Old Surefire 6p now unreliable- need recommendations.

Hey folks I have a job where I need a reliable bright flashlight on a daily basis.

I've had an old surefire 6p since the early 90s. A few years back I changed it over to an LED insert with rechargable batteries. I bought a high quality dropin (I'll leave the companies name out because I don't want to blemish their stellar reputation) and a pack of rechargables.

I'm not sure when it started happening, but I'd notice that the light wouldn't turn on when I pushed the tailcap button. I could disassemble the light, put it back together, and most of the time it would start working without a problem. Then after it sat in the holster for a while, it wouldn't work again.

The problem was really intermittent and I couldn't do anything in particular to replicate it.

I cleaned out the entire inside of the light with Deoxit and eventually even went so far as to use steel wool to clean the places where the light connects (tail cap, and head threads) to make sure oxidized aluminum wasn't causing the problem. The problem continued so I replaced the old style tailcap with a new one from Surefire.

When the problem continued I replaced the batteries with a new set of AW RCR123's. After I still had the problem I bought a new dropin from a different company figuring I just got a lemon.

As of today I still have a very intermittent light. What I've figured out is that if I turn the tail cap all the way down, and hit the light on my leg a few times it will turn on.

Obviously there is a problem....I've replaced every part that I can replace without going back to straight halogen/cr123s and still don't have a reliable light.

Any ideas? This light has traveled all over the world with me so I'd like to keep it functioning as my EDC light if possible.

When I had this problem it was due to a solid body drop-in not making full contact in a C2 because the bezel had come unscrewed ever so slightly (like 1/16 of a turn) Fix was a bit of aluminum foil between the body and the drop-in, this improved heatsinking and made the light 100% reliable. It only takes about 1 inch of foil folded over a couple times to make a 1/4 inch wide strip, just enough to put on the side of the drop-in and make it fit snug.

Yes it sounds like a drop in contact problem maybe you can shed some light on the brand of your drop ins so we can figure out the construction of them and if someone knows the typical problems with the parts in question

Can you post a picture of the drop ins you're using? You referenced having the same problem with both. It would help if we saw what they are (or at least disclosure of the brand name).

The first dropin was a Malkhoff, the second one was a cheapo from Amazon: "Surefire Flashlight Bulb LED Conversion Upgrade - 650+ Lumens - Cree XML - T6 Single Mode Drop-in - P60 Design: Surefire, Hugsby, Etc

I'll try the foil trick when I go back to work and see if it helps. Hrrm....did something strange and now underlining is stuck on.

Hmm, given that you said you installed a brand new tailcap and had these issues tells me it is probably the drop in, but the fact that both drop ins are having intermittent contact issues is strange, too, since you have a new tailcap and new drop in.

I'd send the Malkoff unit to Gene and see if he can diagnose what might be causing the problem. If he tells you the drop in is fine, it would have to be the 6P itself causing the issue.

The underlining is a continuation of the hyperlink to Amazon, a practice that is generally not accepted on this forum.

I agree that the issue seems to be from a lack of electrical contact between body socket and drop-in. With the Malkoff unit, it shouldn't be possible to completely tighten the head against the body. This is intentional, and ensures contact between the two. If a very small gap does exist, then it should not be necessary to use aluminum foil or soda can material to improve the electrical contact, but it won't hurt anything either. If the head does fully seat against the body, then the aluminum will very likely solve the issue.

I know it's a longshot, but if the Surefire Z44 head/bezel assembly has been replaced with an import (SolarForce etc), that could cause the issue you describe.

The reason being, there is an interior ledge to the Z44 that the others do not have, making them 'deeper' with regards to the LED dropin.



Without this interior shelf to reference off of (the H1 dimension, 1.050"), many dropins including the Malkoffs will not have a secure electrical connection to the flashlight body on the other end of the module.

... And now that I think about it, there is always the possibility of the very early Surefire head/bezel assemblies having a different measurement in this regard, but this is only a hail-mary guess on my end ...

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OP, does your light have the "Malkoff Gap" when assembled with the dropin in place?
(This is a good thing to have BTW - very important to maintain the electrical circuit).

