Replace fork oil

Road Slug

Road Slug

Joined
Oct 7, 2024
Messages
74
Location
Idaho
Bike
St 1100
I have replaced fork oil in a quite a few bikes in my lifetime.
Usually taking off the top caps, the springs pop up a several inches. Just have to use a little muscle to get the caps started on threads when replacing.

How much preload is on the st1100 forks when you remove the caps on the top?

Also, I noticed there is some type of sequence when tightening down the front wheel axle bolt?
 
I have not owned an 1100, so I won't speak specifically for that bike, but generally, you want the axle screwed into one fork leg and tightened with the other end free (pinch bolt loose). You then bounce the front end so that the forks position themselves on the axle. Then you check to see if the axle is positioned correctly and tighten the pinch bolts. Some bikes have variations on this theme.
 
I picked up these notes from somewhere.......

(All brake pads removed.)
Loosen fender plate bolts
Wheel on, caliper fitted, axle nut loose
- Bounce -
Tighten axle nut - 65ft lb
Tighten throttle side lower pinch bolts - 16ft lb
- Bounce -
Check axle mark (a ring) for correct alignment and tighten clutch lever side lower pinch bolts - 16ft lb
Tighten fender plate bolts
 
Well I'm definitley no mechanic, but in 30 years of owning my (non ABS) 1100s I have never 'bounced', nor have I needed to remove the brake pads. The front wheel has been out more times than I can count. With the wheel out and calipers removed wheel goes in, speedo drive fitted, spacer on the opposite side fitted, axle pushed through and tightened to correct torque, lower pinch bolts fitted and tightened, calipers fitted and tightened... job done.

I have also changed fork springs and fork oil many times on my outfit. The left fork cap (as you sit on the bike) is the only one with any preload effect (and not much at that), the right fork is is connected to a cartridge so does not 'pop' at all. I make my life a little more difficult because I have spacers fitted to counter the weight of the sidecar so getting the left fork cap on is a bit of a struggle but not insurmountable, and is not particularly difficult with the standard spacer.
 
No need to 'bounce' anything on the front forks as Flexit has said.
Just tighten the axle bolt to the proper torque (65 ft lbs) then tighten the 4 pinch bolts (16 ft lbs).
As far as 'preload' on the front forks it all depends on 'what's inside' - stock, racetech replacement, spacers, etc.
You loosen the top fork 'cinch' bolts a little then loosen the fork caps while they are still in the triple t.
Be careful when you remove the fork drain - IIRC those bolts could possibly be made out of cheese ... ;)
If your ST1100 is an ABSII the cartridge is in the 'other' leg - opposite of the standards.
 
Uncle Phil said:
Be careful when you remove the fork drain - IIRC those bolts could possibly be made out of cheese ... ;)
Click to expand...

@Uncle Phil Cheese.... I eat Edam cheese that is stronger than the alloy in the forks.... :rolleyes: I learnt many, many years ago that it is actually easier to remove the forks to change the oil... I never ever ever ever remove those drain plugs any more :)
 
Flexit said:
@Uncle Phil Cheese.... I eat Edam cheese that is stronger than the alloy in the forks.... :rolleyes: I learnt many, many years ago that it is actually easier to remove the forks to change the oil... I never ever ever ever remove those drain plugs any more :)
Click to expand...
Ah, the voice of experience speaks ... ;)
First time I rebuilt a set of ST1100 forks I ran into that!
The 'cheese' was more like 'cream' cheese ...
 
I also prefer to remove the forks to change the oil, makes the job easier and less messy. However, I do remove the drain plugs and haven't had any trouble with threads stripping in 28 years and 122k miles. I use a short 8mm wrench to tighten them, and stop turning when I feel them seat on the fork tube.

I typically change the oil every other front tire change, that way the wheel is already off the bike anyway, so removing the forks is a small amount of additional work.
 
dwalby said:
I also prefer to remove the forks to change the oil, makes the job easier and less messy. However, I do remove the drain plugs and haven't had any trouble with threads stripping in 28 years and 122k miles. I use a short 8mm wrench to tighten them, and stop turning when I feel them seat on the fork tube.
Click to expand...
Ditto, eases flushing all the old goo outta there...
But I'd also suggest to first loosen the fork caps... always... ;)
 
ST1100Y said:
Not what I meant... ;)

If you'd just pulled in, undoing the drain bolts (without prior equalizing) could end with a "violent oil drainage"... don't ask... :biggrin:
Click to expand...
ah, I thought you were referring to the fact that once the forks are off the bike, breaking the caps loose by hand is extremely difficult, if not impossible.

I totally get what you mean about the drain plugs, yes, those could throw oil across the room if there's some remaining air pressure inside the fork. (and maybe fling that tiny plug bolt out of your hand as well)

I always remove the cap first, pull the spring, then pour most of the oil out the top of the cap. Then I break the drain plug loose and pump the fork inside a bucket to get that last little bit of oil out of the bottom of the fork. The cartridge side is a bit more difficult with the cartridge in place, but its do-able. I think I usually remove the clip and spring, then pump the cartridge rod by hand, and I use a funnel to put the new oil back in on that side. I don't put many miles on the bike these days, so I haven't changed the oil for awhile, I think I should probably give it a change one of these days.
 
You must log in or register to reply here.
Back
Top Bottom