Stupid Fork Oil Question

[snark]

To start with, my forks were getting a bit soft so I thought it might be time to change the oil in them. The seals are good and there are no leaks so I just drained them and refilled with the proper amount of 50/50 ATF and 10W40. They were fine for a few days and are soft again. Still no leaks. I don't want to just add more oil, but I don't want soft forks either. Is there something I'm missing? I have a spare set of fork springs that are what I was planning for my next step. Should I also try a heavier weight oil?

[edhuhn]

not sure about your problem, but what amount of oil did you use ? I will be doing my son's 81 gs450l this weekend, and I'm not sure of the amount of oil.
Thanks
Ed

[Suzuki mad]

Did you check the length of the springs when you stripped them out? They would go soft over years and may be past there service life.

2 tricks to help:-
1. Add thicker weighted oil but will change the bikes handling
2. Put a couple of large washers above the spring to compress them.

If moneys not a problem try replacement stiffer springs.

Suzuki mad.

[snark]

not sure about your problem, but what amount of oil did you use ? I will be doing my son's 81 gs450l this weekend, and I'm not sure of the amount of oil.
Thanks
Ed

The factory manual says 4.9oz. I put in a flat 5 to keep from going nuts.

[Nessism]

The oil is for damping and does not effect the spring rate. I think the manual calls for 50-50 mix of ATF and 10W-30 oil so if you used 10W-40 you are already on the heavy side.

If you want to firm up the ride you can pull the springs and cut off a couple inches of coils and replace the lost length with pvc spacers. I've done this several times with good results before.

Good luck.

[Clone]

Put a 1 inch spacer above the springs if there is not one there now. Use only fork oil, put 15W or 20W in if you want a lot of damping. Otherwise I think you will continue to be unhappy with the results.

[Steve]

Does your manual really say to mix ATF and engine oil? :shock:

I just looked in my copy of the Suzuki 850 manual and my Clymer manual. The Suzuki manual made NO recommendation on what fluid to use, the Clymer says "SAE 10, 15, or 20 weight fork oil or A.T.F. (automatic transmission fluid)" It says nothing about motor oil or mixing oil and ATF.

Personally, I am not sure that motor oil is compatible with the fork seals. I have heard of many people using ATF, though. Personally, I prefer fork oil. It's not that expensive, and you know it's made for the job. 8-[


.

[Nessism]

Does your manual really say to mix ATF and engine oil? :shock:

Yup! :shock: Factory manual for GS550. 8-[

[snark]

I have honestly read some manuals that have said a 50/50 mix and some that say fork oil. Next trip to the bike shop I will probably pick up some real fork oil...but I'm thinking the springs may be shot too.

[trippivot]

buy proper fork oil duh!!

just get proper fork oil!!! no atf!! no engine oil!! in the old days whale/fish oil was used because of the natural anti foaming properties!!

mixing the types of oil will cause foaming and loose the damepning effect due to emulsion of fluid and air which will cause the dampening effect to disappear, especially with sacked out weak springs.

I must also stress spring free length is the most important detail that effects compression rate of a fork assembly probably more important than fluid viscoscity.

the fluid has more to due with rebound, but spring / fluid combo have a integeral relation that needs balance to create a feel you like.

[Steveb64]

Does your manual really say to mix ATF and engine oil? :shock:

I just looked in my copy of the Suzuki 850 manual and my Clymer manual. The Suzuki manual made NO recommendation on what fluid to use, the Clymer says "SAE 10, 15, or 20 weight fork oil or A.T.F. (automatic transmission fluid)" It says nothing about motor oil or mixing oil and ATF.

Personally, I am not sure that motor oil is compatible with the fork seals. I have heard of many people using ATF, though. Personally, I prefer fork oil. It's not that expensive, and you know it's made for the job. 8-[


.

I use Bel-Ray fork oil in my GSX - and other RWU forks - but my Ducati (900SL) uses ATF in its USD forks. Factory and other sources recommended! Works good too - even better after I'd replaced the original factory gunk with some nice fresh BP ATF II oil. Go figure.

[the_journeyman]

I used plain old 12.5wt oil that came in with the springs from Hyperpro when I changed the springs & oil in my Ducati Monster. I've put 10-wt Harley brand fork oil in my CB550, and 10-wt Honda oil in my TS185 ~

JM