Rockers

I would like to discuss the various rockers available for the ABC Sopwith and Gnome Rhone Motorcycles 1919 to 1924. This was one of the weak points in the design and many aftermarket options became available. ( This may have been the start of the Massive aftermarket Motorcycle Business we have today). I have a few bikes and I would like to fit one of each type to my bikes and try them all out. I will be able to report on my findings. I would appreciate if other Members could give me their input into what type or Rockers they have and their experiences with each type of rocker, the good and the bad. I am not sure to what depth we need to get into this as I have noticed that they do not all have the same rocker ratio and I am not sure if this was done to save the push rods from being lost or if it was done to improve the performance . I would also like to use this opportunity to complete some incomplete sets of rockers that I have. I have used the Inglis system this far and have nothing but good things to say about it.










The systems that I am aware of are ;1. ABC Sopwith original. 2. ABC Gnome Rhone original 3. Inglis. 4. Jarvis .5. BEW ( Brooklands Engineering Works) .6.Taylor Young 7. Grubb??( National Museum)
There may be others , please let us know

Hi
I have attached a couple of pictures of my rockers, I assumed they are original but are they ?
The only modification is the use of grub screws for my adjusters.
On the topic of loosing push rods.
I have never lost one and since stopping my bike from dropping out of gear there appears to be less chance. So how real is the problem of loosing push rods ?
Changing the rocker ratio would certainly alter performance, did the factory experiment with different ratios ?
All the best and stay virus free.

Thanks Andrew. Lets look at the original Sopwith Rockers , which by the way I think look the best because they are ORIGINAL. They are mounted using only two bolts and they have a lubrication problem.
Most of the aftermarket Rockers have more than two bolts mounting them. The bolts are spaced close together and the long and short bolt for rocker support were difficult to tighten easily and correctly. I have had to machine a special socket to fit them correctly. Looking at the condition of some of the old bolts that I have collected over time it is obvious that a Screwdriver was used to tighten and in many cases the slot was so damaged that proper tightening would not have been possible. This may have resulted in a loose Rocker Support with the associated problems. On some of the old rocker supports I can see the mounting holes have been enlarged or slotted to correct the rocker alignment, I do not know why this was done because I have found the alignment in standard form to be acceptable.Clean faces on the Head and the Rocker and good bolts and correct tightening are important on all the two bolt mounting systems.
The lubrication is interesting. There are two holes on each of the Rockers that are supposed to get oil from time to time.I am not sure what from time to time is but even if it is every 50 Miles I am sure that when new, lubrication was frequent but as the machines got older the lubrication became less frequent . This has resulted in wear mainly on the Rocker Support. Worn Rocker Supports has resulted in wondering Rockers with the associated problems. With the heat generated by the head ,infrequent oil is not the best option. I have seen some modifications done to use grease and these seem to have far less wear.( See my previous photo of the modified Rocker with Grease Nipple added). Today there is an elevated awareness and I think owners will lubricate more frequently and therefore no modification is necessary
The Adjuster also needs some mention. In standard form it came with a Lock Nut and Spring Washer.When the Adjuster is fully extended it forms quite a big Arc thereby constantly changing the presentation angle with the Push Rod. This can be reduced by fitting slightly longer Push Rods.Andrew , you have reduced this by bringing the Push Rods right into the Rocker and this may be part of the reason that you have not lost a Push Rod. I see that you have also got proper mounting bolts on your Rocker Support. If you look carefully you can see that the Rockers have been heated and slightly bent to achieve correct alignment.
I have not yet traveled any long distance using standard Rockers but I have a set prepared and I plan to use them on a long trip shortly.
Regards

I enclose a picture of the rocker arrangement on the Brooklands ABC. The arrangement is held by 3 1/4" studs (which we have now remanufactured from EN16). The rockers run on 4 sets of free needle bearings, 2 each running directly (as I remember) on each rocker arm and held in place by split shells that themselves are held by the 2 halves of the aluminum shell. The arrangement is lubricated by oil mist generated through a one way valve located on the footbrake side of the engine casing. The arrangement is meant to have rocker tubes, but it is too laborious to fit, if you are regularly taking the heads on and off. Our rocker arms are heavily worn round the bearing points; however as the load is always in one direction it doesn't seem to effect running. They seem to work fine, even going around Montlhery. Our only issue has been a bend pushrod due to an exhaust valve snatching in the guide. Interesting even then the rod did not fall out. If I were to rebuild it again, I would use cast iron valve guides and have 8thou clearance on the exhaust.
regards
Ian

Hi Ian
Thank You for your explanation of the Taylor Young Fully Enclosed Rockers that you have on the Brooklands ABC.There are not many ABCs running with this type of Rocker so we really appreciate your comment and experience.
Do any members with this type of Rocker have any experiences they would like to share with us. This Rocker has Three mounting points
Regards

Hi,

these pictures for your information.

Regards

Wolfgang