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Gudgeon (wrist) pin bush (little end bush)

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
An old blacktracker showed me this method. Get a 1/2" diameter bolt about 3.5" long and a heavy plain washer. Get a socket deep enough to hold the old bush and just wide enough to bear on the con-rod eye. Place washer and new bush under bolt head put bolt through small end. Place socket over other end of small end bush, bearing on the con-rod eye. Fit nut and screw down, being careful to centralise new bush, which pushes old bush out. Then you need to take it to a good engineer to line-bore it parallel to the big-end after cheking the rod for twist, bend and cracks. How did the seat foam go?
 

vibrac

Well Known and Active Forum Website User
VOC Member
If you are fitting a small end bush to a known rod already in situe you may be met with a new bush in position but now too tight a fit for the pin. Thats where a brake cylinder hone in a steady hand drill comes in. A couple of strokes and its done (as the art mistress said to the gardener)
 

jim burgess

Well Known and Active Forum Website User
Non-VOC Member
Be aware that the bush needs to be parallel to big end. Press out old bush first then press in new bush to hollow little end. When you take it to your engineer to ream the job, ask him to replace the bush first...
Jim Burgess
 

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
An old blacktracker showed me this method. Get a 1/2" diameter bolt about 3.5" long and a heavy plain washer. Get a socket deep enough to hold the old bush and just wide enough to bear on the con-rod eye. Place washer and new bush under bolt head put bolt through small end. Place socket over other end of small end bush, bearing on the con-rod eye. Fit nut and screw down, being careful to centralise new bush, which pushes old bush out. Then you need to take it to a good engineer to line-bore it parallel to the big-end after cheking the rod for twist, bend and cracks. How did the seat foam go?
Hiya Chankly, I am going to have a crack at your method on the weekend, however, the rest of the bike is all together, I just pulled the head and barrell off for something to do in the Man Cave on Friday night :) What do you think of the response from Vibrac below? (which will now be above....you know what I mean).
The Pin is a very smooth (not interference) fit into the piston and both look to be in very good condition, some believe the pin should be tight in the piston, what do you think?

Kevin
 

redbloke1956

Well Known and Active Forum Website User
Non-VOC Member
How did the seat foam go? it went really well thanks mate I did some sculpting on the bottom with a Dremel to suit my new (prototype) seat base prototype seat.jpgThanks very much (did you get the money order OK?)seat foam.jpg
 

vibrac

Well Known and Active Forum Website User
VOC Member
With regards to the float in the rod small end and the pin. Mr Kemp on his grey flash racer (with a B50 piston and a smaller pin than the Vincent) made the bush up in phospor bronze with a groove round its middle on the outside and had it fully floating in the small end I did one the same for mine very satisfactory (In those days specialoid over 8:1 were like customers for 118 118 -very rare). The standard bush is too thin for such tricks so a tight bush in rod and a pin that is a push fit in piston when warm (hot rag) is my standard. I think it was a modern tuning manual that gave me the brake hone trick just shows you are never too old to learn.
 

chankly bore

Well Known and Active Forum Website User
Non-VOC Member
Thanks, Kevin. Money received and deposited in Vic. section Spares fund. Vibrac's idea sounds O.K. as long as the previous piston shows no sign of canting. Maybe have a block of wood at the right height to help keep the hone steady. I reckon tight in the piston at 20c. O.K. as long as it is free at operating temperature.
 
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