Fork fluid advice


Information and questions on GL1200 Goldwings (1984-1987)
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sportsfreaked
Posts: 370
Joined: Fri Mar 13, 2015 7:23 am
Location: Independence, MO
Motorcycle: 1981 Honda Goldwing Interstate GL1100I
1985 Honda Goldwing Limited Edition gl1200

Fork fluid advice

Post by sportsfreaked »



Ok folks give me some pros and cons please when it comes to fork oil. Should I just use ATF or should I use 15w synthetic fork oil? I have read so many things about both that now I'm just confused :lol: . I am putting new springs in them as well as slides and guides. Thanks for the tips and suggestions. Don't tell me put atf in one and fork oil in the other and see which one I like :lol: . Everyone please have a safe rider season coming up!


Thanks to all who answer and help. It is greatly appreciated!
Ed

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Goofaroo
Posts: 155
Joined: Mon Jan 16, 2017 7:42 pm
Location: Guthrie, OK
Motorcycle: 1986 GL1200 Aspencade
2004 Kawasaki Concours
1978 BMW R100S
1971 Honda CB500/4
2007 Kawasaki KLR650
2002 Kawasaki KLR250
1992 Kawasaki KDX200
1987 Kawasaki KDX200
1985 Honda XR350R
1971 Honda CT90
1984 Honda NH125 Aero
2008 Yamaha Vino 125

Re: Fork fluid advice

Post by Goofaroo »

I am in the process of doing the same thing. I read your post and saw that you are using RaceTech springs rated at 1.0 KG rate. You didn't mention if you were planning to use air in the forks and I have no idea if the rate of your springs are stiffer or about the same as stock. The stock springs are also progressive in rate and actually have two rates in the longer spring and a different rate in the shorter spring. The tighter wound section is intended to give a supple ride over small bumps but also contributes to front end dive. Thus the TRAC system was implemented to help control dive but in my humble opinion they are marginally effective. They do however give you some level of dampening adjustment.

Anyway, right or wrong, I bought My springs from Sonic because I specifically wanted straight wound springs which give consistent action throughout the range of travel. There will be a very slight loss of suppleness but dive should be more controllable. I'm a 230 pound feller and probably ride faster than I should so I ordered the 1.2 KG spring rate. I also disabled the air to the forks and had the hole welded shut so that I could set up the preload and control the sag without adding air to the forks.

So in answer to your question, the stock fork uses ATF or 10wt oil. That will work fine in a stock configuration but if you stiffen the spring rate (or add air) then your rebound will be quicker- thus requiring heavier fluid.

I'm still not finished with my bike so I can't say how this worked out but I decided to try 15wt when I put my forks back together. I will certainly need more than 10wt but I still want a smooth ride so I'm hoping that 15wt will be a good compromise. Worst case, I'll have to go to 20wt.

Are your springs progressive or straight wound? I'm assuming they are straight wound if they came from RaceTech so you will want a bit more dampening than you needed with the sacked out 30+ year old factory springs but you'll probably just have to experiment to see what you like. Please keep us posted and let us know how your setup works out. I tried to research this topic on the net and didn't find much info and the typical threads that end without a proper conclusion.

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Rednaxs60
Posts: 2352
Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2012 Suzuki DL1000 VStrom
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: Fork fluid advice

Post by Rednaxs60 »

Had the suspension upgraded on my '85 1200 LTD - Race Tech products in the forks and Progressive shocks in the rear. Had a shop do this because I was not as confident in my abilities as I am now. This shop also installed the Traxion (full monty) suspension upgrade on my 1800. I am more inclined now to do this type of work myself as long as I have the tools.

Back to the query. This is what I had done to my suspension for the upgrade. The shop used Maxima fork oil 20W - 16 ounces.

Progressive suspension rear shocks 1200 - 76-1206B
Progressive suspension rear shock springs - 76-1364B
Race Tech Emulators 33.5/26.1/17.0 - 377-2132
Race Tech Fork Springs FRSP 3234 1.0 kg - frsp323410
Maxima Fork oil 20W - 16 ounces
Fork seal dust and oil seal kit 41ml - 51490-MN8
41ml guide bushing - 51414-KCR

The pipe in the forks had the existing holes enlarged to 1/2" and two extra holes (1/2" dia) were drilled in the pipe as well to allow adequate oil flow.

I have been very pleased with the results to date. Huge performance and ride upgrade from the OEM setup. I no longer use air in the suspension. Took off the rear air shocks. I will be changing the fork oil this coming November.

