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F: Frame UFM Dimensions


Pushrod Twin

Well Known and Active Website User
VOC Member
Can anybody help with some dimensions for an early UFM I am restoring, please? It has suffered debauchery & I need to rectify the side plates, front & rear, that attach to the FT1/2 and rear head respectively.
First I removed the added appendages, see pics;
20191231_144810_resized.jpg20191231_144817_resized.jpg
That left me with two holes to match to the FT1/2. From that I can fabricate replacement front side plates, but I would like the coordinates of the rear head fixing hole, please. I know it is slotted, how much and what direction?
20191231_193944_resized.jpg
 

aluminiumbronze

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VOC Member
I think Neal Videan has made the rear side plates, out of curiosity what number is the red headstock, am looking for RC4689 for my red Rapide
 

davidd

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VOC Member
Roy,

Nice little project! You have two good location holes up front. I would use two measurements at the rear: from the valve cap receptacle on the head to the bottom of the oil tank, and from the hole center to the top of the side plate on the rear. This will give you a general location for the rear hole and provide the general position of the remaining front holes that will establish the rake.

With those two rear dimensions you should be able to finish up the front by welding the plates back on.
UFM Mod (1).jpg
You can make the front plates (I used two pieces on mine because it was easier). You don't need the holes in the plates. You can weld up one side and then transfer the holes through the FT1/2 and drill them. The other side can be completed and you can drill the other way. The holes in the FT1/2 were said to be reamed initially by the Factory. You may want to drill slightly undersized holes and ream them at the end. If your careful, I don't think drilling or reaming will make a difference that will be noticable.

Once the front is good and it is within the window that the two rear dimensions allow, I would do roughly the same on the rear. I would fix one side, mark the hole and drill it. I would then restore the other side (minus the slotted washer) and transfer the hole through the FT3. Once the two holes are established, you could then weld on the slotted washers that would finish the rear mount and mill the holes to fit the washers.

You have to be a little careful with the FT/3's. Often they are drilled all the way through, but not to size. You might want to run a reamer through the middle. Many were only reamed at the ends because the through bolt was small diameter, it was the ends only that were sized to fit. It is worth checking them. You don't want to use an undersized rod to locate the mounting holes.

This UFM would be ideal for a racer because you could steepen the rake by lowering the rear hole while doing the restoration. If anyone is building a racer, it would be worth trading Roy a good UFM for his.

David
 

Pushrod Twin

Well Known and Active Website User
VOC Member
I think Neal Videan has made the rear side plates, out of curiosity what number is the red headstock, am looking for RC4689 for my red Rapide
Thanks AB. The red paint is misleading, I'm sure it was bombed on later in life, possibly when the extra holes were drilled into it for what may have been fixed fairing mounts????
It is 4610, I believe from a Comet.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
I would use two measurements at the rear: from the valve cap receptacle on the head to the bottom of the oil tank, and from the hole center to the top of the side plate on the rear.
Thanks David. Yes, it is the height above the engine which I really need. I dont have a "standard" (no such thing! :D) Vincent available to take the measurement from. I do have my loosely assembled B engine which helps. How long is the slot?
Can I assume that the theoretical datum is an horizontal line through the crank and drive sprocket?
Or the two FT3 holes horizontal?
I could level the engine & pass a bar through FT1-2 & apply an inclinometer to set the head angle at 30Deg. (or less, as you suggest, it could stand up 5 degrees with no harm! Welcome to Chopper City!)
That said, I have a pair of Girdraulic legs & some other associated parts, I would like to build this one with Girdraulics, rolling element bearings, modified bottom yoke, coil-over shock, 21" front wheel etc. and dont want the front guard getting to close to the mag cowl!
20191231_194001_resized.jpg20191231_194839_resized.jpg
 

davidd

Well Known and Active Website User
VOC Member
I always reference off the bottom of the UFM. I use the bottom as level and measure from there. It is not that this is the most precise approach, but that it is more difficult to analyze other data accurately, or any more accurately than treating the bottom of the oil tank as level.

I have a mock up engine to test Egli frames on. I can help you out with any dimensions if you want to double check your initial work. The side car measurements might help, but there are so many variables from bike to bike that I think you would be better off copying dimensions from a stock RFM than trying to measure other points.

David
 

Attachments

oexing

Well Known and Active Website User
VOC Member
Hmmm, at around 1500 BP I might look into getting a new oil tank instead, considering all extra work you´d have to do with that f***ed up old piece of scrap to get all critical details right for a safe bike. Many hours to sink into that , for sure, including head scratching. And it does nothing for the identity of the bike either way as I´d see the head lug with its number to register it for road use.

Vic
 

Pushrod Twin

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VOC Member
Hmmm, at around 1500 BP I might look into getting a new oil tank instead, considering all extra work you´d have to do with that f***ed up old piece of scrap to get all critical details right for a safe bike. Many hours to sink into that , for sure, including head scratching. And it does nothing for the identity of the bike either way as I´d see the head lug with its number to register it for road use.

