I have a new set of springs here in an unmarked box. What is their pressure at 1.85" outer/1.75" inner installed height?
Outer: 1.552" OD, .207" wire, 2.595" free height, 5 turns
Inner: 1.030" OD, .142" wire, 2.345" free height, 5.5 turns
How can you possibly get any usable data just from that without knowing anything about material or temper? What caliper measurements determine which springs in the set need more or less shim to equalize the seat pressures?
Well maybe we can't, but we can try.
Outer
Rate =218.5 lb/in
Seat force = 162.8 lbs
Avail lift = 10.2 mm
Nose @ 10.2 = 250.5 lbs
Frequency = 617 Hz
Seat stress = 77,140 lbs
Nose stress = 118,721 lbs
Inner
Rate =151.5 lb/in
Seat force = 90.2 lbs
Avail lift = 17.5 mm
Nose @ 10.2 = 194.6 lbs
Frequency = 510 Hz
Seat stress = 88,585 lbs
Nose stress = 191.160 lbs
If we have the true valve stem height, and correct spring installed height, we can determine shim stack for seat force.
With actual valve lift per cam lobe, we can do the same for nose force.
Given the weight of each spring, valve train weights, valve acceleration and rpm, we could then determine the threshold of valve float and probable valve bounce.
Given the above data, which spring is most apt to lose free length and or break first?
The largest factor that affects spring rate and resultant forces is wire diameter. Wire diameter must be measured
carefully and the wire inspected for corrosion pitting, wear areas due to rubbing, and wire nicks.
Most spring manufacturers use high quality wire which is quite similar in physical properties. Most, but not all.
How would one know if thats anymore accurate than a valve spring tester?
How do you calibrate it?
What do spring manufactures use to confirm their spring specs?
When it comes to springs (of all sorts), what is the expected level of precision and accuracy?
In any arena, a man with two wrist watches does not know what time it is.
tbenzy wrote: ↑Mon Dec 09, 2019 11:41 am
bringing this back from the dead......
whats the latest software anybody has to share for the pt-200 power tech spring tester?
6.2 is what I have and I see there was a 7.3 at least one time.
anybody have something later to share?
thank you, Tom
They're out of business so you'd have to find a copy of the latest from someone else. There's also the option of converting it to use Performance Trends mini USB interface and their software. It uses all of its current sensors to make conversion more cost-effective.
bigjoe1 wrote:By the way, I had a long talk with Harold(Brookshire) last year at the PRI show. We met at the airport and he told me everything he knew about everything.It was a nice visit. JOE SHERMAN RACING
David Redszus wrote: ↑Mon Dec 09, 2019 8:14 pm
Well maybe we can't, but we can try.
Outer
Rate =218.5 lb/in
Seat force = 162.8 lbs
Avail lift = 10.2 mm
Nose @ 10.2 = 250.5 lbs
Frequency = 617 Hz
Seat stress = 77,140 lbs
Nose stress = 118,721 lbs
Inner
Rate =151.5 lb/in
Seat force = 90.2 lbs
Avail lift = 17.5 mm
Nose @ 10.2 = 194.6 lbs
Frequency = 510 Hz
Seat stress = 88,585 lbs
Nose stress = 191.160 lbs
If we have the true valve stem height, and correct spring installed height, we can determine shim stack for seat force.
With actual valve lift per cam lobe, we can do the same for nose force.
Given the weight of each spring, valve train weights, valve acceleration and rpm, we could then determine the threshold of valve float and probable valve bounce.
Given the above data, which spring is most apt to lose free length and or break first?
The largest factor that affects spring rate and resultant forces is wire diameter. Wire diameter must be measured
carefully and the wire inspected for corrosion pitting, wear areas due to rubbing, and wire nicks.
Most spring manufacturers use high quality wire which is quite similar in physical properties. Most, but not all.
How would one know if thats anymore accurate than a valve spring tester?
How do you calibrate it?
What do spring manufactures use to confirm their spring specs?
When it comes to springs (of all sorts), what is the expected level of precision and accuracy?
In any arena, a man with two wrist watches does not know what time it is.
I couldn't tell you, I always picked a cheap spring with the seat pressure I wanted for my install height and application, dbl cked it on my cheap pressure gauge and ran it, never had an issue and never checked open pressure.
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David Redszus wrote: ↑Mon Dec 09, 2019 5:09 pm
Using a vernier and calculator, I can quickly spot check and determine the specs for almost any spring. If I had to measure and sort several hundred springs, I would use a spring tester.
I have a new set of springs here in an unmarked box. What is their pressure at 1.85" outer/1.75" inner installed height?
Outer: 1.552" OD, .207" wire, 2.595" free height, 5 turns
Inner: 1.030" OD, .142" wire, 2.345" free height, 5.5 turns
How can you possibly get any usable data just from that without knowing anything about material or temper? What caliper measurements determine which springs in the set need more or less shim to equalize the seat pressures?
Did you have a chance to test those springs and compare test results to the data that was calculated?
I wonder if the difference, if any, is significant to worry about.
David Redszus wrote: ↑Wed Dec 11, 2019 10:02 am
Did you have a chance to test those springs and compare test results to the data that was calculated?
I wonder if the difference, if any, is significant to worry about.
20-whatever years ago when I got the springs I had access to a Rimac at work and measured 240# at 1.85. I don't know how much variation there is in the set, I don't have a spring tester now.
Spring testers are useful even if they aren't perfectly accurate as long as they are repeatable. The absolute numbers aren't that important but variation among a set is and you can find that using a tester that's 'off' by quite a bit.
Yes, Camino- how did David's calculations compare to measured or vendor's data on those springs?
I am not sure if temper or various types of spring steel have any or measureable impact on spring force etc.
And I totally agree With you regarding spring tester; more for comparing New VS used spring and help to determine if it's time for replacement rather than absolute numbers. Or to check if there's an bad egg in the set of New springs....
I believe the springs came from Pioneer, unknown part number. I looked a little and couldn't find anything that looks like a match but Pioneer's online catalogs are crap, I seem to remember they used to have a whole catalog just for springs but can't find it now.
