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[Les H]

To complete the Loctite information, see:......http://www.loctite.co.uk/uke/content_da ... .....Pages 28-31....Note: it is best to SAVE all these files and then open them, rather than a simple view. Use pdf page arrows for more precise page location.

[Midge]

Diesel time?

[ed.lazda]

Les, I was interested in your comments about Loctite. They say that their metal-epoxy resins are tough enough to use for thread repair, presumably just by filling and tapping. This sounds easier, and possibly cheaper, than helicoils. Any thoughts?

[Les H]

Hi Ed. I’ve checked the downloads for the metal filled compounds but cannot find where Loctite has a product that is strong enough for tapping. If it is 3463, then that can be drilled & filed very much like JB Weld. To get a good strong equivalent threaded hole it will depend on the Shear Strength of any product and for aluminium it is not very high. To get an equivalent shear strength to steel would seem unlikely though. I have tried to get some figures for aluminium but the ones I’ve found are in different units to the (Newton/mm squared) quoted for the Loctite products. Certainly a stud could be fixed very securely and maybe even more strongly than a threaded hole as the entire length of the stud is pulling on the aluminium hole rather than just the tips of the thread of the stud. If a thread made in the filler required a screw to be repeatedly removed and refitted then this might not be so good. I would be interested to know which product you have spotted. I have telephoned Loctite’s technical phone line several times and found them very friendly and helpful.......01442 278100.....they will definitely assure you and advise of the best product to use if you tell them what you have in mind.......but for your application I have no hands on experience, but it would be a very useful product if it does exist.

[Les H]

Just phoned Loctite for a more detailed reply. Yes 3479 (as does all the 34-- range) can be drilled and tapped. The 3479 has the highest upper temperature range and has a decent shear strength. The ultimate strength might not be a strong as the original aluminium but certainly strongth enough for most applications as long as the torque point wasn't putting the original aluminium thread close to its thread stripping point.

[JOHNNY SINGLES]

Ed, Is this in alloy if so for a better and more permanent repair to a thread is to use LOOMYWELD or a simular make. These are low melt alloy rods which are very easy to use and do a great job. Again youtube is very helpfull in showing you how.

[Les H]

For thread replacement in aluminium you cannot get better than the "Helicoil" type thread fixings (there are other makes)....Reason: the Helicoil's outer diameter is wider than the original diameter of the stud or screw and therefore the strength and pull-out resistance is far greater and so is the durability of the thread. High quality engine manufacturers use this technique as a design improvement. Putting back or replacing the aluminium for re-tapping only puts you back where you started with the original size thread. So if the original bolt is pulling out and stripping... eg the threaded stud hole in the Bullet alloy barrel, sump plugs etc (common problems) then the best fix is a thread insert which bolsters the strength and greatly increase pull out resistance. If you repaired the parts with alloy filler the problem would still remain.

[JOHNNY SINGLES]

Les, yes I agree with a lot of what you say as I do use heiloils. There are instances however where fitting a helicoil is not practical as with a thin walled thread housing, have seen helicoils fitted in A10 primery cases where the thin walls have broken due to them being fitted and I have had to remove them and repair the damage with alloy welding, then retap them to original thread size. also super rocket alloy heads.
If it is a sump plug thread I personaly would retap it and fit a brass stepped threaded insert but that is me.
I am not trying to be contadictory here, just offering an alternative.

[Les H]

Hi Johnny. You are right and I agree with you there are situations that, as you say, on thin walled edges of timing cases for example, there is a chance of breaking through, so the ally filler does seem an excellent method, my only reservations with it are thus....1) you have to take the part to the expert who can do the job......2) not that cheap for the service........3) once the filling has been done the dead centre of the new thread has to be re-established...4)The drilling has to be done to maintain absolute perpendicular to the surface as the original hole has been lost...not always that easy. If you DO not have the problem with metal availability then the Helicoil is the better option in that all the 4 points I make should not be a problem... plus you get the bonus of gaining some thread strength. BUT, as you say, when the Helicoil option is NOT easily implemented due to shortage of the surrounding metal or broken area, then the alloy filler seems to be a lifesaver and certainly well worth knowing about, so thanks for that. BTW...I had a search on YOUTUBE for the video but couldn't find any....would be v. interesting to see how the job is done...Many thanks...Les...PS...I hope this extra stuff is helping taper if he has some threads stripped.

[Les H]

I don't know why but the format of this thread has become spread too wide.....IF IT HAS ...To read it more easily just hold Ctrl key and hit the - key once...this will reduce the font size.....Ctrl with + key will boost size again.