LeDfLaShEr said:

....
I've had an old surefire 6p since the early 90s....

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välineurheilija said:

Yes it sounds like a drop in contact problem....

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Kestrel said:

.... And now that I think about it, there is always the possibility of the very early Surefire head/bezel assemblies having a different measurement in this regard, but this is only a hail-mary guess on my end....

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I think this may be a very good guess ...

OP, do you happen to have a modern Z44 to try swapping bezels ?

Does your bezel have an "anti-roll" hexagonal rim ?

I just measured the "H1 dimension" on my pre-Z44 lexan 'smoothie'-style head/bezel, the depth is 1.043", pretty much identical to the 1.050" of the modern Z44's (with the hexagonal rim as mentioned by Archimedes).

So I'm not going to bet on an issue with that exact configuration, but overall a non-Z44 could easily permit the absence of the "Malkoff Gap" and lead to electrical connection issues.

Clean the head and tailcap threads on the 6P body, then the Z41 and the bezel. Actually it could be a Z31. Who knows? Dirty threads can significantly contribute to electrical conductivity.

Yoda4561 said:

When I had this problem it was due to a solid body drop-in not making full contact in a C2 because the bezel had come unscrewed ever so slightly (like 1/16 of a turn) Fix was a bit of aluminum foil between the body and the drop-in, this improved heatsinking and made the light 100% reliable. It only takes about 1 inch of foil folded over a couple times to make a 1/4 inch wide strip, just enough to put on the side of the drop-in and make it fit snug.

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+1. I have had the same problem with several 6P (SF and other brands). A piece of aluminum foil will solve the problem.
To test the tail cap, you can use a piece of copper wire to short the batteries to body. If the light would not come on, then the problem is not the tail cap.

Surefire has excellent customer service. Call them, and if it is determined that the tail or head is faulty, they will likely send you a replacement.

m4a1usr said:

Clean the head and tailcap threads on the 6P body, then the Z41 and the bezel. Actually it could be a Z31. Who knows? Dirty threads can significantly contribute to electrical conductivity.

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There is no electrical connection on $urefire threads.
The main problem is missing of negative spring on many aftermarket drop ins.
By adding little aluminum foil as suggested above, between drop in body and top of flashlight body, this will be solved.

fresh eddie fresh said:

Surefire has excellent customer service. Call them, and if it is determined that the tail or head is faulty, they will likely send you a replacement.

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Replacing original lamp with LED drop in considered modification and $urefire doesn't support them. Even if they do, it is not fair to take advantage of their excellent customer service.

The Malkoff shouldn't need any foil or springs. It should fit, unless as kestrel mentioned the interior dimensions are different in the old school 6P compared to the newer versions.

LEDflasher, would you mind posting a picture of the light in question? I think that would help us, help you! :thumbsup:

This isn't my personal light, but very similar to this one and it looks like this guy bought it in 1991, about the time I bought mine.

Have you tried inserting an incan bulb and eliminate the tail cap causing the problem? Also, have you tried the drop in in another body to see if it works that way?

fivemega said:

Replacing original lamp with LED drop in considered modification and $urefire doesn't support them. Even if they do, it is not fair to take advantage of their excellent customer service.

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May I ask what your source is? I read the Surefire warranty, and I did not see that... but I might have missed it. I did see that if damage was caused by an alteration it is not covered, but I do not see where adding an aftermarket LED drop-in would void the warranty on the tailcap. Is changing the lamp to a Surefire SHO version also considered a modification?

http://www.surefire.com/warranty

I think what he means is surefire does not expect it to work with the aftermarket drop in... If you have a problem still with a P60 or P61 installed then that would warrant a call to surefire.

Mikeg23 said:

I think what he means is surefire does not expect it to work with the aftermarket drop in... If you have a problem still with a P60 or P61 installed then that would warrant a call to surefire.

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If no one here works for Surefire, then probably none of us should be speaking for them, or their warranty. Is it really so bad for the OP to call Surefire Customer Service, explain the situation and let them decide if they want to replace or repair it? If it is not covered, then I'm sure they will let him/her know.