The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: barry2 on 24.08. 2018 07:32

Title: Dynamo drive slipping
Post by: barry2 on 24.08. 2018 07:32
Hi Mates
this is my first post, I'm Barry from Western Australia , just bought a 1954 RR A10, the dynamo seems to be slipping , not striped it down yet,   i must I think be a belt conversion, do they have special oil resistant belt's?
Barry
Title: Re: Dynamo drive slipping
Post by: beezermacc on 24.08. 2018 08:18
The belt conversions are usually toothed belt type so it shouldn't slip. However there are some V-belt types around which I would recommend swapping for a toothed type. SRM sell a toothed type but still recommend putting grease in the cavity.
Title: Re: Dynamo drive slipping
Post by: Greybeard on 24.08. 2018 09:11
 *welcome*
Title: Re: Dynamo drive slipping
Post by: coater87 on 24.08. 2018 10:44
 Welcome Barry

 I think we could guess all day, and not get it right.

 Popping the outer timing cover off is not an in-depth job at all. You will get to know your new bike better, and we will find out exactly whats happening inside there.

 Lee
Title: Re: Dynamo drive slipping
Post by: duTch on 24.08. 2018 10:56

 Whether it's sprockets & chain or a belt, the sprockets/pulleys  are on tapers,  but can't remember if they have woodruff keys or not.  Either way maybe the keys are not there and a sprocket/pulley is slipping on the taper/s... *dunno*
Title: Re: Dynamo drive slipping
Post by: morris on 24.08. 2018 11:00
 *welcome*

Could be just de nut from one of the pulleys that came loose. As Lee said, five minute job dropping the cover and have a look.
Keep a container underneath because there will be some oil in the lower part of the case and remember which case bolt came from where as they are of different lenghts.
Title: Re: Dynamo drive slipping
Post by: bsa-bill on 24.08. 2018 12:20
Welcome Barry, agree with the comments so far, the vee belts not as positive as a toothed belt, sometimes the cork washer supplied with toothed belt system ( goes behind the large pulley) can be a bit too thick and holds the pulley off the taper, needs cut in half
Title: Re: Dynamo drive slipping
Post by: Greybeard on 24.08. 2018 12:25
...and remember which case bolt came from where as they are of different lenghts.

I have a special tool to ensure those bolts go back in the right place. It's called 'A piece of cardboard with a rough outline of the case drawn on it and holes punched through with a screw-driver'.
I have the equipment to manufacture these special tools if anyone wants one; only 20UKP each, postage extra.
Title: Re: Dynamo drive slipping
Post by: RichardL on 24.08. 2018 12:31
...and remember which case bolt came from where as they are of different lenghts.

 'A piece of cardboard with a rough outline of the case drawn on it and holes punched through with a screwdriver.

Same here. Julian S's version is probably milled from stainless steel. (Am I jibing the right master machinist?) *smile*

Richard L.
Title: Re: Dynamo drive slipping
Post by: muskrat on 24.08. 2018 12:38
G'day Barry, another sandgroper. We have a few over there.
Lots of good tips above. That will cost you a proper intro in https://www.a7a10.net/forum/index.php?board=13.0
The dynamo drive sprocket/pulley is on a taper without a key so can slip if the nut comes lose.
Cheers from the other side.
Title: Re: Dynamo drive slipping
Post by: LJ. on 24.08. 2018 12:42
All genuine and well used. Very hard to find nowadays.  *lol* *yeah*
Title: Re: Dynamo drive slipping
Post by: duTch on 24.08. 2018 17:44

 
Quote
I have a special tool to ensure those bolts go back in the right place. It's called 'A piece of cardboard with a rough outline of the case drawn on it and holes punched through with a screw-driver'.
I have the equipment to manufacture these special tools if anyone wants one; only 20UKP each, postage extra.

 My version is a bit more 'Universal', works for the Chaincase too, and also Gutzzi sump screws, and postage may be cheaper from East coast;
Title: Re: Dynamo drive slipping
Post by: chaterlea25 on 24.08. 2018 19:39
Hi Barry and All,

Barry , glad you made it over from the Britbike forum with your questions

I must have got the upmarket case screw holder, mine is made from a piece of white painted wood  *ex*

John
Title: Re: Dynamo drive slipping
Post by: duTch on 24.08. 2018 22:11

 Hiya NBarry/Baz- I didn't say *welcome*, so *welcome*

 What makes you suspect it's slipping ?
Title: Re: Dynamo drive slipping
Post by: barry2 on 26.08. 2018 08:10
Hi Dutch
I "flashed" with a 12 v battery  ( by mistake, should have been 6v ) and it started turning,  sill on bike
Barry
Title: Re: Dynamo drive slipping
Post by: duTch on 26.08. 2018 09:44
 
Quote
....I "flashed" with a 12 v battery  ( by mistake, should have been 6v ) and it started turning,  sill on bike....

