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8 & 10 cyl Bristol cars From Type 407 onwards

Window lift motor replacement?

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Old 08-07-09, 01:04 PM
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Default Window lift motor replacement?

Does anyone have any experience replacing the window lift motors on earlier (409-411) V8 cars?

Anyone sourced any modern alternatives?
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Old 08-07-09, 01:19 PM
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Quote:
Originally Posted by Kevin Howard View Post
Does anyone have any experience replacing the window lift motors on earlier (409-411) V8 cars?

Anyone sourced any modern alternatives?
The motors for my 410 windows work well, but I have had problems with the microswitches. Few of the 409 and 410 had electric windows at all, and it was to special order only I believe. These earlier cars used a chain-driven Piper mechanism, as fitted to many R-Rs, Bentleys and Astons, which I understand to be completely different to the 411's mechanism.

I spoke to Bentley specialist Introcar when looking for new microswitches (which they couldn't supply), who said they tend to junk the Piper system and fit more modern motors when they have to fix them. Might be worth trying them for suggestions?
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Old 08-07-09, 03:11 PM
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Originally Posted by Sam410 View Post
The motors for my 410 windows work well, but I have had problems with the microswitches.
I only have experience with the later system used on the 412, but here the switches can also prove to be troublesome (as is the case on many other systems of the period). It is really worth taking them apart (watch for any springs and little ball-bearings!), cleaning them up with a contact cleaner (one of the glass-fibre pencils is also useful) and reassembling them this always worked for me. The other problem on the 412 was that even the later type of motor got very wet and many of the connections suffered corrosion. After rectifying this along the same lines as the switches, I glued builders polythene inside the door to stop any water landing on the motors.
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Originally Posted by Sam410 View Post
I spoke to Bentley specialist Introcar when looking for new microswitches (which they couldn't supply), who said they tend to junk the Piper system and fit more modern motors when they have to fix them. Might be worth trying them for suggestions?
As I currently have an R-type (anyone want to buy it?!!) I have had quite a few dealings with them and they are a pretty helpful outfit.

George
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Old 08-07-09, 04:15 PM
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Default Window lift motor replacement?

Hi all -

"The other problem on the 412 was that even the
later type of motor got very wet and many of the
connections suffered corrosion. After rectifying
this along the same lines as the switches, I
glued builders polythene inside the door to stop
any water landing on the motors."

Don't know if this applies, but an expert on
Imperial (Mopar) window motors found that the
window motors were corroding internally because
the hot motors drew in moisture when cooling,
which collected on the bottom of the casing and
could not escape. Fortunately, these same motors
were used in nearly all Mopars for about 20 years, so easily sourced.

There is also an Imperial owner who offers a
service to rebuild window switches.

Bob
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Old 08-07-09, 10:12 PM
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Default Window lift motors

Trsut my car, a 409, to have the odd ball units, ie the Piper motors! However that might mean some input from some RR contacts. These are chain driven- noisy. ( Sounds like a port cullis raising!)
Raising the glass is assisted by some coiled spring devices which resemble steel tape measures.

I have not taken anything apart yet, but the problem seems to be that on one window, the motor raises the galss to it closed position. For a couple of times, it will work up and down, never failing in an intermediate position. Then on closing, it fails to reopen-a click is heard.
Wind the screwdriver in the hole and it will work for a while.
So, am I correct in thinking this looks like limit switch?
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Old 08-07-09, 10:52 PM
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Default Window lift motor replacement?

Kevin,



I had the motors on the 412 rewound about 8 years ago and they still work fine. Is this an option?



Peter
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Old 09-07-09, 04:06 AM
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Quote:
Originally Posted by MYTA21 View Post
Trsut my car, a 409, to have the odd ball units, ie the Piper motors! However that might mean some input from some RR contacts. These are chain driven- noisy. ( Sounds like a port cullis raising!) Raising the glass is assisted by some coiled spring devices which resemble steel tape measures.
That sounds very different to the 411 set up (as Sam said).

The 411 uses a screw inside a tube with a slot down one side. There's a bracket fixed to the screw which in turn is connected to the bottom of the window. (I'll post some pictures later from a different PC.) I'm sure it's not helped by the fact that the tube which carries screw is vertical but the motor is mounted horizontally, so the screw/tube has to bend through 90 degrees! But maybe they do that to stop water running down the tube into the motor!

