the sleeve/housing that will position the gear in the proper location to engage the gear within the transmission. If the sleeve that comes in a 5-speed transmission is used, the smaller 6-speed gear will be free-floating and will not engage. Thus, no readings.
M502-17-441 - This is the actual gear.
9922-20-214 - Spring Pin for holding the gear in the sleeve.
9958-60-8166 - Oil Seal for inside the sleeve.
1011-17-443 - O-Ring for the outside of the sleeve.

I used the same parts on my 6-speed and 3.63 swap but my speed is worse now than ever before. It reads like 8mph too fast. Running on 225/45/15 Rivals. I think @wrengel just left his 6-speed stock with 3.63 rear and his speedo is more accurate than mine.

Just a heads up. I have a 6-speed and 3.63 diff. My speed sensor is for a 3.9 diff and shows the speed correctly with 225/45-15 Rivals.

Yes, I have an NA 5 speed speed sensor in my 6 speed and 3.63 swap. My in car speedo reads 5 mph high at 75mph (so actual speed 80) on 245/40/15 Rivals. That is totally livable in my book.

Just an FYI you can have revlimiter make you a new gauge face using the stock sensor in the car, but shows the correct speeds. He has a spreadsheet where you do the swap, then fill in some values while driving with a GPS. It is what I did in my car originally.

Subbing because in the same boat.
the gears themselves cannot be swapped. The shaft that the gear sits on is D-shaped and has a circlip for the NB electronic speed sensor and circular on the NA mechanical sensor that is (i believe) press fit.
There are both 19 and 20 tooth gears you can fit to a frankenstein sensor depending on wheel/tire setups.

Bear in mind that although this will correct the speedo, it will not correct the odometer. There will be a discrepancy (faster-than-true accumulation of miles), if that matters to you.

This post is an accurate accounting of what you require to put an NA compatible speedo gear into a 6 speed transmission with a 3.636 differential.

Which seals are different on the 6-speed? I ordered input shaft housing seal, output shaft seal, shifter boots and shifter bushing for the 5 speed before I committed to a 6-speed. Just need to know which parts to sell and get 6-speed specific seals and boots.

On the 6, the output seal is the same, and the input is different. You have a cover with a gasket on the 5, on the 6 there is a seal and a cover that is gooed on - the seal is different.

Is your 6 an early or later box?

NB2 transmission.

Changeover is mid year 2001 on the shift bushing, NB2 isn't enough unfortunately. "mid 2001 at VIN 220739"

https://www.miataturbo.net/suspensio...er-help-75863/

I know a 5 speed shift fork boot will fit the 6 speed, and it's cheaper than the 6 speed one when I last bought one.