handling issues after spring swap

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I've rebuilt the forks again and went back to the factory springs and solved my problem already, but I'm still curious as to what the actual problem was so I'm posting my issues to see if any conclusions can be made by those here that are smarter in the area then I am. But I'm in no rush for answers because as I said, I've resolved my issue by going back to factory internals.


After finding a faulty fork seal and knowing that I had some slop in the stem bearings I decided to tear down and rebuild my front end (and I never want to do 20 year old 60K mile old steering bearings ever again. The steering neck is a little buggered up and getting the old ones out and the new ones in was more than a challenge) I went with some race tech 1.0kg springs for the front (I weigh in at 230lbs, mom is another 150 and is usually riding with me) to replace the wore out front springs that are fairly bouncy with both of us on the bike and will bottom out on hard braking.

Long story short everything goes together but I had to cut about an inch out of the measured preload spacers to get everything to go back together because I just couldn't get the cartridge side to go together without doing it. I couldn't compress the spring enough. I ended up cutting an inch out of both sides to make sure that I took an even amount of preload out of both.

On my test ride the bike felt wrong.. it was more twitchy to input than my race bike, and it didn't feel stable at all in a corner, it almost felt like it wasn't connected to the road. Braking however was greatly improved and I actually tested emergency braking and brought the rear tire off the ground a couple times trying to get used to the feel. I return home and realize (probably under my emergency braking drills) that the fork seal on the left side had wandered out of its groove when the c clip that holds it failed. No matter I had ordered new ones and kept the old ones so I just took everything apart and put the old one back in. Swapped springs back out to the factory springs that I didn't need to mess with the preload to install and refilled the oil (with the springs out of course)

My question is, do you think it was the fact that I did the fronts and the rear is so worn out that I upset the balance of the bike, do you think it was the fork seal that may not have been set right in the first place that could have caused the ill handling, or do you think it was the fact that I should have used a mathematical equation to figure out how much preload to cut out of each spacer instead of a straight inch out of both that caused both forks to be sprung differently. Or even was it just a horrible combination of two or all three?

Either way the bike is fine now and I'm glad to have her back. I still have some work I need to get done to her, clean the carbs after sitting so long, new fuel, vacuum, and water hoses. I've got all the parts on my shelf, I just wanted to enjoy the tail end of the riding season before it got too cold for mom and I to both enjoy it
 
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First off - do you really ride with your mom??:confused:

So you have put it back together with OEM springs, but what about those OEM spacers that you cut down? Did you get new ones for the re-fit? If not, then your OEM springs aren't loaded properly now.

When I installed Progressive springs in mine, the instruction sheet said to cut a section off of ONE spacer only, can't remember which now. I think your problem was with what you did with those spacers. The right fork IS a bear to get back together and I have always needed four hands to get that spring washer and retainer back into position, mine compressing the spring while the wife is holding the damper rod by a wire, to keep it from falling back into the tube and slipping the retainer into position.
 
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First off - do you really ride with your mom??
LOL.

I fitted hyperpro fork springs and 10wt oil,new slider bushes and tapered head bearings and replaced the anti dive valve,that and a new wilbers rear shock made the bike better than new handling wise in my opinion, I'm about 250lbs suited up and with her indoors onboard and full luggage for touring makes her a heavy rig but she handles the weight perfectly.
@insulinboy,maybe the rear shock needed replacing also to match up with the new fork springs,just a thought.
 

ST1100Y

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...maybe the rear shock needed replacing also to match up with the new fork springs,just a thought.
That too, but I guess he lowered the front by cutting the spacers, tilting the steering head steeper, thus the wiggly feeling...
 
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I think his mom has Alzheimers, and loves to ride....good on him...wish my mom was still around..........ff
Good man insulinboy,fair play to you, I had my 80 year old aunt on for a short spin one day,she's great craic and not like a woman of 80,she fairly enjoyed the short spin.

I hope Tina doesn,t read this post Brendan
Too late Pat,she's sitting here beside me on the sofa:)
 
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From what I have read in the RaceTech Suspension "Bible" Handbook, it probably doesn't matter if the spacers are different lengths. Some bikes even use different weight springs in each fork !!

What is important is that when you are on the bike, off the stands, that the front & rear suspension is 1/3 compressed. That would be about 50 mm compression on the front forks. If you have that amount of static compression, the spacer length is correct.

I think the problem you experienced was because you still had the stock cartridge & damper rod.

I also installed a set of RaceTech 1.0 mm/Kg springs along with a RaceTech Gold Valve & Emulator kit, and like the results.
 
