Very Cool.
Steven
Steven
New AVO coil-over for B and C series, plus damper update.
- Thread starter ClassicBiker
- Start date
Although coil-overs for the C and D are already well established, I was concerned about the redistributed suspension loads. For this reason the bottom mounting has been made much wider so that the suspension loads on the bottom bolt are nearer to the RFM bearings, to ensure the bottom bolt does not bend. Plastic bushes are also used to introduce a bit of compliance. I thought this was a useful precaution, as a lot of different parts of the bike have to be machined and assembled with perfect accuracy if the damper mountings are going to be perfectly aligned and square to each other. No wonder the D series coil-over was rubber mounted! The top mounting also has a steel bush rather than a bronze one. This is so that the top bolt can be tightened firmly, improving the rigidity of the top mount. With the bronze bush fitted, anything more than gentle pressure causes it to be crushed onto the bolt by the spacers.
From a cosmetic point of view, at my request the alloy bits have been left natural. AVO would normally have red anodised them, which looks a bit anachronous.
As was my intention, I think the appearance is a lot like the D series. Can anyone tell me if the D series coil-over was bare as standard? Many bikes seem to have rubber bellows/gaiter fitted, but was this a rider mod? If so, who supplies the bellows?
For convenience, four steel bushes are also supplied to replace the spring eyes so that the original spring bolts can be used.
The first prototype used my original Vincent D8 top mounting. This proved the design worked, so AVO then designed and produced their own slightly modified version of D8 that is better able to support the spring collet. (This new D8 is also now used in the ready-t0-fit dampers.)
The second prototype then went to Big Ed, who did the two-up testing.
After I had done 1000+ miles and Big Ed had done 2000+, AVO had both units back and stripped them for inspection. Both passed with no problems, so I have a lot of confidence that riders will find them easy to fit, very comfortable, and reliable. They can also be rebuilt by AVO, but I think they would go a very long way before that is required.
As requested, this is the appearance on my bike. My cobbled-together-in-a hurry luggage rack rather gets in the way, but I can assure you there are no clearance problems. The offset bottom mounting lifts the unit well clear of the battery.
This is the revised damper, now sold complete and ready to fit
Damping adjustment on all units is by allen key.
Coil-over price is £200 +vat. Dampers are £140+vat.
Thanks to both you and Big Ed for all the time and effort you have put into this.
This has just made it to the top of my must have for my Vincents List.
Steven
Steven
How do I go about getting them?
Steven
Steven
AVO UK Ltd, Caswell Road, Northampton, NN4 7PW, phone 01604 708101.
Website : http://www.avouk.com/ -but Vincents dampers etc are not on website.
A note about “short” and “long” versions of AVO rear dampers and coil-overs.
When I developed the first AVO rear damper in 2012, my primary objective was the shortest possible closed length, but combined with a long stroke. This is why the rear mounting is offset.
The purpose of this short closed length was twofold.
The first was to make the best possible use of the short standard springs. When the shortness of the standard spring results in much less than 1” of bump travel, even a ¼” gain is valuable.
The second was a low saddle height.
However, I recognised that if this short damper was fitted to a bike that had been converted to a fully sprung seat, it became quite likely the mudguard would hit the seat at full bump on many bikes. As there is so much variation between bikes, the only way to be sure is fit the damper only, lift the wheel and see what happens.
So we produced a second “long” version of the rear damper that had a similar closed length to the original Vincent damper and would be a “safe” choice for everyone.
Four years on the situation is a little different. The benefit of the extra short damper is diminished by using different springs. The remaining benefit of a 3/8” lower seat is unimportant to many riders, or at least does not justify modifying the seat/mudguard clearance. Lastly, the different combinations of specifications required AVO to frequently make-to-order, which is inefficient because of set-up times.
For these reasons, the “short” rear dampers will be discontinued when existing stocks are exhausted.
HOWEVER, as a favour to me, AVO have produced just one batch of “short” coil-over units.
They will not be advertised, but if like me you have weak and wobbly legs and appreciate even a slightly lower seat, you can order a short version of the coil-over or a short version of the new “ready to-fit” rear damper, while stocks last. Same prices!
