Clutch spring compressor tool

dero

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I am duplicating a clutch spring compressor tool & have come to an internal thread in the end of the bolt 5/16" x 24 , what is it for ?
 
Hi dero,

That thread your asking about takes the clutch rod adjustment screw. That screws into the clutch pressure plate. If that is a Diaphragm type clutch.

ELLIS
 
ELLIS said:
Hi dero,

That thread your asking about takes the clutch rod adjustment screw. That screws into the clutch pressure plate. If that is a Diaphragm type clutch.

ELLIS
Click to expand...

The adjuster screw is 1/2" x 20 and has to be removed (from the spring centre, not the pressure plate) to fit the compressor bolt.
 
That is what I have always done , which made me wonder what the internal thread was for .
Also I see some made with pipe caps , which makes me wonder if the lock nuts are necessary , as it seems they would not be accessible with a pipe cap .
 
I think he is asking about the 5/16 UNF interior thread, not the 1/2 UNF exterior thread that mates with the diaphragm.

Clutch spring compressor tool
 
dero said:
That is what I have always done , which made me wonder what the internal thread was for .
Also I see some made with pipe caps , which makes me wonder if the lock nuts are necessary , as it seems they would not be accessible with a pipe cap .
Click to expand...
The lock nut is for jamming against the diaphragm so you don't bottom out against the clutch rod.
 
Thanks & yes it is the smaller internal thread I was thinking of .
 
dero said:
Also I see some made with pipe caps , which makes me wonder if the lock nuts are necessary , as it seems they would not be accessible with a pipe cap .
Click to expand...
The internal nut isn't necessary, I think it's only purpose is to keep the assembly together when not in use. The bolt is just screwed in a few turns and then held while the outer nut is tightened to compress the diaphragm. I've never found the need to use the internal nut as a lock nut.
 
Last edited:
johnm said:
I have two clutch tools. Neither have that internal thread. And I have never needed it in 40 plus years of removing Norton diaphragm clutches.

So it's a bit of a mystery to me why it's there.
Click to expand...

I think perhaps I've found the answer that the internal thread is intended for (some?) Norton rotary clutches that have a (5/16" UNF?) pull rod.
The compressor bolt is screwed onto the pull rod which is then used to compress the spring.
andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.
andover-norton.co.uk
 
Last edited:
Thanks , I have drilled it to suit the thread , but won't bother to tap it .
 
dero said:
That is what I have always done , which made me wonder what the internal thread was for .
Also I see some made with pipe caps , which makes me wonder if the lock nuts are necessary , as it seems they would not be accessible with a pipe cap .
Click to expand...
If the stud is long enough, they are reachable. However, they are not needed if you have a double nut on the other end and keep it from turning while tightening the nut that actually releases the diaphragm.
 
I made mine from a cast iron pipe cap about 45 years ago. The bolt is long enough to allow snugging the inner nut.
Clutch spring compressor tool
 
marshg246 said:
However, they are not needed if you have a double nut on the other end and keep it from turning while tightening the nut that actually releases the diaphragm.
Click to expand...

I see no reason to have double nuts inside or out because the bolt hexagon can be held while tightening the compressor nut as demonstrated, below.
steadfastcycles.com

Norton clutch spring compression tool Commando 1968 69 70 71 72 73 74 75 06-0999

Norton clutch spring compression tool Commando 1968 69 70 71 72 73 74 75 06-0999
steadfastcycles.com
Clutch spring compressor tool
 
L.A.B. said:
I see no reason to have double nuts inside or out because the bolt hexagon can be held while tightening the compressor nut as demonstrated, below.
steadfastcycles.com

Norton clutch spring compression tool Commando 1968 69 70 71 72 73 74 75 06-0999

Norton clutch spring compression tool Commando 1968 69 70 71 72 73 74 75 06-0999
steadfastcycles.com
Clutch spring compressor tool
Click to expand...
The drain cap variety I've made and have seen made use all thread, not a bolt so there is no hex on the end. A double nut is the easiest way to provide one.
 
I feel the caution note in the factory manual from memory is a little over the top in regaurds to the amount of spring pressure danger and the over engineerined equipment to put the diaphragm spring in a neutral position.
I made mine out of heavy wall plastic drainage pipe counter sunk plywood cap with a small steel centre (a flat plate with a hole in it would suffice)...no nut required ...tighten bolt while holding the compressor tool...job done
 

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