Primary chaincase for Dominator

The inner chaincase should feature a sliding metal seal affair, basically two large thin washers each side of the case rivetted together, sometimes with a felt seal in the middle.

Regarding the rubbing, what width sprockets are you using? Some people for reasons unnecessary fitted the wider Atlas sprockets. Trouble was there was not enough clearance and the chaincase gets worn in the way you describe.

Have just measured the OEM spaceron my stripped 1962 Dommi. It is made from 5/16" bar. Thespace is 42mm with 8mm of 5/16" threads at each end. Note the inside nut is halfthickness.Peter B

I think the change was from 1/4" to 5/8" on the Atlas, obviously with rear sprocket to suit, It doesn't sound much but add in the general beefier construction of the chain and it changes the situation from one with a working clearance, to one where with the tiniest of flap the chain is rubbing the the inner chaincase.

Previously nigel_orchard wrote:

Previously rob_hodder wrote:

The inner chaincase should feature a sliding metal seal affair, basically two large thin washers each side of the case rivetted together, sometimes with a felt seal in the middle.

Regarding the rubbing, what width sprockets are you using? Some people for reasons unnecessary fitted the wider Atlas sprockets. Trouble was there was not enough clearance and the chaincase gets worn in the way you describe.

Many thanks for this information. Which dimension of the sprocket width do I have to measure? If the cogs were too near the chaincase, the alignment with the rearsprocket would be wrong. If the teeth were too wide, the chain would not fit or would be loose on the rear sprocket. Sorry if I am missing the obvious. I'll now need to look into sourcing the sliding seal or making one up. Nigel

Previously rob_hodder wrote:

I think the change was from 1/4" to 5/8" on the Atlas, obviously with rear sprocket to suit, It doesn't sound much but add in the general beefier construction of the chain and it changes the situation from one with a working clearance, to one where with the tiniest of flap the chain is rubbing the the inner chaincase.

Previously nigel_orchard wrote:

Previously rob_hodder wrote:

The inner chaincase should feature a sliding metal seal affair, basically two large thin washers each side of the case rivetted together, sometimes with a felt seal in the middle.

Regarding the rubbing, what width sprockets are you using? Some people for reasons unnecessary fitted the wider Atlas sprockets. Trouble was there was not enough clearance and the chaincase gets worn in the way you describe.

Many thanks for this information. Which dimension of the sprocket width do I have to measure? If the cogs were too near the chaincase, the alignment with the rearsprocket would be wrong. If the teeth were too wide, the chain would not fit or would be loose on the rear sprocket. Sorry if I am missing the obvious. I'll now need to look into sourcing the sliding seal or making one up. Nigel

hello this may be ok but you find you will have to change your chain guard as well as 3/8x5/8 heavy duty chain will rattle like hell in your chain guard that was made for 1/4x5/8 chain

Yours Anna J

When I changed my rear chain from 5/8" x 1/4" to 5/8" x 3/8" (Width)back in the day, the only rattle was from the full rear chainguard -so I had to remove the bottom half - then lost it over the years of course! Luckily I managed to buy a good full one from aStafford Show for about £40 (Top and bottom!) as I'm going back to original 5/8" x 3/8" for Concours. (If you look at my club pics of the bike "as found" you'll see why I went this route!)Perhaps we're talking at cross-purposes though as people here are saying changes from 1/4" to 5/8". I don't know much about primary chains if that's what this is about. The stud spacer is available new in V. expensive stainless steel from eBay and probably many other sources - maybe even Andover Norton?

Previously nigel_orchard wrote:

Previously anna jeannette Dixon wrote:

Previously rob_hodder wrote:

I think the change was from 1/4" to 5/8" on the Atlas, obviously with rear sprocket to suit, It doesn't sound much but add in the general beefier construction of the chain and it changes the situation from one with a working clearance, to one where with the tiniest of flap the chain is rubbing the the inner chaincase.

Previously nigel_orchard wrote:

Previously rob_hodder wrote:

The inner chaincase should feature a sliding metal seal affair, basically two large thin washers each side of the case rivetted together, sometimes with a felt seal in the middle.

Regarding the rubbing, what width sprockets are you using? Some people for reasons unnecessary fitted the wider Atlas sprockets. Trouble was there was not enough clearance and the chaincase gets worn in the way you describe.

Many thanks for this information. Which dimension of the sprocket width do I have to measure? If the cogs were too near the chaincase, the alignment with the rearsprocket would be wrong. If the teeth were too wide, the chain would not fit or would be loose on the rear sprocket. Sorry if I am missing the obvious. I'll now need to look into sourcing the sliding seal or making one up. Nigel

hello this may be ok but you find you will have to change your chain guard as well as 3/8x5/8 heavy duty chain will rattle like hell in your chain guard that was made for 1/4x5/8 chain

Yours Anna J

Thanks Anna. Rob put his finger on the chain width issue and, of course, someone has fitted the 3/8 sprockets to my Dommie. My bike has only a top run rear chainguard so maybe that will not be a noise problem. I now need to decide whether to change the gearbox sprocket and brake drum to fit the smaller chain. I am not looking for concours, just a chain that does not rattle and wear the primary chaincase.

Nigel

yes well my 650 manxman had a 3/8x5/8 chain and sprockets on and I have changed them back too how it should be too 1/4x5/8 chain and sprockets now it runs nice no more rattles or knocks and I have renewed the primary chain as well for good measure. yours anna j

It's also worth remembering that not all chains are equal, width wise. I'll bet it's only the pins on the split link that are catching the back of the primary case, as these tend to stand prouder than the rest of the riveted ones.

