Spax also stopped making Jaguar shocks due to the failiure rate.
FF: Forks Modified Steering Stem
- Thread starter greg brillus
- Start date
Here are some force versus displacement graphs for three different rear springs. Two barrelled shaped and the 'D' straight coil. They are all linear.
Help, I still have a Spax on my L/ning, Been on the Comet for a while, Works well and no leaks, Can't remember how many years I have had it. Cheers Bill.
Thanks for putting me straight on the springs. I just assumed that because the diameter of the coils varied, the spring rate would rise. That will teach me not to assume!
Greg, about three years ago I fitted a twin disc front set-up. The only difference is it now stops much better. As far as I am aware it is otherwise standard, vincent shock home made seals, filled with auto trans fluid. For a 66 year old bike I find the suspension unremarkable, except the rear on big bumps. This may be due to 40 years with americas finest. Relax, the last harley got sold a while ago, the vin is far superior.
My experience is as follows. Although I used to race, sprint, hill climb etc. it was only when I tried Dick Sherwin's Knight out with its newly installed front disc brakes that I realised just how much the bike rises up, over the front forks, when braking. I had been perfectly satisfied with my drum brakes but with the added braking power of the discs the whole of the dashboard, front screen and handlebar muffs rose up in the air in an alarming manner. It could not be missed and yet with the drums, even when braking hard at the end of a straight when racing, I had never noticed this. DaveD's short springs were a first attempt to prevent this and then John Emmanuel showed us all how to do it. The question for Roy is whether he has noticed that his handlebars, petrol tank etc. seem to be coming up to meet him when he brakes hard? If not then how does he manage this with the standard suspension layout? Does he find that his suspension has locked up or what?
Yes I would have thought that better brakes would very much highlight the bad characteristics of the front end using stock components. Perhaps the feel of the better brakes makes one overlook the suspension..........The open "D" Rapide I had ridden earlier this year had quite comfortable and soft front end, which I found very nice, but when I squeezed the front brake quite hard the front end definitely "locked up". I think to carry out these tests you need to be on a piece of road where you can look down and focus on the fork action and not worry about hitting anything, or any on coming traffic, whilst still riding over bumps in the road surface and try this with and without brakes to really see what is actually going on. I found this is the best way, and is not difficult at all.
I say unremarkable because it does nothing frightening or uncomfortable. Maybe I spend too much time looking where I'm going. I have a bit of an idea that the 5" speedo mount acts as a limit stop as the paint on it and the forks keeps chipping off. The only time the forks stiffen is sticking it into a roundabout at a fair pace, now I'm expecting it , it does not appear to cause any trouble. I did however make a mistake when fitting the front wheel, Phil Read suggested that a slightly smaller front tyre would "sharpen up" the steering, I put a 90/90 19 on. It worked, but at 80 plus mph in crosswinds it gets nervous. 110/90 19 come spring time will correct this. Because it aint broke I am leaving it alone. Basically I like it compared with the 14 harleys I had previous.
What's on the back Roy, I would have thought 100/90/19 would be enough,With maybe a 110 on the back, I made a big mistake years ago, A tyre man told me to fit 2 tyres, The front one was a different shape to the rear and was wider than the back one, Even though the size was marked smaller. Cheers Bill.
When he said smaller did he mean thinner? Racing little Ducatis and Suzukis in the '70s there was a tendency to put massive 3.50 rear tyres and 3.25 front on them. An international racing guy said I was going the wrong way and should put a 3.00 or 3.25 (at the most) rear and 2.75-3.0 front. Lap times improved after the change. IMHO 19" front on a standard Vincent is only good for super smooth roads and moderate speed. IF you change the suspension etc. then obviously other things change. I love my 21" front wheel.