F: Frame AVO COIL OVER WANTED HELP PLEASE

[kerry]

Hello Brian,
Thank you for your suggestion, to conclude what happened, on the Wednesday I bought a Knight, the previous owner to last was Frank Griffin,
Being 5ft 7" the first thing I intended was to buy the short version coil over from Avo but found out they had shut down the day before,.
I bought from one of their customer an 11" Avo which once modified

with help of course seems to me to be very similar to the one supplied by Avo.
It has actually lowered the bike just under 1,1,2"
I tried the bike today for the second time and have to say it gives a smoother softer better ride than my C Shadow, especially good over speed bumps.
Drawing below.
I am trying to find out a bit more on this bikes history now and have found a couple of bit's on old forum posts with Frank Griffin too, I understand now he was a real Gentleman and very much A Vincent Man
So thanks to all.

 

[timetraveller]

Thanks Brian, I will try them. Norman

 

[twobyfour]

Protech's website looks very interesting. Adjustable dampers from 10" upwards and any size/rate of spring we could need. Also, the spherical bearings should be an improvement over the plain, single-plane tube mounting of the AVO's.

A really useful contact, Brian! I look forward to hearing from Norman after he has been in touch with the firm.

Allan.

 

[Peter Holmes]

Wow, what an incredible find, they even have a custom build form you simply fill out with your requirements, down to the last detail and they presumedly send you a quote, and they look good, lets hope they are good.

 

[timetraveller]

Just to keep you up to date, I spoke to the mobile number which Brian gave us and that chap is at home with a bad back but he passed on my interest to someone back at the factory and I am waiting for a call back. Note that our front AVO dampers are only 8" top eye centre to bottom eye centre which might be too short for them. I will post more when I have it.

 

[timetraveller]

OK Just spoke to their chap and I will send them a front AVO down to check damping rates, total travel etc For the rear of the 'B's and 'C's I need to have feedback from others. First note that I am only considering fully sprung rear ends. My own feeling is that the extra movement at the rear with the rear of the seat bouncing up and down is likely to be unacceptable to most people. In order to get the full movement AVO had to resort to an offset lower mounting. There has been some problem with the upper mounting bending the rear of the oil tank. It seems to me that a case could be made for returning to two units, one each side, as the original spring boxes, which means the the forces involved would be taken nearer to the supports and that would prevent the bending problem. I am proposing two coil overs at the rear, with adjustable damping and with shrouds to hide some of the spring length. Given two units the spring rate should probably be about half of the AVO one, say half of 275 lbs/inch, 140 each and, of course, they would have adjustable pre-load as well as adjustable damping. The damping rates would have to be specified by the manufacturers who will have more knowledge than I do about such matters. Feedback, ideas, please.

 

[brian gains]

I don't know if this has been mentioned in this thread previously, however one thing to be aware of as Dave Hills said 'decide on what rear springing you are going to use first as this may affect the height of the main stand you need or the efficiency of the one you have'.

 

[BigEd]

OK Just spoke to their chap and I will send them a front AVO down to check damping rates, total travel etc For the rear of the 'B's and 'C's I need to have feedback from others. First note that I am only considering fully sprung rear ends. My own feeling is that the extra movement at the rear with the rear of the seat bouncing up and down is likely to be unacceptable to most people. In order to get the full movement AVO had to resort to an offset lower mounting. There has been some problem with the upper mounting bending the rear of the oil tank. It seems to me that a case could be made for returning to two units, one each side, as the original spring boxes, which means the the forces involved would be taken nearer to the supports and that would prevent the bending problem. I am proposing two coil overs at the rear, with adjustable damping and with shrouds to hide some of the spring length. Given two units the spring rate should probably be about half of the AVO one, say half of 275 lbs/inch, 140 each and, of course, they would have adjustable pre-load as well as adjustable damping. The damping rates would have to be specified by the manufacturers who will have more knowledge than I do about such matters. Feedback, ideas, please.

