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Author Topic: Thank you Ducati Scotty  (Read 1301 times)

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Adrian II

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Reply #30 on: October 10, 2018, 03:53:27 pm
There seem to be different versions of the new type forks (well, newer, the CGT, Himalyan and now the twins are different again).

The first type of fork with the internals as shown in Haggis' picture appeared on the AVL 350 Thunderbird models in India, and are disk brake leading-axle forks (BENT??? come on, guys!). The stanchions have plain tops and push into the top yokes, as well as having screw-in caps on a standard R/H thread. The alloy sliders have central mounts for the front fender. The same forks were used when the 350 Thunderbird went UCE.

Next we have the early C5 and early B5 forks as per Scotty's original tutorial. These are also leading-axle, disk brake, though the sliders have lugs for traditionally mounted fender stays. The stanchion tops on these have the traditional RE external threads and will screw into just about any pre-2009 RE India headlamp casquette or even a Redditch Interceptor alloy top yoke. The stanchions have screw-in caps too, though these are on a LEFT HAND thread.

Then we get to the 2012-on type C5 forks, as in Haggis' photo - same internals, but on ther slider the axle is now in line with the center-line of the forks, plain stanchion tops with the Thunderbird-type right-hand threaded tops. 2016/17 B5s ended up with these too.

Finally we have the interim B5 forks (2012-2016?), still with leading-axle sliders but with the plain stanchion tops and r/h threaded screw cap as above.

There's also a drum brake version of these on some Indian 350 UCE models.

I think that's the lot unless anyone knows of more.

You CAN modify these forks for in-situ oil changes, I shall be doing a set of B5 forks soon and will post some photos.

A.

Grumpy Brit still seeking 500 AVL Bullet perfection! Will let you know if I get anywhere near...


Haggis

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Reply #31 on: October 10, 2018, 05:11:06 pm
One my main question was that my forks have teflon coated bushes top and bottom for the fork leg to slide on, just like a normal Japanese bike fork.
Looking at the leading axle forks there does not appear to be any bushes. Just the alloy slider straight onto the chrome stanchion.?
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Arizoni

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Reply #32 on: October 10, 2018, 05:38:48 pm
I guess I can toss in comments about the 2011,  G5 forks.

For reasons unknown to me, the G5 forks have a dedicated oil drain plug at the bottom of each fork.

To change the fork oil, all that is required is to remove the top caps (plugs), remove the drain plugs at the bottom and pump the forks up and down to force the oil out.

Then, reinstall the drain plugs, pour in the fork oil and replace the top caps.  Couldn't be simpler.

I don't know why RE didn't use these forks on the B and the C models.  Poor planning I guess.
Jim
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Richard230

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Reply #33 on: October 10, 2018, 05:47:16 pm
Of course on my 2011 B5 you can't remove the fork plug without first removing the entire fork. Since you have to remove the fork cap to get the oil in, you might as well just dump it out via that route and ignore the bolt at the bottom of the fork. Besides I was worried that it was threaded into the damping rod and getting it removed and then screwed in again would likely be a hassle without a tool to hold the damping rod steady. So upside-down and into the pan for draining it went.  ;)  Just like most newer forks.

The little drain screws that made changing fork oil so easy on Japanese bikes are long gone.  I hope the manufacturers spend the few cents that eliminating the fork drain screw wisely.   ::)
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Bert Remington

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Reply #34 on: October 10, 2018, 06:06:07 pm
Adrian II -- if you hadn't noticed there are a number of seniors and other mature folks on this forum who have fun with the English language.  I live in one of those San Diego neighborhoods where the terms "bent" and "straight" are applicable as is the term "Hillcrest sandals".  I'm not the only one -- recently there's wildbill's "2. long term it would improve their vision...LOL".  We're retired.  We need our small pleasures.

Reverse engineering RE's fork evolution and variants is a mug's game.  Basically we need to look at the evidence at hand and shared on this and related fora.  There are several curious aspects.  For instance, the top and bottom steel bushings in Haggis's picture.  And the missing spacer washers.  Finally there is that small steel tube to the right of the damping rod -- what's its function?

I am looking forward to your photos as I try to better understand RE fork operation and possible improvements.

