1994 ST1100 Soft Front Suspension

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Oct 9, 2017
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Pelzer S.C.
Just purchased a 1994 ST1100, wonderful shape, under 33000 miles. Only issue is what seems to be very soft suspension in front. When in about any gear, if I give it (wot) the front forks becomes or comes close to full extension. When abruptly release throttle, forks seem to compress immediately at least three, maybe four inches. It is in my winter maintenance plan to remove forks and replace oil. No record of this task ever being preformed. But, after a little research in this forum, sounds like perhaps the anti-dive assembly may be faulty. With the info I've provided could someone verify this. If not, what is a better way to test it's proper function. Thanks in advance. Please don't be disappointed if you respond and I don't reply back right away. It's been raining every since I trailered it home. Just got it cleaned back up, and I see sunshine today. Will be gone part of the day on a good ride. PO was kind enough to supply a full tank of gas with the sale.
 
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The anti-dive valve could be the culprit... Another thing to look for is the pivot points on the left front caliper. Make sure it is free to pivot when the brakes are applied. If this is not the case, you should remove the caliper and lube the mounting points... be sure to remove the race from the needle bearings and lube the bearing with some waterproof grease. When reassembling, clean and lube the shoulders of the mounting bolts also.
 
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Thanks vinny, will work my way through what you suggested and the anti- dive assembly. Not meaning to hijack my own post, but going to post a few thoughts on my first local ride. Rode about thirty miles of narrow two lane curvy blacktop,and ten miles of interstate. I am very impressed. This is the smoothest, almost electric motor smooth, motorcycle I've ever ridden. And I've owned three Goldwings, Almost silent power delivery, and very good handling for the way I ride. I know better riders than me could have numerous suggestions for better suspension. But the bike could easily make a rider like me think I'm a better rider than I really am. To me thats a bike designed for better than average stock handling. The interstate down here at times moves at a pretty fast clip. Fast lane was around 85 today. When the car in front of me moved to the right, about a half mile was left between me and the car in front of me. Opened it up a bit and over a ton came pretty quick. Bike reached that speed without any effort, remained silky smooth in engine performance, and felt as if I were bolted to the road. Excellent design for a bike going on to 24 years old. Just my humble appraisal on my latest purchase. My last bike and project was a 2002 Harley Sportster. If my goal had been to find a bike the exact opposite of my sportster. Don't know if I could have done any better.
 
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2005 ST1300
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8901
The ST1100 fork is a fairly long-travel unit for a road bike at 150mm; most other road bikes would be in the 110-130mm range, and my guess is a Harley fork would be short travel also. That means you will see a lot more movement from a full open throttle to a full closed throttle. The antidive unit (which provides an increase in compression damping by restricting oil flow) will only come into play if you use the front brake, the rest of the time it is not active.

The ST has a deliberately "soft" fork, both in springing and damping. That provides more comfort but sometimes at the cost of chassis control, and that is a compromise bought on by the design of the fork and components. The ST fork uses a damper rod in the left leg, and a cartridge damper in the right. It is possible to modify both of these to change the suspension action, and to change the springs as well. Damper rods are cheaper to manufacture but are not the best for damping control as the damping force generated is not proportional to the speed of movement, which means they are a bit slushy at lower speeds but can become more jolting at high speeds.

On my own bike, I have extensively but not expensively re-worked the forks, and it is now a really competent handler across any road surface, without too much impact on comfort.
 
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Thanks TerryS, from your description it is operating and functioning correctly. I did notice the front only compressed about 1 inch when front brake is applied. I realize this is for the most part old info discussed many times. So thanks for taking the time to share with me the history and reason for design. Have owned somewhere around 50 bikes over the years. Mostly Japanese and british. Don't recall any street bike with that much travel that I have owned, other than old dirt bikes. I'll call myself happy with it and just change fluid and clean/lube other components.
 

RobbieAG

Robert
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Apr 4, 2014
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522
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Greensboro NC
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2005 ST1300
Have you checked the sag? You can change the preload by adjusting the fork spacer length. I just ordered some straight rate springs for my weight from Traxxion Dynamics. That's a very cost effective way to improve the front suspension.
 
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In the past, I have added up to a half inch of spring diameter pipe to firm up the front end. Sometimes for me thats good enough.
 

ReSTored

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You didn't mention how many miles the bike has on it but as it is a '94 I'm assuming you have more than 50,000 miles. Maybe you're on the original fork springs and shock and they are probably worn out. Who knows how long it's been since the fork oil was changed.

For the front I'd remove the forks, check the spring, probably replace it with a Race Tech or Progressive, clean the anti dive assembly and use a heavier fork oil. If it is a high mileage bike you might want to check the fork bushings and change out the seals while everything is open.

If the rear is acting like a pogo stick replace shock with a Progressive 465 series which is pretty inexpensive compared to other alternatives and it performs fairly well based on forum feedback.
 
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Seems I was lucky and found a like new, for the most part well maintained, low mileage bike, with 32732miles at purchase. Rear shock operates as it should, no POGO stick action. Waiting for this weekend to give my wife a chance to be a passenger. Will see if it still functions normal two up. Could you suggest a fork weight that would work better. I'm guessing I'll be happy with just replacing with heavier oil. When a manufacturer states they balanced options that would work for the average rider. I'm that guy. Thanks ReSTored
 
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Thought I'd give a little update since riding two up with my wife. We/She loves it. We seem to enjoy the benefits of the somewhat soft, long travel of the front suspension, and rear shock.
Took about a sixty mile ride on local roads where we know every ripple, bump, and patchwork. If the idea of the engineers, was to give a comfortable car like ride, they succeeded. Being somewhat older 60/54, seems the bike was built just for us. She has declared it is a better ride for her then anything else we've owned. Including three Goldwings. We are happy with the power and handling, so time and money spent this winter on hoses, and belt will be well spent. Will take a little time to make an old guy comment. Have been discouraged this past year with shoulder issues. Bone spurs and some arthritis, pretty much ended my dreams of more long distance rides once retired. The set up the PO installed, bringing the handle bar up from standard position is almost perfect for me. Have five other bikes and some days in just six miles I'd had enough. So, being able to ride pain free with my hands down further than can be achieved with the other bikes, was an unseen benefit of this purchase. Thanks all for replies of function and build goals to help me understand all is OK, just maintain, ride, and enjoy.
 
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