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MG MGA - MGB Wiper Motor

Has anyone installed a MGB 2 speed wiper motor in an A?

Obviously the wiper boxes are a different ratio, and the B ones will not go in.

Any comments from anyone??

Colin
Colin Parkinson

Yes

Read the archive. I think Les or Barney also have posted the wiring diagram from my conversion.

You take the wheel out of the A motor and put it into the B one. The wiper boxes remain unchanged.
dominic clancy

Start here: http://mgaguru.com/mgtech/electric/et218.htm

After due consideration, a lot of that appears to have been done the hard way.

The late MGB wiper drive uses longer cable travel. The crank arm in the gearbox has longer throw, and the wheelboxes have larger diameter wheels. To avoid having to modify the gearbox you need to use the late MGB wheelboxes to go with the late drive motor.

The late MGB 2-speed drive has dynamic braking with a 5-wire hookup and a complex control switch. I have a schematic for a circuit using two small relays on the motor itself, a standandard MGA lighting switch in place of the wiper switch, and only one additional wire between the motor and switch.

I recently procured a late MGB 2-speed wiper motor and a spare lighting switch. The relays are about $5 eash at RadioShack. I still need the late MGB wheelboxes to complete the conversion set. If I ever get around to actually doing it, I wlll have it documented on my web site. If anyone beaats me to it, do tell.
Barney Gaylord

Barney, the MGB wheel boxes will not fit on the A. They are phsically bigger, and the spindle is shorter, so even making up very short angled spacers they still will not fit.

Dominic, I will have a look at replacing the wheel.

Colin
Colin Parkinson

I will scan in the wiring diagram again and mail it to Barney and to Colin.

The switch used is a standard B wiper toggle switch - as Barney says there is no suitable Lucas pull switch to do this. I have mine mounted with a chrome Lucas bracket under the bottom edge of the dash to the left of the steering wheel. All that changes in this scheme is the motor and the electrics, the gear wheel and rack from the standard A setup is reused. I'll take a photo of this too.
dominic clancy

All sent, so hopefully Barney can posst it on his site as an alternative to his other methods.

Barney, if you can supply your other schematic with the relays, I may well try it, as I have a spare pull switch around, and it would be more in character (could fit in place of the foglamp switch and lose the toggle switch completely)

Thanks

Dominic
dominic clancy

I believe that John Mangles used a B two speed motor on his A V8. He mentions using a modified A headlight switch and relay for the wiring. Here's a link to his site: http://www.themgdoc.com/
Bill Young

I'd just be satisfied to get my A wiper motor working. Everything checks out on the bench but when it's installed it doesn't run.
Bill
Bill Boorse

On this two speed motor, does it make it go faster than the regular MGA motor or create two speeds one which is slower than it is now. I have wiper delay on my car with a switch under the dash on the dash support arms. It works great when it is just misting.
JEFF BECKER

Barney has now posted his "Relay" version, but has so far shown no sign of posting my version - NIH perhaps. If anyone else wants to post it on their site, I'm happy to provide the details

Thanks Bill. There's no description on that site, but Barney has a version now which he has put up - the link to the relay version is here
http://mgaguru.com/mgtech/electric/et219.htm

Barney says that you must use a B rack and wheel boxes. This is not the case. You either have to modify the A gear to fit the B motor, or do what I did and get the correct 105 degree gear wheel for the B motor to fit to the A windscreen. Then you keep all the A rack etc. This system was worked out by Brown and Gammons and me, so it does work very well indeed.

Jeff, the B motor "slow" speed is about the same as the standard A motor, the "fast" actually works at keeping the screen clear in heavy rain at a sensible speed (something the A motor is a miserable failure at doing). If it really starts to hammer with rain, then the whole thing becomes academic because either the water starts sticking to the inside of the screen (top down) or the screen mists up (top up). This second problem is the instigator of the next planned mod - a B heater motor and fan fitment in the A heater box. This again is an easy mod, and should keep the screen much clearer in the wet. I guess you can fit the delay thing in the circuit too with a little thought.

dominic clancy

Dominic, so it is the 105 degree wheel that does the trick??

Many thanks

Colin
Colin Parkinson

Dominic

What is the Brown and Gammons part number for the 105 degree gear wheel? I just checked their site and didn't find any listing for it.

I don't have a site to post it on but I would be interested in seeing what you have done IF it is easy to forward it to me by email.

Thanks

Larry
58A
Larry Hallanger

I followed Dominics conversion, and it works a treat, although we havn't had any decent rain in this part of Australia for many months now. The 105 wheel is only available from the MG Owners Club, which is where I source mine.
Gary Lock

http://www.mgocspares.co.uk/acatalog/

WASH / WIPE
Gear-105° -RD 37H3045
Price: £12.58 Including VAT at 17.5%

ELECTRICS
42 - Switch - Wiper - Two speed BHA4786 [42] More
Price: £19.95 Including VAT at 17.5%
dominic clancy

Dominic, can a person use a headlight switch using one position for low speed and the other for high speed
JEFF BECKER

No, this switch has a connection inside which is required for the parking effect on the wipers to work properly on a B motor (complicated stuff this!). If you want to use the headlight switch, you have to use Barney's electrics with the relays and my mechanics.
dominic clancy

Check out Paul Hunt's web site at http://www.mgb-stuff.org.uk/ and go to "Wipers". He makes the statement "A square 2-speed motor will only require a simple switch which connects a ground to the slow speed winding or the fast speed winding, disconnecting from both to park. As well as a 2-speed GT wiper switch any toggle headlight switch will do the job."

FWIW

Larry
Larry Hallanger

That's the difference, the square motor is for early Bs and is VERY expensive. The (common) round motor is cheap, but electrically different
dominic clancy

Dominic:

Before this thread slips off the board and into the archives...

In one of your postings in this thread you state that the A wheel is used in the B wiper motor housing:

"You take the wheel out of the A motor and put it into the B one. The wiper boxes remain unchanged."

In the later postings, you specify that the 105 degree wheel is used for the B motor:

"You either have to modify the A gear to fit the B motor, or do what I did and get the correct 105 degree gear wheel for the B motor to fit to the A windscreen."

These two statements are not necessarily conflicting, just a bit confusing.

The question that I have is: If you use the square bodied 2 speed B motor, what gear wheel do you use?

(I thought that the round bodied B motor drive housing and the square bodied A/B single speed motor drive housings require a different length gear wheel shaft, respectively. I'm not sure about the square bodied 2 speed motor gear and housing.)

Thanks,
Steve
Steve Brandt

Steve

Either

1. you can use the square bodied early B motor, and the gear from the A motor should fit, (see Barney's site for any required mods for parking)

or

2. you use a round B motor with a 105 degree motor.

As the last "titbit" of info on wipers, to change from LHD to RHD or vice versa, you just turn the wiper boxes through 180 degrees under the dash, so that the rack runs on the other side of them from where you started, then it all works fine. Not something I expect many people to need but.....

As fas as I can make out, the 105 degree wheel was fitted to some Bs in the round motor, but I can't find any info on which ones.
dominic clancy

Thanks Steve and Dominic. That's a lot clearer now.

I know a guy who has a box of secondhand gears. I will see if there are any 105s.

Colin
Colin Parkinson

This thread was discussed between 20/05/2006 and 03/06/2006

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This thread is from the archive. The Live MG MGA BBS is active now.