Featherbed 650 headsteady stud

AndyDMC · Jul 18, 2024

Hello all.

The cylinder head steady stud has stripped its 3/8 thread in the ally head of my 650 Std.

Does anyone know if this can safely be repaired with a thread insert, without breaking through into the rocker box?

I am presuming there will be enough meat to cut a larger thread for the insert, but can anyone confirm this??

Thanks in advance
Andy

AndyDMC · Jul 18, 2024

Looks like it will take a helicoil? Anyone confirm before I risk it?

S

Thread 'head steady stud threads in head'

Nov 25, 2018

the head steady stud is 3/8 what? in the head. I know it is british. If the threads cannot be saved what is the best way to make new threads? There is not much aluminum to work with. Is there enough room to accept a helicoil for american?

AndyDMC · Jul 18, 2024

The pilot drill in this kit is 9.9mm (tho I would prefer not to use a stainless insert as the new RGM stud is also stainless. Will ask AN if they have a mild steel replacement stud...)

3/8 x 20 BSF Thread Repair Kit - engineeringsupplies.co.uk

distributors of quality & performance carbide inserts, toolholders, boring bars, drills, milling cutters, taps, reamers and other engineering consumables.

www.engineeringsupplies.co.uk

And this video shows that it can (in theory) take a half inch tap down it without disaster:

hybridracer · Jul 18, 2024

I have checked my 650ss head, which should be the same as your std head in that area and found that mine must have suffered the same fate as yours because it has a 1/2" X 16 tpi BSF stud fitted. I checked the drawing and the side clearance is fine but you must not drill the hole any deeper., nor should you go larger than 1/2" dia. stud or whatever the helicoil dia. is for refitting a 3/8 stud.

hybridracer · Jul 18, 2024

I nearly forgot - DO NOT use a mild steel stud!!

Mike40M · Jul 18, 2024

On my 650SS some PO vandal had threaded M12 and fitted an homemade stud. Not happy about that.

AndyDMC · Jul 18, 2024

hybridracer said:
I have checked my 650ss head, which should be the same as your std head in that area and found that mine must have suffered the same fate as yours because it has a 1/2" X 16 tpi BSF stud fitted. I checked the drawing and the side clearance is fine but you must not drill the hole any deeper., nor should you go larger than 1/2" dia. stud or whatever the helicoil dia. is for refitting a 3/8 stud.

Thanks, that's really helpful!

So I should be ok, as the OD of the insert will be c. 1/2" I think. I have ordered a free running wire thread insert kit from RGM.

NOTED to go no deeper!

Although why not mild steel stud?? I have both a stainless replacement from RGM but have fallen foul of galling previously when using stsinless fasteners, so also ordered the mild steel EN1A version from AN.

THANKS A LOT!!
Andy

Mike40M · Jul 18, 2024

AndyDMC said:
Although why not mild steel stud?? I have both a stainless replacement from RGM but have fallen foul of galling previously when using stsinless fasteners, so also ordered the mild steel EN1A version from AN.

Andy

What's wrong if the stud is galling? You'll never need to remove it. So galling will keep it in place for eternity. As long as you use a carbon steel nut.
Or am I wrong as usual.

hybridracer · Jul 18, 2024

AndyDMC said:
Thanks, that's really helpful!

So I should be ok, as the OD of the insert will be c. 1/2" I think. I have ordered a free running wire thread insert kit from RGM.

NOTED to go no deeper!

Although why not mild steel stud?? I have both a stainless replacement from RGM but have fallen foul of galling previously when using stsinless fasteners, so also ordered the mild steel EN1A version from AN.

THANKS A LOT!!
Andy

AndyDMC said:
Although why not mild steel stud?? I have both a stainless replacement from RGM but have fallen foul of galling previously when using stsinless fasteners, so also ordered the mild steel EN1A version from AN.

~Because that is one of the highest loaded studs on the bike.

AndyDMC · Jul 18, 2024

Mike40M said:
What's wrong if the stud is galling? You'll never need to remove it. So galling will keep it in place for eternity. As long as you use a carbon steel nut.
Or am I wrong as usual.

I guess, yes, galling won't be a problem, as long as the stud doesn't break, strip, or otherwise need any attention.

AndyDMC · Jul 18, 2024

hybridracer said:
~Because that is one of the highest loaded studs on the bike.

OK, noted. Tho was it not mild steel from the factory? And should I avoid a stainless nut if I use a stainless stud??

elefantrider · Jul 18, 2024

I have at least one 650 head with a helicoil insert in the top stud hole.

On untouched heads, I've found if that stud is frozen in there, I stop and don't try to take it out else it will pull out the threads. Same with the 3 bottom studs. I don't mess with them if they are frozen in there. Those are usually worse .

AndyDMC · Jul 22, 2024

AndyDMC said:
Hello all.

The cylinder head steady stud has stripped its 3/8 thread in the ally head of my 650 Std.

Does anyone know if this can safely be repaired with a thread insert, without breaking through into the rocker box?

I am presuming there will be enough meat to cut a larger thread for the insert, but can anyone confirm this??

Thanks in advance
Andy

It can. Thanks all, especially Hybridracer for checking the drawings. Once the blind hole is cleaned out it's plenty deep. I never like home-machining of crucial, hard to find parts!

acotrel · Jul 23, 2024

I would be looking for the smallest oversize bolt which could successfully threaded into the hole and tap the hole to suit. A helicoil is about 1/16th inch in the thickness of the coil. Using one of those would mean the hole would need to be 1/8th inch bigger

Featherbed 650 headsteady stud

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