NB8B Owners - a gearbox Question.

Rocky · Postby **Rocky** » Sat Oct 20, 2012 5:20 pm

My low-mileage NB8B has always had a vague area off to the right of 5th gear that you can easily get into if you shift up too enthusiastically from 4th.
It is accessed out of the east/west neutral plane and slightly up to the right from 5th. It is like a 'dead-end' that shouldn't be there.
If you don't know what I am talking about you have never got into this territory.
Old Dude and I were discussing it and he mentioned that what I describe is not possible in his car - there is nowhere other than 5th or 6th gear that is possible out of the neutral plane on that side of the gearbox.
As it seems unlikely that something is broken (been there since new) I am curious to know if anyone else has such a 'phenomenon' with their NB8B.
I always just assumed it was a peculiarity of the 6 speed gearbox but Old Dude's similar mileage car does not have it.
If you can't understand my description, say so and I will try again.
I wait with interest...

Postby **NitroDann** » Sat Oct 20, 2012 5:38 pm

Thats on the way to reverse.

Dann

Silvia · Postby **Silvia** » Sat Oct 20, 2012 7:00 pm

I've experienced it, more often in the early, learning phase of driving the car, but no answer as to what it's about I'm afraid....

Old Dude · Postby **Old Dude** » Sat Oct 20, 2012 9:14 pm

Hal
I was just thinking about our discussion, and as Dann said thats on the way to reverse (over and down), now on my box the spring pressure on the reverse gate is quite strong so I wouldn't be able to get that far over without proper intention, but maybe your reverse gate spring isn't as firm and its allowing you to go further over.
Having said that I did start my car and push it over to the reverse gate side but could still not push it north into "no mans land".

Just a thought mate

Cheers
Dale

koop21 · Postby **koop21** » Sat Oct 20, 2012 10:58 pm

NitroDann wrote:Thats on the way to reverse.

Dann

+1 sounds like your pushing to far to the right, or your reverse lock out is loose?

Caffeine · Postby **Caffeine** » Sat Oct 20, 2012 11:08 pm

I had the same issue with my NB8B from new, the nylon shift bushing was loose on the end of the gearstick, the gearstick would come out of the bushing and get 'lost' somewhere around 5th.

$7 or so for a new bushing fixed it, it's been fine for the subsequent quarter of a million ilometres

Rocky · Postby **Rocky** » Mon Oct 22, 2012 4:15 pm

Thanks for the comments.
I just took it for a short run on the highway to review the suggestions.
As Dan and others said, the 'dead end' is via the neutral plane that you would use to get to reverse.
Probably the issue for me has been that it is easy to miss the slot up into 5th and end up a fraction too far to the right and into the 'dead end'.
Usually only happens when I am changing up enthusiastically - like when passing something - which of course is the worst possible time as you are out beside a truck in neutral looking for a gear (at about 120ks).
Maybe I have been spoilt with the nice 5 speed boxes in previous cars where there was nowhere to go except 5th.
It seems that for some MX5s (and some drivers) it is easier to get to the dead end than for others.
I will obviously have to concentrate on that change a bit more.

hks_kansei · Postby **hks_kansei** » Mon Oct 22, 2012 4:25 pm

It's also worth looking at the nylon bush mentioned above.

It's relatively easy to access, and easy to change.
They're a wear and tear item, so need replacing every so often (the nylon wears and it slowly gets more freeplay)

Just buy a new Mazda one (nylon) for the $10 or whatever they cost.

There are aluminium and brass ones made, but from what I've heard they aren't worth the extra cost (changes are apparently a little bit better, but I would be concerned that the brass/alloy is going to help wear the base of the gearstick, or simply as they wear they might deposit bits of brass/alloy into the gear selector area)

Locutus · Postby **Locutus** » Mon Oct 22, 2012 5:43 pm

can't say i've ever had this problem in mine. learning to find 6th on the 6sp was a bit of an experience though :shock:

, as the gates on that end of the box seem to have a a slight dogleg to them.

4th on the 6sp with the standard diff ratio is good for ~160km/h :wink:

Mr Morlock · Postby **Mr Morlock** » Mon Oct 22, 2012 6:45 pm

I never get a problem shifting 4 th to 5th- always positive. It has absolutley nothing to do with reverse. 5th is on the way to 5th.

Rocky · Postby **Rocky** » Wed Oct 24, 2012 1:07 pm

Hi MM, you seem to have a similar experience to Old Dude.
The 5 speeds that I have owned over time all required at least a gentle pressure towards the right (towards my L thigh) as I changed up to 5th.
I am probably (when concentrating on other things) continuing to apply that same pressure with the MX5 and I find that as the lever comes out of 4th it tends to fall naturally into the neutral gate off towards the right rather than moving smoothly up to 5th.
Seems that maybe the spring loading against that spot varies a lot from car to car.
Can you feel that neutral 'doorway' if you apply a bit of right pressure as you shift from 4th to 5th?

Old Dude · Postby **Old Dude** » Wed Oct 24, 2012 1:29 pm

Hi Rocky
I have the same pressure on my car when I go into 5th as well, its just that I have a lot , lot more pressure to go into the reverse gate area which would bring me to that "no mans area" you talk about which lines up with reverse effectively.
What about the Nylon bush Caffeine was talking about on the end of the gear stick, could yours be loose also?

Cheers
Dale

Postby **NitroDann** » Wed Oct 24, 2012 2:15 pm

This issue is caused by years of pushing hard right and then up going into 5th on most cars and its simply difficult to manually stop your arm from pushing hard, as that what you have always done.

If you want proof that you are pushing it harder to the right than you realize use your clutch foot on the brake and then your brake foot on the clutch on a quiet backroad or parking lot at walking pace, after you actually try this you will realise just how hard you push your clutch foot down, but you never realised it.

Go do it, and then you will understand why you dont believe you are pushing the gearstick hard to the right, but actually are.

Dann

Rocky · Postby **Rocky** » Wed Oct 24, 2012 2:53 pm

I'm inclined to agree with you Dann. The 5 speeders I owned all required a slightly 'special' technique when shifting up to 5th - and I'm thinking that I have trained myself to apply a bit extra pressure that isn't required on the MX5 box.
When I'm concentrating on the gearchange I don't have any difficulty but I occasionally have a problem when I'm passing something because I'm focused on a bunch of other factors (speed/distance etc) and the gearchange is happening as a reflex action.
It's not a big deal, but I'm picky with my cars and it has always been a minor annoyance that I wondered about.
I don't however discount the possibility of a worn bush or similar.
("worn bush" - sounds like a painful complaint)

deviant · Postby **deviant** » Wed Oct 24, 2012 3:23 pm

The NB8B box in the race car was a POS in the 4-5-6-5-4 movements.

I suspect the spring that blocks out the reverse gate was weak or broken. Going 4th to 5th you could basically move to far to the right, fall in to the gate and not be able to push forward in to 5th.

Going 5th to 6th was the same, as you pass the gate it would slip to the right a bit more and end up in the gate for reverse.

It took some getting used to, very very easy to end up going 4th to 3rd or 5th to 4th trying to 'aim' the gear stick yourself.

The NB8B I have now has the best MX5 'box I have used. As tight as a drum and takes some effort to push in to the reverse gate...more effort than it takes to hold the stick to the right when changing gear even at track speeds.

Remember a gearbox is designed to work for you, dont try and aim the stick yourself as you will keep missing the gate. Start changing gear just with the flat of your palm and don't grip the knob.