Unknown switch on dash P4 105R

#1
Hello brand new member just joined.

I only yesterday bought a 105R. Had a few problems. Would not start (Starter Solenoid). She now purrs like a kitten and I had it down the freeway as smooth as silk.

What I am hoping is someone of you boffin's out there can explain what this switch is for. I have the original Owners manual & a immaculate full maintenance manual, complete in its original box. Also original letter from Rover to the new owner, dated back in 1957.

However nothing what so ever gives me a clue to what this switch is for. No pictures can be found of it. It looks absolutely original.

Can someone please help and explain what it is for and its operation.

See first picture.... It is the switch next to gear changer, to the right, marked normal and low ???? Second and third picture are of the lovely new girl in my life :)

Thanks in advance to anyone that can help.

Regards


Mike, from Melbourne, Australia.
 

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#2
It seems that in normal drive the car starts in high gear but in conjunction with the gearknob switch, you can set it to start off in low gear, assumedly for when the car is loaded or hill starts......etc.

The Rover 105

That is indeed a lovely car. I regrettably sold my '64 110 18 months back. I had three years of very enjoyable daily use from her.
 
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#3
Mnnn. OK... Unusual though... On the gear stick, there is already what they call 1st gear.. You pull the gear leaver down and it goes really low ratio. Then there is a switch, to go into overdrive. So that is why I thought that switch did something else
?
 
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#4
You can try The Rover P4 Owners Guild for some insight as to why it's there. There's a farceache page or the online forum.
It's an interesting piece of machinery the 105R's Roverdrive gearbox.
 
#6
Fine looking car. I suspect the reason that it's not in the workshop manual is probably for the final model year, ie 1959, the (manual) 105 replaced both the earlier 105S and 105R (the P5 3-litre had just been announced and that was available as an auto instead).

I have an old artist's drawing (Rover), so not a definitive photo, showing a switch immediately to the right of the 105R's gear lever. Unfortunately, the drawing is at an angle, rather than straight on, so the switch is partly obscured by the gearlever. However, the writing visible at the 6 o'clock position of the switch reads 'on overdrive'. So, not exactly the same as yours but I would assume that it was original and possibly either prevents the overdrive kicking in if in 'low' or, as 105Rs normally pull away in the higher of the two gears in the main gearbox, 'low' might ensure it pulls away in the lower gear, much as many modern auto cars usually start in 2nd gear (unless under full throttle) or, if in 'Sport', pull away in 1st gear. An early 'sport' button? :)

I'm guessing that emergency low locks it in low gear; my understanding (from what I've read, but not guaranteed as being correct) is that there's nothing to stop selection of it at any speed but recommended max speed in low is 30mph. It was designed for ascending or descending steep hills.

Probably best to drive it and experiment.

For interest, I have a copy of the road test of the first 105R in Australia; it's in b&w so can't see the colour, regn no. was BJH 300
 
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#7
So the workshop manual isn't for this car as far as the gearbox goes as we can see from the title page (105). The dashboard illustration looks as if it's from the owners manual but if it is then even if it's the one supplied with the car (which sounds doubtful), it's clearly not for this particular model, as it's showing a manual car rather than the Roverdrive layout. So in that case it's not surprising you haven't got the relevant instructions to hand. You should be able to lay your hands on the correct manuals with the help of the internet.

Tony's explanation sounds logical but if the gearlever is used to put the 'box into low range then the dashboard switch will maybe lock it in the low gear until you switch it out whereas the gearstick selection will introduce the low gear into the auto-gear range, which sounds much as Tony said.
 
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#8
Fine looking car. I suspect the reason that it's not in the workshop manual is probably for the final model year, ie 1959, the (manual) 105 replaced both the earlier 105S and 105R (the P5 3-litre had just been announced and that was available as an auto instead).

I have an old artist's drawing (Rover), so not a definitive photo, showing a switch immediately to the right of the 105R's gear lever. Unfortunately, the drawing is at an angle, rather than straight on, so the switch is partly obscured by the gearlever. However, the writing visible at the 6 o'clock position of the switch reads 'on overdrive'. So, not exactly the same as yours but I would assume that it was original and possibly either prevents the overdrive kicking in if in 'low' or, as 105Rs normally pull away in the higher of the two gears in the main gearbox, 'low' might ensure it pulls away in the lower gear, much as many modern auto cars usually start in 2nd gear (unless under full throttle) or, if in 'Sport', pull away in 1st gear. An early 'sport' button? :)

I'm guessing that emergency low locks it in low gear; my understanding (from what I've read, but not guaranteed as being correct) is that there's nothing to stop selection of it at any speed but recommended max speed in low is 30mph. It was designed for ascending or descending steep hills.

Probably best to drive it and experiment.

For interest, I have a copy of the road test of the first 105R in Australia; it's in b&w so can't see the colour, regn no. was BJH 300
 
#9
If it helps, I did find a photo on the P4 Drivers Guild showing a 105R, complete with exactly the same switch as shown in your picture. No explanations but it does tend to confirm original fitment (unless it was a picture of your car ;)).
 
#11
Update:

It's an Overdrive isolator switch.

I've been digging around in some books and found some references to it. From Jan 1957 all 105Rs were fitted with a new 'Overdrive isolator' switch, on bracket marked 'Normal' and 'Low', adjacent to steering column. It doesn't explain how to use it but it would seem obvious that Normal allows the overdrive to cut in automatically, as designed to do, depending on speed and throttle position, whereas Low would lock-out the overdrive.

