Is PAC's 1243 Coil Bind spec accurate?

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BradH
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Is PAC's 1243 Coil Bind spec accurate?

Post by BradH » Mon Feb 12, 2018 4:39 pm

PAC 1243 dimensions:
- Mass (g): 140.0
- Outer Spring I.D. (in): 1.136
- Outer Spring O.D. (in): 1.550
- Inside Spring I.D. (in): 0.812
- Install Load (LB): 240
- Install Height (in): 1.900
- Open Load (LB): 625
- Open Height (in): 1.200
- Coil Bind Max (in): 1.100
- Lift Max (in): 0.700
- Frequency Outer (CPM): 27566
- Frequency Inner (CPM): 29978
- Damper: No

I would have thought the max lift spec would have been a bit higher if they're saying coil bind is still .100" under it. Have people who have used this spring found that CB measurement to be accurate? Thanks - Brad
Last edited by BradH on Mon Feb 12, 2018 4:46 pm, edited 1 time in total.

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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by af2 » Mon Feb 12, 2018 4:41 pm

That is for a big as cam!!! .100 lift.
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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by turdwilly » Mon Feb 12, 2018 5:30 pm

AFR specs the coil bind on it as 1.155" (as AFR-8000). My actual measurement on that spring was 1.125". When I called PAC, they said "The AFR-8000 is a proprietary spring we build for them". PAC lists coil bind on the 1243 as 1.100". My thinking was that there may be a different level of prep/surface treatment between the two, which caused a slightly different solid stacked height.

But....PAC also lists coil bind on the springs I ended up running on that deal (PAC-1343) at 1.150". When I received them, the actual coil bind I measured was way off from the spec listed on the box (same as their catalog spec). So when I called them, they said "oh that spec on the box & in our catalog is wrong, it should be 1.xxx" (I can't remember the number.) Another thing - that spring as an assembly including the correct retainer with .100" step bound on the inner spring - not the outer - at which point the outer still had like .125" clearance! I had to make special spacers for the outer springs only in order to tighten up the coil bind clearance on the outers.

Of course the very definition of coil bind is also subjective - measured coil bind can vary quite a bit depending on one's interpretation of the definition of when coil bind actually occurs - & depending on how hard they crank the vise/spring tester. Some say crank it down hard until you see no more measured movement, some say its at the absolute moment when the spring load no longer increases at a linear rate.

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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by turdwilly » Mon Feb 12, 2018 5:45 pm

Also I forgot to mention the AFR-8000 I had measured nowhere near the open pressures listed by AFR or PAC (on the PAC-1243). Iirc AFR stated 240# @ 1.950" back then. PAC hasn't changed & lists the 1243 as 240 lbs at 1.900". I measured somewhere around 215# @ 1.950 iirc. AFR has since changed the listed seat pressure on their spring spec chart to 220# @ 1.950".

I could be off a little on that old AFR spec, it's been several years so I'm not certain, but I am certain the actual seat pressure we measured was WAY less than teh listed specs by AFR or PAC.

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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by MadBill » Mon Feb 12, 2018 6:01 pm

It's amazing how many companies' specs are out to lunch. I was browsing the Isky Tool Room springs the other day and there were probably a dozen errors, from misplaced decimals to coil bind heights greater than open heights, diameter errors, etc.. #-o
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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by turdwilly » Tue Feb 13, 2018 10:49 am

turdwilly wrote:
Mon Feb 12, 2018 5:45 pm
Also I forgot to mention the AFR-8000 I had measured nowhere near the open pressures listed by AFR or PAC (on the PAC-1243). Iirc AFR stated 240# @ 1.950" back then. PAC hasn't changed & lists the 1243 as 240 lbs at 1.900". I measured somewhere around 215# @ 1.950 iirc. AFR has since changed the listed seat pressure on their spring spec chart to 220# @ 1.950".

I could be off a little on that old AFR spec, it's been several years so I'm not certain, but I am certain the actual seat pressure we measured was WAY less than teh listed specs by AFR or PAC.
I just noticed this error in my post. Should have read "seat pressures". My bad.

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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by BradH » Wed Feb 14, 2018 12:31 pm

Obviously, I'll need to check my springs at some point to know for sure, but I'm still looking for anyone else's feedback on the subject question. Thanks - Brad

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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by Walter R. Malik » Wed Feb 14, 2018 12:37 pm

BradH wrote:
Wed Feb 14, 2018 12:31 pm
Obviously, I'll need to check my springs at some point to know for sure, but I'm still looking for anyone else's feedback on the subject question. Thanks - Brad
I use that spring often and their #1244 also.
The catalog specs have not been exact but, are certainly withing a few percent of what I have measured.
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Re: Is PAC's 1243 Coil Bind spec accurate?

Post by BradH » Wed Feb 14, 2018 3:21 pm

Thanks. I may be making some changes that reduce my coil bind clearance and wanted some feel for when I better not take things for granted based on the specs listed.

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