[xj] XJ12 Series III Gearbox -no forward drive issue

XJ
1

Hey Everyone, I have a pretty major problem with my XJ12
that it’s recently lost the ability to drive forward. It
does however drive in reverse no problems which isn’t very
useful.

It was driving fine, but I was getting the whining noise on
cold startup coming from the gearbox. It was also sometimes
a bit erratic as shifting up gears. So I changed the oil and
filter in the gearbox by dropping the sump (removing the
gearbox mount - thanks to the XJS bible for the heads up on
that). On the morning I drove the car to my workshop to
change the gearbox oil the car was really struggling to move
forwards. The engine was revving but the car just not moving
with any great force until it would barley move at all.

After the oil change it has had no effect and it still wont
drive forward.

I’m suspecting that the gearbox has had it, but just wanted
to ask for some advice on this. Maybe its not so bad at all
and there is something simple wrong with it? Any advice
would be great.

When driving in reverse the car feels totally normal not
sluggish so I guess the torque converter is ok though I
could be wrong.

Thanks, Marko–
'87 XJS Racer
Scotland, United Kingdom
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2

In reply to a message from elmarko sent Mon 20 Dec 2010:

How many miles are on the transmission? Sicne you have reverse,
that says the fluid level is probabyl ok, and points to interal
failure. What was the old oil like that you took out? Any sort of
burnt smell to it, or was it nice and red?

One failure of the GM transmission is the steels in the clutch
packs have a scalloped edge, and they can break there. This
happened to my transmission, so in effect both first and third were
engaged at the same time. If that’s the case, its rebuild time.
Mine failed at 110,000 miles, I’ve heard of others failing in a
similar manner once over 100,000 miles.–
The original message included these comments:

Hey Everyone, I have a pretty major problem with my XJ12
that it’s recently lost the ability to drive forward. It
does however drive in reverse no problems which isn’t very
useful.

–
Craig 95 VDP/ 90 DS420/ 94 XJS/ 66 S Type EFI
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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3

In reply to a message from Craig Talbot sent Mon 20 Dec 2010:

Thanks for the reply, it’s done 101,000 miles from memory…
the oil that came out of it was very black and smelt burnt. It
does almost move when I trap it in first but it’s only just
gently rocking it when I try accelerate.

Hmmm so looks like the box will have to come out. Is it a
really difficult job ? I may just take it out and hand it to a specialist for repair.

Thanks for your advice–
The original message included these comments:

How many miles are on the transmission? Sicne you have reverse,
that says the fluid level is probabyl ok, and points to interal
failure. What was the old oil like that you took out? Any sort of
burnt smell to it, or was it nice and red?
One failure of the GM transmission is the steels in the clutch
packs have a scalloped edge, and they can break there. This
happened to my transmission, so in effect both first and third were
engaged at the same time. If that’s the case, its rebuild time.
Mine failed at 110,000 miles, I’ve heard of others failing in a
similar manner once over 100,000 miles.

–
'87 XJS Racer
Scotland, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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4

In reply to a message from elmarko sent Mon 20 Dec 2010:

Sounds like it needs a rebuild, black and burnt means the clutches
are gone.

I’ve not pulled a transmission out seperately, it can be done
though. Much easier on a hoist and you’ll need a transmission jack,
as the GM box is heavy. If you’re a skilled mechanic it’s possible,
but I don’t think this is a driveway sort of job, mainly because of
the clearance you’ll need to have under the car.–
The original message included these comments:

the oil that came out of it was very black and smelt burnt. It

–
Craig 95 VDP/ 90 DS420/ 94 XJS/ 66 S Type EFI
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5

Marko,

Any way to check the bands that work on moving forwards?

Am not an auto-box expert but might take a look. That said, if the fluid smelled burnt then
would guess that the bands are toast already.

Joe AOn 20 Dec 2010 at 7:42, elmarko wrote:

Hey Everyone, I have a pretty major problem with my XJ12
that it’s recently lost the ability to drive forward. It
does however drive in reverse no problems which isn’t very
useful.

It was driving fine, but I was getting the whining noise on
cold startup coming from the gearbox. It was also sometimes
a bit erratic as shifting up gears. So I changed the oil and
filter in the gearbox by dropping the sump (removing the
gearbox mount - thanks to the XJS bible for the heads up on
that). On the morning I drove the car to my workshop to
change the gearbox oil the car was really struggling to move
forwards. The engine was revving but the car just not moving
with any great force until it would barley move at all.

