Pardini trigger adjust screws coming loose

[dronning]

After several range sessions my trigger starts to slide back. The "Vertical Trigger Rod - P/N 758-N2 " slides back on the "Horizontal Trigger Rod P/N 758-N3". Does anyone use Blue Loctite on it? I'm thinking about putting it on the rod not the screw. I'm using a torque wrench to tighten the screw and I'm pretty sure I don't want to crank on it any more than I am.
- Dave
Gun is a brand new Pardini 6"

[Christopher Miceli]

Depending on what you are torquing to now use these numbers to decide on the correct thread lockers
All numbers are inch LB with the fist as break and second as prevail
Loctite Purple 222
53/30
Loctite Blue 243
230/40
Loctite Blue 248
222/36

Loctite Green 290
90/260 (yes i typed it correctly 90/260)


When we apply a threadlocker to a bolt and finger tighten a nut down, we let this sit for 24 hours and allow it to fully cure. We then take a torque wrench and break the bond. The initial reading on the unseated assembly is the breakaway value (remember, this is not torqued to a specified value such as 100 in lbs). This shows us the strength of the threadlocker alone. They then continue turning this and the average of four quarter turns provides us with our prevailing torque value. This shows us how much friction or drag is left to continue turning the nut. If for example, on the other hand, we torque the assembly down to 100 in lbs, and we use a threadlocker with a breakaway of 50 in lbs, the breakloose value initially on this seated assembly is 150 in lbs (100 + 50). The difference between what you torque this down to (100 in lbs) and what you breakloose at, (150 in lbs) is 50 in lbs and this is referred to as torque augmentation. The main function of any threadlocker is to maintain your torque. It's been determined that over time due to various factors such as vibration and side sliding, that you lose up to 30% of your on torque. The goal is to choose a suitable threadlocker that provides a breakaway value equivalent to 30% of what you torque the assembly to in order to maintain your torque over time

[Rover]

Delightful to read something on here that is not regurgitated I-net babble.

Cin cin!

[Christopher Miceli]

Delightful to read something on here that is not regurgitated I-net babble.

Cin cin!

Or what I do is...tighten it still I hear some creaking then go a little more. After I shear off the screw I get another and just don’t tighten it as much.

[Rover]

That's the American Way!

[10M_Stan]

Fingernail polish works as a thread locker for small screws. I generally keep clear around, but some like green, others red, or white. Colored fingernail polish provides a positive visual indicator that something was applied to the screw. Never had a problem removing a screw which had fingernail polish applied. Loctite products sometimes require heat or Kroil (and patience).

[JKR]

Hi Dave,

That's part # 758-N2 right? How about widening the slot a bit so it can clamp tighter.

That said, I'm sure blue thread locker will keep it in place. However it won't be so easy to move it in the future.

Good luck.

Jim

[TenMetrePeter]

A couple of caveats. Loctite works by being totally enclosed in a joint (anaerobic). It also is catalysed better by two ferrous parts in contact.
These two parts may have only point contact. Its an open clasp on a rod. It may still have air spaces.
They are also aluminum.

The nail polish idea may be more effective at gap filling. I might also use a silane based adhesive once you are happy with the fit.

[dronning]

Hi Dave,

That's part # 758-N2 right? How about widening the slot a bit so it can clamp tighter.

That said, I'm sure blue thread locker will keep it in place. However it won't be so easy to move it in the future.

Good luck.

Jim

Jim,
The post 758-N2 is no longer "split" and there is no screw coming up from the bottom as shown, the post is solid on the bottom and they changed the way the trigger is secured, it now uses a very tiny set screw coming in from the side verses the bottom.

The 2 screws that are coming loose are 758-N1 & 758-N4 and when the -N4 comes loose the trigger slides backward shortening the reach.

I went with Blue Loctite 242, when I need to remove them, if needed, I'll use a soldering iron to apply heat to the screws.

- Dave

[TenMetrePeter]

Ignore my post then. I was answering your original question using your supplied diagram.

[Gregbenner]

I use purple locktite on the small fasteners on all my guns, particularly trigger adjustment screws. It is less that blue in terms of strength. I order it from Amazon, many of the local hardware store don't carry it (or the green for that matter).

[dronning]

Ignore my post then. I was answering your original question using your supplied diagram.

Won't ignore it I may need to use the nail polish trick some time.

Thanks,
Dave

[Dipnet]

I had that problem because I overtightened the steel torx screw in the aluminum vertical trigger rod and ended up replacing the rod. When I use loctite on fine threads, I only use purple formula, and I clean parts with 90% isopropanol and let dry. Even care can lead to issues: I'm currently dealing with a stripped grip busing for a 1911 that was put in with purple loctite. If at all possible, I try not to use loctite and tighten carefully. dipnet