6 Spd Gearbox

[Keith Jones]

Does anyone know whether the NB 6 speed gearbox is any stronger than the 5 speed?
250bhp under full race conditions was finally too much for my 5 spd.
The Quaife gear set from FM looks great but the price doesn't, so I am looking for a cheaper alternative. If you ignore 1st gear the 6sp box gives a better set of ratios that the 5 speed for race use.

Keith

[poison]

Hey Keith, good to see you're still here

Have you driven a 6 speed? If not I'd take one for a test drive before changing boxes. My NB is a 6 speed and I still find it risky changing down from 5th or 6th into 4th, the ratios are good but the left right movement is much closer on the 6th speed and it's far too easy to pop it into 2nd instead of 4t. Well it is IMHO anyway. I only use mine now and again and after 18months I still have to "Think" about the downchange, it's not instinctual like the 5 speed/4 speeds I spent my life driving. Maybe you can adapt quicker than me

Anyone else had this issue?

[Psycho_Dad]

well my fathers mx5 is a 6 speed, and yes it does take me a good few minutes of gear changing and remembering 6th before i get used to it... id say it would take a warm up lap before i was sweet so i guess it wouldnt be much of an issue

ive never accidently hit 2nd instead of 4th tho, it would have to be forced to do it when your doing over 100 since it would be limiting at about 90 wouldnt it?

PEace
Psycho_Dad

PS: best thing about these cars is dikhead boyracers dont drive them so the synchros are allways sweet

[Keith Jones]

Hi Gazza

Thanks for the heads up.
Sounds like the reverse problem of the 2nd to 3rd, oops that's 5th, shift in the 5spd. All too easy to do in the heat of battle. I got round this one by putting a stiffer detent spring in the 5th/reverse gate. It might be possible to reduce the risk of a 5th to 2nd shift by putting a stiffer spring in the 1st/2nd gate.

Keith

[jif]

there was some speculation on the powerlist (by Ray, the MiataLink coder) that the Millenia 'boxes were properly aligned (more contact area between teeth) and better able to handle torque than the less-carefully-aligned mx5 ones.

I've seen several in which the gears are offset such that only about 3/4 of

the tooth surface is engaged .... usually 2nd gear. I've always suspected
that many Miata transmissions are rejects from the Millennia 4-dr-sedan assy
line.

[poison]

it would have to be forced to do it when your doing over 100 since it would be limiting at about 90 wouldn’t it?

Nope, no forcing at all required, slips in nice and easy it's a manual and all mechanical, no protection there. I have put it into second maybe 4-5 times at over 100, not so nice

I like Keith’s idea of the stronger spring. I now have to make a strong mental note not to 'push' left when coming out of 5th/6th and let it 'fall' into place and then push forward. And because of this it slows my downshift considerably.

Maybe it's just my car but the guy I got it off had it stripped down under warranty (by his friends company) so anything that was even slightly worn got replaced. All up was around $3000 had reciepts.

[Keith Jones]

I don't think it's just your car Gazza.
Been doing some checking of the US forums this morning and there were a number of comments about the less precise gates of the 6 speed.

I think I have also answered my question about the relative strengths of the boxes. Apparently the Miata Cup guys have had problems blowing the Aisin 6 spd.

Guess I just have to ask Santa nicely for the Qaife gear set.

Keith

[SLYDIT]

AWR racing sells the quaife gearset also....not sure if theres a price difference as FM can be a bit pricey.

[Keith Jones]

Cheers Glenn

I have checked the prices on FM, AWR and Quaife (US) and they are all the same.

Keith

[Ian]

Keith...if you decide to go with the Quaife set, let me know, as I may be interested in a kit also.
Do you have a feel for the time/cost to have this kit professionally installed?

Cheers, Ian