Feedback:-
I have an AVO coil-over on the rear of my Rapide and a concentric conversion with an AVO damper on the Girdraulics so personally I am all set. A few thoughts that may be relevant. If you are bothered about originality (not a consideration for me) a single damper unit between the rear springs looks pretty good with the AVO damper and looks not too different so something similar would possibly be acceptable if the price was reasonable. Two coil-over units could maybe could be made to look somewhat original but they would be easier to spot due to their position as far as originality goes. Also, two coil-over units would be more expensive if you are looking for a budget solution.
Probably overthinking before we know what might or might not be available Protech.

 

[oexing]

Well, my view on this matter is , liberate your thinking from coil over monoshocks ! These got their flaws and limitations as I have mentioned above. I wonder how much stroke the coiled shocks got in the photo above, with adjusters plus bump stops on ?? Not even 75mm / 3" I guess ?? Yes, monoshock at the rear is not the best idea, bending bolts and all, plus the space there does not offer much travel for the shock, 250mm / 10" between centers oiginally.
So I found an option in the offroad biker world, an air shock with exactly 250mm between centers - and all imaginable settings you´d ever want. There are not many offers at reasonable price of around € 300.- and 250mm length, travel is 75mm !! Bump stops not much required as air gets very progressive with air space compressed as it approaches full stroke. Preload is easy for any application as you fill air to your desire for one third "sag" when stationary seated on bike. Certainly I expect you change oil fill for a heavier grade on a motorbike for getting hydraulic damping compression and extension more effective - no big deal. Plus the airshock is servicable at home , spares are cheap, no need to buy a number of springs when first or second try was not quite as desired - and all that shipping around when only the factory can do tweaks. This was exactly my reason not to pursue AVOs and all for hopefully arrive at a damper one day that suits my bikes.
The SR Suntour Triair airshocks got 300 psi/20 bar max pressure so two of them at the original place at the rear should do nicely - well, looks not quite like the spring boxes, but less obvious than coilovers - and don´t bend bolts, while offering 75mm travel.
Funnily an SR Suntour seems to be had below € 300.- in my country at lower prices than from UK or US, so you´d google for dealers for getting the 250mm/75mm type, not so easy to find.
Anyway, we´d need someone for test driver now. I´d think you can stick the airshock on the bike same day, just maybe the eye bushes will have to be made for the bolts on the rear. See some SR Suntour Triair Youtube clips for learning what stresses the bike shocks endure, mud , jumps and all, so when you keep anodised parts clean they should last a long time , spares are quite cheap for services. So what´s not to like about these, tick most boxes for our needs. And Norman will be not bored saving him from finding manufacturers for AVO alternatives, got more jobs already to stay entertained.
For the girdraulic I think the SR Suntour could be overstressed at 300 psi, don´t know what that means in forces and ride height. And end lugs cannot modded on the SR Suntour for bolting them on the girdraulic , so any ideas for this ? Certainly a Fournales special can be made that will be the optimum, at a cost. But the ride will be worth it I strongly believe. Some on here can recommend Fournales on bikes for nice rides.

Vic
Ebay SR Sunride:
SR Sunride

dealer low price:
SR Sunride 250mm

Youtube clips:
YT SR Sunride

 

[timetraveller]

Just watched some of the videos Vic. Very impressive but I can't see me trying some of those stunts. Two things occur to me. How easy is it to get 20 bar pressure and where from. Secondly, some of the units have the extra cylinder on the side. If mounted centrally under the seat with the secondary cylinder above the main cylinder that would probably not fit between the main cylinder and the base of the seat and if it was mounted below the main cylinder I suspect it might hit the battery on a twin. There is also the problem of the top and bottom spherical mounts. Is that something that one can buy or would they have to be designed and made. Remember, I try to make, or do, as much of the work as possible before shipping the units as many people do not have access to the skills to make this kind of thing.