Fork DDC kit install and seal replacement.

[fleetingyouth]

Basically, this thread is on my upgrade and results and trying to better understand how changing different things correctly effect the bikes suspension so I can better tune it for myself.

Ok so My other thread was about a fork seal leak so when I installed my DDC kit from Cogent Dynamics this weekend I also replaced all the seals and bushings.

I'm terrible with suspension tuning and knowledge. While I can usually follow a discussion I don't really understand the finer points or math. I watched several videos from other NC members and read all the relevant threads.
So here is how I installed the DDC kit, new .64 springs and caps from a CB1100.

I measured the sag with me on the bike at 65mm which seemed like too much. I know Dave(dduelin) in his thread mentioned his was 55mm and that was 40% of the full 137mm. So mine is roughly 48% and it was mentioned that 33% was a good range to be in.
Now the springs I installed are closer to my weight(.64) than stock and I'm pretty sure I weigh more than Dave. I wasn't sure how or if the new spring would change the sag being for a heavier weight so I did the installation to match the original sag measurement.

I measured the DDC thickness and cb1100 caps at half extended. The new springs were shorter even with the added thickness of the DDC and caps so I made a new spacer longer than the stock by the difference.

I also did the 5wt Honda oil and measured it out to 140mm per recommendation.

After put the bike back together the sag is still measured at 65mm which I suppose means I did the correct math? However, the front end does feel a little higher though I don't notice it in my stance on the ground.
I still have to install the new rear shock from Cogent but I believe the overall geometry of the suspension is now off and I'm not very happy with the result which I believe is because of the rear as a result. I need help understanding what adjustments need to be made etc because I just don't know enough.

I took the bike down a dirt road on my way home(by accident) plus an hour on the highway and yesterday road my usual commute.

The sharp bumps on the front end feel worlds better but the front also now feels floaty all the time on every little surface. The rear feels hoppy like the front is taking the hit and the rear is made worse by that. I dont know if that means the rear needs to be stiffer or what etc.
In the corners, the bike holds a line way better than it ever did I honestly feel like I could do a corner with no hands where I never felt that tight on it before. It also feels a little harder to turn in once in the corner though. Also as mentioned the front end feels a little high.

I'll probably do the rear shock soon but want to have a better understanding of how to adjust the suspension to work better with the front but also adjust the front if I need to which seems like I do?

I believe the caps have about 10mm total in adjustment and I set them halfway so about -+5mm. My understanding is the caps adjust the preload of the fork spring for weight but I'm unsure how much is being adjusted in either direction or which is for more or less haha
I'm also confused about how a bigger spacer or smaller one changes the sag and how getting my sag closer to the 33% would affect the bike geometry and seat height. Or whether I should not and wait till I put on the rear shock?

The bike is ridable but not overall great and I'm pretty sure its because the front and rear arent in balance with each other now. I did the push test on the front end and it seemed alright maybe a little too much settling back in place.

Sorry for the long and detailed post I really just want to try and provide what might be useful so I can learn to better make adjustments moving forward.

Mike

 

[dduelin]

Mike, you’ve started and are well on your way to what you are trying to accomplish. Good start! I don’t know how you measured rider sag but if you are confident in the 65mm figure then we will want to reduce it and that’s done by lengthening the spacers and/or adding preload with the fork caps. I seem to recall the CB1100 caps have 15 mm of adjustment. Try turning them in clockwise until they bottom out and remeasure sag. If you can screw them in some then the sag should reduce by the same amount the caps screw in. Adding preload with the fork caps and/or longer spacers will reduce sag and raise ride height.

At a start point of 65 mm I think the spacers might need to be a little longer so you will have some adjustment left in the fork caps. You are almost there it’s a matter of fine adjustments now. The oil, was it Honda SS-7 or what?

 

[fleetingyouth]

Thanks Dave
For rider Sag, I did the zip tie trick sat on the bike then lifted the front end and measured the distance. I have the caps at halfway so can compress them all the way and see what that does.
If I add spacer length the sag will be reduced but the ride height will go up? So if I wanted to reduce sag but keep the ride height do I have to adjust the fork position in the tree? Or does it need a stronger spring? I did get the .76 springs with the kit.

The fork oil is the Honda pro 5w they make.

I was rereading the instructions on the CD website and I think maybe I measured the oil incorrectly. I measured the oil with all the parts in the tube and fully extended. It says compressed, so does that mean without the spring and spacer installed with the tube pushed in?

 

[dduelin]

If you make the spacers 15 mm longer or have 15 mm of adjustment in the fork caps you can slide the forks up 15 mm in the clamps to simultaneously reduce sag and keep ride height the same. I have a fender extender and at 15 mm drop in the clamps the fender extender just makes contact with the front of the engine at full on hard braking. It has worn a little spot on the plastic extender.

Oil level is measured with tube fully compressed into slider but without springs and spacers in the tube.

