FT: Frame (Twin) Rear Inner Spring Boxes

timetraveller

Well Known and Active Forum User
VOC Member
In reply to Peter's question in #17 above I would not expect any damage to the outer spring boxes from the diamond hard chroming of the inners. It will be important that the inner spring boxes are well polished before plating so that the chrome is on a smooth surface, otherwise I do not think there is anything to worry about.
Now, #20 above; there was a lot of thought that went into the design of the JE system and the range over which the wheel moves is controlled by the front damper. I do not know how the dimensions of the Thornton unit compare with the AVO one. All the tests and measurements which I did were with an AVO unit without oil, even to the extent of having a scale on the outside of the damper and another on the outside of the inner spring box, just to measure where the limits were. I do know that one person raced a twin with a JE front end used a Thornton and found that it handled so well that he did not feel that he needed a steering damper. That is until he got into a tank slapper, after which he fitted a hydraulic steering damper and possibly reverted to the AVO. Just make sure that the front wheel spindle movement is upwards and backward for the whole of its travel.
 

oexing

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I guess the matter of this thread is to protect the inners from scratches in use, because they are not centered in the outers. One way I have seen elsewhere is to have protruding dimples on the inners near the open end. So the dimples keep the inners centered and no scratches to be seen. Either try dimples from inside, not that easy to do, or I´d try copper or bronce rounded head rivets, four of them. Simple drilled holes and chamfered from inside and very short rivets, dremeled flush inside more or less. The heads filed to just fit in the outers and even replacable with wear after long use. You have to keep shrouds well greased anyway for lubricating the springs - not a great design. But then, the Norton Roadholders and other types had springs outside of tele stanchions , even worse in my eyes . Allright for quick sales but hurt in my eyes being perfectionist in some aspects.

Vic
 

highbury731

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VOC Member
How should I prepare my front inner spring boxes before sending them off for hard-chrome plating?
There is some scoring. I have cleaned them and de-rusted using Jenolite, which has dried leaving an anti-rust coating.
Paul
 

Peter Holmes

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Your first mission should be to find some spring boxes that are not scored or pitted, the plating process will not cover damage, the plater might be able to polish out some very light damage, but that is all, they will not be able to plate over a Jenolite treatment of the scores and pits, I actually prefer the duller finish of DHC When compared to bright chrome, and it is a far more durable finish. Good luck Peter
 

timetraveller

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VOC Member
Peter is right and it will all depend upon how deep the scoring is. A really thorough plating job is copper followed by nickle followed by chrome. If the scoring is sufficiently shallow that a good layer of copper followed by a polish will hide them then go ahead. Otherwise save your money. Do you think that stainless steel will not be up to the job or not look right?
 

highbury731

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VOC Member
Well, I hear that ss spring boxes are prone to scoring. That's why I decided on hard chrome. Of course, the Jenolite has to be removed prior to polishing and plating. I used it just to clean the metal and prevent further corrosion. Should I try to polish the metal or leave it in its clean / corrosion-free state?
Paul
 

timetraveller

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Have a talk to the people who will do the plating. They are often known as "platers and polishers" the reason being that they do the polishing as part of the job. I would show them the work first and then take their advice. If the tubes are capable of being polished then they will almost certainly be able to do a better job than you. That is not to decry your skills. It is just that they will have better equipment and a more experienced polisher.
 

Marcus Bowden

VOC Hon. Overseas Representative
VOC Member
Why have spring boxes at all, remove them and save a 1/3rd of the weight make these. fit sintered bronze bushes into the alloy cylinder with an air hole to add a drop of oil from time to time.

P1040318.jpg



P1040319.jpg
 

highbury731

Well Known and Active Forum User
VOC Member
I saw pictures of these (I think they installed on your bike) a while ago. I liked the idea - but I have an AVO rear coil-over. My spring-boxes for hard-chrome are the front ones.
Paul
 
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