Dynamo pulley alignment

[amoledigginginahole]

Greetings all, I'm a new owner of a '68 Danbury Bay conversion, and having some trouble with the fan/generator belt.

The old belt is worn and I got a replacement 9.5x905 Continental belt. However it is toothed, and the old one is smooth. Because the generator pulley is not perfectly lined up with the cam pulley, the toothed belt twists itself off within a few revolutions.

I've refitted the old one for now, but would like to know

a) where can I find a smooth belt to replace the original, or
b) how can I tweak the pulley alignment so the toothed belt works ok.

And is a) even a good idea, or should I definitely be pursuing b)?

Thanks in advance!

 

[Araon]

whats the tension on the belt like and post a pic or two

 

[amoledigginginahole]

The tension is ok, about 1.5cm deflection and just shy of 90 degrees twist. I'll post pics in the daylight tomorrow.

Does the second part of the dynamo pulley (the 'front') just pull off once the back half and shims are removed? I cant seem to shift it.

 

[sparkywig]

The tension is ok, about 1.5cm deflection and just shy of 90 degrees twist. I'll post pics in the daylight tomorrow.

Does the second part of the dynamo pulley (the 'front') just pull off once the back half and shims are removed? I cant seem to shift it.

Not easily, I've broken two trying to remove them, so gave up.

 

[amoledigginginahole]

Here's some photos, you can see the dynamo pulley is slightly more towards to front of the vehicle. The 'after' shots show how this causes the toothed belt to twist itself.

Flickr album

 

[sparkywig]

Have you got the right backing plate fitted to the fan housing, or even the correct one on the wrong way round?

 

[amoledigginginahole]

Good question... how would I know? It looks like original tin-work.

 

[sparkywig]

Can you put a pic up of the backing plate?

 

[amoledigginginahole]

I've added a couple of photos to the flickr set - the plate has a dip in the middle (around the dynamo, diameter about an inch more than the dynamo itself) which goes in towards the front of the van a few mm. I cant see how the plate would fit the other way around...

 

[Trikky2]

Since its only a bit out it could be the tinware was fitted slightly out of true or too far forward during a previous re-build.. Its a bit fiddly but that amount of mis alignment can be "adjusted" out. It may of course also be because the dynamo and/or its backing plate have been replaced with an incorrect one. The easiest way to check this would be to have a look at another one and compare/measure IMO.

Either way the alignment should be corrected since running a smooth belt may not cause it to flip but will still damage the belt and put unwanted stress on both the pulley and the dynamo - essentially storing up problems in future.

 

[amoledigginginahole]

Thanks, how would you adjust it out? Just release the generator strap and try to move it towards the back a little?

 

[sparkywig]

Stick your hand round the back of the fan housing and see how much of a gap there is between the fan and housing. Ideally there should only be about a couple of mm.

 

[amoledigginginahole]

Seems like a couple of mm, although I'm not 100% what I'm feeling for.

I tried taking off the generator strap but the generator still seems very much locked in place, no movement for me to tweak the alignment. I've also noticed there isn't enough generator shaft spare for me to put shims behind the pulley, so even if I could get the pulley off that option is a no-go.

 

[dubs and classics]

Is your engine a 1600 tp? just wondered if you have a 30 amp dyno on there from a 1500 sp or something. They are slightly shorter than a 38 amp dyno.

 

[amoledigginginahole]

It's a 1600 single port.

 

[dubs and classics]

Ah ok. I cant remember if 1600sp' had the long or short one on to be honest Maybe some kind chap with a singleport on here might measure theirs for you just to confirm if you have the right one.

 

[sparkywig]

Ah ok. I cant remember if 1600sp' had the long or short one on to be honest Maybe some kind chap with a singleport on here might measure theirs for you just to confirm if you have the right one.

I'll measure my dynamo tomorrow for you.

 

[sparkywig]

The dynamo body off my singleport is 7" from the fan end to the pulley.