Vic
Thank you for your sage advice Vic. ;)Some of us enjoy the challenge of returning damaged pieces to useful service. There is satisfaction to be gained from starting with the remains of a worn out old engine with the gearbox chopped off and turning it into a reliable, usable bike. That was achieved over a long period of time for less than the cost of buying a complete bike. While 1500 GBP may not be a lot of Euros, it immediately doubles to become 3000 Pacific Pesos, ($NZ) then there is freight to the bottom of the earth and taxes on both the purchase cost & the freight, it becomes a bit expensive.
I will continue to rectify my old piece of scrap and have the satisfaction of knowing that I have made a safe, useful component to contribute to the preservation of another piece of motorcycling history, and I will keep you updated along the way. :D
The next step is have the tank "tanked" It needs to spend time in a chemical tank to remove the paint and whatever dried sludge may be living in the bottom before carrying out the weld repairs.
Classic Biker has PM'd me with dimensioned photos which have answered my questions, thanks Steve.
 

bmetcalf

Well Known and Active Website User
VOC Member
Several have found that chemicals don't get all the deposits out and install a Conways manhole or cut a window out of the side for mechanical cleaning. Any thoughts on doing that?
 

Vincent Brake

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VOC Member
Yust a question, before i start a difficult (well to me) surch;

WHO can sell me an ALUminum
HEADstock.

Please
 

Robert Watson

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VOC Member
Danny Smith found his alloy headstock about 1/2 way between his lathe and his mill. It did need a few extra bits of metal removing, have you thought of looking at the same place in your machine shop??
 
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timetraveller

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VOC Member
Talk to me Vincent. The ali head stock together with the ali JE steering head save about 5 kg weight. Can be supplied fitted with taper roller head races and fully assembled, with or without a hydraulic steering damper. Both types of head stock can be provided.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Yust a question, before i start a difficult (well to me) surch;

WHO can sell me an ALUminum
HEADstock.

Please
Vincent, for you an aluminium headstock would be OK if you machined one from a slab of 7075 or 7050, or better still, had one forged from same. However, I would be really reluctant to have one cast as I believe may have happened in Australia.
 

Pushrod Twin

Well Known and Active Website User
VOC Member
Several have found that chemicals don't get all the deposits out and install a Conways manhole or cut a window out of the side for mechanical cleaning. Any thoughts on doing that?
Yes, I have thought of that, and may follow down that path if I have any suspicion that the chemical, or rinsing,has not removed everything. Having once been in charge of an aircraft engine component cleaning facility, I have plenty of faith in, and respect for,hot caustic soda.I also need paint removed from the outside before welding.:)
 

timetraveller

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VOC Member
A question for Pushrod Twin, what happened in Australia with a cast aluminium steering head. The ones which I know of and which are being produced locally are LM25 heat treated. The casting shape is slightly beefed up in certain areas so is there evidence that there has been a failure somewhere?
Secondly, with regard to cleaning the inside of UFM. Good luck with the hot caustic soda but when I cleaned mine out I tried a variety of solvents and shaking a collection of nuts inside the oil tank and a pressure washer. I then cut a hole in the top for a manhole and there was about quarter of an inch of really solid black gunge in the bottom of the tank which required mechanical scraping to remove it. I could not have got that tank clean without the manhole. On another, I made the hole for the manhole and the tank was still completely clean inside. My guess is that it is a function of how the bikes have been used and what oils have been used as to how bad the problem is but you cannot see how bad it is without either a man hole or a fibre optic probe.
 

Vincent Brake

Well Known and Active Website User
VOC Member
Talk to me Vincent. The ali head stock together with the ali JE steering head save about 5 kg weight. Can be supplied fitted with taper roller head races and fully assembled, with or without a hydraulic steering damper. Both types of head stock can be provided.
Talking to you Norman:
Please send me only a B "Fork" type over.
Although i would use it on a C bike.
I will fill up the gap in the head FT3/2
And put interf fit bush in the lot with a M8 12.9 bolt to clamp up
So it stays as stiff as possible.

Thanx in advance
 

vibrac

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VOC Member
I think that in the perfect world Time traveler is right and if I ever get to that sort of strip down I might do as he suggests however the key word in his posting #15 is "solid" if the muck is solid it aint going anywhere fast by definition its a deposit its not in the oil flow it has been exposed to hot oil and high vibration for seventy years however remember these two points:
A. dont use modern detergent oils
B. change the oil and filter at high frequency

I wont clean the RFM on my racers, hells teeth there might be some mineral oil lurking in those solid deposits!
 

peter holmes

Well Known and Active Website User
VOC Member
Talking to you Norman:
Please send me only a B "Fork" type over.
Although i would use it on a C bike.
I will fill up the gap in the head FT3/2
And put interf fit bush in the lot with a M8 12.9 bolt to clamp up
So it stays as stiff as possible.

Thanx in advance
Vincent, Oh dear, M8 12.9, Brexit can't come quick enough, lets get these foreigners out of the club, metric indeed!
 

timetraveller

Well Known and Active Website User
VOC Member
Just to worry you Vibrac; after I had the UFM clean I decided I would see how much dirt there was in the oil ways in the timing cover. It was not just dirty oil in there but something more determined. It took quite a long time before the dark material stopped flowing. No chunks of shiny aluminium like an oil filter but just black dirt of some sort.
 

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