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F: Frame Series ‘D’ Rear Bodywork mounting to Series ‘C’ Comet



craig

Well Known and Active Website User
VOC Member
#1
I want to mount a series D closed fiberglass tail to a series C Comet.
Can this be done?
do the mount points allow for this?
Has anyone done this and can address any issues?
Thank you
Craig

Here is a photo of an open series D for ref.

SeriesDRightSideView2.jpg
M091D.jpg M090D.jpg
 
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peter holmes

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VOC Member
#2
I think there are a couple of replica Victors around, Brian Wherritt had his at this years annual rally, very nice it was to, so it can be done, not sure how to contact Brian though, I have never seen him on this forum.
 

vin998

Well Known and Active Website User
VOC Member
#3
Spoke to Brian at the Annual about his Victor replica and he had a lot of problems fitting bodywork to the Comet. There are a lot of things that are in a slightly different position to a twin such as the swinging arm pivot which changes the mounting position of the bodywork.
I don't believe Brian is on this forum.
 

timetraveller

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VOC Member
#4
I'm going to try to make some helpful comments here but note that I have never done this conversion. However, I do own the original works prototype Knight and can see some of the things they had to do. First, it depends upon whether you wish to continue to use the original UFM. oil tank etc, or try to make a Victor. If the latter then you can use the original wheels, forks, engine/gearbox and so on but you will have to buy, and modify, a 'D' UFM, rear end, oil tank, and rear frame triangle (more on that later) and some method of supporting where the rear cylinder would be on a twin. If you wish just to fit the rear enclosure on to the original UFM then you will find these problems, There might be more. You will need the long stud and special bolts etc which act as the pivot and locators for the rear frame and support for the lower front end of the rear enclosure. You will then find that the top pivot for the upper front fixing of the rear end is too high and you will have to make something up to extend the holes at the rear of the 'C' UFM upwards to allow for this height difference. This does not immediately solve the problem of the fixing point for the hinge at the front of the 'D' saddle but some ingenuity might get round that. You are now left with at least one other problem.. The rear cowl is held in the 'up' position by a prop such as holds the bonnet/hood up on a car. On the 'D' rear frame triangle there is a hole for this purpose. On the prototype, which was built using a 'C' RFM, a piece of tube had been welded or brazed onto the top of one of the RFM upper tubes to take the lower end of this prop. You now have to consider the bracket which supports the silencer. On the prototype this was made of part of an original aluminium rear footrest plate and part of a rear brake torque arm. When I bought this bike, well over 50 years ago, I had no idea it was the prototype and so I replace the fabrication with the proper 'D' component. To ease the worries of those who think we should preserve such artefacts I have saved many of the parts which I took off to replace with more robust items. Do you wish to use the 'D' centre stand? If you do then you have to obtain all the parts to go with that including the pivot plate. I'm pretty sure that I have seen 'C' mudguards used inside 'D' rear cowls. However 'D's had a short steel mudguard at the front with an inclined flat piece of steel welded to it. The prototype had this fabricated from part of an aluminium mudguard to which had been welded a flat piece of aluminium plate. Once I started using the bike this fatigued rather quickly and was replaced by the standard 'D' item. It has long seemed to me that this would be much better if it was replace by a fibreglass component which could be made wider to allow wider tyres to be used and could be moulded in such a way that it was also the chain guard.
Over to you.
 

b'knighted

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VOC Member
#5
I have an open D seat frame converted to fit Comet dimensions, it also has a Craven carrier welded into the back. It appears to have some angles changed and some tubes lengthened but i don’t know how much was to enable fitting and how much was to facilitate the carrier clearance (with Thornton coilover rear). Brian’s Victor uses a D UFM so would present different problems. The D seat hinge mounts on the rear tank mount bolts, the rear cowl pivots on a tube a little behind this. If the Comet UFM seat mount is not in the correct position to pivot the cowl it could carry a bracket with spigots for the cowl to pivot on. These brackets may need bracing to the sidecar mounting hole. Similarly if you have a standard twin rear cowl and don’t want to alter its frame (which I’m sure will be too wide at the swinging arm pivot) you could fit studs on brackets from the pillion plates, if need be to locate with new tubes bolted into the tapped lugs inside the cowl.
 

