Somehow messed up fork oil change

[Bergman16]

So I put new 15W fork oil in my fairly soft SG forks and now they are terrible. Not only are they mushy but I can hear the springs sort of singing inside, if you know what I mean. And there's a clicking sound at the top of the rebound.

I drained them well and put in about 220 ml of 15W into each tube. No chance I put in the wrong amount.

I had the bike on the center stand with a jack under the front frame with the tire just touching the ground so the wheel wouldn't fall to either side. Caps came off pretty easy, and using the advice here I didn't have too much trouble getting them on. Definitely not stripped. The schrader valves are fine as well, and putting about 15 pounds of air into them made absolutely no difference.

Did I put the springs back in wrong somehow? Perplexed.

Steve

[BA80]

Did you disassemble the forks or just take off the caps and pull the springs out?

5W or 10W is the most common weight fork oils in these bikes. I run 15W because I prefer the stiffer suspension.

I went from 10W to 15W on my last rebuild and found I had to drop the air pressure in the front air forks on my special way down to get a decent ride.

[Bergman16]

I didn't rebuild, just pulled out the springs to see what kind they were. Didn't even measure them like a dummy, just looked them over to see if they were progressive or not. (not--they must be original). After I put in the oil I just slid them in. I didn't pivot them or anything.

I picked 15 because I thought I'd like to try a stiffer suspension and I just put on a fairing that I expect to load down with 'stuff' if I take longer overnight rides.

I wonder, if the innards are in bad shape is it possible the 15 isn't getting to where it needs to go? The stuff that came out was thin and black and not a lot of it.

I only have my concrete front 'yard' to work in, so I try not to get too ambitious with repairs--esp the kind that take the bike off the road.

[Rasputin]

If you do not take the forks apart and clean them well, you will never have properly operating forks. The crud that has built up over the years and settled in the bottom of those forks is incredible.
Do yourself a huge favor and take them apart and clean them thoroughly. After that the weight of oil used is preferential to your style of riding. Myself, I find a wee bit heavier than stock oil to be great, but I am in the heavyweight division so that may not work for you.

[Bergman16]

Sounds like a good idea. I enjoy learning how all this stuff works although each time I try something new (which is every time) I end up learning by messing/stripping/etc.

Funny thing, I tried the Festus method so I wouldn't strip the caps and ended up, comically, spraying oil all over my right side brakes. So that meant new pads (which I needed anyway) and an alcohol clean of the rotor.

I work in my concrete front yard in Harlem and EVERYONE sees my three stooges act. Very amusing for them.

Funniest part was when I just bit the bullet and took the caps off, they went back on with no problem following the tips and tricks here (marking the cap where the thread starts was genius).

[BA80]

If you do not take the forks apart and clean them well, you will never have properly operating forks. The crud that has built up over the years and settled in the bottom of those forks is incredible.
Do yourself a huge favor and take them apart and clean them thoroughly. After that the weight of oil used is preferential to your style of riding. Myself, I find a wee bit heavier than stock oil to be great, but I am in the heavyweight division so that may not work for you.

+1.......35 years of nasty stuff in the bottom of those forks and tiny bleed holes in there. Pull them apart and reseal them. Not a tough job at all.

Those old seals can be a booger to get out though so be careful not to damage the lowers.

[Bergman16]

+1.......35 years of nasty stuff in the bottom of those forks and tiny bleed holes in there. Pull them apart and reseal them. Not a tough job at all.

Those old seals can be a booger to get out though so be careful not to damage the lowers.

Exactly the kind of thing I do TOO often.

I would kill for a real garage...

[jetmechmarty]

FWIW, heavier viscosity oil will not make the suspension stiffer. It will make it slower. The damper rod holes don't change. Changing the viscosity changes the rate that the fluid passes through. If you want stiffer suspension, you need stiffer springs.

[Bergman16]

I'm assuming at this point that the holes are so gunked up the heavier oil doesn't circulate, although who knows. Just seemed weird that it is so sloppy-feeling.

Now I'm considering new springs. I have some showas for the back as soon as I get the front sorted out.

[TopCatGr58]

Hey Bergman,

First, IF you are going back in there, then just order new seals and replace them. Secondly, measure the springs...but you'll probably find that they are in spec length. You can stiffen them up a little by just putting in a SPACER... some PVC or piece of PIPE is what I used. If you get a nice piece of simple black pipe several inches long, you can CUT different sized spacers, starting with 1/2" or 1", and above. It will just be a little bit more difficult to put the fork cap nuts back on due to the extra tension encountered with the spacers...so you may want to have the front wheel off the ground to allow the most extension of the forks/sliders for the most room and least amount of mounting tension.

I have 4" over length uppers on my Special...normally takes a 4" spacer, but I was having a little dive action, and so I put in 5" spacers, and it really helped to prop up the front end a bit better...I like my bike HIGH since I'm 6'6" tall!

I also used a slightly heavier weight oil...but I actually used some dexron II ATF fluid, cheaper, non-foaming, detergent, supposed to be ~15 weight, YMMV!

T.C.

[BA80]

FWIW, heavier viscosity oil will not make the suspension stiffer. It will make it slower. The damper rod holes don't change. Changing the viscosity changes the rate that the fluid passes through. If you want stiffer suspension, you need stiffer springs.

EXACTLY Marty. Slower = stiffer.

TC, synth ATF is what I was using before but I was getting a bad front end dive and had to run 20 psi in the forks to stiffen it up. I put the 15w in there and had to drop the air pressure down to about 10 psi so the front end didn't ride like it was solid.

I may go back, I liked the ride and handling better with the ATF.

[Bergman16]

Ordered my seals, now I have to forgo the temptation to order new springs until I can test out the cleaned up forks.

[Rasputin]

Ordered my seals, now I have to forgo the temptation to order new springs until I can test out the cleaned up forks.

Simply support the front end and remove the caps from the forks. Then pull out the springs and measure them. Stuff them back in the fork and tighten the cap. You are now no closer to fixing your problem, but you will know if you need to order springs.

[Radioguylogs]

Ordered my seals, now I have to forgo the temptation to order new springs until I can test out the cleaned up forks.

I recommend heat to help get the old seals out.

I use a heat gun.

I heard other's use the oven when SWMBO is out.