Anyone have experience cutting fork springs?

[squiggy]

With this economy affecting my income I'm not going to able to afford buying correct length springs for my front end conversion project. I did find a set of correct diameter springs, however the length is about 1 inch (one coil wrap) too long. They are also at this point the correct spring rate.

The new conversion forks have preload adjusters that are already back out as far as can be. As such the springs are about one inch too long.

The research I've done shows that cutting a spring can be done even though the spring rate will change to a degree. To cut a spring, a grinding/cut-off wheel can be used. From there a torch to heat the end of the spring then bend it to flatten it like an original would be. To cool the spring, wait until the hot red colored metal turns black-ish again then dunk it in oil.

Is this information correct?

What kind of torch will heat up a spring to be able to bend it. Just regular propane or a combanation of map gas and oxygen?

[Kfreak]

I'll comment on the oil. Yes, cool it slowly in oil, it will temper the metal. A propane torch with a certain type of tip. I prefer to use oxy/acet for heat.

[Tmod]

That never works out all that well, Just save your money and buy the correct springs.

Are these springs coming out of the top of the forks? If not just shorten the spacer.

Tmod

[Kfreak]

[squiggy]

Are these springs coming out of the top of the forks? If not just shorten the spacer.

Sorry, I should have stated that these are cartrige forks.

[Tmod]

IMO I would just save for the correct springs as shortening them changes the rate and since you are spending the time to adapt cartridge forks you might as well do it correctly.

Tmod

[scottynoface]

I cut mine down on my Jetta, worked out fine but I was always worrying.

[GSXfs600]

If you heat up a spring, it will no longer be a spring, unless you also heat treat it after the cut.

[Black_peter]

As I understand it the key is to cut it while it is in water.. The wire diameter of these springs is pretty small, So find a deep container, sink all but what you want to cut and use a cut off wheel in a grinder. If you have enough water the spring shouldn't even get hot. Remember though that now you have fewer turns so the spring gets stiffer..

[squiggy]

If you heat up a spring, it will no longer be a spring, unless you also heat treat it after the cut.

From Google search, by cooling it in oil, it did not say what kind, it will cool it appropriately.

As I understand it the key is to cut it while it is in water.. The wire diameter of these springs is pretty small, So find a deep container, sink all but what you want to cut and use a cut off wheel in a grinder. If you have enough water the spring shouldn't even get hot.

That I did not come across. Interesting.

Remember though that now you have fewer turns so the spring gets stiffer..

It would only be one turn of the spring. How much difference in ridding experience I can't say, though.




Keep the comments coming.

[Black_peter]

Remember though that now you have fewer turns so the spring gets stiffer..

It would only be one turn of the spring. How much difference in ridding experience I can't say, though.

I doubt you will notice one turn missing, but this thread will live on.. Floating around cyberspace for years, decades, centuries! I wanted to be sure I passed that tid-bit on to future generations...

[Kreylyn]

Just a couple of quick things to know about heat and steel...

1. Heat it very hot = completly removing all previous heat treatment (spring) from that part.

2. Heat it very hot and cool it very quickly (quenching it) will make it hard and springy again, but there will be stresses that need to be relieved to prevent breakage.

3. Heat it very hot and cool it very quickly, then re-heat much lower temp and cool it slowly will temper those stresses.

Variances in heat during any of this process will cause very sporatic changes to the heat treatment making pretty major changes to the springs performance. Doing what was mentioned with heating the end of the spring up and cooling with oil... will cause a very hard end, soft spot between, and change up the spring rate for the spring for a several inches (not just the 1" you want).

I would recomend for best results with the least amount of possibly chances in ruining the spring to do as was mentioned with cutting it in water so that it does build up heat.

I also highly recomend reading some basic information on forging and heat treatment for steel and how it relates to springs so you have a good understanding of what a torch will do to your spring when applied before attempting to make any changes at all. There are alot of great online resources available, including many custom smiths who will answer specific questions on discussion forums.

Krey

[squiggy]

Even though I'm only heating the end to flatten it? All I need to do is bend the spring that coils vertical to the point of laying horizontal. This way it contacts the end tab more flusherlynessful.

[Kreylyn]

Even though I'm only heating the end to flatten it? All I need to do is bend the spring that coils vertical to the point of laying horizontal. This way it contacts the end tab more flusherlynessful.

But your not only heating the end... when you apply heat at the end, it's going to travel... getting the end of it hot enough for you to take a hammer and flatten that point at the fastest possible, means that your going to have a direct affect on 4-6" of metal in the aspect of it's heat treatment at minimal. Using a propane torch (while hot, isn't that hot and will take a while to heat up the end to the point your speaking of, allowing more heat to travel along the spring) isn't the best option.

The only sure way not to end up with a spring that has a huge flux in heat treat at that point, is to evenly heat and quench the entire spring once shaped, then temper the entire spring. I would say you would really need to have a good understanding of the quench and temper aspect to get it anywhere near back right.

I'm not saying that it won't work somewhat... I'm just saying that there is going to be alot more change to the spring than just taking 1" off of it by that method, potentially (depending on how much you do to it, how many times heated and re-heated, how it's quenched, so on) makeing pretty huge changes to it's basic function.

Knowledge is power, read up on heat treatments, and the process before applying a torch to your spring. This is something you should know before doing it, so that you know what to look out for and perhaps be able to take steps to counter the issues that may arrise.

Krey

[jeremy_nash]

cut it down, then use a grinder to smooth the end? smooth alittle, then dunk in water. if you dont let it get very hot, then the springyness shouldn't be affected

put the cut end up, so that it cant try to cock the fork leg, an I wouldn't forsee a problem with it