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FF: Forks Modified Steering Stem

Gary Gittleson

Website User
VOC Member
OK folks. I am getting interested in this mod. I have a Series D Rapide with Thorntons front and rear and David Dunfey short front springs. There's no tendency for the forks to roll over the links, even with my Speet front brakes applied vigorously. So far, so good but I do think the fork could be softer and my aging body might like that.

So where does one start? Is the kit still available? If so, from whom? I see that there are numerous options; lower-link bearings, springs choices, shocks etc. I don't mind engaging in some experimentation, but why repeat what's already been done?

Gary
 

macvette

Well Known and Active Website User
VOC Member
Well, I decided to take the damper off. With the standard set up, before doing the mod, I could do this with the bike on its centrestand. After loosening the eyebolts and the top pivot, it was impossible to collapse the damper because there was so much load on the damper that the eyebolts were jammed solid as was the top pivot. Eventually, I used a ratchet strap around the steering head anchored on the front wheel spindle to compress the suspension with the bike on its centrestand and took out the top spindle to free the damper. I released the ratchet strap and with the bike on its centrestand and the damper at its max length and long eyebolts snugged up, the top bolt hole was 1 ins lower than the matching holes in the steering stem. There is no binding or friction in the suspension so now I think I need to shorten the springs but by how much?
 
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chrislaun

Well Known and Active Website User
VOC Member
Hi Macvette, with the bike on the centrestand the forks will extend further than the damper, you need it on it's wheels to estimate what wants doing with the springs. I'm surprised you could get the damper off even with the standard set up.
 

timetraveller

Well Known and Active Website User
VOC Member
Mac, Chris is seeing this more clearly than you. There is two inches of preloaded on two 45 lb springs, total 180 lbs, when the front wheel is off the ground. By all means chop things about if you wish but I can send you two 36s in about two weeks time.
 

macvette

Well Known and Active Website User
VOC Member
Hi Macvette, with the bike on the centrestand the forks will extend further than the damper, you need it on it's wheels to estimate what wants doing with the springs. I'm surprised you could get the damper off even with the standard set up.
Yes I know that the damper limits the full extension of the suspension and I've had the bike on and off its wheels several times. With the bike on its wheels, no rider,with this set up there is still no compression of the of the damper and it is not possible to collapse the damper to remove it because of the load on it imposed by the springs locks the eyebolts and the top pivot bolt even when they are slackened off. These are long eyebolts. I didnt notice this when I did the mod because the damper was in place before I fitted the springs. This also a standard Vincent damper with 3 ins of travel. If I had short eyebolts on, the preload on the damper would be even higher.
With the bike on the side stand the back wheel is off the ground so there is some load on the front but I would expect the damper to be compressed slightly when dropped onto its wheels. When I do this the bike bounces once and settles quite freely but the damper remains fully extended ( topped out or bottomed out however you express it) and it is not possible lift the front of the bike to extend the front suspension even marginally.
I know exactly what I am seeing having cycled through this procedure several times. So this is why I think I need less preload or to shorten the spring to bring the damper a little off its stop when on its wheels with no rider
 

chrislaun

Well Known and Active Website User
VOC Member
Ah yes I see what your saying, there is too much pre-load even on it's wheels. As you have the damper off what sort of angle are the links at when it's on it's wheels ? They should be parallel to the ground.
I have 45lb springs and 11mm packers on mine and have had no trouble swapping dampers when on it's wheels, that includes Standard, Armstrong, Koni, Thornton and AVO dampers.
 

greg brillus

Well Known and Active Website User
VOC Member
Even the original springs I had made which were about 38 to 42 odd pounds per inch, I have had to chop the lot shorter to get the bike sitting right. It was a pair of these springs we used in my friends Comet, and stock Koni shocker on its weakest setting, the bike felt fabulous on the first ride. The pre-load was about 20 mm, we could almost compress the upper spring box by hand and install the upper fixing bolts.
 

vibrac

Well Known and Active Website User
VOC Member
Even the original springs I had made which were about 38 to 42 odd pounds per inch, I have had to chop the lot shorter to get the bike sitting right. It was a pair of these springs we used in my friends Comet, and stock Koni shocker on its weakest setting, the bike felt fabulous on the first ride. The pre-load was about 20 mm, we could almost compress the upper spring box by hand and install the upper fixing bolts.
Interesting at 30 lb unhortened springs even no damper my comet wa not the smoothest and with aVo damper very stiff
 

greg brillus

Well Known and Active Website User
VOC Member
Springs are still too long...........Too much pre---load. I'll swap you a good set of roadholders for those pesky Girdraulics if you want.............:)............. I don't want to say anything negative, but the AVO on a light bike like a Comet is way too stiff..........I should start charging for all this info...............
 

greg brillus

Well Known and Active Website User
VOC Member
Girdraulic's with this mod, way better than Brampton's. I rode three bikes in the one day several times, two Rapide's with Brampton's and a Shadow with Girdraulic's with this mod, the Girdraulics were more comfortable, more controlled and with better travel. You only have to look at Cam Donald's discussions about the Flash, and he is one hell of a rider.
 

peter holmes

Well Known and Active Website User
VOC Member
Sod the road holders pass me the Brampton's😁
Tim, Your fork of choice is obviously Brampton, aesthetically I also prefer them, but how do you control the spring, do you still rely on the friction dampers, or are you using a Woodhead Munroe unit or something along those lines, I guess undamped they would be like riding a pogo stick, and friction damping surely ceases to function well (if they ever did) once contaminated with dirt, water or grease, just interested in your thoughts or solutions.
 

chrislaun

Well Known and Active Website User
VOC Member
I have to agree with Greg on the AVO damper, I run mine on a twin with the damping on the lowest setting, and I'm 130kg, the problem is the AVO for the bushed front end is too soft for the ball bearing front end and the AVO for the bearing front end cannot be softened without an expensive complete re-design, they are totally different dampers internally.
As almost all the testing was done on twins might I suggest perhaps someone will volunteer to try the Bush type damper on a single with the bearing mod and see how it performs.
 

vibrac

Well Known and Active Website User
VOC Member
Tim, Your fork of choice is obviously Brampton, aesthetically I also prefer them, but how do you control the spring, do you still rely on the friction dampers, or are you using a Woodhead Munroe unit or something along those lines, I guess undamped they would be like riding a pogo stick, and friction damping surely ceases to function well (if they ever did) once contaminated with dirt, water or grease, just interested in your thoughts or solutions.
Brampton CO.jpg
Courtesy "The Vincnt Black Shadow"
 

macvette

Well Known and Active Website User
VOC Member
Mac, some previous owner hasn't packed up the springs previously and left some thing down the lower spring boxes have they ?
No Chris🙄, I' ve done a lot of measuring, checked the length of the spring boxes with the springs on and off the bike damper connected and disconnected checked the spring strength etc, took advice from Greg the up shot is that today I cut 22mm of one spring and now have about 5mm of compression at the damper under just the weight of the bike on its wheels. Standing by the bike, I can now bounce it up and down where before " up"was impossible. When I sit on the bike I use about 1/4 to 1/3of damper travel. As an aside, I can now remove and replace the damper as I did before doing the mod with the bike on its centre stand wheels on, no ratchet straps. The links look to be in good position so now I just have to try it on the road but I'm now happy with the preload. The spring I shortened could be fitted preloading it by hand
Regards Mac
 
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