cutting fork springs

[erik]

Ok, spacers made, springs installed, bike testridden.

It's definately firmer than before. I think I like it. But I think it's going to take a while to get used to it. I haven't only changed the springs, the tyres are also different (new, still just scrubbing them in), and because I've set the preload to 30% where before it was at 45% the front is 16mm higher, which I think was fairly noticeable, it seemed higher, but also I think it didn't seem as twitchy as it did when I first tried it with the new tyres and the old front suspension. Maybe I'll drop the trippleclamps down the forks a bit to liven it up, I'll wait and see.

I guess I'll just use the springs as they are and maybe open it up in a few weeks to make sure nothing nasty is happening in there.

Woo!

[Milky]

surely you could temper the springs slightly yourself... Not having done it before or being experienced in this sort of thing, I am not sure of the best way to go about it, but surely it is possible. :spudwhat:

[FROSTY:Me]

Eric, you are on the right track.

To the others with your thick oil & preload ideas; respectfully
–Wash your brains out with soap!

.

You and I will have to agree to disagree here dude.
My advise is from real world experience specificly dealing with Yamaha mid 80's front suspension. In other words I've done it I know it works.
Also keep in mind when offering advise (I mean this genericly not specificly) that the person you are dealing with is of questionable mechanical ability.
I don't doubt that an experienced person couldn't acheive the result you suggested.
But the result was as I suspected it would be

[erik]

Milky, I was thinking about it, but I think unless I quenched and tempered the whole spring, I think I'd end up with a soft bit between the old tempered bit and the new tempered bit.

Frosty, in the end it's my decision whose advice I follow. I made a small mistake because of my inexperience, next time I'll know not to overheat the springs.
I suspect that if I had simply increased the spacers so that the sag was at 30% and left the spring rates alone, it still would have been too soft.

[F5 Dave]

. ..
My advise is from real world experience specificly dealing with Yamaha mid 80's front suspension. . .

Gee me too, but not limited to.

PS: I should Advise you the word you were looking for is 'Advice'.

. ..
Also keep in mind when offering advise (I mean this genericly not specificly) that the person you are dealing with is of questionable mechanical ability.
I don't doubt that an experienced person couldn't acheive the result you suggested.
But the result was as I suspected it would be

And how does one gain mechanical experience?

Yup you have to roll your sleeves up & jump in. Bit of reading & advice is always nice.

Sometimes the best experience comes from the mistakes, but it was hardly an ‘I told you so’ moment.

Erik I'm glad you at least had some reasonable results. Think that article mentioned just heating it up enough so it would move with pliers.

So basically you have an end that is not flat? Hmm, I wonder if the preload spacer could be matched & just run the spring upside-down. It may tend to still slide sideways a bit but at the top of the fork I don’t think you would notice.

[FROSTY:Me]

Milky, I was thinking about it, but I think unless I quenched and tempered the whole spring, I think I'd end up with a soft bit between the old tempered bit and the new tempered bit.

Frosty, in the end it's my decision whose advice I follow. I made a small mistake because of my inexperience, next time I'll know not to overheat the springs.
I suspect that if I had simply increased the spacers so that the sag was at 30% and left the spring rates alone, it still would have been too soft.

Not having a go at you eric.
My methodology (sp) has always been to take the simplest solution first then ramp up to the next level if it doesn't work.

[DEATH_INC.]

I was talking about Snells, a friend that's into cars told me maybe they could help. How come it's a waste of time?

Because they don't know the alloys and original temper of the springs,they just guess.A large percentage of their compressed and re-tempered car springs sag after a while.....
Glad it worked out ok

[Warr]

I see this thread is about done, but with so much expertise being shown thought I could tap into the same ... etc etc.

My '84 XJ900, Most riding is 2 up. Just had new fork seals fitted and with no air it hits hard when trying to get over anysort of bump. So top the air up and loosing oil out r/h leg. Reduce air to 10 psi (I think). Now oil under control but still inclined to bottom out. Especially when negotiating driveways at slow speed.

From reading all the above I like Frosty's $4.00 worth of 20c the most just top give it a bit more height. Or is a heavier grade of oil going to be a better solution.?

[F5 Dave]

Did you click the link in the quote of the first thread?

Air pressure just tends to make the forks bouncy (air isn’t a linear spring so will overwhelm damping if relied upon too much) + far more likely to blow seals.

Heavier oil & excessive preload will mask the symptoms but not effect a cure & have side effects like harsh on small bumps stuttering likely.

But go on, knock yourself out, fire in a weeks wages of 20c pieces & diff oil.


[edit]
Sorry I’m having a cynical afternoon.

[DEATH_INC.]

'preload' can be more accurately reffered to as ride height,this is all you're changing with it.
Remember,the spring holds the bike up,the oil(damping)controls how fast the suspension moves....

[erik]

I see this thread is about done, but with so much expertise being shown thought I could tap into the same ... etc etc.

My '84 XJ900, Most riding is 2 up. Just had new fork seals fitted and with no air it hits hard when trying to get over anysort of bump. So top the air up and loosing oil out r/h leg. Reduce air to 10 psi (I think). Now oil under control but still inclined to bottom out. Especially when negotiating driveways at slow speed.

From reading all the above I like Frosty's $4.00 worth of 20c the most just top give it a bit more height. Or is a heavier grade of oil going to be a better solution.?

From what I've read, the laden sag should be about 30 to 35% for street riding (http://www.strappe.com/suspension.html). As I understand it, if you have less sag, the front wheel won't follow depressions in the road as well (if I'm wrong here, or there is more to it, please comment).

You could try setting the laden sag to the correct amount using either the coins or some pvc tubing spacers, and if it still bottoms out or feels too soft, then you'll know you need to increase the spring rate with new springs or by other methods...

That's my 5c worth

[Kickaha]

'preload' can be more accurately reffered to as ride height,this is all you're changing with it.
Remember,the spring holds the bike up,the oil(damping)controls how fast the suspension moves....

I am sure someone will correct me if I'm wrong but I think they are slightly different otherwise why would you bother having seperate spring preload and ride height adjustment on some rear shocks

[FROSTY:Me]

I see this thread is about done, but with so much expertise being shown thought I could tap into the same ... etc etc.

My '84 XJ900, Most riding is 2 up. Just had new fork seals fitted and with no air it hits hard when trying to get over anysort of bump. So top the air up and loosing oil out r/h leg. Reduce air to 10 psi (I think). Now oil under control but still inclined to bottom out. Especially when negotiating driveways at slow speed.

From reading all the above I like Frosty's $4.00 worth of 20c the most just top give it a bit more height. Or is a heavier grade of oil going to be a better solution.?

Specific advise regarding your bike.
If you can afford to I would pay the $120 ish dollars for a set of progressive springs.You wont believe the difference they will make.
I would dump the fork oil and replace it with 15 weight oil (50/50 10 and 20 weight). I would use 5-10ml extra oil in each fork leg.
Don't use any air at all
To get it just right you will need to experiment a bit on this basic formula but it will give ya a good benchmark to start wit.
Once ya have it real close use up to 10psi to do the really fine tuning.

[ajturbo]

i put in aluminium (sp?) spacers in mine.. (87 model) they were solid and aprox 40-50mm ( cannot remember the excate lenth) added the 15 w oil! also

this was done when brand new!!!! (after first service)


andy