Tank mounting misalignment

[davidd]

Hello David, Wish I had use of those kind of tools, Always wanted a Mill', Not that I would know what to do with it !!, What is the Standard Headstock made of ?, Cheers Bill.

Bill,

I do not know what the standard headstock is made out of. I know it is not aluminum! That is one of the reasons I had to make a pattern. I wanted to beef up many areas for greater strength. I also made it big enough for taper rollers.

I don't know how to use a mill either so it was better to do it on Pat Manning's. They were his FT4's also.

David

 

[davidd]

Bill,

I meant all the bent FT4's were Pat's, the aluminum ones I built for the next two specials.

David

 

[Oldhaven]

Quoting J Bickerstaff MPH 642:

"The more common ‘B’ item, however, was a malleable iron casting, forked to bolt either side of
the front head-bracket. This I suspect turned out to be a bit weak - perhaps in crashes. It is nice and light, but I have seen examples that have cracked or distorted.
So the factory produced the next type, a strong, I-beam, forging- but markedly heavier. (Just one of many ways the bikes
picked up weight over the years). This had a simpler lug for the head-bracket, which became slotted to accept it. This may
have been to make the forging operation easier, but it does narrow the attachment point quite significantly and so the fit and
tightness of your studs and sleeves at this point is quite important for maintaining rigidity"

To further her remarks, mine is the early rounded type and the tail part that connects the head mount fork to the steering column is a hollow tube shape. You can see right into the steering column from the fork end. This picture from earlier simpler times for me shows this. The structure makes me wonder if it might be easier to make a custom headstock this way, similar to the Egli UFM, rather than making an I beam shape. the whole thing could be made up in separate bits of large tubing for the main steering column and structural parts with rods through holes or milled slots in the large tubes for oil and petrol tank bosses and the"outie" head bracket fork sliding over the down tube. The whole lot welded together in a jig, then finally machined. See post 7 for another good picture to illustrate.

I wonder if Terry Prince made a billet UFM for standard Vincent suspension and petrol tank to cover situations like this if it would sell?

Ron






. .

 

[greg brillus]

I have actually spoken to Laurie Binns in Victoria, Australia who as some of you know is a very skilled machinist, about the making of headstocks from alloy, whether cast or machined from billet, and he said that no matter what alloy you made it from, the strongest of alloys is only at best, as strong as mild steel. His thoughts on an alloy headstock were not positive. After seeing how many of the factory headstocks are bent, I am inclined to think he may be correct.....of course not all of us will crash our bikes, given how little they are used these days, verses when they were new.......Greg.

 

[Bill Thomas]

I think I have said befor, One of the lads I raced with had an very bad crash, Which was not like him, He was fast but safe !Not sure if it was an 1050 or 1150, With a Burman gearbox. The Alloy headstock broke, Not sure what came first, The crash or the break !. This is all new to me, Not heard of bent standard headstocks till now, Still Learning !! Cheers Bill.

 

[Oldhaven]

I may have a chance at the matching number UFM to my engine, but need to find a good one of the fork end type to exchange. Wish me luck.

Ron

 

[davidd]

I think I have said befor, One of the lads I raced with had an very bad crash, Which was not like him, He was fast but safe !Not sure if it was an 1050 or 1150, With a Burman gearbox. The Alloy headstock broke, Not sure what came first, The crash or the break !. This is all new to me, Not heard of bent standard headstocks till now, Still Learning !! Cheers Bill.

The Stu Rogers pre-war Norton that was featured in Classic Racer a few years ago is in my class. I once asked why the steering head was all taped up with black tape. The answer was there were so many holes in the steering head that they did not think it would pass scrutineering, so they taped it up. If it failed it would know if a failure caused the crash or the crash caused the failure.

The Maughan aluminum copies were just that. They did not do any redesign to compensate for the use of aluminum.

My machinist is pretty good with metallurgy we ran the numbers years ago and I was reasonably confident. The cast steel is not very strong or we would not be chatting about it. Also, if you remember Paul Packman's prang, the steering stem tore through the front of the steering head in a most impressive manner. The wall thickness on the stock part is 1/8". I think it is 7/8" on mine.
David

 

[Oldhaven]

Stone Axe Engineering

Back home and able to look at my bent UFM more closely. It is in fact bent between the fork head mount and the steering column. The bad news is that the steering column is both rotated clockwise around the steering axis and bent to the right. The good news is that there is no discernible misalignment of the head mounts at the front or the rear as rods through the head mounts are parallel in all axes. It was not necessary to remove the oil tank to see this. I put a .500 tool steel rod through the front head mount fork holes, mounted it in a 1/2' collet in my milling machine, and looked at a 1" rod through the steering column. It is even measurable with a machinist's square from the mill table to the bottom face of the column, where I measure a 2 degree misalignment. It is amazing how much that moves the steering axis visually with the long rod through the column, as it is very noticeable, though I know human vision is optimized for seeing non parallel or perpendicular lines. I thought it would be more than 2 degrees. I was also right that the through hole for the tank mounts is a great indicator for misalignment by comparing it to other rods through the head mounts and sidecar holes, assuming they are straight.

I have a few more checks I want to run and need some help. My engine is not here right now, so as a minimum, could someone tell me the distance of the lateral offset from the right hand machined surfaces of the head brackets for the front and rear heads? Since this is the fork type UFM this means the outside machined surface, not inside for a slotted type. This will be a relative figure, but ideally it would be good to know the actual distance of offset from the centerline of the headstock and steering column to the right hand inside machined surfaces of the UFM. I looked in the forum and other references for this figure, but could not find it, though I was sure I had seen it somewhere. Page 6 of the Riders Handbook helps but is not the whole story.

That's the engineering part, the stone axe part is that I am going to try to straighten the UFM as a unit with the headstock in the oil tank by stabilizing the unbent part and slowly moving the bent part in a direction opposite the bends. It stands to reason that part of the oil tank is bent, and if I just fix the headstock, it will not fix that damage. I think I have a scheme to do this in a controlled way, but I need that offset figure to do it. It will be a few days until I can try it since it requires the head brackets and they are with my engine, which should be back here in a week or two...

Also found out that the rear UFM plates that hold the seat, damper and sidecar tubes are bent a bit to the left, but that is an easier thing to correct. Page 6 of the Riders Handbook will help here

Ron.

 

[Bill Thomas]

Hello Ron, You made me Sweat there for a while !, I am wanting to build a bike soon and have the UFM on the bench, I thought what do I do if mine is like Ron's !! I have never heard of this problem befor, I am a feet and inches man, So don't take my word for it, Near as I can tell it's half an inch offset, The head bracket is two and three quarter inches across the flats where the tank goes over, I don't have the tools you have , so this is how I see it, Hope this helps, Good Luck, Bill.

 

[Oldhaven]

Thanks Bill,

I'm getting close to that, but I obviously don't trust my UFM right now. For a what I hope is quick check on your alignment, if your UFM doesn't have the steering stem installed, put a straight 1/4 rod through the tank mount holes and a close fit 1/2 through the front head mount hole and/or a 5/8 rod through the sidecar mount like I show in my pictures above. You should be able to see any misalignment worth worrying about by viewing at different angles without requiring V-blocks or a surface plate. It would be good for me to know if my assumption about the tank mount hole being parallel to the others is correct since I intend to use it as a visual guide. If I am wrong, you are about to worry yourself needlessly.


Ron