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MG MGA - MGB wiper motor in the MGA

I am planning to adapt an MGB wiper motor to my MGA. I have read the postings and archives plus the MG Guru comments to see what is involved. Several postings said that the round, two-speed, late MGB wiper motor with the addition of a 105 degree wheel will work in the MGA.
I got myself a late, round, two-speed wiper motor, and when I opened it, I found that its drive wheel was marked “105.” I have seen postings on this site which noted that the 105 degree wheel was fitted to some round-motor Bs. It looks like I found one by accident.
My question is whether the 105 degree motor that I have will work in the MGA without further alteration. Can I expect it to wipe and park correctly as it is?

Thanks for your comments! This site has been very helpful.

Mike
M.E. Whalen

Mike, I finished my own 2-speed wiper conversion project earlier this year and I wrote up the entire process for the MGCC magazine Safety Fast. They have just published it this month, albeit slightly edited to fit into the space available.

Like you, I got the idea from MGA GURU and decided to give it a try.

I used a 100 degree wheel at first but once fitted I found that this still caused the wipers to sweep over too wide an arc and the blades slightly ran over the windscreen frames at either side causing damage to the rubber blades.

So I next tried a 90 degree wheel and this was perfect with the blades stopping just short of the frames on each side of the arc.
So I would recommend the 90 degree wheel.

The wiring up is easier using the MGB toggle switch but I prefer the look of the MGA pull switch and I finally used an MGA light switch with Barneys two-relay circuit.

The 2-speed works really well and I am delighted with it.

If you (or anyone else) would like a copy of my full write up of the project I would be pleased to email one to you along with my wiring diagram etc.

Cheers

Colyn

colynfirth@msn.com
Colyn Firth

Colyn

Perhaps you could provide the part number for the 90 degree wheel

Dominic
dominic clancy

Dominic

I have just checked on the delivery note I received from Stafford Vehicle Components and it just says that it is a 90 degree crankwheel.

Its a hand written delivery note and so I assume that they dont have a computerised stock and ordering system.

Their website is worth a second look though, they have lots of parts and info for classic cars and they are really helpful.

Colyn

Colyn Firth

Please send me the information on this conversion.
Thanks Colyn

Jeff Becker
JEFF BECKER

I sent Jeff all the info as requested.

Jeff pointed out that it could be more difficult to fit the 2-speed to LHD cars as the master cylinder is in the way.
The new motor is a little wider but about the same length as the original single-speed and so it should fit into place ok.
I see that Barney on mga guru takes the pins out of the brake push rods and pulls the pedals down to make more space.

Dominic, I suppose we should ask you how difficult it was to fit the 2-Speed motor on to your LHD car?

Did you need some kind of "Mission Impossible" body harness like Tom Cruise to be able to do the job? :-)

Mike,
my write up includes how to set up the park switch so that it parks on the correct side. If your motor is from an American car it should already be set up to park the wipers on the right hand side but it is easy to change this when the motor is off the car.
Let me know if you still want a copy.

The main things that need to be done to make the motor fit the MGA are as follows:

Make a larger motor mounting plate (as the 2-speed is a bit wider than the 1-speed) and fit this on top of the original mounting brackets.

Fit a 90 degree crankwheel.
(making sure that the white plastic park switch ramp on the underside of the wheel is fitted either opposite the crankpin for LHD cars, or next to it on RHD cars)

Finally, a tip before you start wiring it up.

The connectors on the 2-speed motor are virtually impossible to get to when it is fitted to the car and so I would recommend that you should fit a short loom to the motor with a plug and socket connector to make life easier. Its easy to hide the connector behind the motor.
On my first attempt I didnt think to fit a plug and socket and when I had to remove the motor again for alteration it was easier to chop the wires off and start again than try to disconnect them.

The motor was designed for negative earth cars but I have tested it by running it for more than an hour in positive earth set up and it was fine.
It does run in the reverse direction but this doesnt affect the operation of the wipers.

I did notice that the running speed was very slightly slower when connected as negative earth but still very much faster than my old motor.

Colyn

Colyn Firth

Colyn's comments about access made me chuckle. Been there. Not the easiest of jobs connecting up the drive shaft in situ either, then putting the motor cover back on.

For me the wiper motor is redundant as it tends to scratch my perspex sports screen. Lots of Rainex on the outside instead.

Steve
Steve Gyles

It is not possible to insert or extract the motor in a LHD car without disconnecting the wiper rack. Even then you have to be a contortionist and have small hands. There is inevitably a need to work by touch alone as there is no way to see what you are doing with your hands in there too.

What I would strongly suggest on a LHD car is placing the motor under the right hand end of the dashboard as it is mounted in the MGB later GT models.
dominic clancy

The two speed motors have a plug and socket arrangement so it is easy to install the wiring in situ. The motor does fit in the original position, and the original rack can be reused with the new motor, but if you are installing a used motor from a B then it would be much easier in a LHD to mount it under the dash. For RHD cars this space is occupied by the master cylinder bolts so it probably is easier to mount in the original location.

dominic clancy

Dominic, when you said :- "It is not possible to insert or extract the motor in a LHD car without disconnecting the wiper rack",
do you mean that you just unscrewed the big nut from the flared tube so that when you take the motor out, the rack pulls out of the tube still attached to it? (like I did)

Or did you mean that you have to actually take the top of the gearbox off is situ so that to completely detach the rack from the motor?

If it was the latter, it must have been very difficult to do.

Im surprised that once the motor is unbolted from the car, the big nut is unscrewed from the gearbox end and the wiper arms are removed, you cant just pull the motor out with the rack attached to it.

I would have thought that if you remove the M/C pushrods and pull the pedals down out of the way, there would just be enough space to get the motor through.

Colyn
Colyn Firth

The last time I had to do anything here I found it impossible to get the motor out of the car without disconnecting the whole rack, so having to take off the top of the wiper gearbox. This was still less work than removing the pedals, which I also tried first. That is why I recommend the BGT position for the LHD cars

On the same subject stay clear of repro wheel boxes, as I found that the rack constantly jumped with these. As soon as I used NOS ones the problem vanished
dominic clancy

I have just seen Barneys article ET-216 in Mga Guru where John Barratt explains how he also re-located the wiper motor to the other end of the wiper tube on the right hand side of the car.
He cleverly shortened and straightened the tube so that the motor could be located under the dashboard and bolted onto the bulkhead.

It would certainly make access to the motor much easier.

Looks like a nice winter project for you guys in the USA.

Colyn



Colyn Firth

This thread was discussed between 16/11/2013 and 21/11/2013

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