I was excited that I was able to get my clutch assembly back on the M20. I tightened down the assemble nut, mounted a new primary chain and attached/adjusted my clutch cable. The sprocket/clutch assembly has a little movement when the clutch is not engaged. When I engage the clutch (pull the clutch lever in) there is a lot of play in the whole assembly.

I removed the assembly and checked my assembly. There is up and down movement in my assembly as can be seen in the photos below. I took a video of the play when the assembly is on the bike, but photo bucket is fighting me today. I tightened down the clutch nut and have attached a photo of that as well. The sprocket assemble is a NOS original that is in good shape. I replaced the roller bearings in the assembly.

Wishful thinking is that there should be some play in the assembly, but I know better. Any help would be appreciated. I don't relish the potential that I will have to pull the assembly apart again with that massive spring and nut to contend with.

Thanks,

Brian B

email (option): bbrown3407@charter.net

I was finally able to upload the video to photo bucket. The sprocket is a NOS item and I replaced the roller bearings as well. The clutch nut is tight that holds the taper and the key locking the assembly onto the shaft is in place.

Any help is appreciated.

Thanks,

Brian

email (option): bbrown3407@charter.net

Hi Brian...Did you get my e mail?...Ian

email (option): ian@wright52.plus.com

Hi Ian,

I sent a reply a little bit ago, but couldn't get the video to work in the email. I am hoping the video posted here may give you some more insight into potential problems.

The sprocket is a NOS unit and I also replaced the roller bearings. I had the nut holding the assembly onto the tapered shaft on the gearbox very tight, but still had the play as shown in the video. There is up and down movement of the shaft in the assembly as can be seen in the pictures in the first post. Not sure what I have going on. This is major snag slowing my progress in getting this bike back on the road after 20 years.

Thanks in advance for the help,

Brian

email (option): bbrown3407@charter.net

Hi Brian..I've sent another e mail...I'll send a detailed one tomorrow...Ian

email (option): ian@wright52.plus.com

Hi Brian
Let me know what you find as I found the same fault on my bike on Saturday,
it had only 100miles on it .
Michael

email (option): michael@nammech.com.au

There are two problems relating to unwanted movement of the clutch sprocket..'Tilt' and 'Vertical lift'...

'Tilt' is caused by the tolerance present between the clutch rollers, the clutch sleeve roller track and the clutch sprocket roller track..

The tolerances for the three components are fairly close but there is a clearance so even when all new components are used a small amount of 'tilt' will still be evident at the outer edges of the sprocket...

Wear in any of the components rapidly magnifies this effect...The only cure is to fit new components or, possibly, oversize rollers, though these are becoming very difficult to obtain...

For reference...The clutch rollers are 1/4"diameter x 1/4" long, so .250" diameter...

The clutch sleeve roller track when new is 1.5273"-1.5278" diameter...

The diameter of the clutch sprocket roller track when new is 2.0283"-2.0288"

Note these are quite close tolerances with only half a thou. tolerance..

'Vertical lift' is the result of the clearance between the shoulder on the clutch sleeve that the rollers run against, the ends of the clutch rollers and the outer face of the sprocket clutch roller track and the rear face of the clutch centre...

First, check and replace the clutch rollers if they are less than .250" long

It is not possible to determine the wear on these components by measurement of the individual parts (the rollers being the exception) as BSA publications do not provide the information required...

So, the actual degree of 'vertical lift' must be determined with the clutch assembled....I use a dial gauge for this, ensuring that the sprocket is lifted squarely when taking the measurement...

The rear face of the clutch centre should be flat where the roller track runs against it...If it is not the first thing to do is mount the clutch centre in a lathe and machine the face flat to remove any wear...

If removal of material was necessary to obtain a flat surface, reassemble the clutch and check the total amount of clearance again...Note the figure obtained...

When fitted the clutch centre comes up against the spline on the clutch sleeve...

To reduce the total clearance ('vertical lift') material must be removed from the bottom of the recess in the clutch centre..The end of the splines can be seen in this recess....

Using the 'lift' figure obtained after wear was machined from the back of the centre, remount the centre in a lathe and machine .005"-.010" LESS than that figure from the face of the recess (the end of the splines....

This allows the clutch centre to go slightly further onto the spline and reduces the clearance behind the rear face of the centre to .005"-.010"...

