Author Topic: Race Tech emulator/spring front suspension setup help (Read 5529 times)

akabek · « **on:** July 10, 2016, 12:36:31 PM »

I am working on tuning my front fork suspension and while riding it feels like the shocks are not moving. I have a zip tie on one shock and the only time I see movement is when I apply the front brakes. Than I see a fair amount of travel. Installed in the forks are the Race Tech emulators with adaptors and 0.85kg springs. This is my current setup:

Dampner Rod has 6 holes drilled out at the bottom. No pin holes at the top.
Emulator is set to 3 turns
15WT fork oil
Fork oil 160mm from the top with springs removed
35mm preload spacer
Shock fully extended 141mm
Shock distance with me the bike is 113mm

Maybe I an not measuring static sag correctly.

turboguzzi · « **Reply #1 on:** July 10, 2016, 12:44:02 PM »

as a first check, try riding without the emulators to sse if they are the cause. another easy check is to take out the springs and see if fork travel is smooth all the way.
BTW, shocks are the rear suspension, guess you meant forks right?

grcamna2 · « **Reply #2 on:** July 10, 2016, 12:45:57 PM »

What are the static sag numbers front and rear w/ you off the bike while it's sitting straight & level up on it's wheels(you'll need a helper to hold the bike up)and then what are they w/ you in full riding gear and seated in your normal riding position ?

akabek · « **Reply #3 on:** July 10, 2016, 05:46:31 PM »

Quote from: turboguzzi on July 10, 2016, 12:44:02 PM

as a first check, try riding without the emulators to sse if they are the cause. another easy check is to take out the springs and see if fork travel is smooth all the way.
BTW, shocks are the rear suspension, guess you meant forks right

I did mean forks. I removed the front wheel, emulator and springs. The forks have smooth travel but the last 1-2 inch of full extension is moves slower almost like that is a vacuum. Otherwise it seems fine. I put it all back together without the emulators and there still wasn't much movement with the zip tie. Does this sounds like I need new fork tubes?

grcamna2 · « **Reply #4 on:** July 10, 2016, 08:04:59 PM »

Quote from: akabek on July 10, 2016, 05:46:31 PM

Quote from: turboguzzi on July 10, 2016, 12:44:02 PM
as a first check, try riding without the emulators to sse if they are the cause. another easy check is to take out the springs and see if fork travel is smooth all the way.
BTW, shocks are the rear suspension, guess you meant forks right

I did mean forks. I removed the front wheel, emulator and springs. The forks have smooth travel but the last 1-2 inch of full extension is moves slower almost like that is a vacuum. Otherwise it seems fine. I put it all back together without the emulators and there still wasn't much movement with the zip tie. Does this sounds like I need new fork tubes?

When you had the front forks apart did you roll the tubes on a flat surface and check them for straightness ?

akabek · « **Reply #5 on:** July 10, 2016, 08:28:31 PM »

The forks were assembled a few years back but no, I did not check to see how true they are. Time to pull them out and check....

NobleHops · « **Reply #6 on:** July 10, 2016, 09:19:52 PM »

If they are not well aligned that will mess their travel up too. When you are reassembling them, swing by your local glass shop and get a piece of 1/4 inch glass about 8x10 inches. Lay it flat on one fork tube and then lower it to the other. In perfect alignment it touches the other across its full length too.

turboguzzi · « **Reply #7 on:** July 11, 2016, 04:25:52 AM »

if fork travels smoothly without springs, most likely bent tubes are not a problem

but now i notice "15wt oil"

if you welded the the little holes, then go with 5wt

akabek · « **Reply #8 on:** July 11, 2016, 06:09:41 AM »

Quote from: turboguzzi on July 11, 2016, 04:25:52 AM

if fork travels smoothly without springs, most likely bent tubes are not a problem

but now i notice "15wt oil"

if you welded the the little holes, then go with 5wt

My damping rods did not have any little holes. From what I have read the suggestion was to weld up both little holes if you have them. In the following thread most guys ended up using 15wt oil for rebound.

http://forums.sohc4.net/index.php?topic=84102.0

I will pull the forks and dismantle them so I can start from square one. I have a 4 foot sheet of glass so I will check if the tubes are straight. I will also post pics of my damping rod. I bought the front end from a guy that claimed it was an OEM Honda racing front end. Apparently you could buy a dual disc option back in the day. I have no idea if it is true, I just wanted dual discs on the front.

NobleHops · « **Reply #9 on:** July 11, 2016, 07:07:41 AM »

> Fork oil 160mm from the top with springs removed

Just checking on one detail about this: this measurement was made with the fork collapsed all the way, yes?

akabek · « **Reply #10 on:** July 11, 2016, 07:21:36 AM »

Quote from: NobleHops on July 11, 2016, 07:07:41 AM

> Fork oil 160mm from the top with springs removed

Just checking on one detail about this: this measurement was made with the fork collapsed all the way, yes?

Yes, I removed the spring, compressed the fork, and added 160mm of 15wt fork oil from the top with the emulator installed.

