Hi All,

I have a 1960 MK2 3.8 Automatic. Long, sad story, but I picked the car up from the transmission shop, where the 3-speed automatic was rebuilt, and took it for it's maiden voyage. The car got up to speed and shifted to second gear, maybe to third (in my excitement I wasn't paying a ton of attention). As my speed increased, the RPMs got high. Too high. A bang. A puff of smoke. I threw a rod.

Calling the shop, they said, "Oh, you didn't know about the Overdrive switch on the lefthand side of the steering column?"

Me: "No. No, I did not."

So, I will be pulling the engine out soon to see just how extensive the damage is. From a cursory investigation I can see holes in the oil pan and some shrapnel inside.

But in the meantime I've got to know, how is this supposed to work? I see what I believe is the Overdrive switch (attached). Can I pre-switch this to the proper position (In or Out?), or do I need to wait until I hit a certain speed and then flip it?

And in the back of my mind I keep wondering: Is it reasonable that a 3-speed automatic would redline going 55 mph because overdrive was not engaged?

Any guidance would be much appreciated.

- Temporarily depressed MK2 owner.

 

Really bad news about the engine. I hope this does not deter you from fixing the car and using it - often and hard.
That is a speed-hold switch, not overdrive. As you have it in the photo, it is holding the car is 2nd gear, so yes, the engine over-revved. This switch is designed to allow instant shift-down for hill-climbing, for hill descent, and to prevent gear-hunting in certain circumstances - very, very useful.
To repeat: the normal position for this switch - to allow the transmission to go through all 3 gears - it to have it to the RIGHT. You do not use this unless you want an INSTANTANEOUS downshift to 2nd gear. You do NOT leave it pushed to the left. If uncertain, don't use it at all!
My car isa 1966 3.8 automatic. I use it often - today for example, on the highway. It has no problem at all in fast highway traffic but the automatic does make the engine rev fairly high (3000 rpm at about 65 mph)...but this is in no way dangerous for the engine. If it were in 2nd gear though.....

 

Thank you for the very helpful reply! I've had a week to process the emotions and am getting past it. The restoration will forge ahead.

When the engine is finished, I will be sure to flip the switch as instructed.

Thanks, again.

 

unfortunately, the Speed Hold switch was designed in an illogical reversed fashion, not "user-friendly".

1) in other words, the switch positioned to the LEFT should be OFF, and the switch positioned to the RIGHT should be ON.

2) not to mention it is incorrectly NAMED, because it doesn't HOLD any "SPEED" at all, it simply prevents the transmission from shifting to 3rd Gear, so it should have been named: "2nd Gear Hold",
not "intermediate", not "speed hold" either.

3) not to mention the escutcheon is marked "IN" and "OUT", when it should have been marked "ON" and "OFF".

4) you are not the only one who does not understand this switch. I have had a battle with the darned switch since I bought my S type, also not noticing it was ON while driving.

5) the way I fixed this problem was to add a tiny but bright LED (with the help of electronic wizard Mike Eck), so that the light comes ON when the switch is in the ON position. It was a delicate operation but I did it.

6) it would make sense to me to turn the entire switch 360 degrees around so that LEFT is OFF, but then the escutcheon markings would not match the switch positions, so the LED was the best alternative, being a visual reminder that the dammed thing is ON.

the below picture of the escutcheon shows my first idea to resolve the problem, but then I realized the LED needed to be away from the switch for obvious reasons, so the LED was installed near but away from the escutcheon.

I'm thinking of having a revised escutcheon made with the proper wording and positioning like the second picture.

 

Hi I have a '61 that was fitted with DG box, that had a speed hold.
Ive switched to a bw65.
I was under the impression that only the DG had this(early cars only) as later cars had the BW35.A '66 would have had a bw35 and would not therefore have a switch!!!!!. The BW35 was used in many other vehicle of various makes none of which, to my knowledge had such a device. Can some one enlighten me please.
barry

 

Barry: my 1966 Mark 2 with 23,388 miles as of today, VIN 2243XX, built January 3, 1966, a Canadian-market 3.8 automatic, does indeed have a DG250 transmisson as originally fitted. The BW35 was not universally fitted for the 1966 model. It was fitted from 3.8 VIN 224738 and later cars (this information is in the factory Spare Parts Catalogue, p. 197).

So , my car with the speed-hold switch and the DG250 is perfectly correct and typical of 3.8 LHD cars built up to early 1966.

 

I used to sell Mk2 's way back in the 60's . Some 4 speed manual boxes had an Overdrive . No such thing as an overdrive on an automatic box . I sat in , delivered , drove & even sold a couple of Mk'2's & none of that switch gear is familiar to me . I don't think anything like this was ever fitted in UK spec 60's Jags. ( however it was 50 yrs ago & the mind plays tricks ...)

 

the switch in question causes the Borg Warner DG-250 transmission to remain in 2nd gear, until you switch it to OFF or "OUT". it is not an overdrive as in a manual transmission but a "Stay in 2nd Gear" switch, handy for hill climbing where you don't want the transmission shifting between 2nd and 3rd gears, or for slow traffic where you want to remain in 2nd gear.

As I understand it, all Automatic S type (3.8 and 3.4 'S' models) up to mid 1966 or thereabouts, had this DG-250 transmission fitted at the factory and all had the "Speed Hold" switch. I have friends in the UK who have automatic S type with this "Speed Hold" switch.

