[NB 6 sp] - there is a reverse gear lockout

A few weeks ago I was convinced by posts here suggesting that there's no
mechanism for reverse gear lock-out (when moving forwards) in the Aisin
6sp gearbox. IIRC there was a link to miata.net posts implying the same
- that reverse gear lockout is a myth.
I also checked the 6 speed box FSM, and can't see anything obviously
there to show that a lock-out exists.
So about 10 minutes ago, I tried it out - very carefully at first.
There is in fact a lock-out. I can get the shifter across to the right
into the horizontal part of the gate, but it won't budge down towards
reverse at all when you're moving forwards. There's no way to
accidentally engage reverse say if changing from 3rd directly to 6th.
My NB is '98 production JDM VS 1.8 RHD. Perhaps this is not in all NB 6
sp models.
Cheers.

Me wrote:
> A few weeks ago I was convinced by posts here suggesting that there's no
> mechanism for reverse gear lock-out (when moving forwards) in the Aisin
> 6sp gearbox. IIRC there was a link to miata.net posts implying the same
> - that reverse gear lockout is a myth.
> I also checked the 6 speed box FSM, and can't see anything obviously
> there to show that a lock-out exists.
> So about 10 minutes ago, I tried it out - very carefully at first. There
> is in fact a lock-out. I can get the shifter across to the right into
> the horizontal part of the gate, but it won't budge down towards reverse
> at all when you're moving forwards. There's no way to accidentally
> engage reverse say if changing from 3rd directly to 6th.
> My NB is '98 production JDM VS 1.8 RHD. Perhaps this is not in all NB 6
> sp models.
> Cheers.

I have a 2003 UK 1.8 with a 6 speeder.

There is no mechanism for preventing the engagement of reverse whilst
moving forwards.

I think it's pretty difficult as I don't think reverse has a synchro and
if the car is travelling at any speed, the output part of the gearbox
will be spinning too fast in the wrong direction to engage easily.

--
Douglas

On 13/05/2010 7:27 p.m., Douglas Payne wrote:
> Me wrote:
>> A few weeks ago I was convinced by posts here suggesting that there's
>> no mechanism for reverse gear lock-out (when moving forwards) in the
>> Aisin 6sp gearbox. IIRC there was a link to miata.net posts implying
>> the same - that reverse gear lockout is a myth.
>> I also checked the 6 speed box FSM, and can't see anything obviously
>> there to show that a lock-out exists.
>> So about 10 minutes ago, I tried it out - very carefully at first.
>> There is in fact a lock-out. I can get the shifter across to the right
>> into the horizontal part of the gate, but it won't budge down towards
>> reverse at all when you're moving forwards. There's no way to
>> accidentally engage reverse say if changing from 3rd directly to 6th.
>> My NB is '98 production JDM VS 1.8 RHD. Perhaps this is not in all NB
>> 6 sp models.
>> Cheers.
>
> I have a 2003 UK 1.8 with a 6 speeder.
>
> There is no mechanism for preventing the engagement of reverse whilst
> moving forwards.
>
> I think it's pretty difficult as I don't think reverse has a synchro and
> if the car is travelling at any speed, the output part of the gearbox
> will be spinning too fast in the wrong direction to engage easily.
>
So you're saying that when moving forwards, if you push the shift lever
right - into the reverse gate - you can budge it downwards? On mine,
it's completely locked out.
So this may not be in all the nb 6 speed boxes, but seems strange that
it would be in early ones rather than later.
The Altezza / Lexus is200 and S2000 use the same AZ6 box. I wonder if
they have reverse lockout. I'll check on an S2000.

> So this may not be in all the nb 6 speed boxes, but seems strange that
> it would be in early ones rather than later.
> The Altezza / Lexus is200 and S2000 use the same AZ6 box. *I wonder if
> they have reverse lockout. *I'll check on an S2000.

I can tell you beyond any doubt that this feature does not exist on
the -mazdaspeed- version of the Aisin 6 speed that I own. I have been
told, but have not confirmed, that a regular miata with a 6 speed does
not have the same box as a mazdaspeed. The MSM gearboxes have shot-
peened gears to increase strength from what I have been told.

The FSM that I have does not seem to show any differentiation between
the two cars so it is possible they are the same internally, but that
doesn't mean that USA cars get the same gearbox as a car intended for
a different foreign market.

