Fork oil

Forks are about the crudest things that use oil. Fork oil doesn't get hot so just about any oil will work. Detergent is a bad additive though because fork oil could foam up on a rough road. I've never used diesel oil but it has more detergents. ATF is a good substitute as tramissions are prone to foaming so ATF is anti foaming. Lots of seals in an auto trans so ATF has a bunch of seal conditioners.

Shadetree tip from Tom: If your fork seals leak and you just can't bare to change them you can use ATF and get one of the transmission stop leak products to soften and swell the seals back up.

Another common tip that is widely used is to measure the oil level rather than the quantity. Six inches from teh top with the springs out and the forks fully compressed is the usual distance called for. Don't go less than 6" because the seals will suffer. Make sure you pump the forks up and down to remove the air pocket so you measure the correct level. The air at the top compresses and acts as a progressive spring to limit fork dive but just riding along the forks are as stock over little sharp bumps. Tip: Use the 'pump' from a lotion bottle. Measure and cut 6 to 7 inches from the bottom of the cap and pump out the excess oil to the correct level. My God Man, be sure to clean out the fork oil before you stick the pump back in the wife's lotion bottle.

Tom Graham
 
Cheap fork oil leveler #2 - a 12" length of brass tube from the hardware store loosely gripped with vice grips 6" (or whatever level you're going for) from the bottom. Stick it into the fork top and suck off the excess oil using a plastic syringe attached to the top. I now hook my Mityvac tool to it and use that to draw the extra oil out instead of a syringe.
 
hi i use usa,,,, delray oil....10wt/// works great and easy to get regards oldbiker

Were did you pick it up from and what qty for $$$

Also do you guys use any special devices for setting the oil level?? Do you use those long cylindrical measure tubes? %twins home made device the same as what MikesXS sells?

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I don't use any fork oil at moment the things are dry….:banghead:what was the PO doing?????

I'm getting new seals, putting on some gaitors and need oil. Any special tools or other items likely needed?
 
Cheap fork oil leveler #2 - a 12" length of brass tube from the hardware store loosely gripped with vice grips 6" (or whatever level you're going for) from the bottom. Stick it into the fork top and suck off the excess oil using a plastic syringe attached to the top. I now hook my Mityvac tool to it and use that to draw the extra oil out instead of a syringe.

What size is the syringe? What dia tube?
 
Just like in your pic above. Tube is about 3/16", syringe 3" or 4" long by about 3/4" or 1" diameter. Connect the syringe to the brass tube with a short length of plastic hose. I'll get some pics tomorrow. I have a brass bar with a hole through it for the tube and a set screw in the side instead of the vice grips now. For measuring oil amounts, I use a nice old PJ-1 fork oil bottle. It has nice markings on the side for ounces and ml.
 
As promised, pics of my homemade oil leveler tool. The brass tube is 3/16" O.D. .....

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..... and inserted into the fork tube top .....

OilLeveler2.jpg
 
Cheers, Seems simple enough………Now to find a hard core heroin addict to pinch his giant syringe!

Think the vet would stock something that size don't imagine it used on a human.
 
As I mentioned earlier, I no longer use the syringe. I hook my Mityvac vacuum pump to it and suck the excess oil out that way.
 
Hey 5twins,
I'm on my way to pick up some fork oil (got some ATF) but could you explain ti me how I get to the point where I actually pour in the oil? What are pinch bolts? Are they the clamp bolts that hold (pinch) the fork onto the assembly? I'm online now if you could answer this. Thanks- Bruce
 
Tom if you think fork oil don't get hot try running a few miles of bumpy road and stop to feel the forks.
In the manuals they speced different weights of oil for the forks. The early years used 30w motor oil, then they speced 10w30 oil. The later years speced fork oil.
The weight of the oil controls the speed at which the forks move. A thinner oil = faster, thicker = slower.
The cost of trying a few different oils won't be much. So experiment some. I tried several oils. 10w30, 5w20, Regular ATF. I plan on trying some different fork oils sometime but the ATF works fine.
Ok, to change the oil look down at the bottom of the forks, you will find the drain screws. Outside each fork. Phillips head bolt. Remove the bolt, pump the forks up and down to pump out the old oil.
Now up at the top of the fork where they go through the upper tree, loosen the clamp bolt. It releases the tension of the tree on the fork tube. Now you remove the fork cap in the top of the fork tube. Different years had different caps. Yours might be a 17 mm Allen head or a big nut not sure on the size.
I built a 17 mm tool for my caps. Get a metric bolt with a 17 mm head and a nut. Use a few flat washers and a lock washer. Now tighten the nut very tight on the bolt. Put the bolt in the cap and use a wrench on the nut to loosen the caps.
Remember to put the drian screws in before filling.
With the caps out, springs out, forks compressed just pour 7.5 ounces in each fork. Or a bit more and draw the extra out. so you have the 6 inches down as described earlier. Put the springs and caps back, Tighten the clamp bolts.
You might want to flush the forks before the new oil. I used Kerosene. Remove the caps and springs as descibed, pour in 8 ounces or so of the cleaner of your choise, Pump the forks to speard the cleaner around, drain, do repeat till the cleaner comes out clean. I then flush it once with oil to get the cleanr out, let drain over night, then do the fresh oil.
Leo
 
