Page 1 of 1

1983 GL1100 Fork Oil Change

Posted: Tue May 03, 2016 11:07 pm
by indianakid
I have owned this bike for more than 20 years and never changed the fork oil. The seals still hold fluid and air so all I wanted to do is change the fork oil. So here is how I changed out fork oil without removing spring / fork caps.

Used a small funnel and short lengths of 3/8 and ¼ PVC tube. 3/8 would fit on the funnel and the fitting on the right side. The ¼ tube will fit over the schrader valve and inside the 3/8 on the funnel.

Removed the schrader valve core from the left leg and removed the hose fitting from the right leg (14mm wrench).

Drained out the old oil (10mm wrench for drain plugs). Reinstalled drain plugs and then flushed the forks with ~6 oz of solvent in each leg. With the solvent in the forks they were worked up and down for a few minutes then the solvent was drained out. It almost looked as bad as the original oil. Thought about flushing it again with more solvent but decided to shoot the engineer and get on with production.

To fill the forks with oil (and the solvent for cleaning) I used a short length of clear 3/8 PVC tube on the right side and a 3/8 and ¼ combo on the left. I would pour some fluid in the funnel and carefully pump the forks up and down to burp the fluid into the fork. It only took a few minutes to get 9.1 oz of ATF into each leg.

The front end feels much better than it did with the 30 year old oil. This may not be the most pristine way of changing fork oil but it is much better than it was.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 3:30 am
by Aussie81Interstate
Nothing wrong with doing it like that - I would have personally maybe flushed them again - before filling with the new oil.

You could have even pushed some compressed air through the empty fork leg (drain bolt out) to push out any old crap hanging about.

Easy enough to also top up and experiment with fork oil weight and amount.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 8:38 am
by WingAdmin
I've also seen it done where the fork drain bolts were stripped, so the caps were removed, and a long, thin brass tube was threaded down into the fork. The fork oil was then sucked out from the top with a Mity-Vac.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 10:01 am
by indianakid
My intent was not to make the fork “like new” but to just change the fork oil as easily as possible. I did not want to completely disassemble the fork or even mess with the springs by removing the caps. So one evening while out in the garage with the radio on putting away tools and cleaning up the machines I put the bike on the center stand, placed 2 drain pans one under each fork, a plastic bag over each rotor and removed the drain plugs / bolts (WingAdmin, don’t know how they would be stripped or how the bike could be ridden until they were fixed) removed the valve core and disconnected the air hose on the right side. That took about 5 minutes. As the old oil drained out I cleaned and oiled the lathe and mill and put away tools that had been scattered around the garage from various projects during the past week. That took about a half hour. Good no more oil dripping out so back in with the plugs. (They are just 6mm bolts so take it easy with the 10mm wrench !!! You don’t want to strip them.) hooked up the funnel and poured / burped the solvent into each leg. Now pump the fork to stir things up and remove plugs and let drain. That took about 5 minutes. Pumping the fork got old real quick ! Swept the garage floor while the solvent drained. After it stopped dripping and before putting the plugs back in I blew out the forks with compressed air more with the intent of evaporating out the solvent (im sure it blew out debris as Aussie81 pointed out). All that was left to do is install the drain plugs pour in the oil and reinstall the air hose on the right side and valve core on the left. The oil went into the left fork real easy, the right took a little burping. All in all the time spent working on the wing was less than a half hour. And I had a productive evening out in the garage.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 10:25 am
by WingAdmin
indianakid wrote:My intent was not to make the fork “like new” but to just change the fork oil as easily as possible. I did not want to completely disassemble the fork or even mess with the springs by removing the caps. So one evening while out in the garage with the radio on putting away tools and cleaning up the machines I put the bike on the center stand, placed 2 drain pans one under each fork, a plastic bag over each rotor and removed the drain plugs / bolts (WingAdmin, don’t know how they would be stripped or how the bike could be ridden until they were fixed)
I should have been more specific - not the bolt threads stripped, but the hex HEADS of the bolts that were stripped. It's fairly common, from people who try to remove them using the wrong size allen/hex head tool.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 12:00 pm
by indianakid
OK……………………

I think we have an information error here. If I understand you correctly you are referring to the piston attach bolt at the bottom of the lower leg that can only be accessed with the front wheel removed. It is true that when this bolt is removed that the fork oil will drain out. BUT this is not the drain plug.

The 83 has the anti dive “TRAC” feature so it does not have the readily recognizable drain plug on the outside of the lower fork leg. The drain plug is located on the aft side of the anti-dive case just below the caliper mount pivot.

I made this post so that others can understand how simple changing the fork oil on an 83 can be. Only tools required are a valve core remover, 10mm and 14mm wrenches, small funnel and tubes. And don’t forget the drain pan and plastic bags.

Re: 1983 GL1100 Fork Oil Change

Posted: Wed May 04, 2016 12:15 pm
by WingAdmin
indianakid wrote:OK……………………

I think we have an information error here. If I understand you correctly you are referring to the piston attach bolt at the bottom of the lower leg that can only be accessed with the front wheel removed. It is true that when this bolt is removed that the fork oil will drain out. BUT this is not the drain plug.

The 83 has the anti dive “TRAC” feature so it does not have the readily recognizable drain plug on the outside of the lower fork leg. The drain plug is located on the aft side of the anti-dive case just below the caliper mount pivot.

I made this post so that others can understand how simple changing the fork oil on an 83 can be. Only tools required are a valve core remover, 10mm and 14mm wrenches, small funnel and tubes. And don’t forget the drain pan and plastic bags.
Nope, you're right, the reason I was thinking about that stripped head hex head bolt is because I'm in GL1500 mode, where that can be used as the drain bolt, especially when rebuilding shocks:

Image
Image
Image

However the lowest bolt on the caliper mounting plate is also tapped all the way into the fork, and can be used to drain fork oil without removing the wheel or axle:



Re: 1983 GL1100 Fork Oil Change

Posted: Fri Mar 08, 2019 2:09 pm
by Ochuck01
1983 GL1100I
I’m changing oil and seals on my front forks. Using the drain located by the anti dive trac device I discovered the oil will not flow unless it has some air pressure behind it. This is on the right side, left worked ok. I remove, drained,disassembled,flushed and it still has a restriction in it. It looks as if this is coming out of the trac system. Not at all sure what’s inside that thing? Ideas? I’m pretty new to the site, been reading but so far I can’t find anything.
Thanks,
Chuck

Re: 1983 GL1100 Fork Oil Change

Posted: Sat Mar 09, 2019 9:42 am
by newday777
You should pull the forks apart fully to clean out the old gunk in them, you'll be almost there anyhow changing the seals. The Trac system is not hard to take apart. You have the repair manual??? In the How To Articles at the top of the page scroll down to the gl1100 section.
Ochuck01 wrote:
Fri Mar 08, 2019 2:09 pm
1983 GL1100I
I’m changing oil and seals on my front forks. Using the drain located by the anti dive trac device I discovered the oil will not flow unless it has some air pressure behind it. This is on the right side, left worked ok. I remove, drained,disassembled,flushed and it still has a restriction in it. It looks as if this is coming out of the trac system. Not at all sure what’s inside that thing? Ideas? I’m pretty new to the site, been reading but so far I can’t find anything.
Thanks,
Chuck

Re: 1983 GL1100 Fork Oil Change

Posted: Sat Mar 09, 2019 7:07 pm
by Ochuck01
Thanks, I just got her in January and she is a bit different on a few things than what I’m accustomed to. I will follow your advise and see what comes out of it.