There are other references to the way it works, main gearbox has 2 forward gears, top being a 1:1 drive. Car normally pulls away in the 2nd gear and overdrive kicks in from approx 30mph(varies), with a kickdown facility from overdrive to 'top'.

The clutch is normally engaged and take up is via the torque converter. Pressing the button on the end of the gearlever disengages and then re-engages clutch for 'emergency low' or reverse.

Torque converter is fed with engine oil. Oil change intervals were 3,000miles for engine and 9,000 for tq converter. No reference to the grade of oil but I have read somewhere that tq converter worked better with thinner oils, particularly until warm, however, I don't know preferred grades. Possibly on a plate on the car?

I've also now seen a clear photo of a 105R without the said switch, so presumably an early press car or Motorshow car.

Looking at your colour scheme, I think it's a 1958 model car, export RHD chassis start 6218 - 00001 to 00375(1957 numbers were 6217 - 00001 to 00135). Colour, if original, likely to be Pale Green over Sage Green, with Tan interior.

Yours appears to have optional individual front seats and wheeltrim rings; there was a 105R DeLuxe which had individual seats, cigar lighter, wheeltrim rings and twin spot lights as standard (as per the 105S).

I can add a few small items about changes during production if of interest. Re the road test, it's an old copy so might not be particularly clear in a photo. Not sure whether I could send it to you on this forum, I'll have a look in due course.
 
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#12
Update:

It's an Overdrive isolator switch.

I've been digging around in some books and found some references to it. From Jan 1957 all 105Rs were fitted with a new 'Overdrive isolator' switch, on bracket marked 'Normal' and 'Low', adjacent to steering column. It doesn't explain how to use it but it would seem obvious that Normal allows the overdrive to cut in automatically, as designed to do, depending on speed and throttle position, whereas Low would lock-out the overdrive.

There are other references to the way it works, main gearbox has 2 forward gears, top being a 1:1 drive. Car normally pulls away in the 2nd gear and overdrive kicks in from approx 30mph(varies), with a kickdown facility from overdrive to 'top'.

The clutch is normally engaged and take up is via the torque converter. Pressing the button on the end of the gearlever disengages and then re-engages clutch for 'emergency low' or reverse.

Torque converter is fed with engine oil. Oil change intervals were 3,000miles for engine and 9,000 for tq converter. No reference to the grade of oil but I have read somewhere that tq converter worked better with thinner oils, particularly until warm, however, I don't know preferred grades. Possibly on a plate on the car?

I've also now seen a clear photo of a 105R without the said switch, so presumably an early press car or Motorshow car.

Looking at your colour scheme, I think it's a 1958 model car, export RHD chassis start 6218 - 00001 to 00375(1957 numbers were 6217 - 00001 to 00135). Colour, if original, likely to be Pale Green over Sage Green, with Tan interior.

Yours appears to gave optional individual front seats and wheeltrim rings; there was a 105R DeLuxe which had individual seats, cigar lighter, wheeltrim rings and twin spot lights as standard (as per the 105S).

I can add a few small items about changes during production if of interest. Re the road test, it's an old copy so might not be particularly clear in a photo. Not sure whether I could send it to you on this forum, I'll have a look in due course.
 
#13
Thank you so much for the Information. Clears up a bit, although I am sure mine is 1957. It does have an ashtray, but no signs of a cigarette lighter.
Colors sound right.
 
#14
So the workshop manual isn't for this car as far as the gearbox goes as we can see from the title page (105). The dashboard illustration looks as if it's from the owners manual but if it is then even if it's the one supplied with the car (which sounds doubtful), it's clearly not for this particular model, as it's showing a manual car rather than the Roverdrive layout. So in that case it's not surprising you haven't got the relevant instructions to hand. You should be able to lay your hands on the correct manuals with the help of the internet.

Tony's explanation sounds logical but if the gearlever is used to put the 'box into low range then the dashboard switch will maybe lock it in the low gear until you switch it out whereas the gearstick selection will introduce the low gear into the auto-gear range, which sounds much as Tony said.
 
#16
It's probably not mentioned because the switch was clearly an afterthought and the books/booklets had already been printed when the cars went on sale. However, it's quite possible that a separate additional note was added and perhaps that's gone walkabouts sometime in the past 65-years?

If you're not already aware, the automatic Roverdrive car is believed to originally have been planned as a 'Rover 90 Torque Converter' but it's thought that the performance was such that ways to improve it were sought. It's thought possible that the 105 head/carbs were originally designed for the then under-development P5 but it did fit on the old engine (the head overhangs the block slightly on the 105, but it fits exactly on the later P5) and was found to give better performance, with both the Roverdrive and the manual gearboxes.

The 105S / R was a late announcement at the 1956 motorshow (was the original plan to announce the Rover 90 Torque Converter at the show??), with production not getting started until a few months later and at that time the switch wasn't part of the original design; I can only guess but it's possible that some of the press/early customer feedback on the Roverdrive resulted in the additional switch being fitted from Jan 1957? Perhaps Rover added addendum pieces of paper to some handbooks to explain the switch and it's gone walkabouts sometime in the past 65 years?

Accepting that a lot of changes might have been made over the 65-year life of the car, plastic headlinings were introduced approx Nov 1957 (so most model-year 1958 cars), prior to that it was a woollen material. Two-tone cars prior to the my-1958 cars only had the roof and rear pillars in the second colour.

The best way of confirming the car's model year is by the chassis number, with 1958-model cars going on sale Sept 1957, although it's all a bit academic after all this time :)
 
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