The thing about fork spring rate is it can be highly subjective to the fork set up and rider desires. If you have 60 mm sag initially with the recommended aftermarket or stock spring but can reduce it about 15 mm with more preload, then you go ride the bike and measure how much travel is used under full braking. Your zip ties will record travel. If the fork bottoms out and runs out of travel you can raise the oil level 10 mm and go try it again and see if you can retain 5 - 10 mm of travel in reserve. Cogent gives a 20 mm range of oil level from 130 to 150 mm IIRC. Lighter riders start at 130 and heavier riders 150 mm. More oil = less air in the fork and less air stiffens the compression rate during the last third of travel. Higher oil level makes like a slightly stiffer spring. Vice versa with less oil the stroke doesn't stiffen as much at the end of travel. If you can live with the ride as far as how the spring compresses under your riding style and doesn't bottom out AND the steering effort to turn the bike still feels good you are there. Lowering front end ride height will speed up turn in or raising rear ride height will speed up turn in. I interpret your adjective "floaty" to mean the ride is very soft and that might be due to the oil level being too low first of all and secondly maybe the rate is too soft. But you did say you might have gotten the oil level to low [with the springs and spacers inserted]. The guy I learned from set his NC up with a slightly higher rear ride height after getting the forks right. Raising the rear made up for reducing the initial fork sag figure. That NC was the mule for Rick Cogent's work on the DDC & spring kit.

 

[MZ5]

You have both 0.64 and 0.76 kg/mm springs? Why (or how?) did you get those two rates? They’re wildly different!

 

[fleetingyouth]

Sorry, that was a typo I meant .70 spring. So I have both .64 and .70

I bought the kit used off the forum and that was what came with it.

 

[dduelin]

You can go here and utilize RaceTech's spring rate calculator for your weight and experience. It's for a 2013 but all 2012 - 2020 models should be the same. Click on the yellow link at the top.

 

[Gixus]

fleetingyouth.

Theres a lot of good info on this thread. Be aware that no matter how well you eventually set up your suspension to your satisfaction, there will always be certain roads you ride that it will feel wanting. That also applies to bikes that do come with excellent suspension. It’s always a compromise.

I give this advice because like many I learnt from experience. I had a new gsxr1000 and right from the get go I didn’t like the front end. I couldn’t adjust to my satisfaction. After 2 valving kits and fork springs I gave up and sold the bike.The next sport bike I bought, I adjusted the suspension, and then left it alone, putting up with what I thought was inferior performance on some roads.

I believe personally in working on the rear suspension before the front. A decent shock on the rear of any bike will make the stock front feel inadequate, but the general ride will be stable. A good front but inferior rear will make the bike handling quirky, and if it’s the case of totally worn out rear shocks, possibly dangerous at speed. I learnt this from personal experience.

 

[fleetingyouth]

Ok I wasnt able to measure the full sag distance today but did measure the difference with the cb1100 caps adjusted all the way into the first line. It was about a 5mm difference. So that means I lowered my sag by 5mm and there by the front end height by 5mm?

I'm going to install the rear shock tomorrow and redo the oil levels in the front fork because I definitely did them full extension with spring and spacer installed.

If the current spacer gives me 65mm of sag and I add 20mm to the spacer bringing me down to 45mm then the caps would give me +/- 5mm to play with. But this would also raise the front end by 20mm correct?

 

[670cc]

I

Ok I wasnt able to measure the full sag distance today but did measure the difference with the cb1100 caps adjusted all the way into the first line. It was about a 5mm difference. So that means I lowered my sag by 5mm and there by the front end height by 5mm?

I'm going to install the rear shock tomorrow and redo the oil levels in the front fork because I definitely did them full extension with spring and spacer installed.

If the current spacer gives me 65mm of sag and I add 20mm to the spacer bringing me down to 45mm then the caps would give me +/- 5mm to play with. But this would also raise the front end by 20mm correct?

If you increase the spacer length by 20mm, the front end goes up approximately 20mm.

 

[dduelin]

Using 670cc’s reply if you dropped the forks 15 mm in the clamps the net height increase would be 5 mm. If you did nothing to the rear shock the seat height increases some fraction of 5 mm. You might not even notice.

 

[fleetingyouth]

Ok I re-did the front forks and installed the rear shock yesterday.

I did the oil measuring the correct way this time and put in about 140mm of oil. I also put in new spacers adding 20mm in length making them 85mm spacers. Set the adjustable caps at about the middle setting which should give me roughly +/-5mm.

The rear shock went in super easy once I figured out getting access haha I have it set currently for what seemed good for my weight. Played with what I assume is the red rebound knob to get a feel for how it affected the ride. Its set in the middle now but will test as i ride over the next couple days. Had a friend watch the suspension as I road up and down the street hitting bumps to see how I should adjust it. So for now it feels alright but will ride a few days to get a better feel for it.