Quote:
Originally Posted by MYTA21 View Post
I have not taken anything apart yet, but the problem seems to be that on one window, the motor raises the galss to it closed position. For a couple of times, it will work up and down, never failing in an intermediate position. Then on closing, it fails to reopen-a click is heard.
Wind the screwdriver in the hole and it will work for a while.
So, am I correct in thinking this looks like limit switch?
That sounds like it is a limit switch issue. You could try Dick Smith or RS Components for something similar. When you do delve into the door can you take some photos and either post them here (or send them to me and I will post them for you - high resolution).

The limit switches on my 411 are fine, the problem is the motors operate very very slowly, but they're not noisy.
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Old 09-07-09, 04:09 AM
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Quote:
Originally Posted by 412usa View Post
Kevin,

I had the motors on the 412 rewound about 8 years ago and they still work fine. Is this an option?

Peter
I guess it might be, if I could get them out! Unfortunately All the motor fixing points are rusted solid. I'll post some pictures of inside my door shortly - do you remember of the 412 has a similar set up?

Kevin
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Old 09-07-09, 04:13 AM
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Default Pictures inside 411 door

As mentioned before, attached are the pics of my window lift mechanism and motor. The red arrow points to the "screw tube"
Attached Images
File Type: jpg windown-lift-and-microswitc.jpg (171.1 KB, 87 views)
File Type: jpg windown-lift-motor.jpg (118.6 KB, 76 views)

Last edited by Kevin H; 10-07-09 at 12:35 PM.
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Old 10-07-09, 08:55 AM
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Quote:
Originally Posted by MYTA21 View Post
on one window, the motor raises the galss to it closed position. For a couple of times, it will work up and down, never failing in an intermediate position. Then on closing, it fails to reopen-a click is heard.
Wind the screwdriver in the hole and it will work for a while.
So, am I correct in thinking this looks like limit switch?
I had the same problem, but the other way around - the window would not shut from fully open. The bodies of the microswitches are made of an alloy metal of some sort which had broken up and collapsed (not for the first time it appeared, as it was already glued together with Araldite). These switches are handed left and right, and are unobtainable as far as I can see. As can be seen from the attached photos, I bodged it together with cable ties for a while, though I've now replaced it with a new switch, repositioned and with a new bracket made so that the window striker just acted correctly upon it.

Incidentally, I think these windows are unusual in having a limit switch at the top of their travel. Most windows do not have this, as can be determined by the slight dimming of headlights if you try to close the windows when they are already closed (at least on many modern cars I've tried.) As the problem on your 409 seems to be at the top, it would probably be possible to bypass the limit switch altogether, as the window frame will obviously stop the window going too far. Might be simpler than finding new microswitches?
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File Type: jpg piper_limit_switch.jpg (227.2 KB, 61 views)
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Old 10-07-09, 11:50 AM
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Default Window lift motor replacement?

Many thanks for the picture. At least I now know where the switches should
be.
Mike
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Old 10-07-09, 01:00 PM
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Quote:
Originally Posted by Sam410 View Post
Incidentally, I think these windows are unusual in having a limit switch at the top of their travel. Most windows do not have this, as can be determined by the slight dimming of headlights if you try to close the windows when they are already closed (at least on many modern cars I've tried.) As the problem on your 409 seems to be at the top, it would probably be possible to bypass the limit switch altogether, as the window frame will obviously stop the window going too far.
That Heath Robinson mechanism is amazing - makes the system on the 411 look so elegant!

On proper modern cars they usually use control circuitry to monitor speed of the motor and/or the power exerted by the motor (current drawn) and will stop the motor if it slows down too much or uses too much power.

I don't know how the 409 is wired, but on my 411 the windows were wired directly to the battery, not even on the ignition acc circuit. Nor were there any fuses or relays in the window motor wiring, so I wouldn't recommend removing the limit switch.

Quote:
Originally Posted by Sam410 View Post
Might be simpler than finding new micro switches?
Definitely the way to go IMHO
here's a few 21A micro switches at RS Components
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Old 10-07-09, 07:25 PM
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Hi
I think a lot of manufacturers originally wired them direct so that windows could be opened/closed while parked up.

