Put the pulleys on the 1275s today to check the fan belt length.
I have a cooper s two piece crank pulley and damper approx outside diameter 4.75"
I have a cooper s cast water pump pulley approx outside diameter is 4.5"
I have a one piece dynamo pulley approx diameter is 2.75"
I noticed the dynamo pulley was a long way out of line by approx 3.5mm. The water pump and crank pulley are within 0.5mm of each other so fine for a belt but will need to work out why the dynamo is so far out. Maybe the lug is too big on the water pump or maybe I have the wrong pulley on the dynamo?
I can easily machine down the water pump lug or the dynamo pulley if that turns out to be the incorrect part.
That pulley looks to be too far away from the fan (dynamo) and aren't the cooper s dynamo pulleys almost the size of the fan as well as being stamped tin?..
Cooper S dyno pulleys are a larger dia.than std dyno pulleys and are riveted sheet metal. Std. pulley dia. is 2.75 can't find figure for S pulley. Steve (CTR)
Yup, you should be using the big Dynamo pulley otherwise you will over rev the dynamo. You can sort any minor mis alignment issues by either using stacked washers or custom spacers if you are feeling posh.
Found a used mini dynamo for sale with a pulley to replace my pulley. Asked the guy for a photo and he sent me this...
The pulley does not look much bigger than mine, maybe a few mm. Once again its a solid pulley.
Ill still look out for a larger pulley, did another spec of mini have these small pulleys, seems a little strange both the one for sale and mini both have very small pulleys compared to the picture posted here.
All minis with a dynamo used the large tin pulley depicted a few images above. ST / Comps did however make a large dia steel pully for comps use, like the one in my pic in the mechanical tacho thread.
Other BMC cars used the same dynamo so could have used that smaller cast pulley.
Over the years I have collected a number of dynos and only one had the larger pulley. That one was removed from my 67 S back in the early 70s. I think Special Tuning offered a large pulley. Check with the suppliers. I know I'll be on the look out for one for my 1071 S. Steve (CTR)
Hi Dave,
The pulley you need for a Cooper spec Mini is from a 60's Morris Oxford (or Austin, Wolseley etc). It is bigger in diameter and the same as shown in InimiaD's post above.
mk1 wrote:All minis with a dynamo used the large tin pulley depicted a few images above. ST / Comps did however make a large dia steel pully for comps use, like the one in my pic in the mechanical tacho thread.
Other BMC cars used the same dynamo so could have used that smaller cast pulley.
M
From memory, these were 4" dia. The ones I've seen where aluminum, though I wouldn't doubt they also did steel ones.
I think the reason that ST sold the solid pulleys as the riveted ones were breaking up under load !
Would this one be big enough As found on industrial diesel engine date marked 1970 Lucas C40
Regards
Goff
You do not have the required permissions to view the files attached to this post.
Picked up a new dynamo pulley, genuine bl, with box etc 12a1772.
The pulley is still along way out of line compared to the crank and water pump pulley, around 2.5mm. centre pulley to pulley. Have allowed for the different thickness of the pulleys.
I can machine the back of the pulley to correct this but I am very confused on why I am need to modify a standard part? The dynamo I believe is all standard and the Tin fan part sits 2.4mm off the alu housing of the dynamo. I could reduce the thickness of the spacer on the main shaft but that could allow the tin fan to rub on the alu housing.