I also raised the bars in the triple tree just a little maybe 5ish mm. The overall sitting height doesnt seem that much higher when I'm on it. Maybe a tiny bit taller but I can still put a little more than my toes down on both sides. However, when I put it on the kickstand its lean is a lot more pronounced. So does that mean its resting height is considerably taller now?

I'm going to play with all of the adjustments after I ride it around my normal commute for a few days and see what feels good.
Ive never set up a suspension before so I'm kinda guessing, I also dont have a ton of experience on what a better set up should feel like just comparing it to how it was stock. So any tips would be great.

 

[dduelin]

Ok I re-did the front forks and installed the rear shock yesterday.

I did the oil measuring the correct way this time and put in about 140mm of oil. I also put in new spacers adding 20mm in length making them 85mm spacers. Set the adjustable caps at about the middle setting which should give me roughly +/-5mm.

The rear shock went in super easy once I figured out getting access haha I have it set currently for what seemed good for my weight. Played with what I assume is the red rebound knob to get a feel for how it affected the ride. Its set in the middle now but will test as i ride over the next couple days. Had a friend watch the suspension as I road up and down the street hitting bumps to see how I should adjust it. So for now it feels alright but will ride a few days to get a better feel for it.

I also raised the bars in the triple tree just a little maybe 5ish mm. The overall sitting height doesnt seem that much higher when I'm on it. Maybe a tiny bit taller but I can still put a little more than my toes down on both sides. However, when I put it on the kickstand its lean is a lot more pronounced. So does that mean its resting height is considerably taller now?

I'm going to play with all of the adjustments after I ride it around my normal commute for a few days and see what feels good.
Ive never set up a suspension before so I'm kinda guessing, I also dont have a ton of experience on what a better set up should feel like just comparing it to how it was stock. So any tips would be great.

Great progress!

I made this extremely lame video in 2011 that illustrates the basics of adjusting rebound of a rear shock. It's for the ST1300 but it does show how to make the first rebound damping adjustment as a starting point. Don't expect too much and it might help you.

IIRC I used 130 or 140 mm oil level and found that the forks bottomed out under extremely hard braking, leaving no reserve travel for hard braking over a bumpy surface. Cogent instructions give a range if I recall of 130 to 150 mm. I added 10 mm to the height and then found I retained about 10 mm of travel under the same hard braking. I am sure you saw how to place two small zip ties around a fork leg to measure travel used during a test ride.

 

[mrbios]

My suspension thoughts... [passive / not active] is a compromise just like traditional passive valves in an engine vs Variable Valve timing where adjustments occur in real time based on what the driver is doing.

2012 NC with 45K miles:
Rear shock appears to offer almost no dampening, though it does NOT leak oil and the gas still pushes the piston out.

ME:
I'm 55, weigh about 163 lbs and I'm 5-10 with 100K of total miles since 1988.

Front Forks:
All original including dirty fork oil. I removed ~ 2 oz of oil and added 1/4 oz? of paint thinner (solvent) to thin the oil a bit - not sure how much that effected things.

Results:
Reducing oil even by 1 or 2 oz's has a HUGE effect - dampening will feel mushy / bouncy etc in a big way to anyone, not just OCD people obsessed with minor details.

Key Take-aways:
1. This experiment was an accident. I decided to remove the fork caps to inspect the oil. I used a plastic syringe and sucked some oil and could see it was very dirty and decided to squirt it into my recycled oil container. Then I repeated on the other side and put the caps back on. Immediately when pushing on the handlebars I observed a HUGE change that I did not anticipate. I took the bike for a ride thinking it would bottom out. It did not and has not even when riding up on to a curb!

2. I LOVE the softer ride and would NEVER go back to the harsh stock ride.

3. The Front forks make the biggest difference in ride quality over rough rides so investing lots of time or money in the rear shock wont yield much in the way of comfort.

4. Even though I LOVE a SOFT ride - I recommend the stock spring or a little stiffer if you weigh more than I do - Spring is important to support the weight of the bike & rider and MAXIMIZE travel. Reducing the oil by 2 oz will put that range of travel to very good use.

5. ** IF ** I push on the handlebars while stopped and holding front brake the forks feel very mushy -- even to me! Solution: don't do it ;-) just ride and enjoy yourself.

6. So far... I have NEVER bottomed out in the front (even when hopping a curb to get on the sidwalk) and only bottomed once in the rear going into a weird angled driveway.

7. Is this dangerous or does it compromise the handling of the bike? It could but motorcycling isn't safe to begin with and I can still scrape both pegs so for normal riding I wouldn't call it dangerous or unstable. Also, in many situations safety is actually improved because the tire absorbs bumps and maintains contact with the pavement.

8. I LOVE running over any pavement especially bad pavement and the bike soaks it up. At night you hit potholes that often can't be seen - and the shock to the rider is reduced a lot also cornering with heavy lean on bad pavement is excellent.

9. You really have to have to give it a try: After removing 2 oz of fork oil I now have zero interest in modifying the suspension - except finding a lower rate rear coil if and when I find the time.