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insulinboy
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First the springs came with a rod and I cut the rod down for the new spacers, I didn't do anything to the factory spacers. They aren't long enough for aftermarket springs anyway. Even the cut down spacers were substantially longer than the factory ones.

Second yes, my mother has Alzheimers and rotates between living with me north of Atlanta and my sister in Nashville. She loves to ride and misses it so I bought the ST for us to take trips together with. She rode some with me on the VTR1000 but that was.. interesting to say the least :lol:

Factory yes, the spacers are different sizes in each shock, but I cut the spacers down an inch on each so that hopefully I let out the same amount of preload on both sides so they were still sprung the same and I don't know if that was the right way to do it or if I should have used a calculation IE I cut 30% of the short spring so I should cut 30% of the long spring rather than an inch across the board being 1/8th of the short spring and 1/15th of the long spring.

The front of the bike with the stiffer springs even cutting some preload out still sits taller and had less sag than the factory springs do.
 
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I guess whatever the cause, it is a moot point now anyway, since you say the bike is fine again. Good for you, being the good son, and good for your Mom that she has that connection with you, as it may strengthen her memory of you as the disease progresses. Good luck.
 

970mike

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I guess whatever the cause, it is a moot point now anyway, since you say the bike is fine again. Good for you, being the good son, and good for your Mom that she has that connection with you, as it may strengthen her memory of you as the disease progresses. Good luck.
:plus1:
 
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insulinboy
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We're headed to the Tellus Museum today for a special exhibit (http://tellusmuseum.org/events/heavy-metal-motion/) and afterwords (when its hopefully a little warmer than 50 :O) we will be headed up to Ft Mountain to play tag with the neighbors in their smart car (the thing actually scoots along pretty good, I need to get me one :lol:)

It is a moot point since the problem is resolved.. But I'm just curious and thought maybe someone on here could solve the riddle for me who maybe has had the issue before. I'm sure it was a combination of all the problems but I don't know for sure and I'm never against learning something new about a motorcycle, especially when it could be considered a safety concern
 
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But I'm just curious and thought maybe someone on here could solve the riddle for me who maybe has had the issue before. I'm sure it was a combination of all the problems but I don't know for sure and I'm never against learning something new about a motorcycle, especially when it could be considered a safety concern
With suspension adjustments its best to try one thing at a time, in relatively small increments, and observe the result. Its always more of an empirical process than a theoretical one.

Changing to new springs like you did is a relatively large single step, but they're setup for the bike and many others here have used them so its surprising you got the result you did. I still use the stock springs, so I can't comment on the aftermarket springs. I have increased the spacers significantly on the stock springs during my own experimentation and don't remember ever encountering what you did. I never shortened them, so perhaps your cutting of the spacers dropped the front end enough to steepen the fork rake (as Martin mentioned earlier) and make the bike twitchy. But if that were the case I'd suspect you would have encountered more fork bottoming during your severe braking tests because of the lower ride height caused by the shortened preload spacers. Not being familiar with those springs that's just a guess. It also seems strange to me that you could get the ST to be more twitchy than a race bike by dropping the front a little because its not like the fork rake is steep to begin with, and it isn't going to change that much just by cutting down the spacers a bit. Now that I think about it, when I adjusted mine many (17) years ago, I'm pretty sure I experimented with dropping the fork tubes in the triple clamp to see what that did, and don't remember the bike ever getting twitchy, quite the opposite. I always rode sport bikes up to buying the ST, so to say I was a bit disappointed with its steering response would be an understatement.

So there's some thinking out loud, without any real answers, but since you were asking for info that's what I can provide. Also, I weigh 170 and only ride one-up vs. 230 + mom, so we're looking at different setups anyway, that's why I'm still using the stock springs.
 

John OoSTerhuis

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Hmmm... hard braking shouldn't bottom the front suspension, the anti-dive mechanism should prevent that. Hitting a sharp bump OK, just braking, no. What am I missing?

John
 
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Hmmm... hard braking shouldn't bottom the front suspension, the anti-dive mechanism should prevent that. Hitting a sharp bump OK, just braking, no. What am I missing?

John
Same anti-dive system either way, so if it allowed bottoming with one set of springs I'd guess its also possible that it would allow bottoming with the new springs, since he shortened the spacers. I also said it was just a guess, so I'm not claiming anything.

Maybe he's running too light a weight fork oil as well, or the improper level, he didn't specify. That could also contribute to the twitchy handling, so we might as well ask him that question too.
 
