Tapping a hole, threads stripped in hole.

[bang4dabuck]

As recommended I am looking to ream out a stripped bolt hole and go one size up. BTW Evinrude tech favored heli-coils but I think it's overkill. Anyways the original bolt is a 7/16" 14 thread and I am concerned going to the 1/2" 13 tap/bolt the new threads not lining up may make them vague (14 to 13). I got to put 30 lbs. per ft. of pressure on there. I don't think they make a 1/2" 14 tap. Any thoughts ?

Part #63.

http://www.boats.net/parts/search/BRP/EVINRUDE/1987/E90TLCUR 1987/GEARCASE/parts.html#

Thanks

 

[ezeke]

Re: Tapping a hole, threads stripped in hole.

I don't remember the exact length, but many of the midsections were threaded beyond the reach of the OE bolt, so that a longer bolt would find enough unused threads to hold; you might want to check it.

 

[F_R]

Re: Tapping a hole, threads stripped in hole.

I also favor Heli-coils. Way to go.

 

[bob johnson]

Re: Tapping a hole, threads stripped in hole.

As recommended I am looking to ream out a stripped bolt hole and go one size up. BTW Evinrude tech favored heli-coils but I think it's overkill. Anyways the original bolt is a 7/16" 14 thread and I am concerned going to the 1/2" 13 tap/bolt the new threads not lining up may make them vague (14 to 13). I got to put 30 lbs. per ft. of pressure on there. I don't think they make a 1/2" 14 tap. Any thoughts ?

Part #63.

http://www.boats.net/parts/search/BRP/EVINRUDE/1987/E90TLCUR 1987/GEARCASE/parts.html#

Thanks

if you ream out and go to the next larger thread size, you wont be using any of the old threads....and you wont have to worry about the pitch difference!!!

the old threads will be history.

get the helicoil.......spend the extra money...

if you helicoil it , you probably can use the same size bolt that was originally there

use lots of oil when you tap...

dont cut more than one thread ( one rotation) before backing out a half rotation, to break the chip....


take your time KEEP THE TAP STRAIGHT!!!!

after about three or four threads take the tap all the way out and start again.

good luck

bob

 

[14ftgrumman]

Re: Tapping a hole, threads stripped in hole.

There's a reason why the tech ecommends a HeliCoil.
They work.
Use above mentioned proceedure and use red Loctite when installing the HeliCoil. Make sure that the excess Loctite is removed before installing the fastener.

 

[14ftgrumman]

Re: Tapping a hole, threads stripped in hole.

There's a reason why the tech ecommends a HeliCoil.
They work.
Use above mentioned proceedure and use red Loctite when installing the HeliCoil. Make sure that the excess Loctite is removed before installing the fastener.
It will take the 30 ft/lb.
And be stronger than the original.

 

[bang4dabuck]

Re: Tapping a hole, threads stripped in hole.

I don't remember the exact length, but many of the midsections were threaded beyond the reach of the OE bolt, so that a longer bolt would find enough unused threads to hold; you might want to check it.

I will see if I got at least 1/2" or more virgin threads there if not I am researching helicoil action. I am trying to figure out what drill bit I need to go with 7/16" helicoil figuring I am not going to get so lucky with the extra thread.

 

[bob johnson]

Re: Tapping a hole, threads stripped in hole.

I will see if I got at least 1/2" or more virgin threads there if not I am researching helicoil action. I am trying to figure out what drill bit I need to go with 7/16" helicoil figuring I am not going to get so lucky with the extra thread.

you will buy a small "kit"

it will come with a drill
a tap
a helicoil inserting tool
a tool to break the driver tab
and a few helicoils
and instructions


bob