After the oil change it has had no effect and it still wont
drive forward.

I’m suspecting that the gearbox has had it, but just wanted
to ask for some advice on this. Maybe its not so bad at all
and there is something simple wrong with it? Any advice
would be great.

When driving in reverse the car feels totally normal not
sluggish so I guess the torque converter is ok though I
could be wrong.

Thanks, Marko

'87 XJS Racer
Scotland

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6

In reply to a message from joe@joea.com sent Mon 20 Dec 2010:

Not that I’m aware of on the TH400. On a BW66, yes.–
The original message included these comments:

Any way to check the bands that work on moving forwards?

–
Craig 95 VDP/ 90 DS420/ 94 XJS/ 66 S Type EFI
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7

For the TH400, 100k miles is a pretty typical life span. I’ve had/seen some
go much longer…but also many that didn’t.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Craig Talbot” talbotc@telus.net

Mine failed at 110,000 miles, I’ve heard of others failing in a
similar manner once over 100,000 miles.

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8

Anecdotal evidence suggests that it doesn’t seem to live as long behind
the V12 as it does in GM products. I suspect with the V12’s tight engine
bay that it gets hotter than it does in a typical GM car.

Craig

Doug Dwyer wrote:> For the TH400, 100k miles is a pretty typical life span. I’ve had/seen

some go much longer…but also many that didn’t.

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9

Perhaps so, yes.

However, I can well remember from my early dealership days …when the TH400
was still a very common sight in GM cars…doing many overhauls at 80k-100k
miles. And with my family’s love affair with Olds’ and Buicks…a seemingly
endless string of them over the decades…trans overhauls at 100k or so
became almost routine. We did have one go 225k miles, though, and still
working well when we sold it. The last of the Mohicans, my dad’s '78 Olds
Regency, had 150k on the 400 trans… but we were just nursing it along.
It had been getting slippery and soft for some time before I sold the car
last year. That Lucas transmission additive…“overhaul in a can” is what I
call it…actually helped, as advertised.

When I bought my XJS the records included an invoice for a trans overhaul at
89k. It was poorly done so I had to have it overhauled again right after I
bought it at about 100k.

It all comes down to the oh-so-soft-shifts that the 400s are so well known
for. Firm up the shifts and the darn things will last forever. Great
transmission but an old dinosaur by today’s standards. It was first used in
'64, after all.

Ramble switch turned “off” :slight_smile:

Cheers
Doug Dwyer
Longview Washington USA
1995 XJR----- Original Message -----
From: “Craig Talbot” talbotc@telus.net
Cc: xj@jag-lovers.org
Sent: Monday, December 20, 2010 5:13 PM
Subject: Re: [xj] XJ12 Series III Gearbox -no forward drive issue

Anecdotal evidence suggests that it doesn’t seem to live as long behind
the V12 as it does in GM products. I suspect with the V12’s tight engine
bay that it gets hotter than it does in a typical GM car.

Craig

Doug Dwyer wrote:

For the TH400, 100k miles is a pretty typical life span. I’ve had/seen
some go much longer…but also many that didn’t.

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Jag-lovers Forums - Jag-lovers.

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10

I thought about pulling it out of my limo, but it seems to suit the
character of the car well. For the few miles that I put on it, the fuel
economy doesn’t matter. Any thoughts on the 700R4? is it a credible 4
speed replacement?

Craig

Doug Dwyer wrote:> . Great transmission but an old dinosaur by today’s standards. It was

first used in '64, after all.

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11

Everyone who has gone to the 700R4 seems to be quite happy. Overdrive fourth
gear for cruising, deeper ratio in first gear for more off-the-line scoot.
Locking torque converter. Less parasitic loss.

I’m not so sure dump a properly functioning 400 but when the time comes the
700 is worth considering.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Craig Talbot” talbotc@telus.net

I thought about pulling it out of my limo, but it seems to suit the
character of the car well. For the few miles that I put on it, the fuel
economy doesn’t matter. Any thoughts on the 700R4? is it a credible 4
speed replacement?

