Primary Chain adjuster - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 29 (permalink) Old 06-27-2019, 03:55 AM Thread Starter
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Primary Chain adjuster

This is on a 1973 T140. The primary chain was making some noise, so I took a look at the adjuster, and the adjuster rod threads were completely worn away so the adjuster nut was presumably slipping back under pressure, I ordered a new rod and nut, firstly the new nut (the tube like adjuster) was slightly bigger diameter and wouldn't fit in the crankcase hole, so I turned it down a little on the lathe. Next as I tightened up the new adjuster it gets to about half way down the threaded part and sticks... The new rod now has damaged threads aswell! I eventually broke the rod by forcing the adjuster nut!

Has anyone else experienced this? I think maybe the small cylinder with a hole through (goes into the adjuster blade) it is damaging the threads, it also looks to have an oval shaped hole through it so maybe I should replace this aswell?

The other question I am asking myself is whether the chain itself is too loose and worn and the adjuster is having too much pressure put on it and therefore damaging the threads... Ho bent should the adjuster blade get to adjust the chain correctly, mine is quite bent I need to take a photo? When can you tell if the primary chain is passed useful life?

Thanks for any help.
DaveG

Last edited by DaveG; 06-27-2019 at 03:56 AM. Reason: spelling mistakes
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post #2 of 29 (permalink) Old 06-27-2019, 06:50 PM
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If the tensioner blade is very arched, the chain would benefit replacement. I have had adjuster rods snap due to this ached blade. It would seem your supplier is supplying very cheap parts of dubious quality. It might pay to ask for Harris parts which are likely better than most. A Renolds chain is lasting a very long time on my bike at the moment. A previous cheaper one lasted just 4000 miles.

Now,where did that bit fall off ?
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post #3 of 29 (permalink) Old 06-27-2019, 10:28 PM
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Mine has all the arch in it that the mechanism will allow in order to have the proper slack. I should replace the chain but itís still in spec. I had occasion to remove the mechanism and re- install it and had no problem with its operation in either direction. The only problem Iíve ever had was replacing a worn adjuster, thatís just normal wear and tear. You need to just take it out and find out whatís going wrong.
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post #4 of 29 (permalink) Old 06-28-2019, 04:13 AM Thread Starter
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Thanks for your responses, here is a picture of my chain in situ - what do you guys think?

https://proclassicracinginfrance.blo...djustment.html
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post #5 of 29 (permalink) Old 06-28-2019, 05:29 AM
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I think your primary chain is stretched and needs replacing.
The picture shows the chain/adjuster prior to being adjusted.
As it is difficult to get a screwdriver into the hole for adjustment, I ground a suitable bolt, (shown).
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post #6 of 29 (permalink) Old 06-28-2019, 08:49 AM Thread Starter
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But what does it look like after adjusting?

Thanks,

Dave
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post #7 of 29 (permalink) Old 06-28-2019, 08:51 AM
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Quote:
Originally Posted by Caulky View Post
I think your primary chain is stretched and needs replacing.
I agree, this is a pic of my 500 with the slipper not tensioned but it only takes a couple of adjuster turns for the chain to have the correct amount of slack, 1/2 inch in my case.
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post #8 of 29 (permalink) Old 06-28-2019, 06:28 PM
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That chain in your pic looks very stretched judging by the tensioner blade arch.

Now,where did that bit fall off ?
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post #9 of 29 (permalink) Old 06-29-2019, 02:33 AM
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Hi DaveG, Triumph posted primary chain measuring & wear limit in shop manual. I've always gone by that. At 3/29/18, 23514 miles my chain was less than 1/2 worn compared to wear limit. But you have to remove chain to measure. I compared to new Renold chain at Rabers when I had it apart to work on clutch & reseal rear sprocket. Hmm... New chain has pin play also & my chain had hardly more stretch than the new one. I worked the new chain back & forth to squeeze as much grease from pins as I could. So I reinstalled the old chain which is from new.

