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NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 8:14 pm
by angusis2fast4u
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!
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 8:24 pm
by Magpie
http://www.miata.net/garage/KnowYourCar/S8_Gears.htmlI 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
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 8:25 pm
by NitroDann
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
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 8:38 pm
by angusis2fast4u
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?
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 8:50 pm
by Magpie
Yes a gear calculator and compare, for example
http://www.osella.com.au/gear-ratios.htm
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 11:09 pm
by zoomzoom
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
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 11:12 pm
by angusis2fast4u
Thanks magpie seems probably better than the 5 speed
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 11:16 pm
by angusis2fast4u
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)?
Re: NB 5 speed cost and options?
Posted: Thu Oct 10, 2013 11:34 pm
by zoomzoom
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
Re: NB 5 speed cost and options?
Posted: Fri Oct 11, 2013 1:41 pm
by ja9
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.
Re: NB 5 speed cost and options?
Posted: Sat Oct 12, 2013 10:09 pm
by angusis2fast4u
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
Re: NB 5 speed cost and options?
Posted: Sat Oct 12, 2013 11:03 pm
by orx626