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279
Reverse
gear jumps out - not a new difficulty!
Edward
Corbett (Teal Blue 1916) from London SE has recently bought an MGBGTV8
and posted a message on the V8 Website bulletin board seeking help
with his reverse gear slipping out.
(Jan 03)
Ed
Corbett's posting said "I have just bought an original MGBGTV8
and it runs beautifully apart from when one is reversing, and occasionally
in second gear, the car will quite often slip out of reverse gear.
Has anyone else come across a similar problem and if so is there
a remedy?"
Just
by chance Victor Smith (Harvest Gold 1089) was reprocessing
Volume 4 of the V8 Workshop Notes series the night before and had
seen a Note 121 on that very topic contributed by Mick Westrop back
in 1983, and a reference to an earlier Note 27 from Peter Laidler
in Volume 1 back in 1979! Copies of both Notes were put up on the
V8 Website for Ed to read. By the way Volume 4 is the last volume
to be reprocessed as part of a project to put the whole of the V8
Workshop Notes series on a single CD for distribution to members
by April 2003 in time for the V8 25th Anniversary.
Another
response on the bulletin board came in from Gavin Bailey
(Glacier White 0199) from Surrey - "I had this problem when
I fitted a new rubber boot that sits underneath the gearbox gaiter.
The new rubber boot was far stiffer and less pliable than the old
one and tended to pull the gearbox lever back to dead centre. It
may be that there is some other problem with the gearbox, however
a stiff gaiter could be a contributing factor". Well it
is certainly the least expensive possible common cause to check
first - it is essentially the cause outlined by Mick Westrop in
his Note some twenty years ago.
Gavin Bailey (Glacier White 0199) from Surrey .
(Photo: Victor Smith)
Next came a posting
from Dave Wellings (Black 0974) from Yorkshire who acknowledged
a stiff gaiter was one cause but then outlined further investigations
as follows - "Get the centre console out of the way, remove
the gearknob and gaiter and then look to see whether the gearstick
touches the "hole" in the second or reverse positions,
or top gear. There is a fibre layer around the hole and if there
is any contact you may need to grind away some of the surround to
get clearance. Remember that the gearbox moves slightly under load,
which will close the gap".
Dave then
touched on sloppy gearbox mountings which can cause the rear end
to drop or the box to move about excessively. This will knock the
gearbox out of gear. "If you do all these checks and it
is still no better then the next thing I would look at are the detent
springs. Now I working from memory as it is ten years since I stripped
my gearbox but there are three bolt heads just aft of the bellhousing.
Under those bolts are the three detent springs and balls. One each
for 1st/2nd, 3rd/4th and reverse - three selector rods. It may just
be possible to replace those with the gearbox in place".
"Finally
another possible cause might is slop in the gearbox itself and the
primary culprit I suggest would be wear in the laygear thrust washer.
This allows the laygear to move fore and aft - with the power on/off
which may kick it out of reverse gear. Otherwise it may be general
bearing wear, or selector fork wear and the only solution left is
to take it out and have a look".
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Geoff Allen
(Teal Blue 2101) was asked for his views on the reverse gear difficulty
as he has a long experience of working on MGBGTV8s ever since the
early development cars. He has probably seen more V8 gearboxes than
most V8 enthusiasts as he was in Rectifications Department at the
Abingdon Factory for 27 years which covered the development and production
of the MGBGTV8 and then later ran his own MG maintenance and repair
business in Abingdon before retiring to Cheshire eight years ago.
"I can add a few comments to the notes on the problem of the
V8 jumping out of gear. As the car jumps out of reverse and second,
I think it is more likely to be caused by the gaiter than anything
more serious inside the gearbox. When we were producing the V8 this
was a common problem and was usually caused by the incorrect fitting
of the gaiter. There is always a tendency for the gear lever to be
slightly to the rear of centre of the hole in the transmission tunnel
so make sure the seam in the leathercloth gaiter is to the front of
the lever - that is towards the fascia. Also when fitting the gaiter
make sure that both the ribbed rubber and leathercloth gaiters are
fitted under the console directly onto the carpet, not on top of the
console under the chrome ring. We found this usually cured the problem
on cars at the Factory and I have cured quite a number that way since.
The lower the gaiter is down the lever the less chance there is of
the lever fouling it".
Geoff Allen (Teal Blue 2101), the V8 Historian &
Archivist, was at the Abingdon Factory when the MGBGTV8 was
developed and produced, and in Rectifications Department he
sorted out the faults and niggles from the production line and
road tests. (Photo: Victor Smith) |
"To quote
an extreme case of this problem, I fitted a 1977 MGB gear lever which
has a silentblock bush fitted to a V8 to cure gear lever "zizz"
and had to cut the tunnel and weld in new nuts, then reposition the
console to line it all up. I also fitted the same type of gear lever
to my V8 (Teal Blue 2101) and that went straight in with no problems
so there is obviously quite a difference in position between various
cars."
"On
the subject of detent springs there was a suggestion at one time of
a modification to the three fork rod plungers which are operated by
the detent springs and drop into the recess in the fork rod to hold
it in gear. This modification was to cut the bottom off the plungers
and fit a steel ball in its place to make for a crisper gear selection!
I don't think this was a very good idea as the plunger has around
1" bearing surface whereas the steel ball has only a minimal
bearing surface and can hammer the aluminium hole in the case and
lead to a sloppy location of the lever fore and aft. I have found
this problem on one car in the past and removed the balls and refitted
the plungers which cured the problem - luckily the owner said he had
fitted the balls so I knew what to look for. So having talked a lot
of balls I will now sign off!" Typical jovial false modesty
from Geoff as usual.
The outer leathercloth gaiter covering the inner ribbed rubber
gaiter - a likely cause for reverse gear jumping out. (Photo: David
Waterton)
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