The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: denis on 06.08. 2019 20:37

Title: Behind the clutch
Post by: denis on 06.08. 2019 20:37
Hello all,
Could anyone please tell me how to remove the « thing » from under the 200 mark on the first pic so I can put it on the other engine?  It seems to be riveted in..
Which leads me neatly to the next question; do you have to take out the gearbox to replace the sprocket? Just asking, it seems in good nick but i’d feel stupid not to ask. 
Also, it seems to be the first time the clutch is out, any idea what the « 200  » means? 
I hope the pics came out alright.
Thanks in advance for your help,
Denis
Title: Re: Behind the clutch
Post by: RDfella on 06.08. 2019 20:57
With the primary inner cover off, changing the sprocket is a breeze. As for rivets, I presume they hold the oil seal onto the case.

Ignore above post - just dawned on me it's a semi-unit plunger type so my comment does not apply as the case doesn't remove as with a S/A.
Title: Re: Behind the clutch
Post by: denis on 06.08. 2019 21:07
Wow, quick reply!
I forgot to mention these are rigid and plunger engine, you can’t take the primary inner case off, it’s the entire half that would need to come off.

Cheers, Denis
Title: Re: Behind the clutch
Post by: muskrat on 06.08. 2019 21:14
G'day denis.
Grind the heads off the rivets ans use small screws to hold it in.
To change the g/box sprocket the wholw lump has to come out and the g/box unbolted from the engine. So it's a good time to do all those other jobs.
duTch modified his like an A65 to be able to get to the sprocket. I think orabanda modified for a proper seal for the mainshaft.
Cheers
Title: Re: Behind the clutch
Post by: denis on 07.08. 2019 05:02
Thanks Muskrat, 
Little screws it will be then.
The engine is still in the frame and as said, sprocket seems in a good nick, so the sprocket ‘ll stay in for now.
I’d be curious to see duTch and Orabanda’ s mods though.
I did your mod’ on the primary adjuster yesterday with the white chopping board, (as she agreed)
Thanks for the tip, the grooves were impressive!   I’m surprised how easily you can drill that stuff vs how fast the primary chain will slide on it.  Time and Kms will tell. 
Cheers, 
Denis

Title: Re: Behind the clutch
Post by: morris on 07.08. 2019 09:25
Hi Denis,
When I had to change the oil seal on the plunger I drilled out the rivets and replaced them with 5BA screws.
As the inner cover is to thin to hold the screws I made up a steel ring, drilled and tapped to hold the screws.
Details about this and some more ideas/suggestions in this thread;
https://www.a7a10.net/forum/index.php?topic=4282.msg62295#msg62295

Getting the sprocket off means removing the gearbox and to remove the gearbox from a plunger it's engine out I'm afraid...
Title: Re: Behind the clutch
Post by: Greybeard on 07.08. 2019 10:52
I used small nuts and nylock nuts to hold my seal in place. I found that the nuts touched the gearbox sprocket so I ground some metal off the heads and turned the bolts around. Just check clearance of sprocket plus chain before you put the engine back in the frame.
Title: Re: Behind the clutch
Post by: denis on 09.08. 2019 05:47
Hello,
Tanks all for your input, I love these sprocket mod’s! 
I’ll first try to tap the inner case and red loctite (4 mm thick should be enough for making a thread, or not?) or use rivets as Trev said in another topic, and do the sprocket mod’ next time the whole lump comes off the frame. 
Thanks again, Denis
Title: Re: Behind the clutch
Post by: Greybeard on 09.08. 2019 08:50
I wondered about using sealed Pop rivets:
https://www.rivetsonline.com/blind-rivets/closed-end-blind-rivets#1
Title: Re: Behind the clutch
Post by: duTch on 09.08. 2019 11:35

 
Quote
.......duTch modified his like an A65 to be able to get to the sprocket. I think orabanda modified for a proper seal for the mainshaft.  .........

 Yep-  guilty as charged  *evil* there should be some pics on here somewhere-maybe a search will dig it up, the originals are buried in a Hadrondrive or two somewhere...
Title: Re: Behind the clutch
Post by: Swarfcut on 12.08. 2019 08:38
As standard, the three rivets hold the oil flinger, (the bit you can see), and a further washer behind the chaincase to support the oilseal. As detailed above, morris made a rather clever thicker version of this washer, drilled and tapped to hold  three fixings bolts.

