mx5cartalk.com

From what I have worked out it seems to me that the 6 speed ratios with my 4.1 diff would be perfect for the motor im planing (stock NA8 box is too high for my tastes, i enjoy the punchy feeling of a low/close box, and don't mind crusing at a few revs)

From my calcs, a 6sp + 4.1 diff produces these speeds @ 7000rpm

1st: 49kph (was 59kph)
2nd:81kph (was 98kph)
3rd:112kph(was 139kph)
4th:147kph (was 184kph)
5th:184kph (was 226kph)
6th:219kph (was non existant )

and 100kph @ 3400ish in 6th.

Does that seem right?


So ive been searching the forum for info on a 6 Speed swap for an NA8, but with not a great deal of luck.
From what i can tell its pretty much a straight swap, Yes?
Do you need any other parts besides the 6 speed box?
How hard is the swap? (Have done FWD swaps before, but its not like i have a hoist )

Also can anyone who has a 6sp in an NA offer any comments as to how it drives?

Thanks

I have a 6sp but went to a 3.9 diff which means i am doing about 200rpm less at 100klmph in 6th than I was in 5th in 5sp 4.1 set up.(plus the speedo is now accurate at 100klph rather than previously showing 105 at a true 100 so i amy have gained an even bigger advantage). 6th in a 6sp is lower than 5th in a 5sp so without changing the ratio you have a shorter top gear and have closed up the gaps between the others.I would suspect 1st would be really low in general use.

I have a few extra KW than standard but will be interested to hear how you get on with your setup.

I got mine fitted at the same time as a a clutch swap and they charged no extra so it is straight forward.You can only use 2 bolts on the starter, but this doesn't appear to be a drama at least in an NA8A, tailshaft fits ok but they had to swap the speedo drive box to box.

I must say I have found the 6sp shift quality to be a bit ordinary compared to the 5sp but am happy in every other way with the swap.

Goodluck.

Peter.

Thanks, All very useful info, and sounds like its a decent plan

You make an interesting point about the low first gear, but having another car that does about 40kph @ 7000 in 1st (my lancer) Im not hugely bothered about it.
I plan to do some power mods first, but after that i think i will put in the 6 speed and see how it goes, if it pisses me off i guess i can put in a 3.9

BTDT

I did for the track, I now use 3rd and 4th rather than spend a lot of time in 3rd, particularly at Wakefield. I made the change after 3rd gave out on my 5 speed (this on an NB8A atmo car, not a turbo). The shorter gears give better pull out of corners, and I was quite happy with the conversion on the road, although it is spinning a bit faster in top.

I did not notice a change in shift quality, but then my 5 speed shift quality was pretty ordinary...

Start reading about half way down the page. http://www.mx5cartalk.com/phpBB-3.0.2/viewtopic.php?f=57&t=29490&start=60

Cheers,
Danny

OK Sweet, Im pretty sold on the idea now

I went 6 speed a while ago on my na6 with 4:3 torsen, there is no way I would go back, I love the close ratios, first is a little short but is enough to get you rolling and the rest of the gears work great together.

Here is a link to my old garage thread, look about halfway down for a couple times and also a video Danny took at QR after I put in the 6 speed. In the video I had pretty slippery old semis on, but the difference in speed down the stright(due to launch out of the corners) shows how effective the closer ratios work great. Mine is the white na6 in the video which had intake/exhaust, cams and 6 speed. Before the 6 speed Danny and I were fairly even down the straight.

Tim

zoomzoom wrote:I went 6 speed a while ago on my na6 with 4:3 torsen, there is no way I would go back, I love the close ratios, first is a little short but is enough to get you rolling and the rest of the gears work great together.

Here is a link to my old garage thread, look about halfway down for a couple times and also a video Danny took at QR after I put in the 6 speed. In the video I had pretty slippery old semis on, but the difference in speed down the stright(due to launch out of the corners) shows how effective the closer ratios work great. Mine is the white na6 in the video which had intake/exhaust, cams and 6 speed. Before the 6 speed Danny and I were fairly even down the straight.

Tim

Whoa, it fair hauls out of the corners...

zoomzoom wrote:I went 6 speed a while ago on my na6 with 4:3 torsen, there is no way I would go back, I love the close ratios, first is a little short but is enough to get you rolling and the rest of the gears work great together.

Here is a link to my old garage thread, look about halfway down for a couple times and also a video Danny took at QR after I put in the 6 speed. In the video I had pretty slippery old semis on, but the difference in speed down the stright(due to launch out of the corners) shows how effective the closer ratios work great. Mine is the white na6 in the video which had intake/exhaust, cams and 6 speed. Before the 6 speed Danny and I were fairly even down the straight.

Tim

Don't forget the effect that the lighter B6 flywheel has!

You must mean the lighter cromolly b6 flywheel

[quote="daffyflyer"]From what I have worked out it seems to me that the 6 speed ratios with my 4.1 diff would be perfect for the motor im planing (stock NA8 box is too high for my tastes, i enjoy the punchy feeling of a low/close box, and don't mind crusing at a few revs)

From my calcs, a 6sp + 4.1 diff produces these speeds @ 7000rpm

1st: 49kph (was 59kph)
2nd:81kph (was 98kph)
3rd:112kph(was 139kph)
4th:147kph (was 184kph)
5th:184kph (was 226kph)
6th:219kph (was non existant )

and 100kph @ 3400ish in 6th.

Does that seem right?


Just in the interests of research(of course) I did some figures in my car at the WE.Remember this is a 4.1 and the speedo is accurate at 100klmph (not 5%out like most NA's)

Speeds are approx. as I couldn't believe how hard it was to watch tacho and speedo and get it just right and the 5/6 figures are 3500rpm doubled.
1:44;2:77;3:105;4:146;5:180;6:215.

Your true figures should be approx 5% lower than that(indicated probably similiar), so as has been said first will be low but the next gears just flow together.

Go for it!

Peter.

pcmx5 wrote:Speeds are approx. as I couldn't believe how hard it was to watch tacho and speedo and get it just right and the 5/6 figures are 3500rpm doubled.
1:44;2:77;3:105;4:146;5:180;6:215.

The speedo may be accurate, but the stock tacho probably isn't. Compared to reading from the laptop (megasquirt) my tacho reads low and also lags when you accelerate fast.

P

tinsfci wrote:be accurate, but the stock tacho probably isn't. Compared to reading from the laptop (megasquirt) my tacho reads low and also lags when you accelerate fast.

You speak the truth. The tacho in commonly accepted to be around 500 rpm out towards the top end of it, So the numbers pc got being a little under sound pretty right.

Have a 6 speed for sale if anyone is interested.

Andrew that gearbox in ur car had 30k kms on it when I put it in in march, so proba round 45k when I sold it to you....kill this box before you replace it...