===================================================
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12

elmarko wrote:

Hey Everyone, I have a pretty major problem with my XJ12
that it’s recently lost the ability to drive forward. It
does however drive in reverse no problems which isn’t very
useful.

It was driving fine, but I was getting the whining noise on
cold startup coming from the gearbox. It was also sometimes
a bit erratic as shifting up gears. So I changed the oil and
filter in the gearbox by dropping the sump (removing the
gearbox mount - thanks to the XJS bible for the heads up on
that). On the morning I drove the car to my workshop to
change the gearbox oil the car was really struggling to move
forwards. The engine was revving but the car just not moving
with any great force until it would barley move at all.

At which stage it is about too late, Marko…:slight_smile:

As soon as the bands/clutches starts slipping in earnest the material,
very thin, will abrade very quickly leaving a dead box. With initial
slipping noticed some remedial action is possible, and may work, without
a complete stripdown. Otherwise; there are no adjustments possible,
though some testing is possible in the initial phase of slip - to
possibly pinpoint a lesser problem…

IAW - at this stage a box overhaul is in the cards, or a
replacement/upgrade…

Frank
xj6 85 Sov Europe (UK/NZ)>After the oil change it has had no effect and it still wont

drive forward.

I’m suspecting that the gearbox has had it, but just wanted
to ask for some advice on this. Maybe its not so bad at all
and there is something simple wrong with it? Any advice
would be great.

When driving in reverse the car feels totally normal not
sluggish so I guess the torque converter is ok though I
could be wrong.

===================================================
The archives and FAQ will answer many queries on the XJ series…
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13

In reply to a message from Frank Andersen sent Mon 20 Dec 2010:

Thanks for the advice. It sounds like it is indeed time for
a rebuild. I was thinking about picking up a second hand
box, but I think best to rebuild the one I’ve got as a
second hand one probably isn’t going to be any better.

I would like to look into firming up the shifts to help the
transmission last longer. Do yo know a shift kit that would
do the job ? I just fitted a Transgo full manual shift kit
to my XJS with the 4speed auto box so I guess it would be a
similar kit to that.

Thanks again, Marko–
The original message included these comments:

At which stage it is about too late, Marko…:slight_smile:

–
'87 XJS Racer
Scotland, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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14

Whoever does your trans overhaul should be able to recommend a shift
kit…B&M, TransGo, whatever. There are many out there, most with
“mild-medium-wild” calibrations to choose from. You’ll probably want “mild”.

If you ever plan on taking your V12 up to the 6000-6500rpm range that it is
capable of, make sure to let the trans shop know so they can order an
appropriate torque converter. Use of rebuilt converters is the norm and
perfectly OK…but you’ll want something higher grade than the ordinary.

Cheers
Doug Dwyer
Longview Washington USA
1995 XJRFrom: “elmarko” marko@fxsimulation.com

I would like to look into firming up the shifts to help the
transmission last longer. Do yo know a shift kit that would
do the job ? I just fitted a Transgo full manual shift kit
to my XJS with the 4speed auto box so I guess it would be a
similar kit to that.

===================================================
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15

elmarko wrote:

In reply to a message from Frank Andersen sent Mon 20 Dec 2010:

Thanks for the advice. It sounds like it is indeed time for
a rebuild. I was thinking about picking up a second hand
box, but I think best to rebuild the one I’ve got as a
second hand one probably isn’t going to be any better.

It’s the devil you know, Marko…:slight_smile:

I’m not at all sure that ‘shift - kits’ has any longevity relation - I
rather doubt it. Altering shifting generally means tinkering with the
valve body for some specific effect - so you better be clear as to what
you want. The Jaguar did all this for us - arriving at some result
considered suitable for the engine/body combination…and perceived
Jaguar driver preferences. They likely also added longevity as a factor,
though that is within the driver’s box treatment domain as well…

I doubt if they will guarantee that the kit fitted will make the box
last longer - and if they do I’d like their rationale for so stating…:slight_smile:

The real drawback on the GM 400, and indeed the 6’s BWs, is too few
gears…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)>I would like to look into firming up the shifts to help the

transmission last longer. Do yo know a shift kit that would
do the job ? I just fitted a Transgo full manual shift kit
to my XJS with the 4speed auto box so I guess it would be a
similar kit to that.

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16

Frank,
I’m just putting in a word for the transmission originally installed.

