Register    Login    Forum    Search    FAQ

Board index » Hornet 600/599 » General chat




Post new topic Reply to topic  [ 17 posts ] 
Author Message
 Post subject: Fork oil change
 Post Posted: Sun Feb 10, 2019 10:21 pm 
Offline
Hornet Warrior

Joined: Sun May 27, 2018 6:23 pm
Posts: 152
I can't find any thread on a simple oil change? Does anyone know how much I need to put in each leg? Is the correct level 102 mm from the top? Should I just remove the forks with the spring and specer and simply turn it upside down and pump it? Then put it in a vice and fill oil to the correct level? (Which I believe is 102mm)


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 2:05 am 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
I did this recently - I'm just about to turn in for the day - but I'll post up some links and info tomorrow.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 8:37 am 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Fork Oil Volume Per Leg: 486 cc/ml

Fork Oil Level: 102mm (measured from top of tube with spring removed and fork leg fully compressed).

With the forks still tightened up in the yokes loosen (but do not remove) the top cap bolts on each fork (if the forks are off the bike the top cap bolt has to be removed with the fork in a vice).

Remove the forks from the bike, unscrew the top cap bolt (stick a rag or something over it, apply downward pressure while unscrewing it and and keep your face/eyes out of the way as it is under pressure from the spring and will be launched across the room if it's not kept hold of).

Slide the tube down into the leg and remove the spacer, spring seat and spring from the tube, remove the springs (if they are standard progressive springs note which way up they are fitted).

Turn the fork upside down and pump out as much oil as possible.

Slowly pour in the new oil and then pump it 10 times to distribute the oil, stand the fork upright and leave it a few minutes for the oil to settle then fully compress the fork tube slider into the leg and measure the fork oil level from the top of the tube (you can use a steel ruler or similar - drop it into the leg and measure the distance). Add or subtract oil until you get the oil to the level specified above (you can use a syringe for this).

Extend the fork tube and refit the spring with the tight coils at the bottom if they are the OEM progressive springs, followed by the spring seat and spacer.

Fit a new O ring to the top cap bolt (lube it with oil prior to fitting).

Fit the top cap bolt - you'll have to press it in with some force before you engage the threads as the cap bolt is pressing on the spring - be careful that it goes in level to avoid cross threading, again keep your eyes out of the way as the cap bolt can potentially fly out under pressure if you lose your grip on it.

Install the fork back in the yokes - with the fork tightened up in the yokes torque up the fork cap bolts to 23 Nm.

There are some pics of the process on my resto thread:

http://www.hondahornet.org.uk/messageboard/viewtopic.php?f=6&t=33203&start=120


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 3:55 pm 
Offline
Darwin Award winner 2016
User avatar

Joined: Tue Jan 28, 2014 8:26 pm
Posts: 1328
You can set the oil gap using a syringe (or similar) and cable tie.


Image
Set the required gap (I think this is from my emulator install thread)

Image
Slightly over fill the fork then.. rest the cable tie on the fork tube and withdraw the excess fluid.






:)

_________________
60th cog in the Gear Driven Cam Appreciation Society.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 6:11 pm 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Godammit Biggabit! How can you be so insensitive? I was conceived with a turkey baster! :angel


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 7:24 pm 
Offline
Darwin Award winner 2016
User avatar

Joined: Tue Jan 28, 2014 8:26 pm
Posts: 1328
HOON98 wrote:
Godammit Biggabit! How can you be so insensitive? I was conceived with a turkey baster! :angel


:clap

You got two mums then? :rollin

_________________
60th cog in the Gear Driven Cam Appreciation Society.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 9:34 pm 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Quote:
You got two mums then? :rollin


If you class a test tube and a turkey baster as constituting 'two mums' then yes! :angel


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 9:47 pm 
Offline
Darwin Award winner 2016
User avatar

Joined: Tue Jan 28, 2014 8:26 pm
Posts: 1328
HOON98 wrote:
Quote:
You got two mums then? :rollin


If you class a test tube and a turkey baster as constituting 'two mums' then yes! :angel



Stop it ! :rollin :rollin


WARNING THREAD DRIFT ALERT

WARNING THREAD DRIFT ALERT

WARNING THREAD DRIFT ALERT




Where's admin when you need them. :help

_________________
60th cog in the Gear Driven Cam Appreciation Society.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Mon Feb 11, 2019 10:18 pm 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Yeah your right! sorry to the OP Irongamer - I had some time to kill today and got bored.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Tue Feb 12, 2019 9:57 am 
Offline
Hornet Pilot

Joined: Fri Jan 17, 2014 10:07 am
Posts: 88
Location: Denmark
Great help, and just the way I have done it the few times, just one question:

You spend some detail on which way the spring is installed (I have have also been sure to turn it the right way ...), but does it matter at all? How can the spring see which way it is compressed when installed? Just considering it from a (slightly) theoretical point of view, I cannot get into my head why it should matter which way it's installed!?