BTW I recommend a trip to Race Tech (http://racetech.com/) if for no other reason than to understand how telescopic forks work, the affect of oil viscosity, etc
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Haggis

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Reply #35 on: October 10, 2018, 07:16:26 pm
The top and bottom bushes are teflon coated brass and the small steel tube fits on the bottom of the damper tube.
It has a taper shape which matches a taper hole in the bottom of the stanchion.
As the fork reaches maximum travel it blocks the flow of oil causing a hydraulic lock, this prevents the forks from bottoming out metal to metal.
This only happens in last half inch of fork travel.
Off route, recalculate?


wildbill

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Reply #36 on: October 10, 2018, 07:48:48 pm
ok well how's this for the summary on the forks

STRAIGHT - no bend in the SHAFT...LOL so i'd say STRAIGHT.
BENT - almost straight but a slight curve near the end! so it's classed as BENT!
OFF SET - bent at the bottom but straight at the top/tip...LOL or OFF SET!

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Mad4Bullets

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Reply #37 on: October 10, 2018, 08:44:53 pm
Thanks to all for all of this clarification, but I still have one point of confusion. My late 2014 C5 has straight forks.  I removed the 8mm stainless steel threaded cap from the top of the headlamp casquette which appears identical to those seen in wildbill's photo.  I can see that the larger diameter unthreaded shoulder of the screw bears against a recessed surface in the casquette and the threaded portion of the hole below that is presumably the threaded top cap for the fork leg.  How else could it hold the fork leg in place?  Is that correct?  Is there a hex shaped recess in the cap below these threads used to remove the cap?  That feature is not readily obvious to my eye but seems necessary to remove the cap from the fork leg.  Any chance anyone may have taken a photo or two of the threaded end of the fork tube cap?  These would be most revealing.  Thanks very much.  Great discussion going on here.  Regards,  Kevin Daly


wildbill

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Reply #38 on: October 10, 2018, 10:54:08 pm
lucky you just asked as I am doing it now. after you remove that top threaded screw the only thing holding the fork in place is at the indicator section triple tree. you loosen that a couple of turns and the fork will almost slide out so...hold onto it!
now back to mine. I removed the right fork and took it inside to undo. surprisingly I undid it very easy
now the downside is I only drained out 4.5 fluid ounces or roughly 135 mils so I am 60 miles off target. hopefully this is the issue with the rough front end ride
now I have to pull the other as I am not sure which direction that plastic spacer above the spring goes.
I also hope the other leg is easy to undo too ;)

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wildbill

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Reply #39 on: October 10, 2018, 11:41:00 pm
threaded cap

2011 C5 black/chrome
2012 C5 maroon/chrome 
2013 B5 black
2014 Continental gt
2014 C5 tan
2015 black/chrome
2015 limited edition dispatch
2016 lagoon blue 500
2016  ash white 350
2017 graphite/chrome 500
2018 gun metal grey 500
2018 C5 Pegasus 500
2017 C5 Redditch 50
2018 C5 gun metal grey


wildbill

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Reply #40 on: October 10, 2018, 11:42:35 pm
threaded cap

2011 C5 black/chrome
2012 C5 maroon/chrome 
2013 B5 black
2014 Continental gt
2014 C5 tan
2015 black/chrome
2015 limited edition dispatch
2016 lagoon blue 500
2016  ash white 350
2017 graphite/chrome 500
2018 gun metal grey 500
2018 C5 Pegasus 500
2017 C5 Redditch 50
2018 C5 gun metal grey


Haggis

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Reply #41 on: October 11, 2018, 06:01:36 am
My plastic spacers were fitted with the open end up, towards the screw in cap.
Here is a pic of the top end of the damper rod showing the hex you need to hold if the rod turns when undoing the bottom hex screw.
Only if you are going to split the forks.


Just of interest, I measured the oil level with 195mls added.
No spring, fork fully compressed, 270mm from top of fork to the oil.
« Last Edit: October 11, 2018, 06:08:04 am by Haggis »
Off route, recalculate?


Mad4Bullets

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Reply #42 on: October 11, 2018, 06:21:05 am
Thanks very much for the pics.  They certainly tell the story. I didn't expect to see the flats on the cap diameter.  I suppose a large adjustable spanner is the tool of choice to remove it eh? Regards, Kevin Daly


9fingers

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Reply #43 on: October 11, 2018, 07:10:33 am
That was fantastic, thanks Mr Ducati!
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Narada

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Reply #44 on: October 11, 2018, 09:59:16 am
Couldn't the oil just be sucked out with a hand held suction pump? ???
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