K-tech fork springs

[vanstub]

thanks Mac was thinking of inviting myself to Grainstorm as well but don't know if i can wait that long
i've got the mod bug already aaarrgghhhhh and only had bike 4 mths

Bear in mind you'll be doing the work yourself, with someone checking up and making sure you don't mess it up...

thats cool as long as you think i'm capable i'll have a go and you don't all feck off for a ride once its in bits lol

[MacV2]

thanks Mac was thinking of inviting myself to Grainstorm as well but don't know if i can wait that long
i've got the mod bug already aaarrgghhhhh and only had bike 4 mths

Bear in mind you'll have to put up with my jokes & be doing the work yourself, with someone checking up and making sure you don't mess it up...

Sorted...

Pass the hammer...no fool the biggest one you have !

[vanstub]

okay got the bearings
do i put them in freezer now or not

[vanstub]

And how big is this hammer you speak of

[tony.mon]

okay got the bearings
do i put them in freezer now or not

You have to identify which bit needs freezing, just the outer races, and the lower triple and steering stem. Not the whole bearing. Overnight is fine, but only two hours needed really.

[Dendrob]

I can see that there'd be a benefit in freezing the outer races but the shrinkage of the stem diameter is piffling compared to heating the bearing inner race, surely? Don't apply direct heat tho.

[tony.mon]

Freezing won't affect the temper on the bearing, or its surface hardening.
Heating could do, so I'd rather not apply heat, although a small amount shouldn't hurt.
So unless someone wants to tell me at what temperature the race might be negatively affected I'd recommend playing it safe and using cooling only.

[Dendrob]

Freezing won't affect the temper on the bearing, or its surface hardening.
Heating could do, so I'd rather not apply heat, although a small amount shouldn't hurt.
So unless someone wants to tell me at what temperature the race might be negatively affected I'd recommend playing it safe and using cooling only.

Up to 240 degrees C. But it has to be applied evenly and not by direct flame, but you can use the flame to heat a hotplate.

You won't need to go that high though. When you think a freezer will lower roughly 30 degrees, even if you only heated to 100 degrees that's still a 90 rise, treble the freezing route.

Work out how much a reduction of 30 degrees will affect the size of a typical spindle diameter. It won't be much!

[Dendrob]

http://www.skf.com/uk/products/maintena ... index.html

This hotplate goes up to 200C, so SKF must deem that safe enough not to undermine the hardness, although the steel will be starting to change colour.

You won't need to go anywhere near that though and still achieve a better result than a domestic freezer will achieve in the opposite direction. The main worry is keeping the heat general and even. Don't play a blowtorch directly onto the bearing. You can test for 100C easily enough and this should be enough for the level of interference on a typical stem I would have thought.

I seem to recall fitters, at a place I worked years ago, spitting at the races heating up on a hotplate. If they spat back, they were ready to go on. Wonder what temperature spit boils? These were inner races going onto heavy industrial gearboxes, so they would have had a fair old degree of interference.

Edit:
http://astoundingminds.blogspot.co.uk/2 ... aliva.html

Not too many surprises, it comes out near enough 100c

[tony.mon]

Interesting, thanks.

I'd imagine spit boils at pretty much 100 C....
Not an experiment I want to carry out, really!

To me, the main advantage with heating/cooling the parts is not so much to get sufficient expansion/contraction to allow the bearing to drop in or over the mating part, but that once you persuaded it into place it friction locks into place and won't move subsequently.
Even with heating and cooling i don't imagine the races will drop into place without some drift and hammer action.

[Dendrob]

Interesting, thanks.

I'd imagine spit boils at pretty much 100 C....
Not an experiment I want to carry out, really!

To me, the main advantage with heating/cooling the parts is not so much to get sufficient expansion/contraction to allow the bearing to drop in or over the mating part, but that once you persuaded it into place it friction locks into place and won't move subsequently.
Even with heating and cooling i don't imagine the races will drop into place without some drift and hammer action.

Yes they will simply drop on. As long as one doesn't muck up the procedure too much. They literally drop on. The application I was referring to would have what is classed as a heavy interference fit of the inner race onto the shaft. More than we are dealing with on the bike stem. And believe me, there were some chuffin big bearings to play with. Bearings were also pressed on cold, but the snag here is that a) you need a big press b) you risk removing some material and spoiling the fit, so you need to know in advance what level of interference you're dealing with c) the huge blowtorch playing onto a hot plate kept the workshop a bit warmer

If you have a press, I think the inner race onto a bike stem will go on easily. Most of us don't have one knocking about.

[vanstub]

Yes I have 0.85kg K tech springs in mine, they are drop in using the standard spacers, I have 10wt oil and 140mm air gap, preload set to 25mm, forks dropped 5mm through, you need to drop front as the springs make the bike sit higher at the front (as standard they sag more), might go down another 5mm on mine for the summer.


.

okay just been on the phone to a guy called David @brook suspension advised me that in his opinion i need 9.5 n/mm springs for my weight :?:also just been on racetech site and according to them i need something closer to a 0.90 /9.0n/mm spring

[Dendrob]

Yes I have 0.85kg K tech springs in mine, they are drop in using the standard spacers, I have 10wt oil and 140mm air gap, preload set to 25mm, forks dropped 5mm through, you need to drop front as the springs make the bike sit higher at the front (as standard they sag more), might go down another 5mm on mine for the summer.


.

okay just been on the phone to a guy called David @brook suspension advised me that in his opinion i need 9.5 n/mm springs for my weight :?:also just been on racetech site and according to them i need something closer to a 0.90 /9.0n/mm spring

There are 10 N in 1 kg (9.81 for when we need to be pedantic, or when it matters). Popkat is using "shorthand" and dropping the /mm. The difference between what race tech and brook are saying is nothing. A gnat fart. The figures they are giving you suggest that you're heavier than popkat. Or you intend to be doing Dani pedrosa style stoppies at every turn.

[vanstub]

ok i understand that so if the the man says 9.5 n/mm as the way to go that my best option

[Dendrob]

ok i understand that so if the the man says 9.5 n/mm as the way to go that my best option

How much do you weigh?