have put on 34,000 miles on my 03 GT. It seems now that the wind buffets the bike comeing up behind big trucks now and it did'nt before. Running Avon ST 45 tires, beginning to wonder if a worn out steering stabilzer would cause the problme mentioned.
on my 98 RS at 6200 miles the damper was shot. Rebuilt it and the improvement was amazing. I used 10 wt fork oil in it and it worked great. Untill the temps dropped to 30-40 degree range, now its pretty dam stiff in the early am. ( wonder if I should drink 10 wt for breakfast?) Next time I think I will try 5 wt or ATF fluid.Oh, mine was easy to tell it was shot as it leaked oil all over the front of the bike.FWIW
The 'bolt from hell' is no probs if you do this, the bolt has 3 or 4 threads coated in Loctite, the type that sets hard! get this bolt out first whilst the rest of the damper is fixed.
Get yourself an impact driver that can take the spline wrench, mine is standard 3/8 or 1/2 inch. Be patient, keep tapping away on the impact wrench loosening a few degrees at a time but you must keep the wrench perfectly aligned or you'll ruin the bolt head. Once out, clean the bolt with a wire brush.
Nobody has said whether the bolt should be Loctited when refitted. I guess it's there on oem to stop the damper flapping around if the bolt ever dropped out and fouled your steering.
I read you can recon a damper without removing plastic and such. I didn't do this, I took off the front wheel, calipers and front fender. You can at least test the damper in a vise without pouring oil all over the bike if you got the assembly wrong and you can fill it without leaving an air space! You don't need the side plastic off.
I used transmission fluid. I think 10Wt is a bit heavy.
i tried heating the bolt to release the locktight with a soldering iron on high, but did not work. By the time I figured that out, the head was starting to round out.Next time I'll try the impact wrench trick, if I have enough bite left in the bolt head. I agree,the 10 wt is a bit heavy, seemed fine this summer, but in cooler weather I think its a bit much.
Assuming you have an oem damper and not aftermarket, I can tell you what happens with thick oil (10Wt plus):
After you've filled the damped with thick oil and reassembled it, grip one end in the vise. Then push and pull as hard as you can. You will notice that the outer dust seal lip will be bulging outwards under pressure - a sure sign that the seal is under too much pressure. If you try it in the bike like this and wiggle the forks back and forth I bet you find the seal will eventually burst and pour oil over your fender. There's always a non damped zone of a few degrees before you get resistance.
The oil seals should have two sealing lips. The inner lip is the one that grips the piston rod under pressure, the outer lip you can see is really a dust seal. These seals are really designed for rotational use. I haven't found any solid reference to them being used for hydraulic push-pull sealing - but then the oem seals may be a different spec to the replacements. Dampers that leak will also pull in water, so the oil may not look the same anymore. That's why you must check the little bypass holes in the centre pistons!
PS I am assuming all oem dampers might be like mine. My piston bypass holes were very small. It's possible that later dampers had larger bypass holes, therefore used higher weight oil. That's the problem replacing a key component - oil, in a part like this.
What we really need is somebody to hang a spring balance on a new damper and feedback readings.
Thanks Voxmagna. I've an original damper... and now is on my table.
There is a screw (like a plug) at one end of the shaft: what for?
I've opened the damper, and I see a fluid oil inside, not thick...(?!?!): you advise me to refill with a 5 or 10 oil forks? (sorry for my english)
When I did mine a few months ago I used 10WT fork oil and have had no problems so far, but I live in an area that doesn't get lower than 40 degrees F.
Now that I've been reading that it may be the wrong weight oil, I'd suggest you email Stig at http://www.ppsracing.com/ and ask him what he uses when he rebuilds the Ohlins steering dampers.
Cardano4ever, please realise that nobody can realistically 'advise' on steering part refurbishment not covered in service proceedures. We post our personal experience, but you have to take the risks and we all have different levels of competence.
The weight and type of oem oil has to my knowledge never been established and you are unlikely to find out. The problem we face is dampers are removed when broken, somebody needs to give feedback on the damper resistance for a new one. I'd rather guess lighter weight than heavier. Since the oil weight is a key factor in damper performance, replacing the oil with any standard weight is purely guesswork - unless somebody has had enough of the oem oil left behind to measure it in a viscosity cup. Asking others what oil they use is no good either, since their damper pistons and bypass valves may be very different.
I'm sure the slotted screw head has intrigued you! You shouldn't need to do anything with it, but actually the push rod is in 2 halves joined with a concentric male/female thread. To dismantle and remove the piston bits completely, you'd grip the opposite end whilst unscrewing using the slotted end.
I did research into a replacement and liked the look of the 'Hyperpro' adjustable - but couldn't justify the price when I discovered the oem design has no damping action +- 10 degrees and I don't ride that hard. I think the oem damper is only there to stop low speed wobble, whereas aftermarkets work as true dampers to change the ride steering like shocks. That's why a lot of riders throw the oem away and ride without!
Yeh that's what happened to me! You guys call it ATF (Automatic Transmission Fluid) It's the light oil used in automatic transmissions on cages, usually red color. I never tried the 5Wt fork oil. ATF is definitely lighter than 10Wt. Hope you burst the seal in the vise (like I suggested to test) as it makes a mess over the front fender. Still, I bet you can now pull it apart with your eyes closed! Don't try DOT4 brake fluid or your fender might need a new paint job. PS make sure the pin holes in the pistons are absolutely clear, the end circlips were not distorted when you got them out and fit back absolutely perfectly in the grooves. You might have to fit a new seal. I bought 6 'cos they were so cheap.
Today I'll try with sae 5 oil fork and new seals.
A question: yesterday, when I've filled the damper and reassembled it, if I moved in/out the shaft slowly, resistence was not much; but if I moved the shaft in/out fast, resistence was hard. It's normal this double behaviour ???
Another reason NOT to use 10 wt fork oil. On a cold morning I was pulling out of a parking lot, lost my balance, no biggy, just jerk the handlebars and correct,but the heavy oil made it dam near impossible to correct fast enough.What normally would have been a wobble at worst,turned into a quadruple wobble with an expletive throw in.Yup, one day soon I need to put ATF or??? in it. I ride in temps from 15 to120 so maybe I'm a bit more extreme then others tho.
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