camshaft dropped 2ft high - throw it away?

[raine]

i'm currently in the hunt for a penetrating dye actually. any idea where to find this locally?

sorry bro wala akong idea kung saan meron nitong mga non-destructive test available commercially

[niky]

as far as nicks or dents, none so far.

i tried placing the camshaft back into the head and tried to turn it... "so far" things are still smooth.

Just have it checked at a machine shop to see that the shaft is still straight... should ease any worries you have.

[spyghost]

Just have it checked at a machine shop to see that the shaft is still straight... should ease any worries you have.

honestly, the biggest worry that i have is the possibility of an invisble crack... next to it would probably having a bent portion.

any idea what machine shop has this kind of service/checking with good set of measuring tools?

worst case would be for me to find a similar camshaft or have one made - speaking of "made cams" any idea of any local shop that makes custom cams given a particular spec? - journal diameter, duration, cam height, etc...?

[niky]

Last I heard, around 20k for a custom cam grind. About as much as buying one from overseas.

[duskylim]

Sir:

Because they are made from engineering grade, case-hardening steels, the cams on the camshaft are themselves only brittle on their SURFACES (up to the depth of the case), and not THROUGH-HARD (hard all the way down to the core) as would be the case if they were made from heat-treated TOOL STEELS.

In a case-hardening steel, the hardness extends only up to the case-depth - an outer skin of high hardness typically 0.5 to 1.5 mm thick at most, that has been treated to have a high carbon content.

The rest of the underlying material down to the core is tough and shock resistant - a very desirable combination of properties for an engineering and machinery steel.

The steels I mentioned previously are typical for car parts and machinery of this nature and usage.

AISI (American Iron and Steel Institute) 4140 or 4340 are chrome-molybdenum and chrome-molybdenum-nickel steels with 0.40% carbon respectively - they are a good example of engineering and case-hardening steels.

High Speed steel is an entirely different class of TOOL STEELS used where high hardness, strength and dimensional stability after heat treatment is desired.

High Speed steels are generally not used in automotive or machinery applications mainly due to high cost - they are very expensive steels, and the design requirements can be met by general-purpose, moderate cost, engineering and case-hardening steels.

Going back to your camshaft, like I said before, only the cams themselves are hardened, the rest of the camshaft was not carburized (treated to absorb a large amount of carbon into the steel) and thus is not hard, but rather is tough.

That applies to the bearings and the rest of the shaft - this is the part that Dieseldude said could have BENT.

A good machine shop will put the cam on a set of V-blocks and mount a dial-indicator near it to measure the straightness and runout.

You cannot see a mis-alignment of a few thousands of an inch (few mils) by eye - you need the dial indicator and the correct set-up to do it.

Having made tool-and-die, plastic moulds and semi-conductor tooling, I have extensive work and professional experience with special steels, metrology and precision machining.

Best Regards,

Dusky Lim

[spyghost]

Sir:

Because they are made from engineering grade, case-hardening steels, the cams on the camshaft are themselves only brittle on their SURFACES (up to the depth of the case), and not THROUGH-HARD (hard all the way down to the core) as would be the case if they were made from heat-treated TOOL STEELS.

In a case-hardening steel, the hardness extends only up to the case-depth - an outer skin of high hardness typically 0.5 to 1.5 mm thick at most, that has been treated to have a high carbon content.

The rest of the underlying material down to the core is tough and shock resistant - a very desirable combination of properties for an engineering and machinery steel.

The steels I mentioned previously are typical for car parts and machinery of this nature and usage.

AISI (American Iron and Steel Institute) 4140 or 4340 are chrome-molybdenum and chrome-molybdenum-nickel steels with 0.40% carbon respectively - they are a good example of engineering and case-hardening steels.

High Speed steel is an entirely different class of TOOL STEELS used where high hardness, strength and dimensional stability after heat treatment is desired.

High Speed steels are generally not used in automotive or machinery applications mainly due to high cost - they are very expensive steels, and the design requirements can be met by general-purpose, moderate cost, engineering and case-hardening steels.

Going back to your camshaft, like I said before, only the cams themselves are hardened, the rest of the camshaft was not carburized (treated to absorb a large amount of carbon into the steel) and thus is not hard, but rather is tough.

That applies to the bearings and the rest of the shaft - this is the part that Dieseldude said could have BENT.

A good machine shop will put the cam on a set of V-blocks and mount a dial-indicator near it to measure the straightness and runout.

You cannot see a mis-alignment of a few thousands of an inch (few mils) by eye - you need the dial indicator and the correct set-up to do it.

Having made tool-and-die, plastic moulds and semi-conductor tooling, I have extensive work and professional experience with special steels, metrology and precision machining.

Best Regards,

Dusky Lim

ok, so what you mean is that cracking is not a possibility but bending is?

[niky]

Bending is possible and is dangerous... and you really should have the balance and straightness checked at a machine shop.

[duskylim]

Dear spyghost:

To make a long story short, cracking is very unlikely in a camshaft, the material and manufacturing process tends to insure that.

Bending (1st mentioned by Dieseldude) is the most likely bad scenario - but it is also unlikely from a 2 foot drop.

This is because in normal engine operation, the camshaft is subjected to strong, regular and repeated bending forces from having the cams force open the valve assemblies - especially at high rpm.

Those cams have to push against valve spring pressure in order for the engine to operate and the shaft is subjected to this constantly - while the engine is ON.

But just to be sure, have a competent shop test the cam for straightness - try Keyser machine shop along West Avenue - they do a competent job.

Hope this helps.

Dusky Lim