Suspension mods started

[ohiorider_imp]

Guth, I talked with Dan at TD a few days ago, and followed up with sag information for the fork.
Sag of CB1100 fork (09 25 17)
Bottom of lower triple clamp to top of wiper with front wheel off ground/fork fully extended: 6 ½”
Bottom of lower triple clamp to top of wiper with front wheel on ground, 160# rider in saddle: 5 ½”
So, 1" from fully extended no load to loaded with bike and rider. I had no one to hold me up, but I was able to keep the bike level with very little foot pressure, so I think the loaded reading is good. Used a zip tie on one fork leg to 'record' the loaded sag.

His first thought was that they may have provided spacers that were too long. He asked that I:
- elevate front wheel by elevating and allowing the fork to extend.
- remove one fork cap & measure the distance between top of fork spring and bottom of fork cap.
per Dan this measurement should be between 15-20mm.
- it measured 20mm, and the spring didn't seem to be under undue pressure.
- fork cap against the spacer was easily depressed and replaced.

They will be sending me a lighter set of fork springs to try. Re two additional bleed holes - we discussed, but he didn't indicate doing this.

I will be removing the fork tubes, draining them, removing the springs and GV emulators. I am not planning to split the forks, but leaving the TD damper rods in place. I will double-check the settings on both GV emulator springs. Probably go with lighter fork oil (10-15w), lighter fork springs, and slightly more air space. They recommend 125 mm below top of fork tube without springs or GVE in place.

That's where it stands at the moment.

Bob

 

[Guth_imp]

Interesting. Thanks for sharing! I'll be keeping watch on this thread for further updates.

 

[spacetiger_imp]

Guth, I talked with Dan at TD a few days ago, and followed up with sag information for the fork.
Sag of CB1100 fork (09 25 17)
Bottom of lower triple clamp to top of wiper with front wheel off ground/fork fully extended: 6 ½”
Bottom of lower triple clamp to top of wiper with front wheel on ground, 160# rider in saddle: 5 ½”
So, 1" from fully extended no load to loaded with bike and rider. I had no one to hold me up, but I was able to keep the bike level with very little foot pressure, so I think the loaded reading is good. Used a zip tie on one fork leg to 'record' the loaded sag.

His first thought was that they may have provided spacers that were too long. He asked that I:
- elevate front wheel by elevating and allowing the fork to extend.
- remove one fork cap & measure the distance between top of fork spring and bottom of fork cap.
per Dan this measurement should be between 15-20mm.
- it measured 20mm, and the spring didn't seem to be under undue pressure.
- fork cap against the spacer was easily depressed and replaced.

They will be sending me a lighter set of fork springs to try. Re two additional bleed holes - we discussed, but he didn't indicate doing this.

I will be removing the fork tubes, draining them, removing the springs and GV emulators. I am not planning to split the forks, but leaving the TD damper rods in place. I will double-check the settings on both GV emulator springs. Probably go with lighter fork oil (10-15w), lighter fork springs, and slightly more air space. They recommend 125 mm below top of fork tube without springs or GVE in place.

That's where it stands at the moment.

Bob

Bob,

Good informative post; a few observations:

1. Your static sag measurements are a bit on the low side; 1" out of 6.5" = 0.15. I would think you should be closer to 0.25 or as high as 0.3.
2. I note the preload spacer is long enough that when you get the fork cap on, it is introducing about 20mm of preload on the spring. A bit on the highside, but not bad - it really depends on the steel spring rate. A lower rate would use a longer spacer, a stiffer spring would use a shorter spacer.
3. The advise to set the oil level with the GVE out of the fork is not correct. The GVE will not compress, so it takes up a certain amount of volume in the fork just like oil. If you set the oil level with it OUT, then put the GVE in; the oil level will rise about an inch or 2.54cm. That is a lot. That could be part of the problem.
4. The lighter weight oil is a good thing. I'm going to guess they didn't too much adjustment to the GVE, so I would try the 10wt oil. The 125mm oil level is high as that converts so 4.92".

