FF: Forks Modified Steering Stem

timetraveller

Well Known and Active Forum User
VOC Member
Hi Paul, John Emmanuel who developed the modified steering head had fitted taper roller head races but told me that he did not think it was necessary. I can get this done for you by a local engineer who borrowed three different steering heads from me in order to make the jigs to make this relatively easy. The steering head has to be removed from the oil tank which is actully easier than most people think. My own feelings on this are that if you have cup and cone bearings which are still in good condition then there is no need to do this. However, if the cup and cones are worn or their housings are loose or damaged then the best way to go is to convert to taper rollers. Apart from handling they have the big advantage of not having ball bearings being loose and falling out all over the floor the steering head has to be dismantled. The alternative,if you want to do it without getting the steering head machined there is the VOCSC taper roller conversion, which is based upon a German design and that requires no machining of the steering head.
Hope this helps
 

greg brillus

Well Known and Active Forum User
VOC Member
Taper rollers are nice, but there is little advantage in using them unless the original races are loose like Norman suggests above.........With the original races it is most important that they sit firmly home in their pockets, flat and square........The lower one can be tricky to change in situ and can end up crooked in its pocket (this is the one in the steering head not the stem itself) A race that is crooked will make the bikes handling feel absolutely horrible.......It may be a symptom that is more common than not, and perhaps for this reason.
 

highbury731

Well Known and Active Forum User
VOC Member
I have looked at the races for my bike. They appear unworn. If they pass inspection again, I will retain them - I just have to transfer the lower race to my shiny new steering stem... thanks Norman.
 

timetraveller

Well Known and Active Forum User
VOC Member
Read the intructions carefully and get the race hot before putting it onto the new stem. The taper helps. If it goes sideways and you tap it it will fracture as they are very brittle. You can guess how I know!
 

davidd

Well Known and Active Forum User
VOC Member
I loaned David Tompkins my taper roller stem for a season and then sold him a new stem (for stock bearings) which he machined for taper roller bearings. The reason I built some taper roller stems was that my bike had a problem with the lower race moving around. I solved this problem by replacing the lower bearing again and had no issues. Despite this, I made a drawing to have two taper roller stems made. David, on the other hand, had to adjust his steering head several times and found that the bearing broke. The replacement broke also. He used my taper roller stem and had zero problems.

The lower bearing gets pushed really hard on a road racer, so it is unlikely a design issue. I believe it has to do with the fit of the lower bearing race in the steering head, which is often compromised. I checked with Carleton Palmer and he never had a problem with his race bikes, so I think it is the luck of the draw.

The taper rollers do not affect the handling unless you are breaking lower races. I would not opt to do the conversion for fun, but I would normally install taper rollers on a racer that is being built to make it more reliable.

If you want taper roller bearings, get them from Norman while you can. It is best to have the new steering stem and taper rollers do require a machined stem, which the stock Vincent does not have (although they vary).

DSCN4394 01.jpg


The stock modified stem on the left and the taper roller on the right. The taper roller stem is machined to hold a bearing steady at the top and when seated at the bottom, like a modern fork stem. I also left the stock damper design on the stock modified stem on the left but removed it from the racing stem.

David
 

timetraveller

Well Known and Active Forum User
VOC Member
I went to see the local engineer who can do the taper roller conversion this morning to check the latest price. Machining, supplying and fitting the bearings comes in at about £170 plus P&P. Compare this with a price of about £260 for a pair of cup and cone bearings and you can see at least one advantage. I also learnt that it is possible that there are two ali steering head lugs available, fitted with taper roller bearings. Someone has expressed interest in these so they might not be available but they are about £1,000 each complete with bearings, Both are of the type with the forked lower end which fits over the cylinder head bracket.
 

timetraveller

Well Known and Active Forum User
VOC Member
OK. Chaps. I now have orders for 17 so have ordered 20 to be made. The reason for this note is that I am drawing up a spread sheet of all the parts I need and rather than contacting you all individually I thought it would save time to put a notice here. I need to know the following details from each of you before I can order the parts so here is a list of questions. Some of you have aleady provided the information and you will know who you are so you can ignore this. For the rest could I ask you to email me on enw07@btinternet.com with the answers to the questions.
1) Is the bike a twin or a single and what is your weight? I need this to specify the springs.
2) What do you intend to do about the lower link? I know some are waiting for new ones and I am told by VOCSC that a new batch will be available within a week or two. Those who have given me this information can relax. I think that you will all be using the Greg Brillus bearng mod, which I highly reccomend, so all I need to know is whether you just want the bearings.
3) Do you want a front AVO damper with the kit?
4) Do you want a hydraulic steering damper kit to go with the rest of the kit?
5) Do you want me to supply a rear AVO coil over with the rest of the kit?

Please note that the prices for all the items are in posting #1,208 above.
Thank you
 

timetraveller

Well Known and Active Forum User
VOC Member
UPDATE. This is especially for those of you who are waiting for new lower links. I heard from Marvellous Michelle of the VOCSC this morning that they have now arrived. At least six of you have been waiting and at least two have arranged to have them sent directly to me for the machining and fitting the ball races. One of you found one locally. So if you are unsure as to whether you have arranged to have them sent to me contact either me or Michelle. I need to have two FF6 bushes with each lower link as these are used to line up the boring bar for the rear holes. I will fit and ream these. I am told that ten lower links have arrived and I am going to need five or six of these. Thank you.
 

Chris Launders

Well Known and Active Forum User
VOC Member
Well I finally got round to uploading the video of my forks in action onto Youtube. Better watched with the sound down and ignore the camera shake at speed as the camera was just clamped to the crash bar.

Keep one eye on the fork and bottom link and the one on the eccentric and background to see how stable the bike is compared to the fork movement

 
Top