Topic-icon Change of front fork oil

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5 years 3 months ago #93755 by Shadow
Replied by Shadow on topic Change of front fork oil
Yup, that's what I meant, just didn't quite say it properly :huh:

Remember yesterdays braai, look forward to todays braai, and hope for tomorrows braai.

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5 years 3 months ago #93757 by Darknight
Replied by Darknight on topic Change of front fork oil

Don't work on oil quantities when you change the oil.
rather work by measuring the oil height.
This is done from the top of the stanchion tube with the fork fuly compressed , vertical and the spring removed.

The oi height is the important factor so as to get the AIR GAP correct when the fork is fully assembled again.


Great. Thanks Wookie.

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5 years 2 weeks ago - 5 years 2 weeks ago #98550 by SarelG
Replied by SarelG on topic Change of front fork oil
Front suspension – oil change and oil seal replacement 2013 model

This is once again a long winded write-up of my experience, for those who have not done it yet, as a guideline if you want it and for the old hands to laugh at. This is not necessarily the true and only way to do this, merely how I did it and what I learned from it. Use it at your own risk, as there are probably some better ways to do it.

Based on advice from various Clan members that one should replace the front fork oil at least every 15 000 Km’s, I decided that now is a good time to do this, considering that my bike is on 36,500 Km’s already. I was never impressed with the front suspension since I bought the bike and therefore upgraded to Wilbers progressive springs shortly after I bought the bike. I did not check or change the oil when I installed them, as the bike was on less than 5000 Km at the time. The Wilbers made a great improvement but it was still not excellent, so I accepted that the KLR’s have really cr@p suspension and lived with it.

Replacing the oil and seals is not something that you simply rush off to the agents on a Saturday morning in order to buy the oil seals and you should definitely not start stripping the bike before you have everything you need ready and in your possession. I had to order and waited for the seals. I am not sure if the oil seal is commercially available, but I am sure the pros can comment? If it is, it will probably cost a fraction of what kawa charged me, I did not even think to ask the Clan before I ordered from Kawa.

For the new shape, you will need the two seals, part number 92049-1356 from Kawa, at least 1.5 to two litres of 10Wt fork oil and paraffin to flush the old gung out. The oil is also not readily available from your local forecourt or standard spares shop and only some Midas outlets and bike shops stock it. I was lucky to get Castrol 10Wt fork oil at my local Midas in Centurion at R60 a litre. Apparently bike shops have this and other brands staring at R110 up to R170 a litre.
But let me give the credits first before I continue, as I once again bugged a few clanners for advice, which they happily assisted with. Groenie with preliminary advice, Diesel Dave with running telephonic commentary and advice and Piet, my emergency messaging KLR support help line, thank you!!

Ok, so where to start? The forks need to come out to drain the oil, but before you start, you need to follow some logical steps which I was advised of. On the top fork clamps, you have two 12mm bolts on each side. Loosen these four slightly and then loosen but do not remove the bolts at the top of the fork, the ones that holds the springs in. You cannot hold the fork to loosen the top bolts once it is out of the bike. (These bolts are made from aluminium and are very finely threaded, so be extremely careful.) If you do not loosen the two top clamp bolts first, you WILL strip these bolts.

My next step was to slightly loosen the four bolts on each of the lower fork clamps so that I do not have to shake the bike around once it is raised off the floor. The lower fork holder bolts are extremely tight, as they should be, and definitely loctited. I did this with all the other bolts and nuts that needed to be removed as well. As a precaution, I always “hang” my bike off the garage rafters with tie-down straps, so even if my jack falls out, the bike will stay upright. After lifting the bike so that the front wheel hung in the air, I removed the brake calliper, undid the speedometer cable and removed the wheel. It is now easy to remove the forks by loosening the bolts further. Be ready to hold each fork as you do this, as they slip out easily.