Just screwing into the aluminium chaincase  will not secure this thin original washer, so to do it with nuts, bolts and Loctite is possible but difficult because of limited access. Pop rivets will do, but may not survive long in the vibrating environment and ensuring they clamp the washer presents a challenge. Doing the job properly is an engine and box out exercise.

Swarfy.
Title: Re: Behind the clutch
Post by: AdrianJ on 13.08. 2019 20:11
I've done this and the bike is nearing road testing. It remains to be seen how well my 5BA screws, nuts and loctite stand up to the vibration. Wish I'd thought of Morris's ring washer idea. That will happen if the engine has to come out again.
Adrian
Title: Re: Behind the clutch
Post by: denis on 08.09. 2019 11:01
Hi all,
Ok, so finally got some time to get back to my bike and took the whole thing out to find what a groovy motorcycle I had, ha.
Good day all,
Denis
Title: Re: Behind the clutch
Post by: duTch on 08.09. 2019 11:09

  *eek* yick ....It can't be very thick at the thinnest point...... *eek*   
Title: Re: Behind the clutch
Post by: denis on 08.09. 2019 11:41
At the groove made by the chain i’ve no idea. 
Concerning the oil seal, i’ve 2 or 3 mm left, so not thick enough for a proper oil seal, you guys reckon thick leather or felt would work squashed between the oil flinger and a home made ring? 
I can see the oil seal being there for the dirt not to come in rather than for the oil not to come out, right?
If so felt or leather should work.
Any advice welcome, i’ll have some more shed time tonight yeepee.
Cheers, Denis
Title: Re: Behind the clutch
Post by: muskrat on 08.09. 2019 20:28
G'day Denis.
That chain groove would be because a po had fitted a Xheavy duty or O ring chain at some stage the rear wheel would have been out of alignment throwing the chain to the outside of the sprocket. Standard chains are to be used, well able to handle the mammoth horse power of our bikes  *lol*
The original "seal" was to do both, retain oil and keep dirt out. My 51 A7 still has the original and still works (somewhat) but will be replaced next tear down, possibly with duTch's set up.
Cheers
Title: Re: Behind the clutch
Post by: morris on 08.09. 2019 21:13
Ouch...! that don’t look good. The proper oil seal is 7mm wide. Could try make a ring/washer with a groove turned out to locate the seal?
In addition to Musky’s comment above, could also be that at some point the sprocket nut worked itself loose and the sprocket started wandering around.
Title: Re: Behind the clutch
Post by: Swarfcut on 09.09. 2019 16:17
Denis, Looks from the pictures that whoever messed with it first time round wasn't too good. The groove looks to be the result of neglect, a worn, loose flappy oversize chain, plus probably a loose sprocket, and from the helicoil in the gearbox mount, not too cute on Whitworth threads or  assembly detail.  Before you commit to more time and effort, check the rest of the motor for impending doom. This costs nothing, and better to have a nasty surprise now, rather than fixing this problem and finding a crack or worse in the other crankcase half. Any pulled threads can be all fixed at the same time rather than piecemeal.

 As a start, check the crankcase halves are a matched pair. There should be matching numbers stamped on the front of each, just below the dynamo mounting position.

  For  the seal, I would get a new one, BSA Service sheets give the original dimensions, so any modern seal to that size will do. Or measure the hole, the shaft diameter and decide the width of seal you need, and select from a modern oilseal chart. Fits with the open lips towards the clutch, to keep the oil in.  Then you need to source or make/commission a retaining cup for the seal, as suggested by Morris. Because the case has been thinned, the cup can be made thick enough to hold the seal and have three good deep threads for three small bolts which will hold the dished oil slinger pressing, behind the clutch. A bit like Morris' original washer, but deeper and internally relieved to hold the seal

 The crankcase here is under no great strain, and with the primary cover on will cope OK, despite the deep groove.  Alloy welding is an alternative to build up the thickness to hold the seal but will add to the cost.

 Swarfy.