/ask


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Tue Feb 12, 2019 10:44 am 
Offline
Victor Meldrew
User avatar

Joined: Thu Feb 27, 2003 10:51 pm
Posts: 5363
Location: Worcester
That'll be the difference between progressive ( fitted as standard ) and linear springs.

Progressive springs go in with the wider gaps downwards. I suppose the idea is that the wider bits compress first, then spring gets effectively stiffer as suspension travel is used up and the tighter windings come into play.

I suppose it also slightly reduces the unsprung weight, having less spring metal at the end which moves the furthest ?

I must admit, I find the concept of preload and spring stiffness difficult to get my head around. Adding spacers on top of a spring to add preload doesn't actually make the suspension stiffer, it just increases the ride height and reduces the suspension travel so that you can take a fat bloke on the pillion.

Another weird thing - if you shorten a spring by cutting off a few coils, it actually makes it into a stiffer spring. Intuitively, you'd think that it would weaken a spring by cutting bits off it.

_________________
And then one day you find
Ten years have got behind you
No one told you when to run
You missed the starting gun


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Tue Feb 12, 2019 11:20 am 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Quote:
You spend some detail on which way the spring is installed (I have have also been sure to turn it the right way ...), but does it matter at all? How can the spring see which way it is compressed when installed? Just considering it from a (slightly) theoretical point of view, I cannot get into my head why it should matter which way it's installed!?


Yeah - I have no idea why the orientation of the progressive springs should matter either - would be interesting to find out why - maybe something to do with unsprung weight as Richard suggested.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Tue Feb 12, 2019 12:43 pm 
Offline
Darwin Award winner 2016
User avatar

Joined: Tue Jan 28, 2014 8:26 pm
Posts: 1328
Another thing to consider is reproducible spec.

The quoted air gap tolerance of 102mm was calculated using an OEM progressive spring with the tighter coils at the top.* Tighter coils at the bottom would displace more oil and require a different air gap for the same effect. Probably not by much but if you were to place one spring tighter coils up and the other tighter coils down, the air gaps would be different. Thus the need for predetermined tolerance /spec sheets.

Regards the springs; In this system the lighter coils will always compress first regardless of which way up they're installed. So theoretically (forgetting oil and air gaps) you could have one up and one down and it would make no difference how they compress. All these carefully recorded and reproducible tolerances were wasted on the Hornet, as the end result was awful any way ! :Bang



*The base line (starting with the heavy side of the spring up) has probably got something to do with mass, inertia and un-spung weight.

_________________
60th cog in the Gear Driven Cam Appreciation Society.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Tue Feb 12, 2019 1:14 pm 
Offline
Knob Magnet
User avatar

Joined: Sun Mar 05, 2006 9:38 pm
Posts: 10044
Location: Catterick, North Yorkshire
:clap :clap :clap

_________________

370Steve


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Wed Feb 13, 2019 7:55 am 
Offline
Hornet Pilot

Joined: Fri Jan 17, 2014 10:07 am
Posts: 88
Location: Denmark
Thanks, I get the part regarding unsprung weight (mostly - I guess you want the least weight at the wheel-end) and it also makes sense that you should be careful to have the same "spring-volume" below the oil-level - so the point is: Install the two springs in the same way.

As for which direction they should be installed, I still don't see that it matters for the springs - all they experience is that their length is decreased when compressed, and they will always compress most were they have the least spring-resistance (the tightly wound coils).


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Wed Feb 13, 2019 9:06 am 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Quote:
As for which direction they should be installed, I still don't see that it matters for the springs - all they experience is that their length is decreased when compressed, and they will always compress most were they have the least spring-resistance (the tightly wound coils).


Yeah, I think that you are right on this - I guess only a suspension expert can provide the definitive answer.


Top 
 Profile  
 
 Post subject: Re: Fork oil change
 Post Posted: Wed Feb 13, 2019 9:07 am 
Offline
True Horneteer
User avatar

Joined: Mon Jul 13, 2015 8:08 am
Posts: 1911
Location: In The Garage
Biggabit wrote:
Another thing to consider is reproducible spec.

The quoted air gap tolerance of 102mm was calculated using an OEM progressive spring with the tighter coils at the top.* Tighter coils at the bottom would displace more oil and require a different air gap for the same effect. Probably not by much but if you were to place one spring tighter coils up and the other tighter coils down, the air gaps would be different. Thus the need for predetermined tolerance /spec sheets.

Regards the springs; In this system the lighter coils will always compress first regardless of which way up they're installed. So theoretically (forgetting oil and air gaps) you could have one up and one down and it would make no difference how they compress. All these carefully recorded and reproducible tolerances were wasted on the Hornet, as the end result was awful any way ! :Bang



*The base line (starting with the heavy side of the spring up) has probably got something to do with mass, inertia and un-spung weight.


Great post! :clap


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 17 posts ] 

Board index » Hornet 600/599 » General chat


Who is online

Users browsing this forum: Google [Bot] and 2 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: