NB 5 speed cost and options?

angusis2fast4u · Postby **angusis2fast4u** » Thu Oct 10, 2013 8:14 pm

So i was going to ask what would i expect to pay for an nb 5 speed gearbox but i will take the opportunity to make the right decision.

So i have a stock powered na6 with a new 4.3 nb lsd (stock ratio) differential but the current gearboxes synchros are going and so its time for a replacement. Is the best option the nb 5 speed for strength and ratios? Does the 6 speed ruin the na6 and not worth it unless rolling with more power?

A link to a good thread would be awesome!

Magpie · Postby **Magpie** » Thu Oct 10, 2013 8:24 pm

http://www.miata.net/garage/KnowYourCar/S8_Gears.html

I have a 6 speed box and a 4.1 Torsten diff and with a stock 1.6 it is a good mix. However after the engine build I may look at a 4.3 diff to give faster acceleration as the car will not have enough power to reach the theoretical top speed of 273 kmh (RPM/gears). A 4.3 diff would allow 260 kmh

Postby **NitroDann** » Thu Oct 10, 2013 8:25 pm

I love the 4.3/6 speed combo on a gutless NA, but its a lot of work. It keeps you busy.

Thats what I like about it I guess.

Dann

angusis2fast4u · Postby **angusis2fast4u** » Thu Oct 10, 2013 8:38 pm

NitroDann wrote:I love the 4.3/6 speed combo on a gutless NA, but its a lot of work. It keeps you busy.

Thats what I like about it I guess.

Dann

I dont mind if it keeps me busy because well it is a drivers car.. But im just worried if it will ruin the acceleration of the car, well lack of acceleration it has

also on the highway does it sit lower on the RPM's than a 5 speed?

Magpie · Postby **Magpie** » Thu Oct 10, 2013 8:50 pm

Yes a gear calculator and compare, for example http://www.osella.com.au/gear-ratios.htm

zoomzoom · Postby **zoomzoom** » Thu Oct 10, 2013 11:09 pm

6 speed will improve acceleration, 5th gear is 1:1 (opposed to 4th being 1:1 in 5 speed) and 6thgear is actually a tad shorter than 5th in the 5 speed so highway revs with the 6 speed are slightly higher and there are now 5 gears up to 1:1 where there were previously 4, ie. 6 speed has closer ratios.

Cheers,

Tim

angusis2fast4u · Postby **angusis2fast4u** » Thu Oct 10, 2013 11:12 pm

Magpie wrote:Yes a gear calculator and compare, for example http://www.osella.com.au/gear-ratios.htm

Thanks magpie seems probably better than the 5 speed

angusis2fast4u · Postby **angusis2fast4u** » Thu Oct 10, 2013 11:16 pm

zoomzoom wrote:6 speed will improve acceleration, 5th gear is 1:1 (opposed to 4th being 1:1 in 5 speed) and 6thgear is actually a tad shorter than 5th in the 5 speed so highway revs with the 6 speed are slightly higher and there are now 5 gears up to 1:1 where there were previously 4, ie. 6 speed has closer ratios.

Cheers,

Tim

So youre saying that the 6 speed will cruise at a higher rpm on the highway BUT it will be able to keep the revs higher so its in the usable powerband (which is important for an na6)?

zoomzoom · Postby **zoomzoom** » Thu Oct 10, 2013 11:34 pm

angusis2fast4u wrote:
zoomzoom wrote:6 speed will improve acceleration, 5th gear is 1:1 (opposed to 4th being 1:1 in 5 speed) and 6thgear is actually a tad shorter than 5th in the 5 speed so highway revs with the 6 speed are slightly higher and there are now 5 gears up to 1:1 where there were previously 4, ie. 6 speed has closer ratios.

Cheers,

Tim

So youre saying that the 6 speed will cruise at a higher rpm on the highway BUT it will be able to keep the revs higher so its in the usable powerband (which is important for an na6)?

Pretty much.
5 speed top gear is 0.814 6 speed is 0.843 so the revs will be about 3.5% higher. eg 3.5% at 3000rpm = 3100rpm

Cheers,

Tim

ja9 · Postby **ja9** » Fri Oct 11, 2013 1:41 pm

Yes I agree with everything said as I did the same thing and loved the 6 speed on a NA6. Don't forget there is a massive difference in price between the two boxes.
5 speed approx $250+
6 speed approx $1100+ (if you can find one)

If money is no problem then 6 speed all the way.

angusis2fast4u · Postby **angusis2fast4u** » Sat Oct 12, 2013 10:09 pm

ja9 wrote:Yes I agree with everything said as I did the same thing and loved the 6 speed on a NA6. Don't forget there is a massive difference in price between the two boxes.
5 speed approx $250+
6 speed approx $1100+ (if you can find one)

If money is no problem then 6 speed all the way.

that's for an NB 5 speed right? (which has the stronger synchros?) can't call mx5 plus till monday so i just wanted to confirm because i thought i was up for a grand