 Additional.  The gearbox drive sleeve, the one that carries the gearbox sprocket, should have no in/out movement, as the main ball bearing outer race is located by a circlip, which also retains the sprocket oilseal. A missing circlip and a worn bearing location will allow the sprocket  to move out from the gearbox, on the drive sleeve so take off the sprocket to check the seal and circlip are in place. There should be no play in the ball race, but the mainshaft bushes in the drive sleeve will always have a bit of radial play on a well used machine. The other end of the mainshaft is supported by another ball race and there should be no in/out play.
Title: Re: Behind the clutch
Post by: RoyC on 09.09. 2019 16:47
You could always use HTS 2000 Aluminum Repair.

https://www.youtube.com/watch?v=RCrixbXz4rc
Title: Re: Behind the clutch
Post by: Swarfcut on 09.09. 2019 19:55
Roy, that looks like a modern version of our old friend Lumiweld. With practice and skill, a following wind and fair weather, some folks get good results, not me, so I would  be a bit reluctant to practice on a vital engine part, and leave that to the professionals. Rectifying a poor repair done with this sort of semi soldering/brazing is difficult as it contaminates the parent metal, so only use if you are sure you can do it right first time.

Swarfy.
Title: Re: Behind the clutch
Post by: BSA_54A10 on 10.09. 2019 11:22
Roy, that looks like a modern version of our old friend Lumiweld. With practice and skill, a following wind and fair weather, some folks get good results, not me, so I would  be a bit reluctant to practice on a vital engine part, and leave that to the professionals. Rectifying a poor repair done with this sort of semi soldering/brazing is difficult as it contaminates the parent metal, so only use if you are sure you can do it right first time.

Swarfy.

Dead right Swarfy,
 Lumiweld's patient expired quite some time ago
Every now & then it reappears under a new name claiming all of the same magical properties as Lumiweld used to.
never ever to be used on any engine part as it will soften & run.
Basically a Zinc based solder & filler rod.
Welding with real aluminium or even boging with  Devcon are both substantially better options.
Title: Re: Behind the clutch
Post by: denis on 18.09. 2019 17:38
Hi all a10 Wizards,
Sorry for the late reply, and thanks all for your input.
I’ll turn a washer with a groove as suggested by Morris, and as Swarfcut suggested I did check, it’s a matched pair, but there is another worrying thing that will need welding, I will have to find someone to do it for me as I don’t TIG.. bummer. Can it be done without taking the whole thing apart?
Thanks all, Denis
Title: Re: Behind the clutch
Post by: denis on 18.09. 2019 17:42
Also, the gearboxes were both attached to the engines with 4 bolts and not 2 bolts and 2 studs as mentioned in the part lists, would that make any difference?  Aaaaand yes the gearbox foot set screw holes are already too big for 5/16, and seem just ok for 3/8, which won’t leave any play with the frame..
Swarfcut, on both my gearboxes the thing on which the sprocket go (called drive sleeve?) do have roughly 2,5 mm in and out play (pic with red pencil) is that normal as the seal and circlip you mentioned is the one shown on the other pic? 
Thanks for all, D
Title: Re: Behind the clutch
Post by: chaterlea25 on 18.09. 2019 18:31
Hi Denis,
The sleeve gear can move in /out until the sprocket and nut are fitted
I can see from your photos that the circlip holding the seal is not seated properly (the ends are too close together)
These can be problematic to fit due to the seal inner face having too thick a rubber facing (but it needs to be compressed to seal)

John
Title: Re: Behind the clutch
Post by: Swarfcut on 18.09. 2019 19:26
Denis The cracked case can be left for now unless there was a sign of an oil leak, showing the crack goes through to the inside of the crankcase. To be welded with any success, the cases need to be stripped and cleaned and the extent of the crack examined. Four bolts to the back of the engine make assembly of the box to the engine a little easier, less risk of damaging the new seal, just make sure the bolts do not bottom in the blind holes. Threads are Whitworth.

 Gearbox lower mountings are best helicoiled, if possible. Custom made shouldered  stud is an alternative. Don't go drilling out the frame lug. Another gearbox casing if you can get one.

 Gearbox bearing....Should be free of play in any direction, and be firmly gripped by the gearbox case. With the seal removed, look for a distance from the outer race to the circlip groove, this should be slightly less than the thickness of the outer edge of the seal, as outlined by Chaterlea John.  If the distance is too small, see if the bearing can be knocked further into the case, to make sue it is fully seated. No luck here.....could be the wrong bearing. Heat the case first with a hot air gun or small gas torch, to expand the housing. If the bearing has failed, again heat the case and the bearing will knock out easily.

 The sleeve gear is usually a nice snug fit into the centre race, sometimes tight, but any previous wear may allow the movement you have. With the nut and sprocket in place, this movement will disappear as the nut is tightened.

Swarfy.