C: Clutch Refreshing Vincent Twin Clutch seals and pieces

craig

Well Known and Active Forum User
VOC Member
In fitting an electric starter to an early Rapide, I also decided to look over the clutch and primary drive...and good thing as I found what looked to be small amount of oily items at PD20, PD22, clutch basket C1, seal C18, C20 nut, etc. Not any great amount, nothing appears on friction shoes, but damp.

I am replacing, or planning on replacing PD25 clutch sprocket seal and in the midst of this job, I am looking over all the other leakable pieces in the clutch train as well.

My questions are, as I have gone dumb on this -
Can I knock out the PD24 bush by munching up the existing PD25 seal? I am guessing the answers is yes.
Would it be best to order/replace PD24? rather than clean it up after removal? probably a good thing

Most important, once the PD25 seal is installed with PD 24 installed and the primary pieces go back into place, what tool or fixture is used to keep the PD20 sprocket centered , so as to take the deformation off the new PD25 seal?
MO14PD25Question.jpg
C20C19.jpg
 
Last edited:

timetraveller

Well Known and Active Forum User
VOC Member
If I have understood the question correctly then the shaft of the shoe carrier keeps everything centralised in the sprocket but there is an important mod you can do while it is all apart. At the inwards end of the shaft of the shoe carrier you can machine, grind or whatever a recess about half way through the wall thickness on the inside of this. This leaves either a 'V' shape or a cylindrical recess. Make this fit an 'o' ring which will be trapped between the shaft and the PD21. The idea is to stop oil getting into, and migrating along the splines, rather than trying to stop it getting out at the outer end. That terrible idea of smothering everything in sealing compound is out of date by at least fifty years.
 

bmetcalf

Well Known and Active Forum User
VOC Member
what tool or fixture is used to keep the PD20 sprocket centered , so as to take the deformation off the new PD25 seal?

I use my shoe carrier and am gentle with the seal when I have to pull the shoe carrier out. A pro would make a sleeve to suit.
 
Last edited by a moderator:

greg brillus

Well Known and Active Forum User
VOC Member
Craig, there is a step or shoulder inside the bore of the chainwheel, this will prevent the seal coming out from the side that the thick PD 24 bushing is, you need to remove the thin walled PD 22 bush and remove/swap over the seal from this side. This usually destroys the bush, which is usually worn anyway. It is really a shorter version of the same bush in the center of the clutch plate carrier. These two bushes and the seal should ideally be changed if the chain wheel shows too much play, and even the sleeve section of the shoe carrier does wear over time and use. Use a light smear of grease on the seal and so long as there is not a sharp edge on the shoe carrier sleeve, then it should not damage the seal. Once those parts are all done, you can temporarily assemble the shoe and plate carriers on the mainshaft, do up the C20 nut with its shims up very tight, and check all your end play and shim as necessary. The outer plate carrier needs at least 10 thou end float do not be tempted to set it up with minimal play as this will cause the clutch parts to stick. It is important to check all this with the center nut C20 done up tight, if it is not, the parts that it holds will move and this will definitely cause oil leaks. Good luck with it all...........Greg.
 

vibrac

Well Known and Active Forum User
VOC Member
There is a problem associated with different versions of the C20 nut I tried to search on the forum but C20 is not a long enough search term.
Hasnt one got a recess and the other not?or one is shorter than the other I seem to remember I had the wrong nut on a new bike and a deeply embeded oil seal that looked like part of the assembly it took a lot of pondering before I realised what was up .
It was a long time ago and pre forums it could be lonely in the workshop back then....
 

timetraveller

Well Known and Active Forum User
VOC Member
The later nuts, I would call them 'D' nuts but someone might tell us that they came out with late 'C's, had a recess at the rear to take an 'O' ring to try to stop the oil getting out of the splines and into the clutch drum. This type of nut also required a different end to the gearbox main shaft so you cannot mix and match them. Better to stop the oil getting into the shaft in the first place.
 

bmetcalf

Well Known and Active Forum User
VOC Member
a different end to the gearbox main shaft so you cannot mix and match them.

I have the counterbored nut and use an o-ring there, plus the bonded seal and hylomar on the splines. I'll have to look in 40YO, KTB, etc. to see what the different shaft detail is, so I can inspect it next time it is exposed. Touch wood, but my clutch has been dry since 1980.
 
Top