Shortening valve springs

[68corvette]

Might be a bit unusual procedure, but I need to match a springs now and then to get the minimum distance to coilbind and within a set of springs the CB heights may need to be adjusted.
This is with some engines where selection is very limited and I need to work on what is available.

Usually I use belt sander as it does not collect much heat, but its a tedious job.
Slight touch to grinder, right away to the water and then repeat to avoid any discolor and heating of the spring.
Nice thing with this method is that I can take slighlty more from the binding side of the spring and reduce some canting when spring is close to bind.

Any tips or ideas how to machine springs shorter?
Typically I need to machine between 0.04"-0.08" and if more, then I try to find some other solution.
How are the spring ends machined when manufactured?
Or maby they are heat threated after all machining is done?

[pdq67]

I think this procedure can be found in the old Herb Adams book, "Chassis Engineering"...

He said that people shorten suspension coil springs by clamping them to the needed length/height and then putting them into an oven that is about 400(?) degrees or so for like four hours. The springs relax and shorten but DO NOT lose their original temper/properties.

You might look into this if you want to.

Now I haven't done this, but I did stress relieve my 406's rods by baking them at 450 degrees in a kitchen oven over night. I just wrapped them in aluminum foil is all..

pdq67

[Truckedup]

I would think of using plenty of cooling water when grinding a spring . Using heat to shortened a valve spring may be a place you don't want to visit...

[Alaskaracer]

What is this for to begin with, and have you contacted spring manufacturers to see what they have already? There are literally THOUSANDS of different valve springs out there, shouldn't be too hard to find one for your application without cutting one. You'll change the spring rate by making it shorter, and the other issue is getting it to sit square on the seat and retainer. If it doesn't, it WILL side load the valve...and it won't take much.....I'd do some more research.....

[travis]

Is a different set of valve locks or machining the spring seats not an option?

[Kevin Johnson]

Might be a bit unusual procedure, but I need to match a springs now and then to get the minimum distance to coilbind and within a set of springs the CB heights may need to be adjusted.
This is with some engines where selection is very limited and I need to work on what is available.

Usually I use belt sander as it does not collect much heat, but its a tedious job.
Slight touch to grinder, right away to the water and then repeat to avoid any discolor and heating of the spring.
Nice thing with this method is that I can take slighlty more from the binding side of the spring and reduce some canting when spring is close to bind.

Any tips or ideas how to machine springs shorter?
Typically I need to machine between 0.04"-0.08" and if more, then I try to find some other solution.
How are the spring ends machined when manufactured?
Or maby they are heat threated after all machining is done?

