Fork pre load adjusters

Still waiting for my new fork springs and emulators, should know better than to believe a shop has stock just because their web site says it does! I am going to make some pre load adjusters using original fork caps, I’ve bought some stainless 14mm threaded bar and the plan is to drill and tap original caps and grind flats on the stainless bar for ease of adjustment, it’s the inside I’m still unsure of. I’m thinking of making 10mm thick aluminium discs 40mm wide to act as the pressure plate onto pre load spacers but I’m not sure how well I will need to seal everything, do I need an o ring between aluminium disc and wall of forks or does it not need one, if anybody has done this job before your help will be most appreciated.

Garyb

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Hi Gary,everything needs to be airtight,the gap above the oil level works as an airspring so needs to be sealed in.You are going to need an Oring on the adjuster but that will require a plain section on the cap for it to seal against

Well that makes things a bit more difficult! The only way I can think of doing it and have 20-30mm adjustment is to remove the thread off about 50mm of the stud I’ve got which will bring it down to 10mm, drill cap at 10mm and then bore hole out on underside of cap to take a 10mm o ring then have a block about 40mm long and threaded internally 14mm, where the adjuster comes out of block fit the pressure plate for preload spacer. This would allow me to put markings onto adjuster to show how much preload has been put on each fork and should also seal everything in theory! If anybody knows an easier way I’m all ears!

Garyb

Just thinking outside the box, how hard would it be to remove the threads from a vtr1000 fork cap, build up with weld, then re thread with vf threads.
I seem to remember thinking of this some time back, a tap was available on eBay to cut the new threads for about £25,

Hi Pete, there is one on Ebay and looking at it that is the sort of thing I was going to try and make with the extended part inside the forks containing the thread and the adjusting part with no thread on top though the VTR adjuster is much wider. How wide is the VTR cap because there is not much steel before the aluminium insert also does that insert come out or is it sealed in or is all steel, if it’s all steel it’s feasible. I’ll keep that as plan b and try to mimic its design with the original cap for now as I don’t have any VTR caps to play around with and I would need to get help with the welding plus the expense of the caps and a die to cut thread. Keep any ideas coming though as I’m sure between us we can come up with a cheap and easy method to do this. Unfortunately I don’t think I’m going to get much time in the machine shop this week as we’re going full production on a new car this week and I may have to actually do some work for the company, thoughtless buggers!

A while back I bought a pair of adjusters for a vfr800 which would require the thread turned down and recut to suit the R fork and the alloy adjuster plate reduced to suit too.
I will see if I can find the link but not a lot of work involved if you have access to a machine shop

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PNG
Worth considering I think

They do look good but the m37x1.5 die required to do the thread is very expensive unless it’s from China and then you have a 3-4 week wait for delivery. I’ll try the conversion first and if I fail I’ll order a die and try the vfr800 ones, what size forks are in a vfr800?

41mm but with a much thinner tube wall.I wouldn’t be going down the die route,the machine shop I use for my stainless components made a one off nut for me for work,1 7/8x18tpi left hand thread.
It took longer to set the machine up than to make it.
Cheaper than buying a die you may never use again

I have a small machine shop at my disposal, a lathe two millers a pedestal drill and some sheet metal equipment but unfortunately have to do the work myself, I may be able to send them to our toolmakers area but may be difficult to convince them they’re for one of our machines! And my abilities are average at best especially when it comes to machine cutting of threads. I’ve sourced some aluminium bar and a 14mm tap for the adjuster so if I get some time on nights tomorrow I’ll see what I can do.

Mark 1 adjusters finished.

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Drilled fork caps 9.5mm and then reamed to 10mm, cut recess on underside for oring. Turned aluminium bar down to 24mm and drilled it 14mm to match stainless stud iron. Turned down stud iron ro 10mm for 50mm and marked 5mm graduations to help with adjustment, cut slot in end of stud for screwdriver using 2 hacksaw blades in the hacksaw. Turned other end of stud down to 7mm to match the washers I had and drilled 1.5mm for split pin. Oring fits over shaft between aluminium insert and cap.

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Length of aluminium insert is a bit long but meant even at full adjustment of 30 mm there is still 20 mm of thread.

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Look alright and adjust nicely. Will put some oil into recess on left cap and go for a ride to see if any air leaks out when breaking.

Garyb

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Nice work Gary,let us know how they work out