Considering that it cruises about 1800 to 2,000 at about seventy mph, and that 3,000 is a good healthy rpm for the v12, and that the redline is at least 6,000, and that 4,000 and above is really fun (and not legal anywhere, it seems like),…then we are only talking about economy!

I think someone is choosing the wrong tool for the job.

The biggest problem is that putt-ing around below 2,000 is where the problems in the HE head engine come from…causing the need for high speed runs to clean it out…and a jag V12 run between 3 and 4 thousand rpm, mostly, will need only to get onto the road more often…Drive it ‘Con Brio’ and don’t bother with Italian Tune-Ups, I suggest.

Money spent on fuel beats money spent on cleaning out carbon from choked up engines.

In my opinion, of course.

It’s a great car in snow, slush, crawling on rain-slick ice, and at 100 mph plus, on graded snow way below Zero in any language, and 125 - 145 mph on good pavement and good tires…(if there is anywhere you can find to enjoy that in this crowded & over-regulated world off the race track)

And I have never wished for a higher gear or for a lower one…but for me it’s for grand touring; long distances through open country at high speeds…and no slouch zinging down the Interstate…I wish for higher speed limits, not lower engine speeds.

GM 400 is cheaper to overhaul, “bullet proof” and as adapted for use by Rolls -Royce, Ferrari, Land Rover, etc., I think., as well as the V12 Jag, is a good tranny, and can be tuned up to be more responsive if desired, in the ECU as I recall…‘AJ’ comes to mind.
Marko should be sure, if he sticks with the GM 400 to be sure it meets the Jag 12 specs…and same for the torque converter; it’s
“special”.

Don’t mean you are wrong, Frank…but I’m just focusing on the intent of the Builder and the Owner…

When ‘they’ built the car ‘they’ were aiming at 27 mpg at 55mph…I suppose they got that; I just wouldn’t know, didn’t buy it for that !!

(grin…yellow teeth and sparse white hair but still grinning!)

Bill
Alaska
'86 V12 vdP Canadian Model
'71 xj LumpOn Dec 21, 2010, at 10:29 PM, Frank Andersen wrote:

elmarko wrote:

In reply to a message from Frank Andersen sent Mon 20 Dec 2010:

Thanks for the advice. It sounds like it is indeed time for a rebuild. I was thinking about picking up a second hand box, but I think best to rebuild the one I’ve got as a second hand one probably isn’t going to be any better.

It’s the devil you know, Marko…:slight_smile:

I’m not at all sure that ‘shift - kits’ has any longevity relation - I rather doubt it. Altering shifting generally means tinkering with the valve body for some specific effect - so you better be clear as to what you want. The Jaguar did all this for us - arriving at some result considered suitable for the engine/body combination…and perceived Jaguar driver preferences. They likely also added longevity as a factor, though that is within the driver’s box treatment domain as well…

I doubt if they will guarantee that the kit fitted will make the box last longer - and if they do I’d like their rationale for so stating…:slight_smile:

The real drawback on the GM 400, and indeed the 6’s BWs, is too few gears…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)

I would like to look into firming up the shifts to help the transmission last longer. Do yo know a shift kit that would do the job ? I just fitted a Transgo full manual shift kit to my XJS with the 4speed auto box so I guess it would be a similar kit to that.

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17

Bill de Creeft wrote:

Frank,
I’m just putting in a word for the transmission originally installed.

Considering that it cruises about 1800 to 2,000 at about seventy mph, and that 3,000 is a good healthy rpm for the v12, and that the redline is at least 6,000, and that 4,000 and above is really fun (and not legal anywhere, it seems like),…then we are only talking about economy!

I think someone is choosing the wrong tool for the job.

The biggest problem is that putt-ing around below 2,000 is where the problems in the HE head engine come from…causing the need for high speed runs to clean it out…and a jag V12 run between 3 and 4 thousand rpm, mostly, will need only to get onto the road more often…Drive it ‘Con Brio’ and don’t bother with Italian Tune-Ups, I suggest.

Money spent on fuel beats money spent on cleaning out carbon from choked up engines.

