Loose Primary Chain

[stevejovais]

If long distance, highway running between 60 & 75 MPH is your game, having the primary chain on the looser side is prudent. Being naive & ham-fisted in the mid 80's, I ran too tight a primary on a '70 Roadster from NYC to Niagara Falls, and was rewarded with a failed transmission mainshaft.

 

[Tornado]

Can someone explain how a tight primary chain affects gear shifting or clutch feel? I have a grabby clutch release right at very end of fully releasing the lever, no matter how gradual I release it. Most noticeable when pulling away from a stop in first.

 

[Gilesy]

Norman White told me , much better loose than tight.

 

[Fast Eddie]

Can someone explain how a tight primary chain affects gear shifting or clutch feel? I have a grabby clutch release right at very end of fully releasing the lever, no matter how gradual I release it. Most noticeable when pulling away from a stop in first.

It can effect gear changing by putting strain on the mainshaft and bowing it. But I’d imagine this is only when at the extreme end of the too tight range.

It effects the clutch because the too tight chain tries to pull the clutch drum forward, so when you disengage the clutch it pulls the clutch basket at an angle, an angle different to the clutch centre, thereby making the relationship with the plates unhappy, which shows itself when you engage the clutch again. It makes the clutch grabby and unpleasant.

 

[Tornado]

It can effect gear changing by putting strain on the mainshaft and bowing it. But I’d imagine this is only when at the extreme end of the too tight range.

It effects the clutch because the too tight chain tries to pull the clutch drum forward, so when you disengage the clutch it pulls the clutch basket at an angle, an angle different to the clutch centre, thereby making the relationship with the plates unhappy, which shows itself when you engage the clutch again. It makes the clutch grabby and unpleasant.

That makes sense, but doesn't this also happen with a loose chain as it loads up against the clutch basket as clutch basket pulls against the friction from engaging plates?

 

[RoadScholar]

It can effect gear changing by putting strain on the mainshaft and bowing it. But I’d imagine this is only when at the extreme end of the too tight range.

It effects the clutch because the too tight chain tries to pull the clutch drum forward, so when you disengage the clutch it pulls the clutch basket at an angle, an angle different to the clutch centre, thereby making the relationship with the plates unhappy, which shows itself when you engage the clutch again. It makes the clutch grabby and unpleasant.

Good points.

With the spark plugs removed and the g/b in 4th, bike on center stand, rotate the the primary drive and check for tight point(s); adjust accordingly. when you are satisfied that the primary chain is adjusted correctly have a good look at the final drive chain, it most likely has tightened up. Same drill for adjusting it at its tightest point. If a test ride shows no improvement in the lever position it was previously engaging at then adjust the clutch rod with the cable very slack or removed from the lever. Reinstall the cable which may require removing the pivot bolt/screw. Adjust the cable such that the lever has a modicum of slack; go for a test ride. If these efforts are not rewarded I'd be inclined to think that gear oil may be the villain, but could also be that the hub/basket has become notched in which case the solution has now become rather expensive.

Best.

 

[Fast Eddie]

That makes sense, but doesn't this also happen with a loose chain as it loads up against the clutch basket as clutch basket pulls against the friction from engaging plates?

Not in my experience. A loose chains primary symptom is noise.

 

[CanukNortonNut]

This is actually my biggest worry. The manual assumes no wear.

I’ve now got it set at 1/2” which is more than the 3/8” but I think it’s reasonable. It’s definitely tighter than it was. Both gearbox bolts good and tight. Rear chain adjusted.

Do you feel it in your foot peg? Vibration... I mean? What was it like with your belt drive? You did run both types. Right!

 

[motorson]

I put mine in the same condition as Road Scholar except that I leave the plugs in. In 4th gear with the primary cover off and the rear wheel off the ground I rotate the tire backwards and put a mark (on the inner cover) across the top of the upper chain which is now pulled tight. Then I rotate the tire forward so that the bottom of the chain pulls tight and the top goes slack. I look for the chain to fall away from the mark I put above it. Gravity should pull the slack upper part of the chain down 3/16 of an inch from my mark.