My recommendation until you hearback from TD: Cut a pvc spacer 5mm shorter than your current length. Use 10wt fork oil but go with a lower fill level (set with GVE IN, spring OUT) 7" from top (that is 175mm, not 125mm). That is going to sound high, but look at the side of the compressed fork and put a piece of tape (blue painters tape) and mark the oil fill level. Now look at that mark and picture the where the GVE is in relation to that mark (The GVE sits on top of the damper rod). You will see a BIG gap between the top of the GVE and the mark. That tells you you have plenty of oil to do the damping function - the oil level is to set the air spring. With less preload on the spring and a lower oil level to reduce the air spring + lighter weight oil to flow through the oil passages, I think you will find the bike will ride much smoother. You sag reading at 1" should be around 1.625" (0.25 x 6.5"). The shorter preload spacer and oil fill will help you get closer to that number. Once underway, the compression damping will be lessened so the front will feel better.

Also, can you measure the bike sag? to do this, lift the front end again, move the zip tie down the fork, then lower the front of the bike so only the weight of the bike is on the front suspension. Then lift the bike up and see how far the zip tie moved (it will be less than inch). The difference between that measurement and 1" is attributed to your 160 weight.

Jerry

 

[PowerDubs_imp]

Back in my dirt bike days I would measure sag both by raising the suspension and sitting down (in full gear) - measure- and then push down, let rebound and remeasure.


Sent from my iPhone using Tapatalk

 

[spacetiger_imp]

Back in my dirt bike days I would measure sag both by raising the suspension and sitting down (in full gear) - measure- and then push down, let rebound and remeasure.


Sent from my iPhone using Tapatalk

That gets you rider sag. You also want bike sag. The difference between the 2 lets you estimate spring rate.

 

[ohiorider_imp]

Jerry (Spacetiger,)

Your post is very informative, and I suspect that taking your advice I'll end up with a CB1100 with suspension that works for me. You mentioned dropping fork oil level to as much as 175mm. Got me to thinking about the instructions that came with a Progressive spring I installed on my 2003 Bonneville several years ago. They show a range anywhere between 140mm and 190mm below the top of fork tube.

Thanks again,

Bob

 

[spacetiger_imp]

I bought a set of 2014 CB1100 forks that had been a slight mishap for a different project. If I can get some time this coming week I'll try to get them apart to do some measurements. I just have to figure how to post pics since photobucket is toast.

Jerry

 

[Cormanus]

Pictures: Imgur.com or Postimage.org.

 

[ohiorider_imp]

I bought a set of 2014 CB1100 forks that had been a slight mishap for a different project. If I can get some time this coming week I'll try to get them apart to do some measurements. I just have to figure how to post pics since photobucket is toast.

Jerry

I could supply you with:
- the stock damper rod length
- length of stock springs
- length of stock spacers

Let me know if that would be useful. You may be looking for more detail, however.

Bob

 

[spacetiger_imp]

Bob,

I have a stock fork set, so I can get those measurements. Can you get the bike sag measurements?

Jerry

 

[ohiorider_imp]

Bob,

I have a stock fork set, so I can get those measurements. Can you get the bike sag measurements?

Jerry

Jerry, I don't plan to return the bike to stock springs and spacers. At the moment it has the T Dynamics kit installed, and next step will be to install the lighter.90 springs. I may still have some readings I took with the factory suspension. If so, I'll post them.

Bob

 

[spacetiger_imp]

Bob,

I meant for you to take bike sag readings on your current set up. Those will go with your bike sag readings from your earlier post.

I see your current springs are 0.9 kg/mm? That would convert to 50.4 lb/in. That is a bit high for your weight of 160 lbs. Your total steel spring capacity is preload plus spring capacity over 6.5" so, that would be (0.78" (20mm) x 50.4) + (6.5 x 50.4) = 39.7 + 327.6 = 367.3 lbs for a single fork. I am guessing they used a straight rate spring.

As a data point, I am 20 lbs heavier (180) and in my XL1200T (a little heavier than the CB1100) and I am running 0.85 lbs/in (47.6 lb/in) springs. I also have a shorter front suspension working range than your 6.5". I am also running lower oil levels so there is less air spring effect. In effect, your set up has about 20, possibly 30% (depending on oil fill) greater capacity than mine. And, your are lighter than me (by 20 lbs). You can see, even the "suspension guys" get it wrong. It seems like they set up the front suspension for a 200+ (aggressive) rider.

If I read your weight and spring rate correctly, you will have to go to lighter weight springs. A 0.8 kg/mm spring would lower your capacity to 35.3 + 291.2 = 326.5. That is getting you closer. A 0.75 kg/mm spring with only a 15mm spacer would have a capacity of 24.8 + 273 = 297.8 lb. That looks like a better starting point as you can adjust that capacity with your oil level. I know understand why your sag readings are too low (0.15). Also, the compression damping is adding to your over stiff suspension using the heavier weight oil.

Once I test the fork I have, I can tell you what the stock spring rating is.

Jerry

edit. The front suspension travel seems high at 6.5" The stock is 4.7". Are you at 4.7 or 6.5"?

 

[ohiorider_imp]

Bob,

I meant for you to take bike sag readings on your current set up. Those will go with your bike sag readings from your earlier post.

I see your current springs are 0.9 kg/mm? That would convert to 50.4 lb/in. That is a bit high for your weight of 160 lbs. Your total steel spring capacity is preload plus spring capacity over 6.5" so, that would be (0.78" (20mm) x 50.4) + (6.5 x 50.4) = 39.7 + 327.6 = 367.3 lbs for a single fork. I am guessing they used a straight rate spring.

As a data point, I am 20 lbs heavier (180) and in my XL1200T (a little heavier than the CB1100) and I am running 0.85 lbs/in (47.6 lb/in) springs. I also have a shorter front suspension working range than your 6.5". I am also running lower oil levels so there is less air spring effect. In effect, your set up has about 20, possibly 30% (depending on oil fill) greater capacity than mine. And, your are lighter than me (by 20 lbs). You can see, even the "suspension guys" get it wrong. It seems like they set up the front suspension for a 200+ (aggressive) rider.

If I read your weight and spring rate correctly, you will have to go to lighter weight springs. A 0.8 kg/mm spring would lower your capacity to 35.3 + 291.2 = 326.5. That is getting you closer. A 0.75 kg/mm spring with only a 15mm spacer would have a capacity of 24.8 + 273 = 297.8 lb. That looks like a better starting point as you can adjust that capacity with your oil level. I know understand why your sag readings are too low (0.15). Also, the compression damping is adding to your over stiff suspension using the heavier weight oil.

Once I test the fork I have, I can tell you what the stock spring rating is.

Jerry

edit. The front suspension travel seems high at 6.5" The stock is 4.7". Are you at 4.7 or 6.5"?

Jerry, I didn't mean to imply that the total suspension travel was 6.5", but that when I measured (with wheel off ground - unloaded,) the distance between bottom of lower triple clamp and top of wiper was 6.5". Here's cut and paste from my previous post:
Bottom of lower triple clamp to top of wiper with front wheel off ground/fork fully extended: 6 ½”
Bottom of lower triple clamp to top of wiper with front wheel on ground, 160# rider in saddle: 5 ½”
---------------------------------------------------------------------------------------------
Not related to our discussion, but thought you might like to know: It appears that the stock CB1100 fork springs are progressively wound. I took these rough measurements this morning.

Total spring length removed from fork: 13.25" approx
10 tightly wound coils: 3"
20 loosely wound coils: 10.25"

 

[spacetiger_imp]

got you, I'll adjust the numbers for the stock damper rod length setting the suspension travel at 4.7".

I think the stock spring will be a 2 rate spring, that is what most honda's come with. Your description matches what you would see for a 2 rate spring.

 

[Houtman_imp]

THIS IS ALL VERY INTERESTING BUT THE ONLY THING I HAVE LEARNED SO FAR THAT I HAVE TO LOOSE WEIGHT !
ALL KIDDING ASIDE , THANK YOU ALL FOR EXPLAINING THIS.