I visited a machine shop in Detroit back in the late 1970s. They had a water-cooled diamond abrasive disk grinding machine. It was similar to the plaster-cast model trimmers used by dentists and dental labs except that it employed a plate to mount the object that had two degrees of freedom (X, Y axis). In that way the surface being trimmed could be held square to the cutting disk. You would need to rig a fixture to hold the spring, of course.

~~~~~~~~~~~~~

The plate was given to me by my Great-Grandmother who lived in Waterford. I saw that it needed to be rebuilt (the bearing journals were quite worn) and took it to the manufacturer which still existed in Detroit.

When I showed it to one of the machinists he did not say anything but went to get his boss. It turned out that they thought I might have stolen it somehow because they did not sell them to the public. When I explained that it belonged to my Great Grandfather and that he had used it for gunsmithing they said that it must have been made by the deceased founder of the business. They offered me an apprenticeship on the spot and showed me how it was used for machining.

[68corvette]

Heating and shortenin the spring would not help with coilbind issue as coilbind distance would not decrease, only free lenght.
For some engines, like BMW N57 diesel, there is only one spring manufacturer for aftermarket.
Searching for outer, inner, installed, cb dimensio, herzian stress and spring forces which would fit for this exact purpose is a really hard work.. companies do not habe easy to read lists for all values, or possibility to filter / search suitable springs.
I have had custom springs manufactured, but usually I have 500+ springs made which might not be cost efficient for all scenarios. Especially if customer has springs which can be machined to work with a little effort.

Kevins device looks interesting.
Actually I was thinking about knife sharpener, but thought that machining operation might be really slow.
Diamond disk or coarse stone might do the trick.

[BCjohnny]

I don't think there's much else, on a reasonable budget, you can do other than introducing coolant directly to the process

So maybe adding a fixture to some kind of unloved or obsolete 'wet grinder' might be the way to go

[rebelrouser]

Not an expert, but shortening a spring to get it to fit an application would be my last resort, and I personally would not attempt it. And that is from a guy who has taken used push rods, removed the ends cut them and repressed the tips to make them work, just one example.
With the thousands of springs available, cutting spring seats, any head can tolerate some cutting, and different height retainers, and keepers, how would you ever need to grind a spring? I would think it safer to cut .030 from a spring retainer, or valve pocket etc. than .030 from a valve spring. In removing material from the spring, don't you have trouble with the spring getting thin enough that it is prone to break where the coils are thin? I have seen plenty of springs break off the bottom coil from having a thin coil from the regular manufacturing process.

[engineguyBill]

Like Mark said in an earlier post, there are literally thousands of valve springs available from the hand-full of spring manufacturers who supply the automotive industry. If you are lucky you will find a manufacturer who has the springs you need in inventory. If they do not have them in inventory, they may require you to buy a production run of that spring, which may require an order of one thousand springs (or more).
Or, possibly you could use a slightly shorter spring with a custom-manufactured spring seat to locate and raise the spring.

[Sparksalot]

I noticed you are in Finland so perhaps your resources are limited regarding access to the hundreds of springs available in the USA.

Springs are wound from steel wire, then heat treated: hardened and tempered. High performance springs then undergo shot peening. The end coils are wound to be closed at the ends and then ground square to the axis of the spring.

.

[stealth]

There is no way I would be trimming springs...

If you need more or less height consider different (offset) keepers. You can gain a little there if too tight (coil bind)

[68corvette]

Not an expert, but shortening a spring to get it to fit an application would be my last resort, and I personally would not attempt it. And that is from a guy who has taken used push rods, removed the ends cut them and repressed the tips to make them work, just one example.
With the thousands of springs available, cutting spring seats, any head can tolerate some cutting, and different height retainers, and keepers, how would you ever need to grind a spring? I would think it safer to cut .030 from a spring retainer, or valve pocket etc. than .030 from a valve spring. In removing material from the spring, don't you have trouble with the spring getting thin enough that it is prone to break where the coils are thin? I have seen plenty of springs break off the bottom coil from having a thin coil from the regular manufacturing process.

Like Mark said in an earlier post, there are literally thousands of valve springs available from the hand-full of spring manufacturers who supply the automotive industry. If you are lucky you will find a manufacturer who has the springs you need in inventory. If they do not have them in inventory, they may require you to buy a production run of that spring, which may require an order of one thousand springs (or more).
Or, possibly you could use a slightly shorter spring with a custom-manufactured spring seat to locate and raise the spring.

There is no way I would be trimming springs...

If you need more or less height consider different (offset) keepers. You can gain a little there if too tight (coil bind)

I have had issues finding suitable springs, maby you could help?
Stock springs are:
installed height: 30mm
Outer diameter: 20.5mm
inner diameter: 15.5mm
Seated force: 32lbs
Spring force at 10mm lift: 65lbs
Coilbind: 19mm

I would need something with a more spring force, especially at the seat and at max the same coilbind height or less.
Also I would like to use at max 1000 N/mm^2 hertzian stress for durability.

Spring pocket cutter would be easy, but I would need to fabricate cutter to cut inside 10mm and outside 22mm dimensions, I do not think these are readily available?
Or are you using some adjustable cutter for the work?

Retainers are 1.5mm thick, I do not feel comfortable machining more than half of the thickness away.

Valve locks are standard 5mm 3-groove keepers.
If you can advice where to get offset keepers raising the springs for 1mm, that would be probably easiest, I do not know where I could get those.
Or if you know where to get suitable offset retainers, I could easily machine them down to correct diameter if needed.

[Alaskaracer]

Contact these guys, they can help:

https://www.psisprings.com