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.
Title: Re: Behind the clutch
Post by: denis on 16.07. 2020 10:21
Hi everyone,
Crikey, it’s been a while!  Now my Ural is running again, back to BSA! I just realised I forgot to tell I made a washer as mentioned by Morris, see pic attached if I managed to load them. If not, I will try again.
Next problem is; I made two little dowels to go in the frame, and of course the holes don’t line up anymore.. could anyone tell me the measurements between the holes with the dowels and the front engine mounts on the frame? And how much of a tweak should I allow me to grunt it in? 
Also, is it normal that the frame is much wider than the engine where I put the dowels?  (Roughly 6mm) I can’t see any washers or the like in any part lists?.
As for the crack in the engine cases on the pics in a previous post, a friend told me to drill it oversize and turn another dowel to fit in as the hole is already way oversize, is it a good idea or over the top?
Thanks all in advance,
Denis
Title: Re: Behind the clutch
Post by: denis on 16.07. 2020 10:31
Here goes the other side of the washer as I sent twice the same..
Title: Re: Behind the clutch
Post by: morris on 16.07. 2020 13:34
Hi Denis, maybe picture below may help?
The distance between bottom (dowel) and front engine mount is roughly 10 1/4 in (measured in situ so may be a little out)
Regarding the crack, I would leave it as is. Drilling the hole out will only weaken it further.
Title: Re: Behind the clutch
Post by: denis on 17.07. 2020 07:33
Thanks Morris,
I printed the drawing and a mechanic friend let me use is garage floor, chains and jacks, hopefully it will all fit and come together nicely, just like on a Honda    *conf*
The cracked hole is already so much oversized that I don’t think the whole mm that I ‘m gonna have to take out will weaken anything further.  My axle can be put through the engine without touching anything    *eek*
I wonder what happened to that bike! 
Anyway if I have time today I’ll see how thin a dowel my lathe and I can manage before anything.
Good day all,
Denis
Title: Re: Behind the clutch
Post by: Greybeard on 17.07. 2020 08:54
If a bike with a sidecar is involved in a collision the frame is very likely to get twisted. My own bike used to have a sidecar; it tends to steer left; I think the frame must be a bit off.
Title: Re: Behind the clutch
Post by: Swarfcut on 17.07. 2020 09:30
Denis..The more I read your previous posts, the more i hope this machine was a bargain. From the pictures posted the state of it reflects abuse, ignorance and neglect big time by a succession of previous owners.

  The crack in the crankcases look to me to be fatigue rather than accident damage, most likely cause being a loose through stud allowing movement and the wear to the casting you now have to rectify. A length of threaded bar was the usual backyard fix, but of course a poor engineering solution.

 How you proceed depends on the state of the build. With the cases unassembled, checking for an internal crack is easy, but in any event I would V out the crack and build up a substantial alloy weld web to beef up the lug on both cases. Then accurately drill the through hole to clean it up so that your new sleeve fits firmly, but with no strain on the castings, and a new plain through stud which fits closely to the sleeve ID. What you are trying to do is make the through stud fit the cases with the minimum scope for up/down and forward/backwards movement. This will prevent further damage and also secure the engine unit more positively to the frame, good for reducing vibration.

 The difference between inner frame and crankcase is interesting. Is this measured with the rear wheel in place? This may be pulling the rear together, opening up the front.  Assuming the frame is undamaged, fitting the rear wheel first means the frame will be under less stress if you simply make larger top hat bushes to fill the gap. The brim of the top hat will clamp the crankcase nicely between the frame members, far better than the usual assortment odd washers most folks use.

  I think the reason the bar you showed not fitting across the frame is due to the wear pattern in the holes at the end of the frame. This can be rectified and new bushes made to fit, rather than forcing the frame to where you think it wants to go, and being under strain, a recipe for cracking. If it is as GB suggests, accident damage, you can carefully heat it up and carefully bend it, but only do this if you are super confident and know what to do to control the bend without crushing the frame tube. It is a shame the very dimension you need is missing from the frame drawings. Installing the basic engine unit (crankcase and gearbox) will show where any misalignment lies, use the front mounts and seat pillar/gearbox mount as a starting point, see how the through hole lines up. Aim for a frame and engine in place without any strain.


 Swarfy.

  Additional.  Just done some measuring.

 Plunger Crankcase is 80mm wide at lower through stud lug position.

  Unassembled plunger rear section of frame,,,,Inner sides of frame tubes are 95mm apart at the frame section join, flat cheeks of the join  are 115mm apart.

 Not saying this is how it should be, just that this frame section looks to be a good one. So like yours there is some gap, depending on the width of the front frame section joint lugs.
Title: Re: Behind the clutch
Post by: denis on 01.08. 2020 07:29
Thanks Swarfy, Morris and Greybeard,

Just the fact that you hope this bike “was a bargain” cheers me up a bit, I must admit my enthusiasm about rebuilding these boxes of bits into a bike sort of faded away over the years, luckily other bikes kept me on the road and busy.  I think this lot was more the rejected parts off other bikes the guy had. 

Anyway, I always wanted a rigid a10, and I’ll rebuild it.

I took the rear wheel of as you suggested but the measure at lower through stud lug didn’t change a bit.

The tube at the connection of the front and rear section ‘at the saddle’ , (yes, bolted on frame) is not moving a bit and ID is bigger on one end. ?  the only reason I would take it out is to see how much tension there’s in the frame, should I persist you reckon?  My grandma as a child told me to not use a hammer on a bicycle, so I’ll make a puller as I don’t like hammering things to bits.  Although tempting + it’s not a bicycle.
 
Top hat bushes, ... why did I already turn a straight tube and fitted it in? ... top hat bushes is a far better idea, will do that next week.  Cheers. 
Today I’ll put the engine in (again) to check how far out it is now, or how close in, (think positive!)

Anyway,  cheers all for your input, measures and all.  All very much appreciated.
Good day, Denis
Title: Re: Behind the clutch
Post by: Swarfcut on 01.08. 2020 20:25
Denis The frame join under the saddle is a cross tube for location, and a through stud, threaded at both ends to draw the two frame components together. There is  little chance that anything is amiss here. might look that way, but in any event tightening the nuts each side will keep things in place and located well enough. Not worth trying to drive the tube out, they are usually a tight fit in the front frame lug.

 The real test is how the engine unit you have aligns with its mounting points.  Datum (as a suggestion) is the chain alignment from rear sprocket to gearbox sprocket.  With the age and abuse over time, custom spacers may be required to ensure the engine aligns without any strain on mounting points.

 Even though the parts you have could be the worst of the best, they were made to the high standards of metallurgy and hardness of OEM parts, unlike some repro's. Retain original parts if you can.

 Swarfy.