From britfan1 at epix.net  Mon Sep 23 16:09:01 2024
From: britfan1 at epix.net (S.Carr)
Date: Mon, 23 Sep 2024 18:09:01 -0400
Subject: [Mgs] B/GT gearbox mystery
Message-ID: <1250110833.1317283.1727129345861@epix.net>

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 for Windows

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From dirtbeard at gmail.com  Mon Sep 23 17:12:55 2024
From: dirtbeard at gmail.com (old dirtbeard)
Date: Mon, 23 Sep 2024 23:12:55 +0000
Subject: [Mgs] B/GT gearbox mystery
In-Reply-To: <1250110833.1317283.1727129345861@epix.net>
References: <1250110833.1317283.1727129345861@epix.net>
Message-ID: <CO1P222MB0274FEF35A60B60B25864E45AB6F2@CO1P222MB0274.NAMP222.PROD.OUTLOOK.COM>

Perhaps a shift fork has come loose on is shaft. Does the shift lever move or is it locked in place when you cannot get it into gear?

Best,

Doug
mobile
________________________________
From: Mgs <mgs-bounces at autox.team.net> on behalf of S.Carr <britfan1 at epix.net>
Sent: Monday, September 23, 2024 3:09:01 PM
To: mgs at autox.team.net <mgs at autox.team.net>
Subject: [Mgs] B/GT gearbox mystery


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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From paulbhunt73 at gmail.com  Tue Sep 24 03:08:58 2024
From: paulbhunt73 at gmail.com (Paul Hunt)
Date: Tue, 24 Sep 2024 10:08:58 +0100
Subject: [Mgs] B/GT gearbox mystery
In-Reply-To: <1250110833.1317283.1727129345861@epix.net>
References: <1250110833.1317283.1727129345861@epix.net>
Message-ID: <17032465-c6d5-4d1b-8fab-c42ae14d8fc0@gmail.com>

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
>
>
> _______________________________________________
>
> Mgs at autox.team.net
> Donate:http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive:http://www.team.net/pipermail/mgs  http://autox.team.net/archive
>
> Unsubscribe:http://autox.team.net/mailman/options/mgs/paulbhunt73 at gmail.com
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From paulbhunt73 at gmail.com  Wed Sep 25 05:25:01 2024
From: paulbhunt73 at gmail.com (Paul Hunt)
Date: Wed, 25 Sep 2024 12:25:01 +0100
Subject: [Mgs] B/GT gearbox mystery
In-Reply-To: <1250110833.1317283.1727129345861@epix.net>
References: <1250110833.1317283.1727129345861@epix.net>
Message-ID: <192315f6-0b25-44b0-8c79-39545d037cf3@gmail.com>

Further thoughts.

As well as interfacing at the front of the gearbox under the remote 
control unit the shafts also interface aft of the gearbox proper in the 
extension (to which is attached the overdrive if fitted).? The rear of 
the shafts have curved fingers at right-angles to the shafts that have 
to pass over each other as each shaft is moved fore and aft.? They, the 
pieces at the front with the interlock plate, and the forks that shift 
the hubs all have screws going into holes in the shafts with locknuts to 
keep things in the correct relative positions.? The ones at the front 
and the back are locked with wire, but for some reason (two gearboxes) 
the forks don't seem to have the wire.? It's the fork that sets the 
rotational position of the each shaft, and hence the relationship 
between the interlock components at the front and the fingers at the 
rear.? If one of those has come loose then that shaft could turn and 
prevent the other two from moving as well as itself.? The forks are 
visible by removing the side cover, so you might get lucky.? Several 
pictures of these areas and others taken during a dismantle here 
http://www.mgb-stuff.org.uk/geardis.htm

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
>
>
> _______________________________________________
>
> Mgs at autox.team.net
> Donate:http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Archive:http://www.team.net/pipermail/mgs  http://autox.team.net/archive
>
> Unsubscribe:http://autox.team.net/mailman/options/mgs/paulbhunt73 at gmail.com
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