 

Yes, the automatics all had the speed-hold switch for the UK and every other market - I have offered the particulars of my 1966 car as an example, above.

 

SO!!!!!!!!!!!!!!! Are you all agreed that this switch was NOT fitted to the BW35?.It appears that the DG250 was fitted to US models for longer than the UK market.
Barry

 

it might be so.

all I know about the BW35 is that the Neutral Safety / Reverse lights switch is mounted to the transmission itself, and in the DG-250 the Neutral Safety / Reverse lights switch is mounted to the steering column.

 

Barry: The Daimler version of the Mk 2, the Daimler 2.5 litre V8 used the BW35 transmission, and it is true that this was not fitted with the speed hold switch (see Thorley, Jaguar Mark 1 & 2, page 100). Thorly also states that for the Mark 2 the change toi the BW35 came in June 1965 (p.127) but this was simply the FIRST date at which the introduction began to be phased in (jaguar always introduced changes gradually for cars for different markets and for cars with different engines). Whether the BW35 Jaguars (as opposed to Daimlers, which used an entirely different engine) used the speed hold switch is a matter not entirely settled yet, although it seems likely.
And with regard to the DG250 vs the BW35 on US market cars, I cannot say. I told you that my Canadian- market car (and the US and Canadian market cars were different) built in January 1966 had and has the DG250 and the speed hold switch.

 

I have found a bit more information: Paul Skilleter in his "Jaguar Mk 2 Saloons Super Profile", page 47, says regarding the speed hold switch: "It was discontinued when during 1965 the Type 35 gearbox was introduced to the Mk 2 with its 'D1" and 'D2' facility".
So that seems to settle that question.
BUT it must be noted that cars produced for Canada and the US with the 3.8 engine did NOT use the Type 35 transmission until well into 1966 - and perhaps not at all until the downscale 340 model was produced for 1967. The introduction of the Type 35 for the 3.8 LHD cars was at VIN 224738 - and that would have been built quite far into the 1966 calendar year.

 

Thank you for this explanation. I bought a MK 9 which need some work to get back on the road. I was thinking it is a cruise control switch.

 

Hi, it happens to everybody that has that switch thanks to Jaguar.

After all, "Speed Hold" means "Hold That Speed", no?

aaaarrrgggghhh!

 

I've never owned or driven an automatic Jaguar pre-XJ. However, my Mk2 owner's handbook states:

"With the switch in the " IN " position no upshift will take place between intermediate and direct drive..."

So " IN " means hold on to the second (intermediate) 'speed' of the gearbox or stay " IN " second gear. And 'speed' is short for the gearbox terminology of 'speed ratio' as in five-speed transmission.

Perhaps a Moss box isn't such a bad thing to have after all?

 

Peter, that is correct, but not everybody understands gearbox terminology as you describe it.

A pre-XJ automatic transmission like the BW35 is not a lot different than a BW65 or 66.

But the pre-BW35 DG250 transmission with the "Speed Hold" solenoid is different.

my 1965 S type DG250 transmission operates differently than the BW66 of my 1984 XJ-6.

The main difference ignoring the "Speed Hold" accessory, is the 3rd gear which "feels" more like a 4th gear than 3rd.

So when accelerating the car to speed, you get FIRST, SECOND, and "FOURTH" gear changes. That is how it "feels".

But when in slow traffic, that "FOURTH" gear change can be a nuissance because the engine is bogged down to low torque and rpm's if the transmission has not changed or reverted to 1st or 2nd gear. The same thing as trying to move a car from a stop in 4 or 5th gear in a manual transmission.

Enter the 2nd Gear Hold switch to keep the DG250 transmission from shifting to its "4th" gear or should it be described as a very tall Third gear ?

I have no clue about how the DG250 was designed or its gearing. All I know is how it FEELS. The 3rd gear of the DG250 feels like a 4th gear and it ACTS like a 4th gear. Very tall. for high speeds and lower engine rpm's.

 

Jose, For the terminology, it helps if you're over 50 and born in England somewhere between Oxford and Wolverhampton.

One way or another, three speed automatics rarely seem to cover the required range. They can get close with sufficient engine, but not too perfection. Even with the V12 in my Daimler Double Six, the GM400 could definitely use a higher top gear. And it would be more sprightly off the line with a lower first ... .

 

Being used to my 7 speed Merc Auto with lock up converter & multiple gear kick down in a single change, I cannot imagine driving a 3 or 4 speed Auto.

This behind a 3.5 litre quadcam V6. At SA fuel prices I ran away from the V8 version ~ It would turn me into a hooligan anyway.

That said I don't think one requires their new 9 speed unless you are going to run a lean burn engine within a narrow rev range. Nevertheless it does give amazing fuel economy.

Both are super efficient though compared with old slush boxes. With modern electronics and ECU & TCU constantly communicating & monitoring approx 18 parameters (depending on application), Auto transmissions have come a very long way from the past.

 

I can say the same for the ZF 6HP in my XKR. It's brilliant, efficient ... and, if you want to change your own gears, you can.

Unfortunately, it's close to impossible to fit a modern auto box to an old car. The Ford 6R80 (a 6HP built under licence) is about the only option that has external electronics, but there's still the mechanical problems of adapter plates etc.