Chris

On 16/05/2010 5:47 a.m., Hal wrote:
>> So this may not be in all the nb 6 speed boxes, but seems strange that
>> it would be in early ones rather than later.
>> The Altezza / Lexus is200 and S2000 use the same AZ6 box. I wonder if
>> they have reverse lockout. I'll check on an S2000.
>
> I can tell you beyond any doubt that this feature does not exist on
> the -mazdaspeed- version of the Aisin 6 speed that I own. I have been
> told, but have not confirmed, that a regular miata with a 6 speed does
> not have the same box as a mazdaspeed. The MSM gearboxes have shot-
> peened gears to increase strength from what I have been told.
>
> The FSM that I have does not seem to show any differentiation between
> the two cars so it is possible they are the same internally, but that
> doesn't mean that USA cars get the same gearbox as a car intended for
> a different foreign market.
>
The S2k box feels the same as the Mazda 6sp, and also /seems/ to have a
lockout.
There's apparently a single cone synchro on reverse. Rather than it
being a mechanical lockout, if the synchro is working, then if I've got
this right, it should prevent the selector from shifting to the point
where the gears can mesh. I can't shift mine out of the horizontal gate
toward reverse when moving forwards. Is there synchro on reverse on the
MSM? Worn perhaps? I guess you can tell if there's a slight
graunch/clunk engaging reverse from standstill, or it doesn't always
slot in first time without effort. Reverse on mine seems to select
(from standstill) without ever needing effort - contrast my old nissan
with no reverse synchro, where sometimes you need to try a couple of times.

Me wrote:
> On 16/05/2010 5:47 a.m., Hal wrote:
>>> So this may not be in all the nb 6 speed boxes, but seems strange
>>> that it would be in early ones rather than later.
>>> The Altezza / Lexus is200 and S2000 use the same AZ6 box. I wonder
>>> if they have reverse lockout. I'll check on an S2000.
>>
>> I can tell you beyond any doubt that this feature does not exist on
>> the -mazdaspeed- version of the Aisin 6 speed that I own. I have been
>> told, but have not confirmed, that a regular miata with a 6 speed
>> does not have the same box as a mazdaspeed. The MSM gearboxes have
>> shot- peened gears to increase strength from what I have been told.
>>
>> The FSM that I have does not seem to show any differentiation between
>> the two cars so it is possible they are the same internally, but that
>> doesn't mean that USA cars get the same gearbox as a car intended for
>> a different foreign market.
>>
> The S2k box feels the same as the Mazda 6sp, and also /seems/ to have
> a lockout.
> There's apparently a single cone synchro on reverse. Rather than it
> being a mechanical lockout, if the synchro is working, then if I've
> got this right, it should prevent the selector from shifting to the
> point where the gears can mesh. I can't shift mine out of the
> horizontal gate toward reverse when moving forwards. Is there synchro
> on reverse on the MSM? Worn perhaps? I guess you can tell if there's
> a slight graunch/clunk engaging reverse from standstill, or it doesn't
> always
> slot in first time without effort. Reverse on mine seems to select
> (from standstill) without ever needing effort - contrast my old nissan
> with no reverse synchro, where sometimes you need to try a couple of
> times.

Not sure I understood all of that, but I often have to try 2-3 times to get
into reverse from a standstill in my recently acquired MSM. Seems like I
have to put in 1st, then it will go into reverse. Still learning not to
miss 4th and hitting 2nd when downshifting from 5th or 6th.

In article > , Frank Berger wrote:
>Not sure I understood all of that, but I often have to try 2-3 times to get
>into reverse from a standstill in my recently acquired MSM. Seems like I
>have to put in 1st, then it will go into reverse.

Have you tried double-clutching? Without shifting into 1st,
shift into neutral, let out clutch, push in clutch, shift into
reverse.

--
TJH

tjhiggin.at.hiwaay.dot.net

T.J. Higgins wrote:
> In article > , Frank
> Berger wrote:
>> Not sure I understood all of that, but I often have to try 2-3 times
>> to get into reverse from a standstill in my recently acquired MSM.
>> Seems like I have to put in 1st, then it will go into reverse.
>
> Have you tried double-clutching? Without shifting into 1st,
> shift into neutral, let out clutch, push in clutch, shift into
> reverse.

I'll try it. Thanks.