Once you have the fork out, have your oil recycle container ready and take off the alu nut at the top of the fork while holding it upright. Once it is off, you can drain the oil into your container. (I later on regretted that I did not measure how much oil came out, which I will refer to again later.) Be careful when you tilt the fork as your spacer (if present), a washer and the spring will come out with the oil. Remove the said spacer, washer and spring, wipe down / clean them and put them in a garbage bag or somewhere else where they will not pick up grains of sand etc. Hold the shock upside down and pump it a few times, to ensure that all of the oil is out. Pour some paraffin into the shock and pump it a few times, close the top with your hand, turn it upside down etc., anything to flush out the old oil. Remove the rubber dust boot and hang the shocks upside down to drain for a while.




If you have the standard OEM spring in your bike, it will look like the one below on the left, with the long spacer. The Wilbur spring is much longer, as you can see on the right. (I do not know what displacement effect the different spring setups have on the oil volume, as the oil is simply measured by volume, 585mm on this model, or mm from the top of the collapsed shock before the springs are re-installed. – Maybe this is not important and Wookie can comment on this, please meneer?)




You can now remove the dust cover from the outer tube by carefully prying it loose with a screwdriver.




Underneath the dust cover you will see a snap ring on top of the oil seal, which you need to remove. The snap ring is slotted into a groove on the inside of the outer tube. Do not try and pry the oil seal out with a sharp tool as you will damage / scratch your shock assembly.







To remove the oil seal, you have to undo the bolt that holds the damper rod. The damper rod however spins around if you do not hold it still, but it is inside the inner tube and one cannot get to it. I manufactured a specialised tool for this task, based of detailed advice from Dave and Piet. :)




One old mop wooden handle, properly tapered at the tip and a vice-grip (locking pliers) to stand on, so that the mop handle does not simply spin with the damper rod. Position the fork over the wooden handle, ensuring that the tapered end is catching on the damper rod only. You then press down on the outer tube to create friction and un-do the bolt. Make sure that you do not lose the copper washer on this bolt.



One day I will die, but on all the others I will not, so on those days I will live it to the fullest!!
Last edit: 5 years 2 weeks ago by SarelG.
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5 years 2 weeks ago #98551 by SarelG
Replied by SarelG on topic Change of front fork oil
Be careful when you pull out the “special wooden tool” as the damper rod, springs etc. will come out with it and needs to be re-assembled exactly as it comes out.





Now that you have that out, you simply tug on the inner tube while holding / clamping the outer tube, which will pull out the old oil seal. There is one plastic cup and possibly a small spring that comes out as well. These re-assemble on the damper rod.




Ensure that everything is spotlessly clean, all old oil is removed and that no other rubbish like sand etc. makes its way back into the shock. You can now start the re-assembly by sliding the new oil seal over the inner tube. Make sure that you have it the right way around with the visible spring pointing to the inside of the outer tube





I then re-balanced the damper rod onto the wooden handle, pushed it back into the inner tube and re-fit the spring and plastic cap. This then carefully goes into the upside down outer tube until it is back in its original position, so that you can see the bolt threads from the top. You can now put back the washer and bolt. The copper washer is an oil seal similar to your sump plug washer.





You can now grease or oil the new oil seal and gently seat it into the outer tube. The second special tool is an appropriate length of 50mm drain or down pipe. Make sure that there are no sharp edges on this pipe, as it will damage the seal. Gently tap in the oil seal using the pipe and a rubber mallet. Make sure that the seal seats properly and that it is below the groove where the snap ring needs to set again.




You can now re-install the snap ring, dust cover and the shock boot. (I washed out the shocks with paraffin again after this, to ensure that any possible rubbish is flushed out, then hung them upside down again to drain, while I braaied some meat and enjoyed a few cold ones.)




Ok, back in the garage after two hours. As mentioned above, there are different trains of thought on the volume of oil. I merely went by total volume as per the manual, 585ml of oil for the 41mm shocks. I was advised to “wet” the measuring jug with oil before doing the measurement, so that the oil that stick to the jug does not subtract from the total volume used. The second way is to fill the upright shock, pump it a few times and then pump or suck out the excess oil until a desired level is reached from the top of the compressed shock. (I think it is 170mm on this model? Wookie, Groenie, Cape KLR, Doc?) One way to do this is with a new spray bottle nozzle, where you either cut the downpipe to the desired length or you install a cable tie or such onto the pipe with the desired depth protruding, push it into the compressed shock and pump until nothing else comes out.