Turboguzzi suggested a test ride after removing the emulator which I did. I also did not add oil during the test to make up for the emulator

akabek · « **Reply #11 on:** July 11, 2016, 07:36:41 AM »

What I find odd is the CB550K damping rod has the rebound spring where the CB550F does not. I have a CB550F....

turboguzzi · « **Reply #12 on:** July 11, 2016, 11:58:00 AM »

would still give it a try with 5 wt..... depending on how close the foot valve to damper tolerance is, you might actually NEED two tiny holes in the top behind the rebound spring. BTW, do you feel noticeable difference between extension and compression when operating by hand? you should...

akabek · « **Reply #13 on:** July 11, 2016, 12:13:20 PM »

Both forks move freely the full length so my tubes are good. I took one of the forks apart to see what I installed a few years back and aside from the emulator there is the Race Tech adaptor. It turns out the damping rod DOES have the two little holes on top that I never closed. I had a short conversation with Matt at Race Tech and he said it did not matter whether you leave them open or weld them up. Now that I have more information on my internals I am going to reach out to Race Tech again to see what he suggests.

grcamna2 · « **Reply #14 on:** July 11, 2016, 12:30:10 PM »

How does your triple clamps line-up w/ everything installed? if they are a little tweaked it can cause stiction.

turboguzzi · « **Reply #15 on:** July 11, 2016, 03:04:34 PM »

can you post a pic of those adaptors? never seen one...
from my experience with quite a few sets, shutting off the top holes does make a difference.

akabek · « **Reply #16 on:** July 11, 2016, 03:05:14 PM »

I had a call with Matt at Race Tech and he gave me a few things to try. The emulators have 2 open and 2 closed holes. He suggested drilling out the two closed holes so all 4 are open. Then swap the black 40 pound springs for the lighter silver 26 pound springs with 3.5 turns of preload.

As a baseline for the CB550 the main spring preload should be a maximum of 25mm and the oil level should be around 140-150mm.

We also discussed the installation of the forks. With the bike off the ground using front and rear stands you should be able to raise the front wheel by hand and when you let it go it should drop to full extension under its own weight. The proper way to install forks is to start with the axle and tighten from the bottom up.

With the front wheel removed my forks move easily up and down. I have a feeling my issue was due to the forks binding. I am going to reassemble my forks with no changes to the emulator and using the suggested preload and oil level. Than when I install the front wheel I will tighten the forks from the bottom up and try the front wheel test. I am hoping my emulators will be fine without change the spring or drilling more holes.

akabek · « **Reply #17 on:** July 11, 2016, 06:36:50 PM »

Attached is the pic of the RT Adaptor I have. It is just a cylindrical piece of aluminum.

akabek · « **Reply #18 on:** July 11, 2016, 06:45:26 PM »

Now I am really baffled. I reconnected the lower fork on the one side. When I put the adapter in each fork I made sure they were sitting upright. Then I dropped the emulator in with the spring facing the top. I topped the fork oil to 160mm on each side followed by many full up and down strokes with the fork to get the oil into all the passage ways. What I noticed is the tension increases on the last inch of travel when compressing the forks. Extending them is quicker and easier. Next I installed the springs followed by a washer, PVC spacer, another washer and tighten the cap. With everything back together the right and left fork will not compress. It is like there is an air lock. What did I do wrong? When I take the caps off they will move up and down again.

scottly · « **Reply #19 on:** July 11, 2016, 07:17:10 PM »

Are you trying to compress the installed springs by hand by lifting the front wheel?

akabek · « **Reply #20 on:** July 11, 2016, 07:27:33 PM »

I am just trying to compress the front fork by hand. I barely get any movement on either side....

scottly · « **Reply #21 on:** July 11, 2016, 07:42:00 PM »

Those springs support a hundred or more pounds each.

Put the front wheel back on, set the weight of the bike on the springs, and see how it feels. My gut feeling is you have too much oil.

akabek · « **Reply #22 on:** July 11, 2016, 07:57:03 PM »

Before I removed the fork internals I had the oil set at 160mm from the top and I was able to compress and extend the forks by hand. I just wanted to removed the internals so I could see what I had. I put everything back together with the same oil volume and now the forks will not compress by hand. I even removed oil in one fork dropping it to 175mm and still the same thing.

NobleHops · « **Reply #23 on:** July 11, 2016, 08:04:57 PM »

What Scottly said, I sincerely doubt I could compress a fork assembly by hand unless I had one end clenched between my feet and could lean on it some. I'm not small.

Check the alignment as prior, finish assembly and go take a ride.

Last thought. Even a perfectly assembled fork sometimes feels a bit odd for the first mile. Just go for a 10 mile ride, report back.

scottly · « **Reply #24 on:** July 11, 2016, 08:09:53 PM »

Quote from: akabek on July 11, 2016, 07:57:03 PM

Before I removed the fork internals I had the oil set at 160mm from the top and I was able to compress and extend the forks by hand.

That was without springs, correct? If springs were installed, the forks would extend by themselves...

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Author Topic: Race Tech emulator/spring front suspension setup help (Read 5529 times)