Cylinder Stud Thread spec

[Lachie04]

Hi ya

Ok someone has got to have done this before.

I've snapped a cylinder stud (twice) and now is sitting too close to the case to get a hold of.

I am guessing all the cylinder stud thread dimensions are the same as I'm replacing the 750 short stroke stud to fit a 1052 barrel. 

Looks like I'm going to have to drill the bugger out and maybe fit thread insert 

The nut end is a M10 x 1.25 but the case end thread isn't although it looks very close

My 10 x1.25 tap doesn't run down and die doesn't run on the case end threads 1.50 is definitely out

Is it a M10 x 1.0 ???? (seems rather fine) or is it an M10 at all ???

Anyone

[Gixer1460]

Would be odd as cylinder studs can normally be reversed / fitted upside down ie. threads same both ends M10 x 1.25 (metric fine)!

M10 x 1.0 would be a bespoke thread - not regular.

[Lachie04]

If I reverse it the nut end in the case is definitely loose and wiggles but the case end is nice and tight I tried several and the same.

Major thread diameters measure @ the same 9.84 -9.87 mm  and lining them up together appear to be matched threads/pitch.

I just can't see what the difference is but there is. It's like the case end thread is cut a bit looser Idk but it's all of them and not a one off odd one

Does seem odd to me also which is why I was checking 

There's not much torque when putting the studs into the case but the head nuts are torqued up to 40nm so not really keen on tightening against a loose or non matching case thread, if recut to 1.25 

 

Edited April 10, 2019 by Lachie04

[gsxr1385]

I can only take a guess as to what you are seeing.  Each size of thread have various grades of fit -  tight ,medium, loose etc. (not official terminology). Even though they look the same, there are very slight differences in the size of the shaped thread to get the tightness of fit. Perhaps that is what you are seeing. If that is the case, be very careful in using taps and dies as they may loosen up the tight fit if manufactured that way. You would need a tap or die for that specific tightness of fit.

 

I am about to do the same operation as you and have been fearing snapping a stud. I bought a special stud removal tool that mounts close to the case and also intend on heating the aluminum / steel joint to free the bond. Care to shed more light on how you attempted to remove the studs and why you think the stud snapped?

[Lachie04]

Yeah I'm still a bit skeptical about this but then thats me.

I went to the local specialist hardware and they checked the thread and reckoned it was a m10X1.25 just the thread was slightly deformed which is why I can't get the die nut on it.

I also emailed the guys at APE and they came back and said it was a M10x1.25 I think I read on their site somewhere the H Bus thread was a 3/8-20 and another site I found (Naughton) used a 3/8-20 which is supposed to be somewhat very similar to a M10 but otherwise metric everywhere else. 

So times out on that for a bit I'll revisit this when I finally get the new studs (I'm not paranoid, but who wants to know?,, LOL).

I was hoping someone else would come back with any experiences with thread inserts or whatever but seems not ATM.

When I was taking them out @7-8 came out with not too much trouble just using the double nut technique  (back up two nuts on the nut end)

of the rest I applied the wack it with a hammer technique and all but one dislodged with that.

The bugger one I first tried heating the case but my gas torch wouldn't burn paint of a wall while it was good and hot to touch just not enough heat. 

I then tried heating the stud directly and after I got it reasonably hot quenched it with some penetrating oil (just for cooling effect) using the double nut it did tweak a bit so this was encouraging but I could not tighten it back to get the wiggle happening it actually bent also and I don't know if this was from heating and cooling it.

And then

next choice was to weld a nut directly on the stud with the MIG (maybe I should have used the TIG but I think the result would still be the same

It started coming out and I tried going back and forth in-out like your supposed too but at about 2mm it Snapped again just closer

I don't think it was the heat it sheared very quickly and evenly and didn't twist I was getting some hefty force on it.

 

I was thinking at this stage I'd just be happy to strip all the threads and at least have it out, a friend offered me use of a stud extractor but I didn't take it up just for the reason of potentially just stripping the threads out. the welding technique gets the stud good and hot so does the same effect has using a torch on it. Now it's just too short do do anything else

I know the last engine build we did my mechanic guy said it was a real effort to get the studs out but I wasn't there and don't know what he did to get them out.