Now assemble the clutch and recheck the 'lift' figure..If it is still too great remove the required amount from the recess...If it is now too tight, remove the required amount from the rear face of the centre to provide the correct clearance...I usually aim for .005"-.010" total clearance ('lift')...Ian

email (option): ian@wright52.plus.com

Ian,

Awesome write up!! Time to pull her apart again. I now have the starting point I needed to get to the bottom of this issue.

Thank you very much,

Brian

email (option): bbrown3407@charter.net

I'd be interested to hear how it goes Brian....Ian

email (option): ian@wright52.plus.com

Ian,

Thank you for all the help to date. I appreciate it.

Here is the promised update. I was able to get out to the garage over the weekend and take down the clutch basket assembly.

I measured the new replacement bearings that I had installed. They turned out to be .250" in diameter but only .235" in length as can be seen below:



The clutch sleeve roller track is 1.526".

The clutch sprocket roller track is new and measured at 2.024"

I measured the old roller bearings and they measured .250" x .250" so I reused them and took out the undersized roller bearings.

I reassembled the the unit and replaced it onto the bike. The wobble is much less noticeable and I have included a video of the after.

I think I may have to replace the clutch sleeve if it appears that there is too much wobble. Any additional help is much appreciated.

Brian

email (option): bbrown3407@charter.net

Brian it looks like someone has sold you Triumph clutch rollers. 1/4 x 1/4 rollers won't work in a Triumph! They have to be reduced in length by around 12-15 thou. DAMHIK! Ron

email (option): ronpier@talk21.com

Glad to hear you're making progress Brian...

It's not the end of the world if you have a small amount of free play and 'tilt'...Most M20s that are running do...

The main thing is that the clutch plates seperate cleanly and completely without 'drag' and there is no 'slip' under load...

I wrote a lengthy piece on the clutch that can be found in the 'technical section'...That might be worth reading as well if you haven't already. It covers both 'drag' and 'slip' outlining possible causes and suggested solutions.....Ian

email (option): ian@wright52.plus.com

Thanks Ron.

They came from Draganfly.

Brian

email (option): bbrown3407@charter.net

Ian,

Thanks again for all the help. I know it is hard just by looking at the video, but do you think there is still too much play in the sprocket wheel?

Thanks,

Brian

email (option): bbrown3407@charter.net

Hi Brian

Last week when at russell motors, I treated myself to a new clutch wheel

It looks well made

If you are not happy with your current set up - consider one of these

Best regards

John

email (option): Jonnyob1@googlemail.com

email (option): bbrown3407@charter.net

email (option): welbike@welbiXX.net (think about this!)

Russell Motors also had NOS clutch sleeves a while back (the part you want Brian)...Worth checking to see if they still have them...Ian

email (option): ian@wright52.plus.com

Thanks for the additional information Ian!! Will check to see if Russells still has one available.

Stay tuned,

Brian

email (option): bbrown3407@charter.net

Seems we are un noticed Lex! Ron

email (option): ronpier@talk21.com

As usual!! anyway, just a warning to others, I know what to fit usually!

But if you have a worn clutch centre, 1/4 x 1/4 rollers will work just fine anyway.

Cheers,

Lex

email (option): welbike@welbiXX.net (think about this!)

['For reference...The clutch rollers are 1/4"diameter x 1/4" long, so .250" diameter']...

['First, check and replace the clutch rollers if they are less than .250" long']...

Hmmm....From my initial reply....Ian

email (option): ian@wright52.plus.com

Ian your specifications are quite correct as usual. I was merely trying to point out what the incorrect parts were.....But it don't matter much Ron

email (option): ronpier@talk21.com

Ron & Lex,

My apologies. Certainly didn't mean to slight you. I appreciate the help and hope that I can return the favor some day.

Thanks again and take care,

Brian

email (option): bbrown3407@charter.net

I received the new part below from Russel Motors. They have the best stuff!!



I was able to tear down the clutch basket AGAIN and reassembled the clutch basket again with the new parts. I am very pleased with the result and was able to get the the entire chain case back together again. I am moving forward and can't wait to get this old girl back on the road again.





Thanks all for the help.

Stay tuned,

Brian

email (option): bbrown3407@charter.net