[Mgs] B/GT gearbox mystery

[Paul Hunt]

It's not uncommon to get problems selecting reverse or 1st, but lifting 
the clutch then trying again (if nudging towards 1st or 2nd doesn't 
work) has worked for me on two cars over 30 years. Not had a problem 
selecting 3rd or 4th ... but then I rarely do that at a standstill!  If 
the engine isn't running then you _can_ get failure to get it into any 
gear, or maybe have to try and select all of them before things move enough.

Is it grinding when trying to select reverse but won't go in?  If so 
that's the clutch.  That can also prevent selection of forward gears but 
without grinding.

Have there been any problems getting it out of gear once it has gone 
in?  Any unpleasant noises when you have selected a gear and are 
driving?  If not then selector problems and gear set problems are 
perhaps unlikely.  Also if the problem is with all the gears as you say 
i.e. all the fore and aft movements into reverse, 1st/2nd, and 3rd/4th 
then again selector problems seem less likely as there are three 
separate rods and forks.  The only common points are where the remote 
extension engages with the three rods which is accessed from the top of 
the gearbox i.e. a gearbox out job.  There is also an interlock plate 
which in that area which engages with that end of the selector rods and 
I think prevents more than one gear being engaged at a time.

I can understand the problem coming and going with the clutch if 
sometimes the master cylinder is failing to pressurise the fluid and 
move the slave piston, more so than something having come loose inside 
the gearbox, with the possible exception of that interlock plate.

PaulH.

On 23/09/2024 23:09, S.Carr wrote:
>
> My ’71 B/GT has suddenly developed a gearbox problem—intermittently it 
> will not go into _any_gear, whether the engine is running or not.  A 
> few minutes later it will work normally, then later refuse to shift 
> again.  Any idea where we should look for the cause?  We assume the 
> side plate will have to come off.  We need to fix the problem, as I 
> want to put the car up for sale before winter sets in----
>
> Sarah Carr
>
> ’71 B/GT in PA
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for 
> Windows
>
>
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