Atlas amc clutch assembly questions

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Sparepartz

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I recently purchased a 1965 Atlas that sat for 33 years. Everything seems fine except the clutch. Lever pull is extremely hard. From past experience with motorcycle clutches from sitting it is somewhat normal for the disc plates to stick. I removed the hub and removed the disc's. They were all stuck together. I have 2 questions, first can the disc's be cleaned and reused? They appear to have plenty of material left on them. 2nd question could someone tell me how much movement should I see in the push rod to engage the clutch?

On another note, I'm new to Norton's and the club. scratch another item off my bucket list.
Thanks Guys
Mike M
 
Welcome.

I do not know the Atlas in detail but clean clutch plates in general with Acetone. (Good, bad or otherwise)

I believe the Atlas has a different ratio clutch actuating arm to the Commando so might have less travel at the push rod due to that (easier pull supposedly)
If the Atlas has a clutch any thing like the Commando the clutch plate stack height set will get a light action (as long as the other parts - cable etc etc are in good condition)
 
Sparepartz said:
I recently purchased a 1965 Atlas that sat for 33 years. Everything seems fine except the clutch. Lever pull is extremely hard. From past experience with motorcycle clutches from sitting it is somewhat normal for the disc plates to stick. I removed the hub and removed the disc's. They were all stuck together. I have 2 questions, first can the disc's be cleaned and reused? They appear to have plenty of material left on them. 2nd question could someone tell me how much movement should I see in the push rod to engage the clutch?

On another note, I'm new to Norton's and the club. scratch another item off my bucket list.
Thanks Guys
Mike M
Click to expand...
You should move this to Other Norton Motorcycles. You are in the wrong topic area. Happy to respond later but if you move this discussion you will get more responses.
 
Thread has been moved.

Sparepartz said:
2nd question could someone tell me how much movement should I see in the push rod to engage the clutch?
Click to expand...


There should be approximately 0.80" total pushrod movement but not all should be needed to disengage (pull the lever back to the handlebar grip) the clutch.


Time Warp said:
If the Atlas has a clutch any thing like the Commando the clutch plate stack height set will get a light action (as long as the other parts - cable etc etc are in good condition)
Click to expand...

The Atlas has a conventional coil spring clutch with a mechanism that lifts the pressure plate and not a diaphragm spring as it does in the Commando clutch so increasing the Atlas stack height won't lighten clutch action.

I believe the Atlas pushrod actuator can also drop out of position in the same way as the Commando actuator so could be a possible cause of the heavy clutch action.
 
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AMC stands for (A Man's Clutch). Kidding, but the older 3 spring clutches can be a bit stiffer than Commando clutches. Particularly true if somebody put Barnett springs in it at some point in time.

As mentioned, you can clean and reuse the frictions and steals if in good shape. I ran out of acetone, so I used a toothbrush and mineral spirits and a quick wash and dry in a commercial water-based grease remover. I will no doubt be told that is wrong, but it works.

A thin coat of automatic transmission fluid (ATF) on the plates during reassembly. Be sure to check that the roller bearings behind the sprocket have some lubrication on them and they spin freely.

The manual probably says to use 20 or heavier weight motor oil in the primary. The clutch will release quicker with ATF in the primary.

About 1/16th inch at the clutch rod with the cable adjusters all the way slack. Then make the required adjustments to get 1/8th to 1/4 inch at the lever.

Make sure all the springs are adjusted equally flush or slightly below the top of the spiring cups and the spring pressure plate lifts off the plates evenly.

You may need a new clutch cable and to reroute it so there are no bends causing excess friction on the cable. Lever probably needs a little oil too.

My old clutch is a little sticky and does not release right away after it sits for a long time unless I free it up next day after a ride and check it every few days to make sure it still frees up easily.

Gearbox lube contamination of the plates caused by lube getting past the clutch rod can be an issue and cause the clutch to drag. There used to be a seal kit for the AMC clutch rod, but I'm not sure if those are still around. Running a little less lube in the gearbox helps prevent it, if you can't find or come up with a clutch rod seal solution.

Excuse the TMI.
 
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The Atlas clutch is a bear to release. It is a design that originated with 25 hp 500 cc engines, got an extra pair of plates to enable it to cope with later 600 -650 engines, then stiffer springs to allow it to handle the torque of 750 engines. In short, it has been pushed beyond its limits. The clutch was designed to run dry, but as a practical matter, the plates become wetted with oil regardless of the quantity of oil in the primary.

A teflon lined clutch cable (Venthill mfg.) will lesson clutch pull about 25%. Using ATF in the primary helps as well. I have read that clutch friction plates wetted with ATF have a coefficient of friction 35% greater than friction plates wetted with motor oil. I back off the clutch springs 1 turn with ATF in the primary which reduces clutch pull a little. Barnett clutch plates are designed to run in oil, and have greater friction thus allowing a further reduction of tension on the clutch springs. With Barnett plates, (and ATF) I have backed off the clutch springs 1 1/2 turns but I think that is right on the edge of slippage. If one is not concerned with a little slippage, the clutch pull is very comfortable. The down side of Barnett plates is they stick with non frequent use, and require "freeing up".

There is a clutch rod seal available (http://atlanticgreen.com/ddacrs.htm).

HTH,

Slick
 
Last time I looked that Atlas clutch rod seal was not being made anymore.

Copied directly from Atlantic Green Parts Counter page:

"Produced at the request of several pre commando owners,
this seal performs the same job on the AMC clutch as for the commando.

NLA sorry-sold out"

Baxter's didn't have any either. Searching on some of the other popular US sites is painful, so I don't bother.

I took the Barnett plates out of mine and put the stock dimpled steals and friction plates back in I had boxed up long ago. I left the Barnett springs in it. Works better for me.

I can't back off on the springs, or the clutch will slip, but I know my motor is making more beans than the typical grocery getter.
 
Instead of a push rod seal, I've been using a little dab of Huskey HVS-100 silicone grease in the end of the clutch side of the mainshaft. It's insoluble in mineral oil, so acts as a seal against the oil in the gearbox creeping down the push rod. I don't know how it works with many of the synthetic gear oils, but it completely stops dino oil.

I've ended up using it to seal gaskets and o-rings as well because you get all the sealing advantages of RTV with none of the mess/clean up or risks associated with RTV. It's good stuff.

As far as a hard pull on your clutch lever goes, make sure you've got the correct leverages on your clutch levers. The distance between handlebar lever pivot and and the cable end, and the angle at which the activation lever down in the gearbox has on the push rod are vital to getting the clutch to be friendly to your left hand.
 
The other thing to check for a lighter clutch is the clutch lever. The distance centre to centre between the lever pivot and the nipple hole should be 7/8". A lot of bikes have had their clutch levers changed over the years and some other levers have a centre to centre distance of up to 1 1/8", which makes the clutch much heavier.
 
My two cents will tell you most people over tighten the clutch springs! Obviously too lose clutch will slip, Need to find a happy medium!
 
mean gene said:
My two cents will tell you most people over tighten the clutch springs! Obviously too lose clutch will slip, Need to find a happy medium!
Click to expand...
The spec. on the clutch spring nuts is flush with the top of the spring cup. Then tweek as necessary to obtain even lift off.

Slick
 
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