b'knighted

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VOC Member
#6
You will also need to replace the Tommy bar spindle with a D style hex headed bolt., The short mudguard has been produced in grp but I had to carve the flat plate away for side clearance. I don’t know where my grp guard came from but
I suspect the WCS had a mould for them.
 

davidd

Well Known and Active Website User
VOC Member
#7
Craig,

From the above descriptions it is clear that it the project is feasible. Many Victor replicas have been built. I believe the real question is "do you want a Victor replica or a Comet special?" If you are a fabricator the special is a reasonably easy job. You just need to mount the fairings by fabricating the brackets you need. If you are making a Victor, you need to source a lot of hard to find parts and do a lot of fitting and assembly with a small amount of fabrication.

Most owners will not weld brackets on to their original parts for fear of compromising their investment, which is not really a problem, but it is a psychological barrier for most. Then there is the glass issue. If you are using old glass it is very difficult to fix or modify. Many decades of being oil soaked has allowed that oil to wick into the glass fibers and many parts of the glass is contaminated to the core. This is less likely to happen up front, but more likely for the sides and rear.

I think the special would be the way to go, but I enjoy fabrication.

Victor.jpg

Norman & Ian,

The FT149/3 is the metal mudguard. It is designed to nest with the SL6, which is shown in the D enclosures above on the bottom center of the drawing. Although it is shown as a separate piece, it was glassed into the tub. These parts tended to have short lives because the mated rather closely for the purpose of closing off much of the tub to water and dirt spray.

Cyril used to make enclosures, but did not make GRP FT149/3's. It is an easy part to make. I made quite a few in GRP, but I don't remember sending any to the UK. I got mine from Pip Harper. Maybe Pip made them.

David
 

b'knighted

Well Known and Active Website User
VOC Member
#8
I have my Knight's original cowlings and covers and the RFM did have a section of steel mudguard fitted, ragged at the top level with the top of the RFM presumably where the plate had broken off in the first decade of the bike's life. I bought an unused set of Pip Harper's moulding but they didn’t include this rear guard. These mouldings are painted. The grp rear guard is self colour black but does not appear to have the same quality of high gloss gel coat that most of Phil Primmer's products have. I don't recall where it came from, around the turn of the century, but it doesn’t look like it was made by Pip or Phil. Maybe it was made by Cyril.
 

davidd

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VOC Member
#9
The FT149/3, if metal, is often bent straight up at the top where it is level with the top of the RFM. This bending is done by owners who want access to the lower shock mount of the D shock on the RFM. Otherwise, you have to take the mudguard off to get good access. If bent straight up it can still clear the SL6, assuming it is still in place.

I picked up two complete sets of enclosures from Pip. The GRP FT149/3's were included in both.

David
 

craig

Well Known and Active Website User
VOC Member
#10
I am just trying to create a Comet Special by adding a D tail to a D fairing equipped Comet. No side covers or front mudguard.
So my concern over the mounting and clearance is the C rear wheel/brake/linkage, C rear fender, C rear fender braces. I was planning on leaving as much C components as could be allowed.

My motivation is - this D rear section I am eyeing has the rear molded bags ( Phil Primmer, I think).



 

davidd

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VOC Member
#11
Craig,

You can do that. The tub is a little wide at the front without the side panels closing it back down, but that should not be a big problem. The single rear brake on the D is operated by a cable. No rear fender or brackets are necessary. The difficult part will be the hinge arrangement at the top front of the tub which attaches to the UFM. Someway, the hinge has to mount to the RFM. The tub frame has two top tubes that each have a small tube attached at 90 degrees. A spindle pokes through the end, then through the UFM, and then the remaining tube on the tub to make a hinge.
1955-Vincent-Black-Prince-Project-Bodywork-1-550x412.jpg
The bottom mount is a robust slotted tube that slots on to a longer pivot bolt. The end nuts, when tightened, turn into a counterbore on the tube that locks the bottom in place.

