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Helicoil in aluminium?
snapper - 1/1/21 at 04:41 PM

I have a bad thread in a Duratec that holds the oil pump chain guide, can I use helicoils in aluminium?

DanP - 1/1/21 at 05:04 PM

I had helicoils (3/8 UNC) put into an ali head (RV8) in the exhaust manifold bolt holes by an engineering company, so I would assume it would be ok for the oil pump. Maybe check the thread vs torque ratings to check you can torque them high enough?

[Edited on 1/1/21 by DanP]

r1_pete - 1/1/21 at 05:05 PM

Yes, it actually makes a better job than the original tapping.

If its a blind hole just be careful you don't drill through and cause an oil leak.

02GF74 - 1/1/21 at 05:41 PM

Yes, it will be stronger than the original alloy thread.

I fitted one recently to a cannondale c4 seatpost to allow me to use a m6 bolt, smaller than the original one, to save a few grammes, I know I know.....

Search ebay for
131pcs Thread Repair Kit Stripped Helicoil M5 M6 M8 M10 M12 Rethread Recoil

£20, all the sizes you are ever likely to need.

You can buy different length coils, as I did, very cheap from China.

[Edited on 1/1/21 by 02GF74]

snapper - 1/1/21 at 06:42 PM

Thanks all, it’s an oil pump chain guide so only 10nm, the hole is in the crank cradle so whilst blind would make no difference if I drilled through.
I did consider drilling out and using a larger bolt but it has a flanged head and a fitted tube spacer so much more involved than a helicoil

steve m - 1/1/21 at 07:55 PM

I dont think ive ever done a Helicoil in Alui, but as said above, its probably a lot stronger than the original alui threaded hole

steve

Dingz - 1/1/21 at 09:27 PM

I’ve done M8 and M10 in aluminium with no problems.

rusty nuts - 1/1/21 at 09:55 PM

Done loads in ally over the years with no problems

snapper - 1/1/21 at 10:06 PM

quote:
Originally posted by steve m
I dont think ive ever done a Helicoil in Alui, but as said above, its probably a lot stronger than the original alui threaded hole

steve


As long as the Helicoil doesn’t spin in the new threaded hole I think I’ll be ok, I did think that the weak point will always be the thread in the ally but as i only need 10nm torque, I’ll be a bit more gentle this time (with my smallest torque wrench set a little below the 13.6nm minimum.

[Edited on 1/1/21 by snapper]

coyoteboy - 1/1/21 at 10:14 PM

Helicoiling Alu is standard practice on high load and repeat-assembly fasteners, because its much preferable to straight Alu threads.

Shooter63 - 1/1/21 at 11:30 PM

Last one I did was for a classic mini gearbox oil drain ( alloy gearbox) I just made sure the helicoil didn't overhang the original thread depth by cutting a coil off, then I used a drop of thread lock on it, the sump plug now runs in and out without catching etc a vast improvement

Shooter

motorcycle_mayhem - 2/1/21 at 11:39 AM

I've always had a comprehensive helicoil kit in the paddock, M5-M12 and Imperial.
Not just for alloy (Hayabusa/GSXR clutch slave thread repair (etc., etc., etc.)), but equally essential in magnesium (Dallara gearcases, etc.).

IanmK - 2/1/21 at 03:44 PM

Some companies fit helicoils in Aluminium as normal practise as it provides a stronger thread for a component to be screwed into etc.

snapper - 9/1/21 at 08:05 PM

UPDATE

Fitted the helicoil, slowly and carefully, was an easy job and works well.
I didn’t read the post about a drop of thread lock when you insert the helicoil and have logged that for future jobs as that is a great idea.

Thanks for all the valuable responses.