Fully floating seats and stays.

Michael Vane-Hunt

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Martyn said: ......... said:
Moving to a fully suspended seat is not just a matter of removing the rear FT94 friction struts and replacing them with a straight strut from the seat to a suspended part of the bike. Do this and you may well have serious issues. You need to ensure at least 2 things. 1. that there is no new stress applied to the seat frame and second, that there is no way that any part of the rear suspension can hit against the new seat strut you plan on installing. There will be a detailed article on this in OVR within a next few months. Just to keep you alert to the problems - here is a photo of what happened to a seat frame after a 'simple' strut was used to effect a fully suspended seat. Not nice.
MartynView attachment 15952 [QUOTE/]

Martyn. Is there any chance you could post some pictures of the struts you have put on your bike? Mike.
 
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timetraveller

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The damage shown in Martyn's photograph is what I would expect if the strut to support the rear of the seat is positioned too far forwards at the bottom. It is quite common to see photographs of bikes where people who have done this mod have tried to emulate the appearance of the open 'D's by fixing the lower end of the strut near to the pivot of the rear frame triangle. The 'D's got away with this by having two top tubes to their rear frames about one inch diameter. These supported the weight on the seat and prevented the whole lot pivoting backwards. The two thin supports at the front of a 'C' seat are not man enough for the job. Some people weld a triangular gusset behind those supports but there is a limit to how far this can extend rearwards if one want to use the tool box. In my own case I used two steel tubes, about 17.5" long. At the top these fasten into the two brackets at the rear of the seat which originally took the top of the friction damper arms and at the bottom fasten into the two top most rearward holes in the pillion footrest plates. This means moving the pillion footrests about half an inch forwards but the holes for this are already present. At the bottom, the rear fastening has to be spaced outwards by about half an inch or otherwise the brackets on the rear frame triangle, which originally took the friction dampers, will foul the inside of the two new struts.
There is one rider in the south east of England who has a very neat mod. He uses two thin tubes, fastened at the top and bottom of the rear of the pillion footrest plates. These extend upwards and fasten into each side of the drum in the friction damper. This forms a triangle which intrinsically stops the tension in the seat base acting as a rotation stop and it takes a long time before one realises that the friction dampers are only acting as supports and not being allowed to rotate at all. I don't have any photos of this but one of his local section members might well be able to post a picture of the mod here.
 

vibrac

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My seat supports on the racing comet are just 3/4 alloy square section they are simply bolted to an inverted U section of alloy that takes the seat and also hold the number plates and help secure the silencer (basically in a spacer role) they mount as far back as the abbreviated footrest plate allows. the support stays were in steel but after fifty years of weight reduction within the pre 48 regs they had to go. Its a relief I don't have to save any weight this year as we are taking a busmans holiday. PS we are still on half inch of broom handle perhaps in 2018.... so long as the MSS saves weight as well as improving the fork action.

upload_2017-2-17_11-24-6.png
 

greg brillus

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there's only one place I can think of to use a piece of broom stick on a Vincent and it aint nowhere near the suspension..............o_O
 

davidd

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Having a seat come loose is wildly dangerous. I used the F106 as a support to keep the weight down and to keep the struts well inside. This makes mounting a high pipe and clearing the rider's leg easy. I have the spring off the damper to set the height of the seat.

AHRMA Seat 3.jpg


David
 

timetraveller

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Where is it attached at the bottom Ernie? Top rear of pillion footrest plate if it is like mine It is very shiny. Is it stainless and I like the adjustment built in?
 

ernie

VOC Assistant Secretary
VOC Member
If you are talking about the seat supports they are chrome. Standard seat-stay brackets into a nut welded on top. I wish I could remember who made them! Did a few thousand miles with Craven Comet panniers and Jenny on the back until I got my GIVI set-up. The rack struts are 3x20 stainless from Metals4U and I needed acetylene to heat and bend them. Can be done with 2 butane blow torches but they take an age to heat up. I never got round to polishing them. I still have loads if you need any.


GIVI set-up with a
xhg6uYoCQ7qwVrhHJfzuhQ_thumb_83.jpg
 

BigEd

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VOC Member
VOC Forum Moderator
Martyn said: .................................
Moving to a fully suspended seat is not just a matter of removing the rear FT94 friction struts and replacing them with a straight strut from the seat to a suspended part of the bike. Do this and you may well have serious issues. You need to ensure at least 2 things. 1. that there is no new stress applied to the seat frame and second, that there is no way that any part of the rear suspension can hit against the new seat strut you plan on installing. There will be a detailed article on this in OVR within a next few months. Just to keep you alert to the problems - here is a photo of what happened to a seat frame after a 'simple' strut was used to effect a fully suspended seat. Not nice.

MartynView attachment 15952
 

Martyn Goodwin

Well Known and Active Forum User
Non-VOC Member
Martyn said: .................................
Moving to a fully suspended seat is not just a matter of removing the rear FT94 friction struts and replacing them with a straight strut from the seat to a suspended part of the bike. Do this and you may well have serious issues. You need to ensure at least 2 things. 1. that there is no new stress applied to the seat frame and second, that there is no way that any part of the rear suspension can hit against the new seat strut you plan on installing. There will be a detailed article on this in OVR within a next few months. Just to keep you alert to the problems - here is a photo of what happened to a seat frame after a 'simple' strut was used to effect a fully suspended seat. Not nice .

MartynView attachment 15952
P1060031aaa.jpg
OK here is a teaser photo of the solution I came up with - full article in OVR, April 17
 
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