FF: Forks Modified Steering Stem

timetraveller

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There are several things i do not understand about this mod. For example on some bikes it is necessary to take up to about 6 mm from the rear/bottom of the top link to clear the AVO damper while on others it clears. On some bikes the front mudguard can hit the front cylinder, on others, plenty of clearance. Greg finds that lots of the bikes can have the suspension 'topped out' and yet one of the criteria for setting it up is to watch it settle about half an inch when one sits on the bike so that the lower link is just about horizontal. If one sits on the bike and nothing moves then it is certain that the front springs are too strong or too long. Greg seems not to have to shorten both inner and outer front spring boxes whereas most users find that without that one does not get the full movement. One user reports that he is getting 3.75" of movement on his spring boxes but he is not using the AVO damper. Greg reports that he can get both topping out and bottoming out on rough roads. Does that mean that a stiffer damper should be used? So many questions, so little time :confused:
 

TouringGodet

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It is something I've wanted to do for some time, as the route of the fully sprung seat is practical, but looks ugly in my opinion. The "vacant" seat stay brackets left in the cold on the rear frame looks out of place....... I wanted to replicate the ones that Harry Belleville or whoever it was, that did something similar years ago, but make them look more like a factory made item using modern technology.

If you are referring to the seat stays with the built in shock absorber, I believe Gene Aucott made them.
 

oexing

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There are a few items in this topic to be discussed separately: Any bad excessive "friction" in original oilite bushed girder links is most likely due to poor alignment of bushes, not perfectly line-reamed. So when changing for ball or needle bearings this defect got glossed over or rectified and was not a real snag of plain bushes. Some friction in there is basically no factor as any shock absorber has a LOT more friction in it than that tiny amount in a plain bearing. And in most girder forks you get extra friction dampers as standard for sure . So I would not want ballbearings in there but get maintenance free bushes instead, no grease used and no rust problem on stainless bolts with their bushes.
As to topping or bottoming out nothing will help but having some rubber bump stops in suitable places when not getting real progressive springs or a combo of springs for same effect instead. Some dampers have a strong short spring inside and a rubber buffer on the external damper rod for bump stops. In modern teleforks you can add air pressure for fine tuning to suit different loads, same can be done with dampers. So maybe this could be kept in mind for mods ?

Vic
 

greg brillus

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It is possible that the bearing pockets differ from bike to bike, perhaps from previous front end damage/repair. One way I have found this could be true is on some bikes the top stem nut bottoms out on the inside before the nut tightens enough to take all the adjustment in the head bearings. Generally i have removed the alloy damper housing and machined off a couple of mm from it, then reassemble and all is fine. The lower FF 36 washer is important too, if left out it will alter the geometry........But generally if the lower guard stay is too close to something it is usually because the stay is too high, the wrong one (too long) and also the difference in exhaust header pipes makes a big difference. I have had to alter several guard/stay set ups to allow the full compression of the suspension and this must be done with the shocker connected but the spring cases left off so you can lift the forks up against the shock absorber bump rubber. The lower the links are able to come down at the front, the greater the chance of the shocker like an AVO hitting the rear inside of the upper link, and this will be dictated by the lower shocker eye bolts in particular. Because the stock front end has long stiff springs, this lifts the front of the bike and gives plenty of travel without bottoming out........but this condition is what causes the bad geometry of the links as opposed to the Brampton forks........The girdraulic forks with less travel and the links in a safer position then replicates that of the Brampton's. It is only the spring cases that limit the travel on full compression when the new stem is installed. I take note of Vic's comments about friction, but the facts are that the load factors from the poor link geometry especially on the lower link are proof that at least the interference fit of these large bushes is overcome by high friction and they readily spin in the housing, thus the large eyes wear quite badly and are difficult to reclaim true and square to one another. there are endless ways to improve these bikes, some things you just have to try and see what happens.........To this date there is nothing negative about what has been done, just a bit of fine tuning here and there to suit each bike/rider combination.
 

bmetcalf

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"The number stamped on the damper ends in a 7 for the originals and an 8 for the stiffer ones. "

I've looked at mine and didn't find a number. Where should I look? {It is on the bike.)
 

greg brillus

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The other thing is that some who have installed the kit are not getting the assembly right.......case in question.......On our North Queensland rally back in September last year, one of the riders bikes had the mod done.......he felt the bike was better but not entirely sure........when I checked the bike, the front end was horribly topped out, with all my weight on the bars I could not push the front end down at all. I can't remember what springs he had used, but he had not trimmed them down at all. After I showed him how nice the front was on my bike he realized the difference and hopefully put it right when he returned home.
 

timetraveller

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The number is stamped just above the lower eye, to the right if the damper is held so that the adjuster screw is to the left. On the picture the number is 1447.
1585040417840.png
 

stu spalding

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When I fitted the J.E. kit I was having problems with the top link hitting the damper and requiring the removal of a lot more material from the link than normal to gain clearance. The problem turned out to be that the AVO damper was an early one that was slightly longer between centres than standard and was rectified by plugging and re-drilling FF57 (the long one). Cheers, Stu.
 

stu spalding

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Quite right Norman, it came direct from AVO's and was fitted to the standard steering before I had considered a J.E. conversion. Cheers, Stu.
 
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