General Replacing dynamo brushes in-situ

[lazylobster]

Hi all, your friendly novice mechanic here. I've noted (due to having a voltmeter on my dash) that no charge going to the battery at rev's. I've done the dynamo tests using a multi meter and get zero output. So looks like I will need to open up the dynamo and replace the brushes (best case scenario). Worse case, well, lets not go there just yet!

I'm going to attempt to do it with the dynamo attached to the engine as it's the better option for me than to remove the engine from the car. I'll jack up the engine and remove the rear cross member so as to gain good access. Couple of you-tube video's later and it looks fairly straight forward.

Questions if I may.
The 17mm center nut on the dynamo at the front. This spins freely so guess I'll have to attempt clamp the 3 pin hub to get some purchase upon it.
Not sure if there are any torque settings for clamping down the center nut and the 3 nuts holding on the 3 pin hub?
With regards to above, would you recommend I apply some thread lock?

Any other top tips will be gratefully received.
Cheers
Rob

 

[Bleeding Knuckles]

Hi Lobster, because you have to remove the brush end plate on the dynamo removing the rear valance is a good idea. If you find a copy of the 126 Haynes manual and look at page 31 fig 2.4 you will see a tool being used to hold the dynamo shaft while the fan bolt is being removed. removing the pulley nut can be done the same way. If you can manufacture such a tool it's job done !!! Beware of putting too much pressure on the pulley studs they will bend or at worst snap off.
Ian.

 

[Toshi 975]

Hi all, your friendly novice mechanic here. I've noted (due to having a voltmeter on my dash) that no charge going to the battery at rev's. I've done the dynamo tests using a multi meter and get zero output. So looks like I will need to open up the dynamo and replace the brushes (best case scenario). Worse case, well, lets not go there just yet!

I'm going to attempt to do it with the dynamo attached to the engine as it's the better option for me than to remove the engine from the car. I'll jack up the engine and remove the rear cross member so as to gain good access. Couple of you-tube video's later and it looks fairly straight forward.

Questions if I may.
The 17mm center nut on the dynamo at the front. This spins freely so guess I'll have to attempt clamp the 3 pin hub to get some purchase upon it.
Not sure if there are any torque settings for clamping down the center nut and the 3 nuts holding on the 3 pin hub?
With regards to above, would you recommend I apply some thread lock?

Any other top tips will be gratefully received.
Cheers
Rob

As Ian says take care with the 3 M6 nuts on the studs that go through the pulley sections as on manufacture those studs are peened over at the back of the flange so if they shear off they are a bugger to fix. You will not get any torque ratings for any of those nuts and the big 17mm nut is normally a nylock nut (m10 fine) If you have not already got to work on it I would start with the big nut and one method I used one time was to wrap a strong nylon cord around the pulley a couple of turns then secure the other end of the cord to the crankshaft pulley so that when you got a socket on the nut to undo it the cord tightened on itself locking the Dynamo pulley.
I have just rebuilt a Dynamo myself for my latest engine build and I had forgotten how easy it was to dismantle them. A little harder to reassemble as you have to get the brushes back on the cumutator. I did this by pushing the brushes way back against the springs then lodging the spring against the side of the spring locking it in place. After assembly you can get to the brushes and flick them into place.
an old doner engine I dismantled , when I took off the fan housing top cover I was surprised to find a fan vane lodged over by a spark plug. When I removed the fan I could see it had a missing vane and another one part out. The rest of it was fine and my theory is that someone had put a bar or big screwdriver between the vanes to stop the Dynamo from turning. I had to scrap the fan.