There are two caveats:
1) You will have to decide for yourself if a short unit will fit your bike without seat/mudguard clearance problems. See info below. To the best of my knowledge, there will not be any problems with the original semi sprung seat set up. But if you have (or may) convert to a fully sprung seat, problems are fairly likely. I lowered my mudguard, but you may not want to go to this much trouble.
2) The “long” version of the coil over has a very convenient facility that it is just possible to change the spring without a spring compressor. With the “short” coil-over, a spring compressor is definitely required.
Info you may find useful:
Standard Vincent damper closed length 7.188”
“Long” AVO coil-over or damper closed length 7.195”
“Short” AVO coil-over or damper closed length 6.96”
These AVO closed lengths are calculated by estimating that in the worse case the suspension will come to a halt when the 20mm rubber bump stop is compressed to a length of 8mm by a force of over 1200lbs. (This is in addition to the spring force of around 800 -1200lbs, so it would need to be a BIG bump with a heavily laden bike.) Bump stop calibration curve available on request!
The minimum length of the Vincent damper is much easier to define, as the hydraulic stop is very short and stiff compared to a rubber bump stop, which provides a much nicer progressive rising rate.
When I developed the first AVO rear damper in 2012, my primary objective was the shortest possible closed length, but combined with a long stroke. This is why the rear mounting is offset.
The purpose of this short closed length was twofold.
The first was to make the best possible use of the short standard springs. When the shortness of the standard spring results in much less than 1” of bump travel, even a ¼” gain is valuable.
The second was a low saddle height.
However, I recognised that if this short damper was fitted to a bike that had been converted to a fully sprung seat, it became quite likely the mudguard would hit the seat at full bump on many bikes. As there is so much variation between bikes, the only way to be sure is fit the damper only, lift the wheel and see what happens.
So we produced a second “long” version of the rear damper that had a similar closed length to the original Vincent damper and would be a “safe” choice for everyone.
Four years on the situation is a little different. The benefit of the extra short damper is diminished by using different springs. The remaining benefit of a 3/8” lower seat is unimportant to many riders, or at least does not justify modifying the seat/mudguard clearance. Lastly, the different combinations of specifications required AVO to frequently make-to-order, which is inefficient because of set-up times.
For these reasons, the “short” rear dampers will be discontinued when existing stocks are exhausted.
HOWEVER, as a favour to me, AVO have produced just one batch of “short” coil-over units.
They will not be advertised, but if like me you have weak and wobbly legs and appreciate even a slightly lower seat, you can order a short version of the coil-over or a short version of the new “ready to-fit” rear damper, while stocks last. Same prices!
There are two caveats:
1) You will have to decide for yourself if a short unit will fit your bike without seat/mudguard clearance problems. See info below. To the best of my knowledge, there will not be any problems with the original semi sprung seat set up. But if you have (or may) convert to a fully sprung seat, problems are fairly likely. I lowered my mudguard, but you may not want to go to this much trouble.
2) The “long” version of the coil over has a very convenient facility that it is just possible to change the spring without a spring compressor. With the “short” coil-over, a spring compressor is definitely required.
Info you may find useful:
Standard Vincent damper closed length 7.188”
“Long” AVO coil-over or damper closed length 7.195”
“Short” AVO coil-over or damper closed length 6.96”
These AVO closed lengths are calculated by estimating that in the worse case the suspension will come to a halt when the 20mm rubber bump stop is compressed to a length of 8mm by a force of over 1200lbs. (This is in addition to the spring force of around 800 -1200lbs, so it would need to be a BIG bump with a heavily laden bike.) Bump stop calibration curve available on request!
The minimum length of the Vincent damper is much easier to define, as the hydraulic stop is very short and stiff compared to a rubber bump stop, which provides a much nicer progressive rising rate.
My short AVO rear damper (and a pair of 142lb Girling springs) is sitting in a box waiting for me to finish building the engine. Now there's a far neater and totally integrated unit on offer. So what do I do with my AVO? Can I get it updated to the new spec?
Paul
Paul