One cannot really disagree with that, Bill…but…but…

We are of course talking about ‘old’ technology on the fuel management
side - in principle the engines, fuellling well managed, should not soot
up, but they do. But also; the rpms/speed is not necessarily related to
the number of gears. That this is the case with ‘our’ readily available
options, the 4th gear being on overgear, is in your context
‘unfortunate’ - aiming specifically at economy and disregarding engine
suffering…

Modern 6-speeds are of course paired off with advance fuel control
systems, more able to keep the engine clean. And also; they do not
necessarily go to top gear at the drop of a hat like ‘ours’. The gears
are more closely spaced to allow a better match between the power
required from the engine, rpms, for the driving demands - which
undoubtedly is ‘good’. 6-speed will outdrag a three speed with the smae
engine…

The V12 has of course the torque required for the three gears
available, it would make out even with two :), but the shift points
also tends towards lazy rpms at moderate speeds - or even a bit lower.
The fourth gear on the boxes available isn’t all that much higher - the
‘problem’ is more that the shift points are so designed for excessive
use of it. Which of course is eliminated by a manual box - some swear by
the 5 gear manual, giving the driver a wider choice…and at will…

One can certainly counter this by simply select ‘3’ or whatever - it
will keep the engine clean and happy. The ‘italian tune-up’ is not
really about high road speed, but high rpms - which is readily availabel
by manual gear selection. Cruising at 60 mph locked in ‘2’ will
certainly have the desired effect - but will play havoc with your
milage…:slight_smile:

I notice on list that there are people preferring diff ratios for better
acceleration, and others who go for cruise economy. the latter accepting
the drawbacks you outline - or the fines involved. There is really no
‘right’ or ‘wrong’ in all this - they are personal preferences, with the
consequences to be accepted with the choices…

With options open I would go for more gears, but will certainly not use
money to convert from my well working (touch wood) BW66. But dawdling
remains dawdling - with associated sooting, unless the driver changes
habits…

Frank
xj6 85 Sov Europe (UK/NZ)>In my opinion, of course.

It’s a great car in snow, slush, crawling on rain-slick ice, and at 100 mph plus, on graded snow way below Zero in any language, and 125 - 145 mph on good pavement and good tires…(if there is anywhere you can find to enjoy that in this crowded & over-regulated world off the race track)

And I have never wished for a higher gear or for a lower one…but for me it’s for grand touring; long distances through open country at high speeds…and no slouch zinging down the Interstate…I wish for higher speed limits, not lower engine speeds.

GM 400 is cheaper to overhaul, “bullet proof” and as adapted for use by Rolls -Royce, Ferrari, Land Rover, etc., I think., as well as the V12 Jag, is a good tranny, and can be tuned up to be more responsive if desired, in the ECU as I recall…‘AJ’ comes to mind.
Marko should be sure, if he sticks with the GM 400 to be sure it meets the Jag 12 specs…and same for the torque converter; it’s
“special”.

Don’t mean you are wrong, Frank…but I’m just focusing on the intent of the Builder and the Owner…

When ‘they’ built the car ‘they’ were aiming at 27 mpg at 55mph…I suppose they got that; I just wouldn’t know, didn’t buy it for that !!

(grin…yellow teeth and sparse white hair but still grinning!)

On Dec 21, 2010, at 10:29 PM, Frank Andersen wrote:

elmarko wrote:

In reply to a message from Frank Andersen sent Mon 20 Dec 2010:

Thanks for the advice. It sounds like it is indeed time for a rebuild. I was thinking about picking up a second hand box, but I think best to rebuild the one I’ve got as a second hand one probably isn’t going to be any better.

It’s the devil you know, Marko…:slight_smile:

I’m not at all sure that ‘shift - kits’ has any longevity relation - I rather doubt it. Altering shifting generally means tinkering with the valve body for some specific effect - so you better be clear as to what you want. The Jaguar did all this for us - arriving at some result considered suitable for the engine/body combination…and perceived Jaguar driver preferences. They likely also added longevity as a factor, though that is within the driver’s box treatment domain as well…

I doubt if they will guarantee that the kit fitted will make the box last longer - and if they do I’d like their rationale for so stating…:slight_smile:

The real drawback on the GM 400, and indeed the 6’s BWs, is too few gears…:slight_smile:

Frank

I would like to look into firming up the shifts to help the transmission last longer. Do yo know a shift kit that would do the job ? I just fitted a Transgo full manual shift kit to my XJS with the 4speed auto box so I guess it would be a similar kit to that.

