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Fork legs project


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Hello all -

Current winter project is reconditioning and powder coating the fork legs on my '03 R1150RT.


1) Are the reflectors just stuck on with double-stick tape? Then I can pry them off with a little heat?

2) How far will the legs pull down before they are free of the stanchions?






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Morning Lee


They are just "stuck on" (real good) with 2 sided tape.


Using heat to remove can easily distort the plastic, you might try using some WD-40 & a piece of dental floss or heavy duty sewing thread in a sawing motion between the reflector & the fork leg. Use lots of WD-40 as you work the string back & forth.


Use new 2 sided tape to re-install --(if you only need a couple of small pieces of 2 sided tape most body shops have the good 3M stuff as they use it to re-install auto moldings & emblems). A lot shops will just give you a couple of small pieces if you tell them it is for a motorcycle project.


I see you have the center stand on a piece of 2x4, if the rear wheel is on the ground then you probably have enough clearance to pull the lower fork tubes off. If they won't clear then just have someone push the rear of the bike down on the rear suspension a little more.


I usually have a motorcycle scissor jack under the engine so it's just a crank or two to get the front high enough to remove the lower fork legs.


When you reinstall the fork lowers you will trap air pressure in the forks at full extension. There are little air bleeder screws at the top of the upper tubes but those are about impossible to get to with the uppers still hooked up.


I usually use a very thin feeler gauge stock (like .001" or .0015") between the seals the fork tube during re-assembly then push the lower up, then pull the feeler stock out after the air is bled out.


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Thanks to all who have replied.


I need torque specs for the M8x18 screws at the bottom of the fork legs - the ones I removed to let the oil out. Any loctite involved with these? I will fit new o-rings.


Tnx -

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Afternoon Lee


My BMW service manual doesn't give a torque on those drain plug screws.


Just says____

• Position new O-ring on screw

• Install oil drain plug

• Fill with oil.


I seldom remove those drain plug screws as I just dump the oil out after removing the lowers.


In any case-- no Loc-Tite & seeing as those screws use an "O" ring they only need to be tight enough to not come loose in service.


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Found some string for reflector removal. Used plenty of WD40 and they both came off easily. Thanks, D.R.! I wouldn't have thought of that by myself.


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I may have hit a roadblock to any coating system that includes heat: the "bush" and "pipe" inside the fork as shown below.


So---how do you get these out?


In the parts diagram, 7 is the pipe and 9 is the bush. There are 8 pipe pieces (I assume 4 per side) and 4 bushes (2 per side).




In the picture, the fork seal and washer ("ring" in BMW terms) have been removed and you're looking at the bush and can just see a pipe piece below.


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Afternoon lee


Nothing in the BMW manual on removing the bushings or the spacer pipes.


Personally I haven't ever replaced those on the BMW oilhead either.


I have done other similar motorcycle forks & that usually involves threading a large diameter piece of round stock with a tapered thread so it will screw into the softer bushing, then drill & tap the center to accept a long piece of threaded rod.


Then tread that tapered round stock into the bushing, screw the threaded rod into the center of that round stock, then put a couple of large washers on the top on the fork tube, then a nut & turn the nut down therefore pulling the bushing out. Once you get the parts out then you have to make a proper stepped driver to drive the new ones in.


Or possibly your local BMW dealer can remove then replace them for you (only problem is: they probably haven't done any either).


In your case, you might be farther ahead to find a powder-coater that uses low heat powder (300°f-400°f) the lower the better & leave all those parts in the tubes.


You will have to get ALL the old oil residue out of those tubes though & if you glass bead them you can't get ANY sand inside the tubes or you might never get it ALL out.


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eddd - could you expand on that?


I'll give it a try.


A traditional fork has the job of supporting the wheel and providing a controlled suspension. The forks contain springs that are designed to absorb up and down forces thereby helping keep the tires on the ground. The springs alone can not handle the job adequately so a damping cartridge is also part of a traditional fork. The purpose of damping is to keep the springs from becoming pogo sticks. There is compression damping and rebound damping. Compression damping slows and controls the springs' rate of compression, and rebound damping slows and controls the rate at which the spring, and therefore the suspension, return to the uncompressed position. Damping is accomplished by controlling the movement of fork oil through the cartridge. All of these parts work to give you a smooth ride and keep the tire in contact with the road/ground.


On your BMW the forks primary function is to hold the wheel in place. The real working part of your suspension is the single strut, or shock, located above the wheel. That strut has the spring, which you can see and on the inside are the damping components. The fork oil in your bike just lubricates the fork tubes to allow smooth movement. The quantity and viscosity of the fork oil in a traditional shock is critical to the proper operation. Traditional forks seem to wear out the bushings much faster than the bushing on your style of BMW. Like Dirt Rider mentioned, it is pretty much unheard of to replace the bushing on a BMW like yours. I retired my RT at 175,000 miles and the forks were still in great shape. Those same forks are now in use on a bike that was involved in an accident that damaged the original forks. Contrast this to the fact that I've replaced the bushings on three of my four bikes this year, all of which are traditional forks.


Hope this helps.


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Lower fork legs are out to be coated. In the meantime, am trying to decide whether to remove uppers - question is, with some rather hard hits to the front end (chuck holes) is everything OK up there.


Would have to put them in "V" blocks and check with a dial micrometer. Have dial mic and could build the blocks.


Tempted to just leave them alone.


Maybe it just comes down to this: how often do you see bent upper fork legs?




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Afternoon Lee


On the BMW you don't see the upper tubes bent very often unless the bike has hit something hard.


As far as you are into that bike now you don't have much more to go to check the upper tubes though.


You can unbolt the handle bars then using rope or even string suspend the removed bars from something overhead (that way you don't need to disconnect anything from the bars)


Next, unbolt the upper tubes, then simply roll them on a flat surface, personally I use my granite block but lacking that a large window glass or even a flat table top will work.


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  • 5 weeks later...

Here's an update on my fork project.

First: here's the forks as they looked after 89K mi:



Here's what they looked like after coating with ceramic:



They were ceramic coated to avoid the higher temp of curing with powder coating on advice of the coater. This was because I didn't think I could remove the internal bushes & nylon tubes.


In the end, there was sand and ceramic left inside at the bottom of the fork legs which forced me to remove the internals anyhow.


I used a Harbor Freight internal bearing puller costing about

$18 and ground down at the arms to allow deep enough insertion into the legs:



Here is the puller box:



The coater didn't mask threaded holes and they had to be chased with a tap before the screws could be inserted & torqued.


Could someone remind me of the specified space between the fork legs? Can't find it but know I read somewhere.


Thanks -


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