David
 

craig

Well Known and Active Website User
VOC Member
#12
I am concerned about the dual rear brake C system. Can I mount the existing C Comet brake arms in the low position and still hook them up?
Major mod needed here for rear brakes?

CometRearBrake3.jpg

I wanted to retain the Comet rear fender front section, remove lifting handle, relocate rear brake light switch, Fab an upper mount and lower mount, relocate horn, take off rear stand, take off rear fender flap............bolt this D tail on, wire as needed, and go!
Maybe add Hill center stand.

IMG_8163Mar8small.JPG

Thank you all for help in this project.
Cheers
Craig
 

vibrac

Well Known and Active Website User
VOC Member
#13
You can easily remove one brake drum from a Comet then its just a case of one cable to the rear drum with the sprocket. An alternate is use a sprocket carrier and have one drum like a D twin but on the off side.
I would just forget the cross shaft gubbins and RH drum
Our Comet Racer never had two drums on the rear
 

craig

Well Known and Active Website User
VOC Member
#14
So about these upper and lower mounts differing from a twin.
You think a simple bracket will allow this?
maybe this new bracket triangulated to the sidecar/horn RFM lower tube?

What about the C rear spring boxes interfering with this bracket or tail section?

Will the lower mount (swing arm pivot) be moved forward on a Comet? Causing this D tail to droop down at the rear?


CometUpperMount3a.jpg
 
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davidd

Well Known and Active Website User
VOC Member
#15
Craig,
So about these upper and lower mounts differing from a twin.
You think a simple bracket will allow this?
maybe this new bracket triangulated to the sidecar/horn RFM lower tube?
Starting with the hardest mod first, I would recommend taking the frame out of the tub and once it is modified, refitting the tub to the frame. The swing arm pivot on the Comet is 1/2" forward and 1" up or higher on the Comet than it is on the twin. It could be that you could add an extra free standing pivot to the Comet just to be the lower mount. It is difficult to say without the pieces at hand. Also, the pivot needs to be fairly robust as the entire tub is cantilevered off the swing arm pivot and the top mount. The top is in tension and the swing arm pivot is in compression and has to take all the weight of the riders, tub and gear.

If you look at the Victor photo you can see how much higher the swing arm pivot is. In the photo of the tub for the twin the pivot is at the bottom of the glass and on the Victor it is up much higher.

As for the upper mount, if you remove the frame and modify it you can use it on any of the existing upper tubes. The seat tube may do. I have slotted the sidecar tube and moved the damper and spring boxes down there, so if the height is closer to the second tube down you could do that. Additionally, you can do something like the Reg Bolton mode to bolt to the UFM and move the seat and/or suspension back from the UFM.

I do not know about the twin brake rods because the D RFM does not have the means to mount them so I am not sure about the clearances. However, I would think they would work as is. I don't think the rear guard will fit in the space between the wheel and the tub. As for the brake switch, the stock D brake switch on the balance beam is far safer for all Vincent riders.

Personally, I would separate the frame and the tub as mentioned. It will allow you to modify the frame to fit the way you want, including the seat height and you can put the tub on and trim it to fit well on the bike.

David
 

craig

Well Known and Active Website User
VOC Member
#16
I went out , took the Comet rear stand off , rolled the left rear brake arm to the low position, and hooked up the rod mechanics to see what happens. Not sure about doing this on the right side of the Comet yet.

I want the D series fiberglass, steel tub/frame transferable between a Comet/Rapide/Shadow....so that is my goal.
I need bracketry for the Comet to allow this ....so I may have to move the tub an inch (maybe ½") to the rear on the Comet and come up with top tube and bottom studs.

20181201_201616.jpg
 
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timetraveller

Well Known and Active Website User
VOC Member
#20
Note that the three tubes at the rear of the 'C' UFM are not all the same length and you cannot just put a straight plate against them. You will need packers or to chop the UFM about.
 


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