Hope this helps.
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

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Goofaroo
Posts: 155
Joined: Mon Jan 16, 2017 7:42 pm
Location: Guthrie, OK
Motorcycle: 1986 GL1200 Aspencade
2004 Kawasaki Concours
1978 BMW R100S
1971 Honda CB500/4
2007 Kawasaki KLR650
2002 Kawasaki KLR250
1992 Kawasaki KDX200
1987 Kawasaki KDX200
1985 Honda XR350R
1971 Honda CT90
1984 Honda NH125 Aero
2008 Yamaha Vino 125

Re: Fork fluid advice

Post by Goofaroo »

Rednaxs60 wrote:Had the suspension upgraded on my '85 1200 LTD - Race Tech products in the forks and Progressive shocks in the rear. Had a shop do this because I was not as confident in my abilities as I am now. This shop also installed the Traxion (full monty) suspension upgrade on my 1800. I am more inclined now to do this type of work myself as long as I have the tools.

Back to the query. This is what I had done to my suspension for the upgrade. The shop used Maxima fork oil 20W - 16 ounces.

Progressive suspension rear shocks 1200 - 76-1206B
Progressive suspension rear shock springs - 76-1364B
Race Tech Emulators 33.5/26.1/17.0 - 377-2132
Race Tech Fork Springs FRSP 3234 1.0 kg - frsp323410
Maxima Fork oil 20W - 16 ounces
Fork seal dust and oil seal kit 41ml - 51490-MN8
41ml guide bushing - 51414-KCR

The pipe in the forks had the existing holes enlarged to 1/2" and two extra holes (1/2" dia) were drilled in the pipe as well to allow adequate oil flow.

I have been very pleased with the results to date. Huge performance and ride upgrade from the OEM setup. I no longer use air in the suspension. Took off the rear air shocks. I will be changing the fork oil this coming November.

Hope this helps.

I am assuming that the damper rod holes were enlarged and new holes added to give complete control to the emulators. If that is the case it should be noted that the 20wt oil that is working in your setup may or may not work well with the stock dampening. Also 16 ounces is quite a bit more fluid than the factory spec. Is that also due to the emulators? It's been quite a while since I used emulators and that was in a dirt bike.

Are you riding primarily solo or with a passenger? I would love to eventually get rid of the air shocks but I will be riding about 50/50 solo and loaded with my wife and luggage. Do your shocks have any preload adjuster? Is it a hammer and drift affair or a quick and easy adjustment?

User avatar
Rednaxs60
Posts: 2352
Joined: Wed Nov 18, 2015 12:44 pm
Location: Victoria, British Columbia, Canada
Motorcycle: 1985 GL1200 LTD
1995 GL1500 SE CDN Edition
2012 Suzuki DL1000 VStrom
2008 GL1800 (sold)
Ontario 1985 GL1200 LTD (sold)

Re: Fork fluid advice

Post by Rednaxs60 »

Never thought about the amount of oil. Next time I drop into the shop, will ask about the amount of oil. The OEM service manual states 11.7 ounces. The holes were enlarged to accommodate the emulators.

I ride two up as well, probably 70/30 (solo/dual). I have the shocks set at the 4th notch on the preload adjustment. Have to remove the saddlebags to do the adjustment. I have found that leaving the preload on the 4th notch works well all round. I will be putting the preload up to max when we travel to accommodate the luggage aspect.

The progressive rear shocks I have installed have made one change to the bike. When I put it on the centre stand, the rear wheel is still on the ground. I have had to put a piece of 1/4 to 1/2 inch plywood under the centre stand to get the rear wheel off the ground - minor inconvenience. To keep the bike as upright as possible because these boxer engines tend to leak some oil into the left bank when on the side stand for extended periods of time, I put a piece of 2X4 under the side stand.

Found shocks on Ebay for around $100.00 CDN and reasonable shipping. Contacted the company by email to make sure they were for my LTD. Went to look for them so I could give you the link, but it is not there anymore. I sent a new email to the company about the shocks. The company is in the UK.

Cheers
"When you write the story of your life, don't let anyone else hold the pen"

Ernest

sportsfreaked
Posts: 370
Joined: Fri Mar 13, 2015 7:23 am
Location: Independence, MO
Motorcycle: 1981 Honda Goldwing Interstate GL1100I
1985 Honda Goldwing Limited Edition gl1200

Re: Fork fluid advice

Post by sportsfreaked »

Thanks for the replies gentlemen. The main reason for replacing the springs is that when I took the forks apart one fork had the 2 springs and one had a single spring. I found out why as the one with 2 springs the drain screw at the bottom was all jacked up. I couldn't get it out and so I just ordered a new fork off of EBay. I just need the bottom case as I was able to get the tube out but had to trash the fork in order to get it out. I guess I will try 15w oil to start and see how it goes.


Thanks to all who answer and help. It is greatly appreciated!
Ed

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