Bonneville America Forums Forums Technical Forums General Tech Changing fork oil

Maybe this is a real dumb question, but I have 32k on my 02 BA and think it is time to change the fork oil. I looked in my repair manual and it appears I will need to rip the entire front end apart to do this. Am I reading correctly?

Ted

Yes to do it right - you need to break it down to the point that the fork tubes are removed.

Might be worth a trip to the dealer.

Jack up the bike, remove both fork upper caps, pull spacers and springs, then lower the bike to compress the forks all the way. Measure the amount of old oil in the forks. Draw out as much oil as possible using a hose and one of those large syringes. This will get most of the oil out. Refill to the level you previously had when starting, install springs, spacers and caps.

Not perfect (doesn't get all the oil) but relatively easy.

A turkey baster with a tubing extension works great too. Just don't tell the wife what you did with it.

Sliding a car ramp under the front wheel can be used to compress the forks.

Don't ask me how I know this.

I pretty much did the same procedure that Gregger describes when I installed my progressive front springs and used a set of car jack stands to compress the legs. I used an auto parts hand crank oil syphon to draw out the old oil; the next time I will remove the tubes and hang them upside down overnight to insure a clean, thorough change.

So could this "Gregger technique" be used to change the front springs too? I am working up the courage to change my shocks and the front end is scaring me.

At the bottom of the tubes the width diminishes greatly. With a little finesse, a 1/4" suction hose can makes it's way to the bottom. I attach the suction hose to a long wood dowel with wire ties to gain enough control to get into the little inside diameter.

A long wood dowel from the hardware store with an eye screwed into the end of it will accept a clean rag for cleaning the grindings out of the tubes, much like cleaning the barrel of a rifle. Go easy on the very bottom if you get the rag in there. I sense it's a might fragile on the extreme bottom with valves & seals and other wee gee gaws down there.

Know that this forks on the bike method is messy, and a pile of rags at hand to wipe the suction tube off at each draw is a must. Oil on the ground isn't out of the question either if a nice lawn or blacktop is part of the location.

Forgive me the obvious, but an equal on each side refill is mission critical. Measure the oil level before drawing out the old oil and replenish to a similar level. I do believe the manuals state a replacement quantity of oil far different than reality.

Many here have favored Progressive brand front springs as a replacement to the stock springs. They seem to dive less and handle better. I think Fasteddysports should have them and he is good about getting them to you in a timely manner. He will answer emails and PMs sent from this site if you have any questions regarding price and availability.
http://www.fasteddysports.com/?page_id=3&category=20

One of these is handy too, and will pay for itself when you consider what a dealer would be charging for a fork oil change.
http://www.fasteddysports.com/?page_id=3&product_id=541
http://www.fasteddysports.com/?page_id=3&product_id=595

One other thing - the top caps are very very soft aluminum. I dinged mine up using an (shame shame) adjustable wrench. (at least it wasn't pliers... ;-)) if you need a socket that big, the auto parts chains should sell them for a few bucks, although they would probably require a 1/2" drive to twist them.

Overall this is simple job, and I bet you'll have no problems.

When the tubes are removed and turned upside down, the oil draining out is much darker than what can be siphoned off from the top while the tubes are in place.

Loosen the top caps. Remove the fender and wheel. Loosen the triple tree clamps then draw the tube out of the bottom of the ttttree. Then remove the cap while watching out for the spring that is under pressure. Remove the spring and spacer then turn it upside down. Pump the beast some time. DANG sometimes you will find that after pumping the fork it won't extend fully anymore. Some folks use a wooden dowel (broom Handle) to un-stick it. Huh? Instead of that nastiness simple slide the axle into the fork and using a rubber mallet give the axle a light tap. Viola! Unstuck with no nasty wood bits in the tube.

Hang the suckers upside down for 30 minutes. Heck you can even drain them, pump them to get most of it out then add some more as a flush. Then hang em upside down....

That's what I'm thinking to Moe... just pull the forks and tip them upside down.

couldn't ya just measure the amount of oil drained to determine the amount to refill with, instead of compressing them and making a line?

Oh - sure - do things the right way why dontcha

Thanks for the advice. Don't know what I will do, (shop is out). But, if I go for the leave the forks on method, what am I measuring? After compressing the forks, the distance from the top of the tube to the top of the oil?

If I pull the tubes and do the full monty, I can go with locoponys's advice and measure the amount taken out.

But with both of those ideas, I wonder if the amount originally put in was correct.

And, what is the margin for error. I remember replacing the fork oil on one of my Hondas back in the 70's. I actually think there was a drain plug at the bottom of each fork. Ended putting in too much oil and blew out the seals.

Don't want to make the same mistake twice.

I suggest measuring the refill oil height from the top of the open tube down to the oil level (fork compressed), regardless of the volume you took out. I don't recall what the OEM spec is off-hand. If you do it with the tubes in the tree then a little basic geometry will get you to the proper measuring point.

I changed the oil with the forks on the bike this weekend. As advertised above it was messy. But I found a good way to measure the oil level. Maybe this is already a known, but I used a combination square from my woodshop and put it down the tube to get the known reading. Having the 90 degree edge gave me a known point of departure.(like an incremental dipstick) If I just wanted to replace to the same level, I'd be all set. If I wanted to change the level, I could just do a little math to make sure I had the level in each fork the same.