SOTP Vintage Series
Main Motorcycle: The one between my legs
Join Date: Feb 2009
Location: Upstate NY
Other Motorcycle: A few
Extra Motorcycle: Yes
Proper positioning of Rocker box spindle washer
I did my homework and ran several searches here on various terms including "thackery" to find the various posts on the subject.
Most are posts for later model, OIF or post '69 big twins. My question is for a '66 T120R.
I found the post below from Mr. Pete, whose experience and knowledge I have come to regard highly.
So,how have you got the shims and thackeray washers installed?
Drilled rocker arms have the thackeray up against the arm,and the thrust washer against the rocker box casting.
Undrilled rocker arms should have the thrust washer against the arm,and the thackeray against the rocker box.
This is often done wrong,and was for many years.It affects lubrication of the rockers,valve-tips etc.
My parts manual, which is for 650 twins after DU 24875 and has a publishing date of 9/65 (if I can believe the cover goes with the contents as this is a repop manual) shows the washers up against the casting and outboard of the thackery washers. Thackery washers are against the rocker arms. That's agrees with Mr. Pete's quote above.
The service manual, which is for '63-'70 650 twins shows the washers inboard of the thackery washers with the thackery washers against the rockerbox casting.That is opposite of what Mr. Pete says in his post.
My spindles are drilled and my rocker arms are drilled so the oil from the spindle is fed to the pushrod ball. There are no notches on the sides of the rocker arms. The thrust washers are 1 each 3/8 washer and 3 each 1/2" washers, which agrees with my parts manual.
I then looked at a 1970 parts book that is on-line and it shows the washers inboard of the thackery washers, which matches my service manual. Spindles and rocker arms are the same part numbers as mine. Only the balls are different. Could be they are undrilled. Brit Only shows mine are for '68 and before and the others '69 on. But since my service manual covers all the way to 1970, it could have the later config.
Trying to understand the purpose behind the design, I would think that plain thrust washers go against the rocker arms to maintain oil pressure which forces the oil thru the rocker arm passage to the ball. But I'm also hesitant to question Mr. Pete's experience.
Mr. Pete or someone with more experience on these, can you please confirm the correct order for these parts on this engine?
Anyone out there have an original '66 Service manual they can check for me, please?
Last edited by Snakeoil; 11-19-2012 at 08:32 PM.