Hi all, the rear shock on my 01 m600 feels like it bottoms out way too easy whenever I hit a slight bump in the road. I can easily bottom it out just bouncing on the bike while it's on a stand. I'm pretty sure it's the stock shock and the preload looks like it's set to maximum already (spring compressed, no more threads to be seen). I weigh 125 lbs, maybe 135 with gear. The bike only has 4k miles on it. Is it possible that the spring is defective?
A weak spring is possible, more likely is no nitrogen and maybe no oil is left in the shock. Before you think about servicing it inspect the shaft for worn chrome and pitting.
Your excessive preload is keeping your suspension pinned near the bottom of its working range. You need to properly adjust your preload and if it has to be cranked down more than 10 mm to get the correct sag you need a different spring. At your weight I wouldn't think that would be the case.
I'm with howie - it's 11 years old. If you haven't had it serviced it probably needs it. Weak spring possible (what do you weigh?) but probably not the only cause at this point
I don't disagree with Howie, he posted up while I was typing my reply. I would still set the preload correctly and see what I had before I went any further. There's absolutely no reason the spring should be cranked ALL the way down.
Yeah, it probably should be serviced. Before I do that I'll try backing off the preload to see what that does. Thanks for the replies.
Yep, Carbon has a valid point, free4/cheap stuff first. Might be coil bind, not bottoming.
Quote from: howie on March 15, 2012, 08:29:56 AM
Yep, Carbon has a valid point, free4/cheap stuff first. Might be coil bind, not bottoming.
Actually I've learned to clear the previous owners mistakes before diagnosis.
Just to make it easy you could completely release the spring and then add 10mm of preload. It wouldn't be an accurate setting but at least it would be in the operating range. Then see what you've got for suspension and decide what to do.
Someone with more experience may have a better rough setting than my 10mm?
if you do decide to have it refreshed/rebuilt...I highly reccomend Rick at motocd.com and despite his less than stellar website, his work is topnotch!!! [thumbsup] ...he is Penske and Ohlins certified and he will set up your shock for you based on not just spec, but your weight and riding style, as long as you give him all the correct necessary info.
So I took a closer look at the rear suspension and found that my shock isn't bottoming out at all. In fact my sag is on the low side of the recommended range. Something else is limiting the range of motion and I can't see what it is. Is there a built-in limiter that prevents the rear from compressing down to the limit of the spring/shock?
Could be coil bind that Howie mentioned. But there's no designed stop that I'm aware of - beyond the rubber bumper that's all the way at the bottom of the shaft. But that's not exactly tricky or secret.
Put a big guy on a Monster and it'll bottom out like a champ.
Quote from: JoeP on March 16, 2012, 05:06:39 AM
So I took a closer look at the rear suspension and found that my shock isn't bottoming out at all. In fact my sag is on the low side of the recommended range. Something else is limiting the range of motion and I can't see what it is. Is there a built-in limiter that prevents the rear from compressing down to the limit of the spring/shock?
Sad Panda is correct. The rubber bumpers do deteriorate or disappear with age causing harsher bottoming. Your rear suspension consists of the shock, rocker arm (big aluminum linkage on top) hoop (connects rocker to swing arm), swing arm and swing arm and the swing arm pin (connects the swing arm to the rear of the engine). There are also bushings that support all those parts and allow them to move. Go here http://www.ducati.com/services/maintenance/index.do (http://www.ducati.com/services/maintenance/index.do) and look at the rear suspension for the parts catalog for your 2001 Monster to see the parts break down. Sometimes there is a custom limiter, a tail chop without enough angle on the license plate. This will be difficult over the interwebs. Photos might help as well as a thorough description of what you are feeling. If a bushing is seized you might need to disassemble to diagnose. Oh, the original spring is a yellow progressive spring (windings get closer towards the bottom.
If you've got the capability to hang the bike - a sturdy ladder will do - you can get the weight off the rear. With the bike stabile and light on the wheels you can have the rear wheel out and disconnect the shock after removing the rear wheel. With those out you can manually work the swing arm to and beyond the range of normal work with the shock in. That should help you feel if any binding. If the rocker/hoop set up has never been serviced it's over due for a clean out and some good grease at all the bearings, bushings and hiem joints. Sure can't hurt.
With the shock out you can get a good look at it as well.
So I've isolated the problem to the shock itself. The swingarms and other moving parts have enough clearance for the full range of motion. The shock will compress easily up to a point and then become very stiff. The transition is like hitting a wall, which is why I thought something was blocking the swingarms. So what do you think, service the shock or get a new one?
Stock Sachs? If so, probably not. Hard parts are not easily available and, if you need hard parts you are well on your way to a new shock. Examine the rod. If the chrome is worn or pitted no need to go further. The shock must be depressurized to disassemble (excluding spring). Let us know what you have before going further.
Hey, thanks for all the help. This is a great forum! [beer]
Yes, it's a stock Sachs and it's 10 years old with 5k miles. I wonder if it just needs to be repressurized. Does it also have oil that needs replacing? At this point I'm looking to just get a new (to me) shock.
As long as the chrome on the shaft is good you can overhaul it, new oil, if you want, revalved for you, pressurized and all should be good.
If the spring was compressed all the way for a long period of time it may have taken a "set" and not be able to return to its full length. Measure the uncompressed length and compare it to the stock length to see if it 's okay. Or just plan in installing a new spring of the correct rate based on your weight as part of the project.