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insulinboy
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5wt on the cartridge side (right) and 15w on the damper rod side (left side with anti-dive) per Race techs specs on what was in it stock as I couldn't find it in my manual. 140mm oil height with internals installed and air bled out of forks and then bottomed out but without springs installed. I don't hard brake all at once but gradually apply generally except when doing braking drills which I occasionally find empty parking lots or streets to do. If you don't use the skills you can forget them...

speaking of forgetting skills, after driving the old CB400 Hondamatic for the past 4 months while the ST was in pieces in my garage it was a culture shock to ride the ST again :lol:

And when I say it was twitchier than my race bike. I can hold a straight line on the race bike fairly easily. It seemed like I couldn't keep the ST from wandering around the lane it felt like the slightest movement on my part would get me wandering in the lane. Its been a while since I've been on the heavy beast and it has been an abnormally windy week in my area (with constant 10-15mph winds) so that may have been a factor too. All my other bikes are naked or half naked bikes and the wind gets through them more efficiently
 
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5wt on the cartridge side (right) and 15w on the damper rod side (left side with anti-dive) per Race techs specs on what was in it stock as I couldn't find it in my manual. 140mm oil height with internals installed and air bled out of forks and then bottomed out but without springs installed.
OK, there's another question, do you have the ABS/LBS model or non-ABS, the oil level is way different between the two because the fork tube diameter is different. 140mm is correct for ABS/LBS, but the figure is 190mm for the non-ABS model. So if you set it to 140mm with the non-ABS version you're 50mm too high. Also, the stock oil is SS-7 which is 5W, and for someone your weight that would be most likely too thin. AFAIK, the stock setup is the same oil in both forks, not sure where the 5w/15w combo information came from.


And when I say it was twitchier than my race bike. I can hold a straight line on the race bike fairly easily. It seemed like I couldn't keep the ST from wandering around the lane it felt like the slightest movement on my part would get me wandering in the lane. Its been a while since I've been on the heavy beast and it has been an abnormally windy week in my area (with constant 10-15mph winds) so that may have been a factor too. All my other bikes are naked or half naked bikes and the wind gets through them more efficiently
Another thing I noticed over the years is my ST (also a '97) seemed to ride more true in a straight line with a bias ply tire on the front, which was the OEM tire for the bike. Radials felt better once the bike was leaned over, but in a straight line they always felt a bit squirrely to me, so maybe that's what you're feeling if you have a radial front tire. Also, the ST is very heavily influenced by cross winds, its basically a barn door from the side, so your suggestion that the wind may have been a factor is very likely as well.
 
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insulinboy
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OK, there's another question, do you have the ABS/LBS model or non-ABS, the oil level is way different between the two because the fork tube diameter is different. 140mm is correct for ABS/LBS, but the figure is 190mm for the non-ABS model. So if you set it to 140mm with the non-ABS version you're 50mm too high. Also, the stock oil is SS-7 which is 5W, and for someone your weight that would be most likely too thin. AFAIK, the stock setup is the same oil in both forks, not sure where the 5w/15w combo information came from.




Another thing I noticed over the years is my ST (also a '97) seemed to ride more true in a straight line with a bias ply tire on the front, which was the OEM tire for the bike. Radials felt better once the bike was leaned over, but in a straight line they always felt a bit squirrely to me, so maybe that's what you're feeling if you have a radial front tire. Also, the ST is very heavily influenced by cross winds, its basically a barn door from the side, so your suggestion that the wind may have been a factor is very likely as well.

Non ABS model, reading through the manual I thought I got the fork oil right, but with 4 different models to choose from I guess I'm not surprised I fubared it. Bike has OEM Excedras on it.. well not OEM to the bike (of course 60K on a stock set of tires would be awesome :lol:) but they are getting worn and I have New Roadsmart II's to go on over the winter. I really want to give the radials a shot. Not that I haven't gotten the bike down to the pegs on the bias ply tires, but Its not exactly confidence inspiring when you get lower on them
 

John OoSTerhuis

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One more thought... twitchy handling after a steering bearings and races R&R -- ball or tapered bearings? How did you set the preload?

+1 on the wrong suspension fluid level and weight. Which shop manual are you using?

John
 
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5wt on the cartridge side (right) and 15w on the damper rod side (left side with anti-dive)
Contrary to dwalby and John O., on the recommendation of a suspension specialist, I also run different weights of synthetic fork oil. The two forks are different in their functions and should have a lighter weight, I use 7W, in the right and a 10-15W in the left. I've found no issues with them set up that way.
 
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