 yeah ok- and nothing stopped it I presume......hmmmm, so conversely, it's not generating? Maybe you've had a look to see if it spins at all(or not) by pulling the end cover  ?
 Don't forget to catch the ~70 ml of oil in the oil pump cavity when you pull the timing cover (I've cheated and drilled a hole *whistle*)
Title: Re: Dynamo drive slipping
Post by: Peter in Aus on 26.08. 2018 10:44
Hi Barry  *welcome* where about's in WA are you? i'm Busselton.
I tried V belts bl**** useless went back to chain, tooth belt cost to much.
Cheers
Peter
Title: Re: Dynamo drive slipping
Post by: wortluck on 26.08. 2018 11:57
Welcome Barry.  With the screws, don't you just try 'em to see if they go all the way in *smile*  I find the three in the top right corner are short, then there are two on the left hand side (bit longer) then the rest are the same length. *dunno*  Just wondering now if I put the wrong length screws in the wrong holes, I'll lock the crank up or something equally crazy (maybe that'll explain the grinding and poor performance) *whistle*.  As for the slipping, wot Musky says - no key just on a taper.  Did my (broken) chain recently - was a doddle following advice on here.  Someone suggested a small wooden wedge at the back of the large sprocket.  I did this then tapped round the sprocket gently and off it popped.  *thanks*
Title: Re: Dynamo drive slipping
Post by: Colsbeeza on 26.08. 2018 13:50
Hi Barry,
Welcome. I pinched this from someone on this Forum.
Colin
Title: Re: Dynamo drive slipping
Post by: wortluck on 26.08. 2018 14:17
Looks like some of my screws are all screwed up then.  Perhaps it's too much beer but what are those measurements again.  Is it 1 inch, 2 inch?  What's 13/4" - sorry if this sounds a bit thick.
Title: Re: Dynamo drive slipping
Post by: Greybeard on 26.08. 2018 14:34
What's 13/4" - sorry if this sounds a bit thick.

One and three quarters of an inch, (1.75")
Title: Re: Dynamo drive slipping
Post by: berger on 26.08. 2018 14:34
I have not been to the pub but i'me going *smile* wortluck I thought that on first glance---- 1/34 is more like it
Title: Re: Dynamo drive slipping
Post by: Greybeard on 26.08. 2018 14:37
According to that picture, the various screw lengths are: one inch, one and three-quarters and two inches.
Title: Re: Dynamo drive slipping
Post by: wortluck on 26.08. 2018 14:50
Yeah, of course, can see it now.  If it'd been written 1 3/4" would have got it quicker (I think).  Still a bit dodgy for me as I seem to be missing one of the 1 3/4".  I've got 3 x 1", 2 x 1 3/4" and the rest are 2".  Perhaps putting the measurements in decimal form is a good idea?
Title: Re: Dynamo drive slipping
Post by: barry2 on 29.08. 2018 01:18
Hi mates
I'm in Dianella, Perth WA,  thanks for the tip about the screws, I can't see a prob' about using the old  chain drive, will let you know what I find
Barry

mod edit: Please do not put personal email/phone #'s in topics. Scammers out there.             
Title: Re: Dynamo drive slipping
Post by: TT John on 05.09. 2018 09:29
The belt conversions are usually toothed belt type so it shouldn't slip. However there are some V-belt types around which I would recommend swapping for a toothed type. SRM sell a toothed type but still recommend putting grease in the cavity.

I use a belt conversion kit from Dynamo Regulators Ltd on my A7 also on my two A10s, I believe they are the dogs doodahs, I have never had any problems since fitting them and I think the kit costs about £80 in total, well worth it. Mike Hutchings is the man on wwwdynamoregulators.com or call on 01489 880552
This conversion does not use oil, it's dry but is a toothed 15mm belt drive.

Regards TTJohn
Title: Re: Dynamo drive slipping
Post by: barry2 on 13.09. 2018 00:45
Hi mates
Managed to tighten the slipping belt OK w/o stripping , but the Dynamo only worked intermitently, so I took it it off  and had a look at it,, everything was near new apart from the casing ,, the armature  segments had solid carbon buildup all around them,  then   I could see it wasn't undercut , so I think that was the trouble, have undercut it and now it works fine ( think the undercut stops the build up of carbon that can short it out) , Another thing the Vee belt drive pulley (engine end) had about 2 mm end float , would that be a problem? thanks for your advice in advance
Regards Barry
Title: Re: Dynamo drive slipping
Post by: Peter in Aus on 13.09. 2018 01:09
Another thing the Vee belt drive pulley (engine end) had about 2 mm end float , would that be a problem? thanks for your advice in advance
Regards Barry
That sounds like the seal 67-0708 is missing or disintegrated, was there much oil in the housing where the belt run? that seal usually takes up any slack.
Peter
Title: Re: Dynamo drive slipping
Post by: berger on 13.09. 2018 01:11
I have not been to the pub , there should be a cork washer that usually takes up the float
Title: Re: Dynamo drive slipping
Post by: barry2 on 13.09. 2018 02:11
Hi Peter
Thanks for the reply, No oil or debris in the belt compartment, maybe wasn't fitted ,, could I see if it was fitted? or is it on the other side of the housing

Barry
Title: Re: Dynamo drive slipping
Post by: Peter in Aus on 13.09. 2018 09:36
Hi Peter
Thanks for the reply, No oil or debris in the belt compartment, maybe wasn't fitted ,, could I see if it was fitted? or is it on the other side of the housing

Barry
G'Day Barry, you have to remove the pulley to see it, but if it is not leaking oil forget it, the worm in the bush is doing the job so all should be good.
Peter
Title: Re: Dynamo drive slipping
Post by: bsa-bill on 13.09. 2018 09:54
Quote
the worm in the bush is doing the job so all should be good.

ah hem, I know someone who fitted the wrong bush in there  *whistle*, result chamber full of oil, noticed it coming out past  the cork gasket at the dynamo, thing is the dynamo was charging just fine, toothed belt  = good
Title: Re: Dynamo drive slipping
Post by: barry2 on 18.09. 2018 00:09
Hi Mates
the belt looked good so I put it all back together, I used a solid state regulator from ebay Wasell?that was 31 pounds  all working good
Barry