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18

Frank, it’s well known and accepted that the shift kits can lengthen
transmission life.

The transmission slips …and wears the clutch plates…whenever a gear
change occurs, with luxuriously soft shifts being the result of more
slippage and firmer shift just the opposite. The shifts kits provide a
firmer, faster gear change with less slip. It’s as simple as less slip =
less wear = longer life. Of course there are other places where wear can
occur and the transmission fail, but the clutch plates are the primary wear
item…just as the clutch is a wear item in a manual shift car. And we all
remember what our dads told us about slipping the clutch too much way back
when we still had peach fuzz on our chins :slight_smile:

Besides being capable of tolerating bags of torque from big engines, the 400
was known for very smooth shifts… and wasn’t known for exceptionally long
service life. Jaguar engineers did specify certain tweaks on the 400 but
firmer shifts were not one of them…not as far as I can tell, at least.

As you mention, lack of gears is a drawback to the 400 if compared to modern
transmissions, yes. GM recognized this and made the 4L80 transmission which,
essentially, is a 400 with an extra gear. As an aside I’ll mention that GM
engineers were apparently so fond of the original 400 engineering that the
infamous planetary gear noise in first gear that existed on the earliest
400s in 1964 still existed on the 4L80s 35+ years later, with customers
still complaining about it :-).

Doug Dwyer
Longview Washington USA
1995 XJRFrom: “Frank Andersen” franksue@xtra.co.nz

I’m not at all sure that ‘shift - kits’ has any longevity relation - I
rather doubt it. Altering shifting generally means tinkering with the
valve body for some specific effect - so you better be clear as to what
you want. The Jaguar did all this for us - arriving at some result
considered suitable for the engine/body combination…and perceived Jaguar
driver preferences. They likely also added longevity as a factor, though
that is within the driver’s box treatment domain as well…

I doubt if they will guarantee that the kit fitted will make the box last
longer - and if they do I’d like their rationale for so stating…:slight_smile:

The real drawback on the GM 400, and indeed the 6’s BWs, is too few
gears…:slight_smile:

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: Jag-lovers Forums - Jag-lovers

To remove yourself from this list, go to Jag-lovers Forums - Jag-lovers.

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19

Doug Dwyer wrote:

Frank, it’s well known and accepted that the shift kits can lengthen
transmission life.

The transmission slips …and wears the clutch plates…whenever a
gear change occurs, with luxuriously soft shifts being the result of
more slippage and firmer shift just the opposite. The shifts kits
provide a firmer, faster gear change with less slip. It’s as simple as
less slip = less wear = longer life. Of course there are other places
where wear can occur and the transmission fail, but the clutch plates
are the primary wear item…just as the clutch is a wear item in a
manual shift car. And we all remember what our dads told us about
slipping the clutch too much way back when we still had peach fuzz on
our chins :slight_smile:

Fair enough, Doug…:slight_smile:

To me longevity takes some time to assess, with many variables - and I’m
suspicious of free lunches…

While the GM 400 no doubt is an old and trustworthy contraption - but I
miss the adjustments available on the BW. Not that it is of that much
use, but there is something about ‘doing something’ fairly easily as
opposed to the GM. Sort of ‘maintenance free’ - I just met a despondent
lady with a slipping box on her modern S-type. And we know what that
means…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)> Besides being capable of tolerating bags of torque from big engines,

the 400 was known for very smooth shifts… and wasn’t known for
exceptionally long service life. Jaguar engineers did specify certain
tweaks on the 400 but firmer shifts were not one of them…not as
far as I can tell, at least.

As you mention, lack of gears is a drawback to the 400 if compared to
modern transmissions, yes. GM recognized this and made the 4L80
transmission which, essentially, is a 400 with an extra gear. As an
aside I’ll mention that GM engineers were apparently so fond of the
original 400 engineering that the infamous planetary gear noise in
first gear that existed on the earliest 400s in 1964 still existed on
the 4L80s 35+ years later, with customers still complaining about it :-).

===================================================
The archives and FAQ will answer many queries on the XJ series…
FAQs: http://www.jag-lovers.org/xjlovers/xjfaq/index.html
Archives: Jag-lovers Forums - Jag-lovers

To remove yourself from this list, go to Jag-lovers Forums - Jag-lovers.

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