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Discussion Starter · #1 ·
Ive got an issue where when I walk the bike along I get a slight card in bicycle spokes sound, and then when the chain link goes around the sprocket at the back of the transmission there is a noticeable grinding (the pins in the chain stick out more through the link) Also Ive got a definite leak coming from around that sprocket as well (puddle the size of a pancake daily) So I am wondering is my chain too wide ? (I don't know if its an o ring, x ring, or just regular.. I cant remember from when I purchased it) Ive added photos of the chain and also a photo of where its grinding, anyone else had this issue ? Also the width of the chain at its widest point is 21.9mm (actually 23.5mm at the link)








 

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The gearbox sprocket looks suspiciously close to the gearbox housing in that last picture. It almost looks like the bearing has backed out into the case. That would explain the oil leak too.

I recommend taking the cover off the gearbox and check the main shaft endfloat (see if you can push the mainshaft back and forth). If so I'd tear the gearbox down and see what's going on with the main bearing.
 

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Manx could be right, It also could be a chain issue...there isn't much room to spare on these machines and since all chains are not created equal, it could result in this clearance problem, as you suspect (I've seen this issue arise twice in the last year). The problems I mentioned were the result of people wanting to fit heavy duty non-'O'ring chains (same pitch but slightly wider). Just measured the chain on my Commando...it is 20.6mm across the pins.
 

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the noise could be a chain tension issue, too tight and you'll soon kill the bearing behind the gearbox sprocket which could result in excessive end float, if it's too loose it may be flapping around and hitting the gearbox. modern 520 size x-ring chains are build for thumping MX bikes, they're solid & very narrow, perhaps investigate running one when the problem has been found. let us know how you go man.
 

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are you absolutely sure that you are not running a 530 chain on 520 sprockets?
 

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if you switch that wide 530 chain out for a Renolds 530 imperial chain it will all clear fine. many pre units Triumphs and Norton's have to run the Renolds 5/30 chain.

It's expensive but a great quality chain.

P.S. it works great for more clearance on the 500/16 wheeled Triumphs too.
 

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Discussion Starter · #7 ·
thanks a bunch for the input guys, Im thinking because of the major leak happening at the back of the transmission I should get the outter/inner primary off and have a good look at whats going on. This is delving into territory I haven yet been. So I just want to make sure I have all the tools I need ordered ahead of time. (Ive read through the manual but I am having trouble following just reading text on a screen, Im sure once I have the outer primary off and the right tools I will be able to follow along) So I just wanted to make sure I have straight what tools I need to order.

*Clutch Puller Tool (26tpi Ive got a 55 6T)
http://www.ebay.com/itm/NEW-Stainle...Parts_Accessories&vxp=mtr&hash=item2561fde928

*Clutch locking tool
http://www.ebay.com.au/itm/Triumph-...05?pt=UK_Motorcycle_Parts&hash=item45fdc64849

*Drive shaft adapter (manual mentions this but I cant find one online)

is there anything I am missing ? or planning to buy and dont really need to ?
(Ive got the large flat head screwdriver with the center ground out for the clutch springs)
 

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Looks like a pre unit to me. By the frame, I'd say pre-'54. Most pre units I have worked on have grooves cut in to the layshaft boss your arrow points to (caused by slightly too-wide chain/pins). As long as it's not so deep it hinders the bore or plug, the damage is not critical.
 

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Discussion Starter · #10 ·
its a pre-unit (55 Thunderbird) I would just swap the chain out for an imperial 530 to see if that stops the grinding, but Im worried that the excessive leaking out the back of the transmission may be a bigger issue ? So I think I need to get in there and have a look. Just not sure what tools I need yet
 

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The reason that I asked was because you spoke of removing the primary cover. If it's a pre-unit as I thought it is you would likely want to remove the gearbox outer cover. I strongly suspect that you'll find something amiss with the mainshaft and it's bearings. I've been wrong more than once though.
 

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The tools you listed should do you,done mine lots of times over the years and without a clutch locking tool, but i should make myself one by bolting together an old clutch plate and pressure plate.
There is the clutch centre nut which is a large size,and I don't have a socket which fits it,because if I can recall,there isn't much space around it....so i use a box spanner (like a deep thin walled socket)
 

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As long as you have the clutch hub puller you are in good shape. Having a socket for the large nut on the countershaft sprocket would be good too. Everything else is easy.
Cheers, Dan.

P.S. Duh! I just noticed you mentioned your bike was a '55 in one of your previous posts (although, It looks as though the frame is pre '54; seat post between motor and trans + early axle-plates?). Also, I notice that your brake backing plate is RIGHT up against your frame tubing, and that there has been some welding in that region also. A miss-aligned set of sprockets will definately cause a grinding sound as the chain catches the edges of the teeth of the sprockets, specifically the countershaft sprocket. I hope this helps.
 

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The tools you listed should do you,done mine lots of times over the years and without a clutch locking tool, but i should make myself one by bolting together an old clutch plate and pressure plate.
There is the clutch centre nut which is a large size,and I don't have a socket which fits it,because if I can recall,there isn't much space around it....so i use a box spanner (like a deep thin walled socket)
Agreed! Additionally, I have made my own countershaft socket since it only gets used a few times a year, and is quite deep. A bought one is silly expensive, and overkill heavy-duty.
 

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Discussion Starter · #15 ·
there was still rigid frames in 55 (seatpost between trans and motor) the brake backing plate isnt right up against the frame it just looks that way because of the angle of the photo. The frame has been stretched, but the alignment was checked a billion times and everything is fine. (chain is lined up, rear wheel straight)

so I dont need a "drive shaft adapter" ?


And if I dont have an spare clutch plates or pressure plates will I need to buy a clutch locking tool ?

Sorry for all the questions, when paying for shipping to Australia I want to make sure I am ordering the right tools.
 

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I've never needed a drive shaft adaptor, or clutch locking tool to rebuild pre unit transmissions.
 

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...hello,
with an air compressor and a pneumatic (air tool) you do not need any other locking tool.
a couple of weeeh weeeh and the nut off, then repeat the other way to hold the nut (when you are rebuilding)

I did that several times on my pre unit
 

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Discussion Starter · #20 ·
ok thanks guys I will just order the clutch hub puller tool and see how I go. As I make more sense of the manual it looks like the drive shaft adapter is for dealing with the removal/replacement of the rubber clutch shock absorbers (which Im pretty certain I dont have)
 
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