There were then a number of accidents where kiddies left in vehicles, who stuck there heads out of the open window, knelt on the up switch and throttled themselves.
Putting it on, a first key click accessory circuit or even the ignition on circuit removed/reduced that risk.
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Old 11-07-09, 12:09 PM
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I do not know how true this is of the Bristol implementation of electric windows (although I did it on mine), but on other cars, reducing the amount of effort on the electrics to raise and lower them makes them work better. In addition to keeping the outside of the window glass clean, mine benefitted from spraying a silicone lubricant on to the guides in the door frame where the edges of the glass contact.

After all, just think of the amount of effort required to lift a window with a non-assisted window winder, it is asking a lot of that relatively small motor.
George
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Old 12-07-09, 04:18 AM
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Quote:
Originally Posted by geo View Post
...mine benefitted from spraying a silicone lubricant on to the guides in the door frame where the edges of the glass contact.
I lubricated the guides on my 411 with silicone but it didn't make any difference.

In an attempt to determine what the problem was I played around with the alignment of the window frame and did manage to get the windows working at an acceptable speed. Unfortunately however, when the window frames are aligned so that they seal with the opening in the car body, the windows once again move very slowly. Clearly more power is needed from the motor to overcome the resistance of the frame/guides.

Quote:
Originally Posted by geo View Post
After all, just think of the amount of effort required to lift a window with a non-assisted window winder, it is asking a lot of that relatively small motor.
Yes, that long worm-gear-in-a-tube mechanism has a lot to do.

Modern cars tend to use a gear reduction system acting on a scissor type lever mechanism, which makes much lighter work of moving the window. So the motors are smaller, yet they are able to exert considerable force on the window.

As for the wiring of electric windows directly to the battery, this has been responsible for the deaths of many children over the years. The first one being recorded in 1962. I've been trying remember when wiring them to the accessory circuit (requiring the ignition key) became routine in the British auto industry. I think it was happening by the mid 1970s.
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Old 12-07-09, 05:00 PM
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Default Window lift motor replacement?

Kevin,

From memory, the window lift on the 412 is very different. It is not a chain drive but a scissor type action. As others have mentioned the 412 switches have problems as all the current runs through them. I had an electrical engineer friend design a relayed system but in the end did not install it as the auto electrician who had the motors rewound said that the system was fine as it was, if well lubricated.



Peter
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Old 15-07-09, 09:28 AM
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Default 409 Window lift motors

With the aid of the photos of the
Piper lift motors, l have been able to sort out the problems.
From those, I could see what the whole thing looked like.
The reason the window would not open from a fully closed postion was that the cam attached to the chain went past the limit switch, so by adjusting the clearance, I appear to have solved that! A screaming noise that I thought might have been related to the spring assistor turned out to be due to the manual winder bevel gear just brushing the motor bevel gear. Resolved by new spring, so as to give it clearance. Thanks for the help.
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Old 30-03-17, 08:13 AM
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Hello Kevin,
Has anyone come up with a solution for the replacement of the Piper mechanisms. My micro switches have broken up and I bought two second hand complete units from Bristol Services, but these are not up to much
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Old 31-03-17, 02:34 PM
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Hi Mike,
I haven't heard of any replacement. Mine do still work, albeit slowly. I improved their performance by renewing all the wiring and connectors. However, if it's only the micro switches that are kaput, then I wouldn't think it would be too hard to adapt some modern micro switches to serve the same function. It would just be a matter of changing (re-fabricating) the mounting arrangement for the switches.
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Old 10-04-17, 07:45 AM
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My "Series 6" 410 has a modern window lift mechanism that Bristol sourced from a U.S. company called Speciality Power Windows. It's very effective and look well built. Bristol also sourced a wiper motor mechanism from them for the series 6 that they adapted with a custom wheel.

Here's a picture of the power windows mechanism (I dont understand why the picture is upside down). The switches are standard, although Bristol added a small electronic module allowing for auto up and down.
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File Type: jpg IMG_2220.jpg (237.5 KB, 26 views)
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