Commando primary case seal

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ILLF8ED

ILLF8ED

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Seems the currently available primary rubber band seal doesn't last more than one assembly. I notice this over the last maybe 10 years. I'm in the process of putting my '72 roadster back together after redoing the bushes and bearings in the gearbox and the seal has expanded to where it's too long, then it started breaking apart.
 
fortunately new primary seals are not expensive and even cheaper getting some 1/4 inch tubing local auto store

eventually I found that removing an inch or so of the rubber seal and putting the gap at the top solved the stretch problem and did not leak if at all
 
illf8ed,
I haven't had the problem of breaking the band but if it does and you are using oil/chain combo, then keep the break at the top on the primary inner case. You could crazy glue the O-ring back together after DE-greasing the ends. If you find it gets too long then kneed it with your fingers back into the groove by pushing the o ring to compress the strip and avoid any tenancy to pull on the o-ring while refitting. If that still doesn't work then cut it with an xacto knife and use the crazy glue method to rejoin the ends. I think Loctite makes a glue for O-ring material if you really want to be fancy. :wink:
Cheers,
Thomas
 
My seal seems to have expanded in length after first couple of r&r's of the casing. I reckon it's about 2-3" too long...impossible to refit without surgery. Will try using a blob of automotive RTV polyurethane sealant on the trimmed ends...placed at top of casing.
I've last used ATF type F as suggested elsewhere in the casing...wonder if that expanded the seal.
 
Mine was tacked together with gray gasket maker several years ago , placed at top , no worries , it did come apart last time , so trimmed the ends and tacked it back together again .... maybe 10 years ago had a real nice soft one almost foam , may re-use it when this one fails next time ....
 
Yes I put the foamy one on after first getting bike a year ago...it was recommended by Walridge for better sealing. But it broke in half upon first removal later last season...had a new harder one from. Moto Import and went with...same one now too long. I think either is fine, foamy likely to reduce bending of casing if over torquing the single nut. Would try foamy again, using RTV if ends separate again.
 
Use rubber grease on the seal and it will last a very long time and able to remove it and reuse it many times, the rubber grease will keep the seal soft, and cut it to size if it stretches no need to glue it to rejoin it keep the join up the top and no oil will get out of it, don't over fill your primary and don't over thighten the centre bolt.

Ashley
 
You can buy O-ring cord in all manner of material and section shape, that is all the round section replacements are but probably rubber at the more economical end price wise..... and a yes from me also for a wipe down with rubber grease or even primary case oil.

https://www.theoringstore.com/index.php?main_page=product_info&products_id=40705

Commando primary case seal
 
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eskasteve said:
Have you used this x-ring bead in your primary. Looks interesting
Click to expand...

No, I just googled to see if there was a suitable square section available and the X ring popped up.

As long as both primary covers seal surfaces are in good order and the covers are not bent in some way, leakage should not be an issue but that X ring (if not madly expensive might be an option)
 
I have used 1/8" vacuum hose for windshield wipers with excellent results.
ANCO 1450 is an old stock number on the box I use.
 
I always had more leakage from the trans seal than the O-ring, or leakage from the air filter in my central tank bike. But I always used to think it was the o-ring for a long time. I got rid of most of the leakages by changing the oil tank breather that used to go into the air filter. I've had good luck putting a tiny smear of RTV on the 0-ring against the outer cover after inserting the ring.

Oil leaks don't always come where you think they may.
 
Tornado said:
Yes I put the foamy one on after first getting bike a year ago...it was recommended by Walridge for better sealing. But it broke in half upon first removal later last season...had a new harder one from. Moto Import and went with...same one now too long. I think either is fine, foamy likely to reduce bending of casing if over torquing the single nut. Would try foamy again, using RTV if ends separate again.
Click to expand...
I use this stuff to avoid any distortion of the cases. Buy it by the meter off ebay. 6mm I think dirt cheap
 
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