Factory says make 2 marks 12" apart. That's 32 links. Max stretch is 1/4". I got 3/32 on my chain. The new chain was just a whisker under 2/32".

I pushed chain together & made 2 marks 32 links apart. Then stretched chain hard & made a 3rd mark. The last 2 marks were 3/32" apart.
So where does that leave me? I'll call it less than 1/2 worn.

I find the adjuster screw tends to tension chain about 1/8 tighter for every 1/2 turn once you get close to the proper tension. What is proper tension? I have owners manual & workshop manual from new the day I purchased bike. One says 3/8", the other 1/2".

The chain has only been adjusted 3 times now. Once at about 1000 miles when it rubbed the tube & wire & case. Once at about 12000 miles when I did cush hub rubbers & just recently at 30500 miles a few weeks ago. After the first adjustment at 1000 miles it only took 1/2 turn at each adjustment. I very carefully find the tightest spot when adjusting. Then pull clutch lever & spin pressure plate & retest to see if tension changes. It doesn't seem too. I then find loosest spot & pull chain up hard as I can to make sure it doesn't rub wire tube.

For whatever reason I see many 3 row chain bikes with chain wear marks under clutch basket sprocket area. Also on the alternator wire tube.

I tend to set tension just a whisker under 1/2" measured with a 1/2" wood dowel I put 1/8" apart marks on. I put dowel though primary filler hole. I push down firmly on dowel & push chain up firmly. On my photos my alternator wire tube looks different than original. I fabricated a longer thinner one to keep chain from rubbing as easy, but more importantly it makes it almost impossible for wire to droop when hot & rub chain. I've seen several 3 row chains where chain was rubbing wire.

Regarding your adjuster bolt damaging the threads I ran into that exact thing a year ago on a new repro one. Compared to the original Triumph one the threads didn't go down far enough. It was not too fat though. When threads bottomed out still would need at least 4 1/2 turns to take tension. This used chain measured very close to 3/32" as well. Did not replace chain. The seller exchanged adjuster bolt for a perfect condition used original Triumph. I worked good. Used a new rod & it worked good with the original version bolt. Reused the tension blade as it was perfect.

I find once you get to the proper tension an extra 1/2 of adjuster will feel like something is binding. The chain will feel drum tight when adjuster passes high spot on its cam. Now chain is too tight. It can be hard to back off. If you force it something will break. You need to kick motor over until you find loosest part of chain & pull clutch lever which seems to give a trace more play & it will usually back off without damage.

I really don't know what the 12" means because I can compress chain & it's less than 12".

I don't know how to measure chain on bike. I suppose you could use a large Vernier caliper.

Here is some photos of my '73 Tiger at 12k miles. One some you may notice a 1/4" aluminum tube reaching bottom behind chain. That is the tube I use to siphon primary oil as it takes about all night to drain & the siphon removes a little more oil.

Maybe you could look at the end of the blade compared to the screw holes on case & make a calculation to what you have. I don't know how well my photos actually replicate the arc. To be clear this chain has correct tension in the photos.
Don
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Last edited by TR7RVMan; 06-29-2019 at 02:36 AM. Reason: changed sentence
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post #10 of 29 (permalink) Old 06-30-2019, 03:13 AM Thread Starter
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Clutch basket moves about

Hi Thanks for all the replies, I decided to remove the chain and get some measurements to see if a new chain is required, and both the rotor (magnet) and the clutch basket seem to have a fair bit of side to side movement in them with no tension on the chain - is this normal? The whole clutch basket seems to move 8-9 mm from side to side, I don't think this can be right - and would account for the noise I am hearing, as it only makes a noise when in gear and moving, there is no discernible noise from the left side with the bike in neutral.

Is there anyway to remove the clutch basket without the factory puller? I have one for jap bikes but I assume that this one would be some weird thread?

I am less concerned with the rotor as the engine gears are solid, although I need to check with the thing torqued up correctly.
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