With the oil in the shock, I pumped it a few times and then re-installed the springs, washer and the spacer. I was not sure which way around to insert the Wilbers springs but the most logical advice on another KLR forum stated that the Wilbers factory stated that it does not matter, as long as both are in the same way, but that they normally install them with the compressed spirals in downwards. This makes more technical sense anyway, so that is how I re-installed them.

The last step is to re-install the bolt at the top of the shock. It is extremely important to thread this aluminium nut in by hand, do NOT use a spanner or socket wrench, as you will strip it. I held the socket in my hand, pressed down and carefully threaded the bolts back, ensuring that I was able to thread them all the way in by hand, no tools used. Whalla!!, you are basically done. You can now re-assemble the bike, making sure that you re-install everything in the same way it came out. Remember to carefully tighten the top bolt once the forks are held fast by the lower fork clamps and before you tighten the top fork clamps again.

In retrospect, my shocks are now the best that they have ever been. I know that a lot of you will think that the oil was just so badly deteriorated that the new oil is confusing me. Yes, I agree that new oil will make a big difference, but even after upgrading to the Wilburs, my shocks bottomed out on some speed humps, even at low speeds. I have read on more than one forum that other riders have measured the volume of oil removed and in a lot of the cases, the volume was below specification, where one rider measured the volume that should come from the older shapes in his new shape, e.g. suspecting that the tech that did the pre-delivery service when he bought the bike new, filled up the old volume as opposed to the new? I will never know, as I did not measure it, unfortunately.

This is not a complex or difficult task to perform, so if you are remotely technical, go for it and feel the improvement, you will enjoy your bike much more!!

One day I will die, but on all the others I will not, so on those days I will live it to the fullest!!
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5 years 2 weeks ago #98552 by Dieseldawie
Replied by Dieseldawie on topic Change of front fork oil
Excellent Sarel. Glad you came right.

I like to drink lots of beer??
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5 years 2 weeks ago #98555 by Wookie
Replied by Wookie on topic Change of front fork oil
Nice write up SarelG....

Technically the progressive springs will work either way around and will have no effect on the operation of the actual spring.

Where it does make a difference is in the "submerged volume" of the spring in the oil.
If you fit them as you have with the tighter windings down then you have a greater effect on the operational oil height by submerging a greater volume of the spring in the oil..... making the assembled air gap smaller and the fork response possibly harsher as the "air spring" comes into play sooner in the fork stroke.

As long as you have assembled them the same (L & R) and the forks are not to harsh then all is good.

Just FYI.....The accepted norm is to fit them the other way round with the tighter windings at the top. Reason being, that by doing it this way, it will submerge a similar volume of the fork spring to the original springs and thereby set the assembled air gap to spec ( at recommended oil height).

Cheers

W
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5 years 2 weeks ago #98556 by Abre
Replied by Abre on topic Change of front fork oil
Sarel -- our resident technical advisor, guinee pig and writer :laugh: :laugh: :laugh:

Mine is also due for a change, this will help me a lot.

Abré le Roux
The adventure is out there.....
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5 years 2 weeks ago #98557 by Wookie
Replied by Wookie on topic Change of front fork oil
SarelG....

WRT the oil height.

I don't trust working on straight oil volumes so prefer to measure the oil height.
For the 41mm forks as per the manual the oil height should be set at 135 +-2mm.
This will need to be measured with the spring removed ,the stanchion fully compressed and the fork bled of any trapped air.
Then measure from the top of the compressed stanchion down to the oil.
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5 years 2 weeks ago #98558 by Piet
Replied by Piet on topic Change of front fork oil
Thanks Sarel! Nice write-up! B)
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5 years 2 weeks ago #98559 by SarelG
Replied by SarelG on topic Change of front fork oil

Sarel -- our resident technical advisor, guinee pig and writer :laugh: :laugh: :laugh:

Mine is also due for a change, this will help me a lot.


Abre, you forgot to mention that I run the clan shop as well :evil: :evil: Look out for my next post!!

One day I will die, but on all the others I will not, so on those days I will live it to the fullest!!

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