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FF: Forks Brampton forks

Robert Watson

Well Known and Active Website User
VOC Member
What is the current thought and supply like for a coil over shock for a Brampton front end for a B twin? I haven't really followed this for the last couple of years.
Thanks
 

timetraveller

Well Known and Active Website User
VOC Member
How long ago was that? For a while I was sending out 45 lbs/inch springs and the stiffer AVO damper following road tests over here. However, with more feedback it turned out that was too stiff for all but the heaviest people on twins and nowadays for medium weight people I supply 36 lbs/inch springs and the normal AVO damper. the stiffer damper can be converted back to a standard one by AVO for about £30 but whether they would be happy to do that for a customer in Germany I don't know. If they won't do it and you can get it to me than I could get it done for you.
 

oexing

Well Known and Active Website User
VOC Member
My idea for the Brampton - and the rear suspension - was to get something I can adjust in all ways to my liking. So no readymade shock would do as you always want it a bit different to what you can order. So I came upon the the Fournales oleopneumatic like they designed in aviation. The Fournales is an all threaded design with standard hydraulic seals , oil filling and air pressurized. No bump stops required , the air content does same function, and progressive action is set by the volume of oil and air inside. The damping valve is a very simple design you could fabricate , like the rest, on the lathe. The o.d. of the shock is less than 50mm and extremely lightweight, 800gr . So maybe Fournales would be willing to do specials for Vincent. I will have the upper shroud black, so looks will be close to standard and suitable at the rear as well, no extra damper for damping is needed.
Anyway, when fabricating upper and lower joints for a damper I strongly advice to have some give in the eyes as you do not want any sideloads on piston rods from questionable brackets on the fork or frame . Mostly rubber bushes are pressed in damper ends for this purpose, I got me IGUS spherical slim bushes for my dampers as space around frame is limited. So this would be my approach to have specials made for Bramptons and rear suspension too, like Fournales do with spheric bushes , no rubber . By not taking care for some misalignment in brackets you may be very sorry later as we have seen broken piston rod threads - and not by overload in pure tension load but from cracking by sideload !! So when looking into photos above I don´t like forked joint ends plus bolt as no compensation for misalignment , better have spherical bushes with corresponding bracketry. Sorry, no pattern for the lower Brampton bracket to show, as I am still busy with other items.

Vic

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vibrac

Well Known and Active Website User
VOC Member
AVO re valved the rear unit on the racer to make it harder I see no reason why they cant revalve a front one It was a very reasonable charge just specify your needs in relation to the minimum setting
 

Bill Thomas

Well Known and Active Website User
VOC Member
Should you not wait till Winter?
You say you are going with needle rollers ??
That will mean you will need a stiffer shock ?,
So what you now have will be better ?.
Cheers Bill.
 

timetraveller

Well Known and Active Website User
VOC Member
I supply the Greg Brillus mod of fitting two ball races at each side, four in total. They are 7 mm wide, total of 14 mm each side and I have to use shims out of a selection of 0.1, 0.25 and 0.5mm to centre the link on the concentrics. The needle rollers that others have used are 2 mm wider than the eyes. If you are still using the Oilite bushes then Bill is correct. You will be amazed at how much difference moving over to a modern bearing system makes.
If you tell me the number stamped onto the lower body of the AVO damper I can tell you whether is it the one that you need and under what combination of parts.
 
Last edited:

Martyn Goodwin

Well Known and Active Website User
VOC Member
Alyn Vincent had got involved in this project before Covid struck, understandably for now it seems to have stalled, but I think his intention was to use an IKON damper as the basis of his conversion, IKON is virtually the old Vincent Koni damper, adapted to take a coil over spring.
Alyn is very unwell in cardiac intensive care, but his condition is stable. Could be a while before we hear from him on this forum
 

MarBl

Active Website User
VOC Member
You say you are going with needle rollers ??
Yes, I go with the 16mm wide ones.
needles.jpg
If I am lucky, it will allow the reuse of the avo 1447.
But I'll still try to find the optimum, so I will test the IKON with its different valves too.
A more modern solution with adjustable stroke and expansion would of course be even better (and obviously much faster to optimize settings).

Sorry for hijacking the Brampton discussion.
 

Peter Holmes

Well Known and Active Website User
VOC Member
This was John Renwick's solution to the Brampton Forks coil over challenge, it is fitted to Harvey Bowden's Rapide, sadly we have no idea what coil over suspension unit was used, and sadly we are unable to ask John now, it looks like John removed some metal from the bottom shock fitment, but did not strengthen the headlamp bracket or remove the forged in bracket for the standard spring , so totally reversible should you want to.IMG_2750.jpegIMG_2751.jpegIMG_2752.jpegIMG_2753.jpegIMG_2754.jpegIMG_2755.jpegIMG_2756.jpegIMG_2757.jpegIMG_2758.jpeg
 

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