 

[Derek Wilson]

I always take up the slack in the final drive chain when checking the primary chain, to make sure when the final drive chain is under load that the primary chain has not gone to "dead tight"

 

[kerinorton]

I always take up the slack in the final drive chain when checking the primary chain, to make sure when the final drive chain is under load that the primary chain has not gone to "dead tight"

That's why the instruction to tighten first then back of the the correct tension. [ to stop the gearbox being forced back by the rear chain, which exerts at least 4 times the force backwards than the primary pulls forwards. The basic law of leverages ]

Also when checking the free movement, lift the chain gently. You can force it hard and get a bigger false movement. Its hard to tell from the video how hard the chain is being forced .

 

[CanukNortonNut]

how many have tried the Andychain twin primary set up. was it any better than a belt drive?
I want to know? Im running a belt drive so I would like input from those who have this set up.

 

[Gilesy]

how many have tried the Andychain twin primary set up. was it any better than a belt drive?
I want to know? Im running a belt drive so I would like input from those who have this set up.

I have a twin row chain, from Andychain, actually now Jason, son of Andy, they come in two 'weights'. The heavier one is very very close to the inner chaincase. I have the lighter one and, touch wood, have had no issues. I think I read on this forum that the twin row causes less pull on the outside of the clutch. I also have RGMs 'high torque clutch which transformed the lever pull. Now as good as my modern Triumph.

 

[SteveA]

Can someone explain how a tight primary chain affects gear shifting or clutch feel? I have a grabby clutch release right at very end of fully releasing the lever, no matter how gradual I release it. Most noticeable when pulling away from a stop in first.

Everything goes through the mainshaft, clutch sits on the end of it, push rod goes through the middle of it, sleeve gear and drive sprocket run outside of it, the mainshaft carries gears that slide on it to engage/disengage dogs.

The clutch centre bearing has an amount of float, which is actually a good thing, until it becomes excessive.

A tight primary chain takes up the centre bearing float and puts extra load on the mainshaft.

 

[ashman]

I have a twin row chain, from Andychain, actually now Jason, son of Andy, they come in two 'weights'. The heavier one is very very close to the inner chaincase. I have the lighter one and, touch wood, have had no issues. I think I read on this forum that the twin row causes less pull on the outside of the clutch. I also have RGMs 'high torque clutch which transformed the lever pull. Now as good as my modern Triumph.

My clutch has always been light from new, feels as good as my 2 modern Triumph Thruxtons one or two finger operation if I want to, have never had clutch problems that a lot of people suffer from and I am still running original plates.
My next replacement primary chain will be a twin row from Jason.

 

[BWB54]

Can someone explain how a tight primary chain affects gear shifting or clutch feel? I have a grabby clutch release right at very end of fully releasing the lever, no matter how gradual I release it. Most noticeable when pulling away from a stop in first.

How do you know when to replace the primary drive chain? Does anyone have a stretch measurement guide for a set number of links?
Is the Regina triple chain recommended if a replacement is needed?

 

[Ron L]

Years ago a prominent Norton mechanic told me that if you put your Commando on the centerstand and the rear wheel spins while idling at 1000 rpm and in neutral, your primary chain is too tight. Of course that would also require the gearbox was in good shape also.

 

[BrianK]

I checked mine recently (the reason I ended up looking for/at this thread) because I perceived a bit of "snatchiness" in the drivetrain (and the drive chain was properly adjusted). Lo and behold, my primary chain has about as much play in it as Dave's original "before" video.

Easy enough to adjust, but is that much slop an indication of wear such that I should be thinking about a new primary chain?

 

[74ok]

Years ago a prominent Norton mechanic told me that if you put your Commando on the centerstand and the rear wheel spins while idling at 1000 rpm and in neutral, your primary chain is too tight. Of course that would also require the gearbox was in good shape also.

I'd think too common for anything to do with primary chain tightness.

 

[TheCounty]

Just by the video, I'd snug it up just a tidge.