 

some are easy some are hard 

best of luck you get easy ones

 

FML

 

Edited April 14, 2019 by Lachie04

[gsxr1385]

Thanks for the write up and pics. I'd say you did about everything reasonable to get those out, just bad luck on one. Hope you can get that last one bored easily.

 

I've installed plenty of inserts and helicoils. inserts require a larger bored hole than helicoils, so not sure there is enough metal in the case for threaded inserts. The charts from suppliers in the USA say  helicolis require a 13/32" or 10.5mm bored hole, while threaded inserts require a 31/64", 14mm or a 16mm hole depending on insert thickness. The threaded inserts are stronger of course.

 

Boring and threading a true hole in the case could be a challenge as well

[clivegto]

Exactly the same thing happened to me on the same stud as well, I ended up getting some more crank cases.

[Lachie04]

Yeah, I have a shed full of boat anchors I don't really want another that was the idea to use all the bits I have now.

I'll likely end up heli coiling it I should be able to get it pretty good using the drill press.

[Duckndive]

11 hours ago, Lachie04 said:

 

 

 

still enough meat there to weld a nut on and give it another go......

I spray some diesel down the hole and let it soak in before welding a nut on

[Lachie04]

21 hours ago, Duckndive said:

still enough meat there to weld a nut on and give it another go......

I spray some diesel down the hole and let it soak in before welding a nut on

Yeah maybe, will see, second time might be a treat but I've parked it for the time and dry building the 5 speed swap in and seeing what other goodies need replacing.

[Lachie04]

Postscript,

Gave up and took it to the performance motor shop.

Yep I don't feel so useless they tried it all to and couldn't budge it so after some long time on the mill

Milled and helicoiled 

While at it another little mod out the back to save some weight........... kidding will probably take a leaf out of FBOB and do the valve cover also.

Tapered thread little bit of sealant and nip it up sorted

[canamant]

Lachie 04.  If you are fitting the APE studs be very careful.  They say torque the studs to 12.5 - 15lbft into the cases.  I did that and some of the studs didn't torque up, just wound down into the cases too far.  The originals have a "ring" ring at the end of the thread which butts up to the countersink hole in the cases.  The APE ones didn't have that so there was nothing to torque up against.

 

[Lachie04]

10 hours ago, canamant said:

  The originals have a "ring" ring at the end of the thread which butts up to the countersink hole in the cases.  The APE ones didn't have that so there was nothing to torque up against.

 

Yep I remember reading about something like that thanks for the info good advice

I'm just using new OEM studs so should be fine 

[Gixer1460]

12 hours ago, canamant said:

Lachie 04.  If you are fitting the APE studs be very careful.  They say torque the studs to 12.5 - 15lbft into the cases.  I did that and some of the studs didn't torque up, just wound down into the cases too far.  The originals have a "ring" ring at the end of the thread which butts up to the countersink hole in the cases.  The APE ones didn't have that so there was nothing to torque up against.

The fitting torque isn't critical to fitting studs IMO - as long as they are screwed in, using thread locker and all with correct fitted length, they will be fine - the nuts provide the clamping force, the studs just resist it! I don't think i've ever used a torque wrench on a stud - just wound them in, finger tight - mostly full thread depth unless height was critical - job done!

[canamant]

Thanks for that feedback.  I've unwound the studs to the correct position (or what they were on the old cases) and loctited them.  The threaded depth of hole in the crankcase is deeper than the length of thread on the stud.  I had considered screwing carefully measured bits of old stud in the hole to give the new stud something to bottom against  when it gets to the correct position.  Wondering whether that would cause problems.

 

[Gixer1460]

Not sure if this is right / wrong and universal to all stud types, but the head ones i've used, generally have a short thread and a long thread either end and i've always threaded the short end into the case up to the end of the thread - never bottomed one out. My reasoning is the longer thread is designed to cope with different barrel / head heights so providing sufficient thread for nuts in all situations. Case studs (M6 and M8) I fit with long thread in fixed case position with nut on short thread as they don't ever vary.

[Lachie04]

The studs are sized to the height of the barrel the OEM studs are fixed in with the long thread into the case.

Also the new studs I have are coated with a green thread lock on the long thread like the brake rotor bolts have.

while they probably will fit upside down I would doubt very much I would do that