 

[ohiorider_imp]

Some of the post below may not compute, since I was responding to Jerry's PM. Point is, the CB is much more compliant over semi bad roads now that lighter springs and different fork oil level have been done. I may still contact Ikon to determine if they can supply rear shock springs that are a notch or two lighter weight. I think a lot of my problem may be that I spent so much time on older BMWs over the past 30 years, that anything other than a lounge chair ride feels harsh to me. Anyway, the following is the latest update on my suspension issues.
-------------------------------------------------------------------------------------------
You're getting old?! WTH, Jerry, I'll hit 75 this coming January. I know the feeling. Although I still ride my 2008 Moto Guzzi 1200 Sport (love that bike!) she's a bit too top heavy and overall heavy for me, so it isn't my jump on for a 5 minute ride to the grocery store.

Well, the CB front end is much better after following your directions.
- we pulled the 1.00 spring, spacer, and RaceTech valve.
- I very carefully set the RaceTech valve preload to 3 turns in from zero preload.
- replaced the 20w fork oil with 10w Honda fork oil.
- after inserting RTV, set fork oil level 175mm below top of fork tubes.
- installed the .90 springs and spacers from Traxxion Dynamics.

Even with the Ikons on the rear, and the improvements to the forks, the CB isn't an R100R, but she is finally rideable (for me.) Before making any more changes, I think I'll try to get in some riding as we rapidly drift toward cold weather. The poor little Honda has only had 2200 miles put on the odometer since April of this year. Not fair to such a nice bike! I will admit, I'm having a somewhat difficult time adapting to the smoothness of the 4 cylinder DOHC engine, after so much saddle time on twins, whether Kaw W650, Triumph T100, or my long time ride, the BMW R100GS. I do like twins!

Jerry, once again, thanks for all your advice.

Bob

 

[ohiorider_imp]

Some of the post below may not compute, since I was responding to Jerry's PM. Point is, the CB is much more compliant over semi bad roads now that lighter springs and different fork oil level have been done. I may still contact Ikon to determine if they can supply rear shock springs that are a notch or two lighter weight. I think a lot of my problem may be that I spent so much time on older BMWs over the past 30 years, that anything other than a lounge chair ride feels harsh to me. Anyway, the following is the latest update on my suspension issues.
-------------------------------------------------------------------------------------------
You're getting old?! WTH, Jerry, I'll hit 75 this coming January. I know the feeling. Although I still ride my 2008 Moto Guzzi 1200 Sport (love that bike!) she's a bit too top heavy and overall heavy for me, so it isn't my jump on for a 5 minute ride to the grocery store.

Well, the CB front end is much better after following your directions.
- we pulled the 1.00 spring, spacer, and RaceTech valve.
- I very carefully set the RaceTech valve preload to 3 turns in from zero preload.
- replaced the 20w fork oil with 10w Honda fork oil.
- after inserting RTV, set fork oil level 175mm below top of fork tubes.
- installed the .90 springs and spacers from Traxxion Dynamics.

Even with the Ikons on the rear, and the improvements to the forks, the CB isn't an R100R, but she is finally rideable (for me.) Before making any more changes, I think I'll try to get in some riding as we rapidly drift toward cold weather. The poor little Honda has only had 2200 miles put on the odometer since April of this year. Not fair to such a nice bike! I will admit, I'm having a somewhat difficult time adapting to the smoothness of the 4 cylinder DOHC engine, after so much saddle time on twins, whether Kaw W650, Triumph T100, or my long time ride, the BMW R100GS. I do like twins!

Jerry, once again, thanks for all your advice.

Bob

Does the CB ride like an older BMW R100R or R100GS yet? Nope! But for my weight, she's a lot better now than stock. I may still contact Ikon and Traxxion Dynamics and go for slightly lighter springs. Some good days left this season, The remainder of this week in NE Ohio will be in the 70s during the afternoon. For some reason I haven't yet determined, the old R100GS has developed a case of vibes not related to carburetor balance. Hope it's nothing as serious as big end bearings or tranny bearings or driveshaft failure. Actually, what I hope is that I can determine the problem without a lot of false and expensive starts. Could be anything at 155,000 miles.

In the meantime, I can finish out the 2017 season on the Moto Guzzi Sport and Honda CB1100.

Bob