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MG MGB Technical - Wiper Motor 67 GT

Can the round style later wiper motor and assmbly be a direct swap on a 67 BGT instead of the square early type if the motor and cable assembly is replaced as a unit? Seems like the Moss catalog shows the change in 67?
Ralph

My '67 GT has a later 2-speed motor installed. The PO did the conversion but I do have the wiring diagram he made if you need it.
Steve Simmons

Thanks Steve, So the mechanical aspect of the bolt in is the same? Just the wiring is a bit different?
Ralph

My 67 gt had the round motor installed in it also. I purchased a square one ( was part of a group of parts I got on e-bay. The distance for the wiper wheel boxes does not fit the MGB GT. Then I don't know it is from an MG.
Bruce Cunha

Thanks Bruce So the 67 square motor with wheelboxes DID NOT bolt into the GT? I am assuming that the roadster and GT must be different in some small fashion with regard to the bolt up. My two GT's, both 67's had a round motor setup in them as well but were not bolted in correctly, so I assumed (again) that they were some PO attempt to rememdy a previous problem. Seems like 67 BGT's may have had the round motors in some cases? Interesting perhaps the cable is different.
Ralph

My 67 has a round wiper motor and the wiper stroke is too short. I believe the round motors are for the 3 wiper cars? I have a square one and I will try to install soon

Pete
Pete

Hi All

I am new here and am getting my '64 MGB on the road after being in storage a bunch of years. As I remember I have a single speed wiper on my '64. I also have a '72 wiper motor and three wiper set-up. How easily can I easily exchange the motors to give me more speeds and a better wiper?

Later

bikerbum
bikerbum

There is a round one on E-bay and the seller says it is for a 67 B Gt. States it is specific for 65 to 67 BGT. But I am unsure if that is correct.

http://cgi.ebay.com/ebaymotors/MGB-GT-67-Wiper-motor_W0QQcmdZViewItemQQcategoryZ42612QQitemZ7999802348QQrdZ1QQsspagenameZWDVW

Clausager says Tht GT has a 12W wiper motor with 115 degrees of wipe.. From 68 on, both the GT and Roadster were fitted with the two speed 14W motor.

I know my motor is a single speed. I will check the number on it tomorrow.
Bruce Cunha

My motor appears to be round. I'm not sure exactly what the PO did, but it's a 2-speed system and I remember him mentioning it was a later unit. Perhaps he was referring to other parts of the system?

Here's a photo of the motor in my '67...

http://www.lbcnuts.com/mg/mgbgt/wipermotor.jpg
Steve Simmons

1)The single and two speed wipers use different switches and wiring. I believe that all GT used 2 speed wipers, or perhaps it was an option - seems to me that all the GTs in Pittsburgh had them, we thought that it was the cat's meow at the time!
2) the round and square motors take different brackets and cable attachment bits.
3) On all, the sweep is controlled by:
a) the drive gear in the wiper motor - interchangeable between motors, but I don't recall if between square and round motors. This is what changes to make the (round) MOTORs fit different cars - most Brits from 68 on. The gear is the same for rdst and GT from 69 on. Many cars use the same motor but different gears giving different sweeps.
b) the number of teeth on the wheelbox gear. There are a few different ones, but I "think" all GT are the same, there is a rare very early rdst one, one for most 2 wiper roadster thru 67, and one for 3 wiper rdst. Wheelboxes may differ in shaft length as well as # of teeth. I believe that most wheelboxes that came on round motor systems have the same # of teeth, which is why the drive gear in the motor can be stamped with the degrees of sweep.
4) The cable racks are different lengths for OE, but are supplied as generic "cut to fit" for replacement. (cut with a torch to keep the cable from coming apart!)
5) The metal tube rack housings are precise to length for each wheelbox spacing. Can be made from fuel pipe and flared on the ends.

Mixing up bits from cars before 69 could result in some odd consequences, but a complete 69 on GT system should work on any GT. A rdst motor, rack, and rack attachment ferrule/nut should fit into a GT as well, but if the GT had a square motor, you would need to make sure the first section of rack housing was correct length, and might have to make a new one to get the correct nut on it - not sure about the nut.
FRM
FR Millmore

All GTs had the two-speed system that was used on later roadsters i.e. the round motor which is backed by a ground and the switch connects 12v to either the slow speed winding, the fast speed winding, or the park ciruit.

Some roadsters seem to have had a simpler two-speed system wired to the same principles as the single-speed i.e. square motor was backed by 12v and the switch connected a ground to either the slow or fast speed winding. Parking on this system was from a ground at the motor via the park contact.

The later system uses more wires 'tween switch and motor, but an early toggle headlamp switch can be used as a wiper switch with later motor and wiring which enables the dash to look the same.

I think there are at least 3 combinations of gear/sweep, arm length and blade length according to whether it is for a roadster or a GT and where the wiper spindles come relative to the bottom of the screen.
Paul Hunt 2

A further complexity (or help, depending on how you look at it!):
Early wheelboxes have hex chrome nuts holding them; later ones have octagonal nuts with notches on the corners. They have different threads. I believe that the change matches the square to round motor transition in general, but there may be some overlap, esp. in the late 67 to 69 period. There are probably early wheelboxes with the same dimensions and teeth as later ones, especially the early GTs. Some of this had to do with wiper sweep requirements in the US; there may be a couple of different setups that were supplied. They all worked, and most combinations would work too. Use of early wheelboxes with late motors may give sweeps different than what is marked on the gear.
FRM
FR Millmore

This thread was discussed between 11/09/2005 and 13/09/2005

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