My Dommi came to me with 3/8 sprockets and the same clunk clunk problem. Being too tight to buy new chainandsprockets, I overcame the problem by using a Renold chain (which had the narrowest profile I could find) and using a 1mm thick washer behind the inner cover bottom mount, which brought the back out just enough to allow sufficient clearance for the chain.

Previously martin_rowe wrote:

It's also worth remembering that not all chains are equal, width wise. I'll bet it's only the pins on the split link that are catching the back of the primary case, as these tend to stand prouder than the rest of the riveted ones.

My Dommi came to me with 3/8 sprockets and the same clunk clunk problem. Being too tight to buy new chainandsprockets, I overcame the problem by using a Reynold chain (which had the narrowest profile I could find) and using a 1mm thick washer behind the inner cover bottom mount, which brought the back out just enough to allow sufficient clearance for the chain.

well then Reynolds chain is now made in France . and there not as good as the British made chains , I use Japanese chains as there some of the best you can get now . I used a 520 with 110 links in Titanium gold finish . yours anna j

I'malso being a tightwad. My '67 650 has the 5/8 x3/8 chain and sprockets and I had exactly the same issue as Martin - it was only the spring link catching. I didn't replace anything.

Instead of spacing the case out a bit further, I simply put the split link in from the outside so that the spring clip is on the inside run. Immediate end of issue.

George

Previously martin_rowe wrote:

It's also worth remembering that not all chains are equal, width wise. I'll bet it's only the pins on the split link that are catching the back of the primary case, as these tend to stand prouder than the rest of the riveted ones.

My Dommi came to me with 3/8 sprockets and the same clunk clunk problem. Being too tight to buy new chainandsprockets, I overcame the problem by using a Renold chain (which had the narrowest profile I could find) and using a 1mm thick washer behind the inner cover bottom mount, which brought the back out just enough to allow sufficient clearance for the chain.

I meant that I'm going back to 5/8" x 1/4" for Concours of course! I want to use the full rear chainguard which was part of the bike's original owner's spec. They are especially designed to catch all the dirt and crud and use it to wear away the chain - as everone knows! My Navigator D/L has a cut-down Dommie top rear chainguard. Odd?

Cheers, Lionel

Previously nigel_orchard wrote:

Previously lionel_yexley wrote:

When I changed my rear chain from 5/8" x 1/4" to 5/8" x 3/8" (Width)back in the day, the only rattle was from the full rear chainguard -so I had to remove the bottom half - then lost it over the years of course! Luckily I managed to buy a good full one from aStafford Show for about £40 (Top and bottom!) as I'm going back to original 5/8" x 3/8" for Concours. (If you look at my club pics of the bike "as found" you'll see why I went this route!)Perhaps we're talking at cross-purposes though as people here are saying changes from 1/4" to 5/8". I don't know much about primary chains if that's what this is about. The stud spacer is available new in V. expensive stainless steel from eBay and probably many other sources - maybe even Andover Norton?

Thanks, Lionel. I have only ever had a top rear chainguard and did not know there was a bottom half. This is about the rear, not primary, chain. Fortunately, a friend has turned a spacer for me so no need to go for expensive eBay offerings.

Nigel

Previously george_farenden wrote:

I'malso being a tightwad. My '67 650 has the 5/8 x3/8 chain and sprockets and I had exactly the same issue as Martin - it was only the spring link catching. I didn't replace anything.

Instead of spacing the case out a bit further, I simply put the split link in from the outside so that the spring clip is on the inside run. Immediate end of issue.

George

Previously martin_rowe wrote:

It's also worth remembering that not all chains are equal, width wise. I'll bet it's only the pins on the split link that are catching the back of the primary case, as these tend to stand prouder than the rest of the riveted ones.

My Dommi came to me with 3/8 sprockets and the same clunk clunk problem. Being too tight to buy new chainandsprockets, I overcame the problem by using a Renold chain (which had the narrowest profile I could find) and using a 1mm thick washer behind the inner cover bottom mount, which brought the back out just enough to allow sufficient clearance for the chain.

well after 1966 all nortons went to 3/8x5/8 chains but earlier Norton had the 1/4x5/8 so there you have it,

Hi Lionel, The enclosed case has a bad reputation for collecting the crud, But it is very easy to improve the situation.Spray and grit is thrown by the rear tyre onto the top face of the swinging arm and is deflected sideways onto the chain run. All that is needed is a mud flap fixed to the bottom of the mudguard (which a De-luxe should have) which extends down into the swinging arm.A vast improvement. The lower half of the guard needs to be modified with a drain hole .

Previously nigel_orchard wrote:

Previously rob_hodder wrote:

"The inner chaincase should feature a sliding metal seal affair, basically two large thin washers each side of the case rivetted together, sometimes with a felt seal in the middle".

I have now obtained a replacement inner chaincase with the sliding metal seal to which you refer. However there is no felt seal and no apparent way of fitting one. I thought that a piece of felt would or could be sandwiched between the two large thin washers but their inner edges meet tight together. I was thinking I might glue or rivet a piece of felt to the outer or inner one of these washers, but the radial clearance onto the gearbox output shaft is very small - less than 1mm on the diameter and this thickness of felt would quickly wear away. Further, I have the belt primary drive so there is no oil splashing around to lubricate any felt.

I am very reluctant to let the sliding seal rest on the shaft as it could cut into the shaft and would probably be noisy.

Advice, please.

Nigel Orchard

Nigel, the felt seal is available for a few bob from RGM. It has to be creased up and folded a bit to get it through the hole into place.

i did it on my Commando today.