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Stock fork spring question
I'm changing out the fork oil on a 1986 SEi. From the looks of the oil I don't think that it has ever been changed. Anyway, I paid very careful attention to how everything came apart. I have everything ready to go back together now here is my question (I've searched so many threads my eyes are tired) The order that I took the springs apart, Cap, short spring, oil separator, long spring BUT the long spring had the tight coils at the bottom? The service manual says tight coils to the top on a single spring, it doesn't say the same for a dual spring, are you to assume it is the same?
My Clymer says NOTE: If the fork spring has closer wound coils at one end or if the spring is tapered at one end, install that end pointing down.

My Haynes manual says tight coils to the top.

I read Trickys rebuild thread which is more or less a reprint of the manual so it doesn't directly address the dual spring orientation either.

Have the front springs been removed at some point and re-installed following the Clymer manual? Is anyone 100% sure that the tight coils go up on the dual spring set-up?

In the CB900 (81) they are also a dual spring, air assist system and the tight coils go to the top?
1986 SEi Limited Edition. 1985 Aspencade
If it's not broke, I can fix that!
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#1 04-26-2013, 10:08 AM,
although i dont think it would matter i'd install tight coils to the top
what really would matter is that the springs are within correct length limits,most people seem to have installed new progresive springs
1987 Aspencade 129K
1986 SEI 93K
2014 Tri-Glide HD 17K

Hancock,MD
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#2 04-26-2013, 10:23 AM,
I love my new Progressives in the front.

I would experience severe dive on braking, stock springs, decent fork oil and 6psi pressure. Just felt "Saggy" although the ride was smooth.

It does sit a little higher and I will still need to tune a bit for rebound for the smaller bumps. No Air pressure and used ATF for fork oil.

I seem to remember when I pulled the stock springs on mine the short was on top, spacer, Lower spring, tighter coils on the bottom.
Not sure if that was right and not knowing the history so can't vouch for correct or not.
Andy
Silver 1984 Interstate
GWRRA WAO
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#3 04-26-2013, 10:31 AM,
Yes I've read all about the Progressives and there are tons of reply's about them, just not many on a stock set-up
1986 SEi Limited Edition. 1985 Aspencade
If it's not broke, I can fix that!
Reply
#4 04-26-2013, 10:42 AM,
This is just the way my mind works………

Did anyone else notice this thread?

Forking by Frank!

This should ring a bell with some of the older members.

(just observation)
enjoying the view from the saddle....... due mainly to the people and information found within this site
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#5 04-26-2013, 03:22 PM,
A friend of mine who goes by the name, Genesound sent me a message about fork springs that best explains the how, why and where of tight coils and tapered coils. These rules could be applied to any spring.

You're missing the purpose for the way you want them to go. What you want is the end that moves, the part with the wheel on it to be lightest. Therefore you put the tighter wound coil end nearest the crown, and the looser end at the bottom. Whenever you install springs that's the logic behind the way they are installed. The heavy end goes towards the stationary end, and the lighter end goes towards the moving sprung piece.


It doesn't matter up or down, it matters where the unsprung weight is, and where the sprung weight is, that is, inertia.

You want to keep the sprung weight (mass actually) as low as possible, so the spring, and piece it's acting on, responds the quickest and adds as little mass and inertia to the moving piece as possible. Not a huge consideration in a shock absorber or fork, the springs aren't likely to float, and the wheel and tire are way heavier than the spring, but in a valve spring, it's real important that the pieces moving back and forth be real fast and as light as possible, so it doesn't offer extra resistance to movement and change in direction, just due to extra mass of the spring with the heavy end moving. It could even take too long to respond and increase the tendency to float the valves at high RPM if put in upside down, if the tolerances are already close to floating (not responding fast enough) in the design.

Even when the piece being sprung is heavy like in a fork, you'll still tend to have less wear if the moving end is the lighter one, and the heavier end is stationary. It's always best to practice conservation of spring energy.
1986 SEi Limited Edition. 1985 Aspencade
If it's not broke, I can fix that!
Reply
#6 04-28-2013, 07:56 AM,
That makes sense. Never really thought about the spring mass in a slow moving item like fork spring. I know it makes a difference in valve springs on a high rev motor.
Andy
Silver 1984 Interstate
GWRRA WAO
Reply
#7 04-28-2013, 07:45 PM,
I took my forks apart this weekend on my LTD, as the seal on the left fork started leaking. Oil looked to be original, but everything cleaned up nicely and the bushing all looked good (54,000 miles). Was getting ready to put the springs back in, but measured them first. The short spring was right on for length, but the long one measure 15.7" instead of the 16.02" showing in the service manual. Confused
There was alot of pressure on them when I took them apart - enough that the cap shot off.
I'm tempted to put them back together as I really didn't have any complaints on the ride quality before, even with the old crappy oil.
I haven't riden more than 400 miles so far this year because of the leaking fork and I'm really anxious to get back to riding it (but my CB750F has been happy about it!)

Anybody want to talk me out of it?
Thanks
Philroy
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#8 07-14-2013, 08:10 PM,
My free length measured a little short too but I can live with it
1986 SEi Limited Edition. 1985 Aspencade
If it's not broke, I can fix that!
Reply
#9 07-14-2013, 08:24 PM,


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