mx5cartalk.com

Posted: **Wed Nov 01, 2017 12:44 pm**

Hi everyone,

I've recently had the 3:6 diff in my 2003 Series 3 NB replaced with a 4:1. Trouble is, I now have a 10% "slower" speed discrepency with my speedo.

I've been told that I can change the speedo sensor located on the side of the gearbox. I searched online and found that the one suggested is the "red" version, however, they also say it is for a "5 speed" box, whereas mine is obviously a 6 speed.

Can anyone please clear things up regarding this? Will this particular sensor work with the 6 speed, or is there another varient that you'd suggest?

If anyone knows the one I'll need or may have one for sale, could you please message me on how much you'd want for it including P&H to Kempsey, 2440, NSW.

Thanks very much for any info that may help.

Cheers, Wayne.

Posted: **Wed Nov 01, 2017 12:49 pm**

well,

I'm not an expert

The speedo sensor would have to take the speed from a constant source, like close to the driveshaft & it has the correct ratio for a 4.1:1
this should theoretically be the same in a 5 or 6 speed gearbox.

the one part I don't know if the actual fitting is the same in both 5&6 speed gearboxes

Posted: **Wed Nov 01, 2017 2:27 pm**

I've seen around 6 side by side and they all look physically the same, they seem to only have different coloured spindles which contain differing teeth sets.

Posted: **Wed Nov 01, 2017 3:27 pm**

90% sure they're identical.

If they aren't, you can also use a Speedo pulse adjuster, which wires in between the Speedo sender and the gauges, it basically speeds up or slows down the pulses to let you change what the Speedo reads.

Posted: **Wed Nov 01, 2017 3:29 pm**

Have a look at this thread I made a little while back when my sender failed.

http://www.aus-cartalk.com/forum/viewtopic.php?f=29&t=74545&p=909820&hilit=sender#p909820

The senders are the same, just the different coloured cogs have differing teeth counts.

This is the table they have worked out on miataturbo forum which is not 100% guaranteed as it is for the USA and based on user findings not a Mazda book.
P/N: - gear teeth, gear colour >> trans+rear+tire (year)
M527-17-400A - 23-tooth, Green >> 5MT+4.3+15" (99-05)
M526-17-400A - 22-tooth, Red/Burgundy >> 5MT+4.3+16" (01-05)
M526-17-400A - 22-tooth, Red/Burgundy >> 5MT+4.1+15" (99-00 Euro market?) I guess this would be the Australian spec NB8A
M528-17-400A - 21-tooth, Yellow >> 6MT+4.1+16" (04-05, and 14" on Euro NB1s)
M528-17-400A - 21-tooth, Yellow >> 6MT+3.909+15" (99-00 Euro market?)
M534-17-400 - 20-tooth, White >> 6MT+3.909+16" (01-03)
M533-17-400A - 19-tooth, Blue >> 6MT+3.636+16"/17" (Australia market only)

Also that pic you have with 5 side by side are NA mechanical units, not NB ones.

Posted: **Fri Nov 03, 2017 6:37 pm**

Thanks for that Luke.

The closest one on that list I guess would be the "M528-17-400A - 21-tooth, Yellow >> 6MT+4.1+16" (04-05, and 14" on Euro NB1s)".

You see I have the exact same set up. The 6 speed box, 4:1 diff, but I also have 17" wheels fitted to mine, so I'm still not quite sure how this particular cog would go.

I have looked at a couple of electronic sensors that have been suggested, and if worse comes to worse, I suppose I'll have to go in that direction, but I would like to try to solve it with just changing the cog if possible.

If you or anyone else hears of a solution, please leave a comment.

By the way. The other day I was following a semi and it threw a rock up and disintegrated my right hand fog light lens. Would you know of anyone that has one they could sell me. I only need the glass if possible.

Thanks again mate. I appreciate your help.

Cheers, Wayne.

Posted: **Fri Nov 03, 2017 7:00 pm**

Thanks also to "hks_kansei" for his recommendation. I may have to go that way eventually, but if possible I'd like to try the cog solution first.

Cheers, Wayne.

Posted: **Fri Nov 03, 2017 7:09 pm**

I just re-read a comment made from an earlier discussion I was having, where someone said that because the 17" wheels on my car are fitted with low profile tyres, it negates the extra 1" in diameter, so maybe the yellow cog may be the answer afterall.

Would anyone have one that they might want to part with please?

Cheers, Wayne.

Posted: **Fri Nov 03, 2017 7:58 pm**

5isalive wrote:I just re-read a comment made from an earlier discussion I was having, where someone said that because the 17" wheels on my car are fitted with low profile tyres, it negates the extra 1" in diameter, so maybe the yellow cog may be the answer afterall.

Would anyone have one that they might want to part with please?

Cheers, Wayne.

I don't have a cog but can comment further on the wheels and tyres.
I assume your 17's are 205/40/17. So 596mm diameter. 1871mm Circumference.
Factory 16's with 205/45/16 are 591mm in diameter and 1856mm circumference.
A very small 0.8% difference.
Aussies NB8B's that had 16 inch and SE's that had 17 inch both had the Blue Cog with 3.6 diff.

One thing the list I posted earlier is missing is that US Mazdaspeed Miata's run the Yellow Cog from factory. They had a 4.1 diff with 205/40/17 tyres.

Posted: **Fri Nov 03, 2017 9:46 pm**

You want the electric sender type in lower picture with the wire coming from it for a later series 5.
As stated the top pictures all are mechanical drive NA type which use a mechanical cable drive.
The beauty of the later type is that you can use a speedometer corrector as offered by jaycar (catalog no. #AA-0376) to dial in your speedo to a more accurate reading regardless of tyre O.D. disrepancies. It would be best to get as close as possible with a cog change on the speedo sensor and then adjust from there.

Posted: **Sat Nov 04, 2017 1:22 pm**

Thanks again for the suggestions received.

I purchased a red cog last night ($60.00), which apparently will give me a true reading of 97kph with my speedo showing 100kph, which is much closer than I am now, however it seems I'll still have to put an electronic device in and have it dialed in to the correct speed.

My worry is, I don't know how to install these devices so I'll need to see an auto electrician to do the work.

Does anyone have any idea of the sort of money I would be looking at to get this done?

I didn't think by changing out a diff that this would turn into the nightmare it has. You'd think that you could just contact Mazda, tell them what changes you've made and they'd be able to sell you the correct cog, but like Paul Keating said, "Life isn't meant to be easy".

Anyhow, please keep the replies coming if you have any other solutions.

Thanks all.

Wayne.

Posted: **Sat Nov 04, 2017 2:53 pm**

Big lettering indicates YELLING.

Posted: **Sat Nov 04, 2017 3:12 pm**

All CAPS indicates yelling.

Not sure if larger font means anything apart from easier to read for us 'ol folk

Sent from my SM-G930F using Tapatalk

Posted: **Sat Nov 04, 2017 3:58 pm**

KevGoat is correct. It's only a larger font. It has absolutely nothing to do with yelling.

If it were in capital letters, that would be considered yelling.

I'll revert to a smaller font though to keep "bruce" happy.

Posted: **Sat Nov 04, 2017 4:19 pm**

I know this.
Big font is probably screaming!

mx5cartalk.com

Speedometer Sensor

Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor

Re: Speedometer Sensor