OK Guys - a question
I have fitted MikesXS fork dampener kit
have 2' over forks and Progressive springs that match
Filled her up with ATF - which I have always found to be very good as fork oil
After the restoration she rides as if I have no rebound at all- rides like a rigid- tho the cable ties show that the forks have actually moved somewhat
have drained the ATF and am adding 5W fork oil - have also reduced the fork spring preload so that the top caps screw straight in without needing to be pushed
I will report next ride
Any set up advice appreciated - thanks
 
Fork dampener kit? If you are referring to the cartridge emilators, you should go to the Race Tech web site and read a few things on setting up forks. Oil weight and preload are not guessing games. There are ways to sort both closely without a vunch of time. You should be running 10 or 15 weight oil, and setting laden sag to get your front right.
ATF is a horrible substitute for lubricant. It's avsolute shit in a fork. That's why nobody uses it in new bikes with the same type of forks.
 
Thanks JD
That is an excellent site- so now have much reading/work to do
Cheers
 
YOU Guyz rock!!!!! First, thanks for all the info on oil for forks!! 2nd Thanks for the pure reading mateiral !!!! and never mind my spellin im dislesic:bike:
 
As I mentioned earlier, I no longer use the syringe. I hook my Mityvac vacuum pump to it and suck the excess oil out that way.
Why do you have to suck anything out? Why can’t you just measure the exact amount of ounces do you want to put in and dump them in?
 
Because it's more accurate to measure the oil level than it is to use a fixed amount.
There is always some old oil left in the forks unless you do a complete teardown.

I use the racetech website at work. Frequently has better settings than stock.
Sometimes it calls for a volume instead of a level so get out your graduated cylinder or ratio rite for those.
 
If you're draining old fork oil and adding new stuff, you may not get all the old oil out. Then your refill amount is going to be what you measured out plus what's left in there. In effect, you'll end up with more oil in there than you actually measured out and poured in. So, the most accurate way to set fork oil amounts is to slightly over-fill then suck out the extra to a certain level measured from the top of the tubes, springs removed, forks fully compressed. A general rule of thumb is to set the oil level 6" from the top of the tube.

I just did this on my '83 forks. I initially filled them with 7 ounces of oil. They were a bit stiff so I decided to remove some oil and hopefully lessen the increased air spring effect more oil adds. Checking the level on what was in there, I found it at about 5 1/4" from the top. I set it to 6" from the top. I put the oil I extracted into a measuring bottle and found I had taken just under an ounce out combined for both tubes, so maybe about 3/8 of an ounce from each. These '83 forks are a bit of an experiment for me. Instead of replacing the springs, I just added about 1" preload spacers. This made them a bit too stiff so I shortened the spacers to 13/16" and pulled some fork oil out. They're better now.

Here's my thinking and the theory behind all my spacer work - the stock adjustable top caps add 10mm of preload for each step, so a total of 20mm can be had. I've tried stock springs like that and they were still too soft. So, I wanted to preload them just a bit more than that max available setting. I figured 1" (about 25mm) would be good. But, what I failed to take into consideration was that you add another washer with the preload spacer, and that adds another couple of MM to the preload. So, I had ended up with 27 or 28mm of added preload, almost another full step of adjustment had there been one, and that proved too stiff. So now, with my 13/16" spacer AND the added washer, I've got maybe 23mm of added preload, and that seems pretty good.
 
Thanks man but I guess what I’m asking is if you take out 4.5 ounces why can’t you just put 4.5 ounces back in?? Yeah there might be another half oz at most in there but what’s the harm? And every time you do it eventually all the old shit is gone....especially if you do it at let’s say 1000 miles or less.
Not to mention the manual calls for replacing it with 4.5 ounces and that’s exactly what came out so I’m not sure why that wouldn’t be close to spot on. And I’m not talking about adjusting the stiffness or anything with extra fluid. I’m talking about Just straight apples to apples. (Ounces to ounces)
 
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