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By Scott at Team Harco
#46761
This is not 928 specific, but it can apply. I just discovered that the shop that fixed by 944 S2 block removed the head studs and replaced them with ones that are too short. It's not realistic for me to take everything apart and send back to them to correct their mistake.

So what's the recommended procedure for getting the studs out? I've attempted the double nut method. I'm not sure I can get that to work. Do I need to apply heat to the stud and then crank on it with super Vice Grips?

Image

Image
User avatar
By worf
#46811
I can't help you with specifics about the head studs. All the 928 blocks I've touched are 87+ with head bolts.

However, here are some concerns:
- a shop that can't put correct length studs back into the block is not to be blindly trusted for anything they did. Did they touch the interior surface of the cylinder walls in any way? If they did, did they use a torque plate? Are they aware of the special treatment Alusil walls require? Did they deck it?

- Of what material will the new studs be composed? Is the material different from the OE studs? Does any change effect the process for torquing the head? I've run across references that new studs ordered from Porsche are a different, weaker, material than the originals. As a result - on a 928 - if you do the 20 N-m and 3 x 90° you will - apparently - strip the block. 20 N-m and 2 x 90° seems (IIRC) to work. I have a torque wrench that shows angle and torque simultaneously so that I can detect any irregularities in torque when turning head bolts through the two-stage 90° procedure.
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By Scott at Team Harco
#46820
worf wrote: Sat Jan 02, 2021 3:06 pm I can't help you with specifics about the head studs. All the 928 blocks I've touched are 87+ with head bolts.

However, here are some concerns:
- a shop that can't put correct length studs back into the block is not to be blindly trusted for anything they did. Did they touch the interior surface of the cylinder walls in any way? If they did, did they use a torque plate? Are they aware of the special treatment Alusil walls require? Did they deck it?

- Of what material will the new studs be composed? Is the material different from the OE studs? Does any change effect the process for torquing the head? I've run across references that new studs ordered from Porsche are a different, weaker, material than the originals. As a result - on a 928 - if you do the 20 N-m and 3 x 90° you will - apparently - strip the block. 20 N-m and 2 x 90° seems (IIRC) to work. I have a torque wrench that shows angle and torque simultaneously so that I can detect any irregularities in torque when turning head bolts through the two-stage 90° procedure.
All good questions. All solid advice. The shop I sent my block to was through 928motorsports (US Chrome). Maybe I was naïve in thinking they knew what they were doing. I actually have faith in the work that was done, other than the stud screw-up.

The question remains. What are good options for getting the studs out?

A set of proper studs, based on PET is on the way. Damaging the ones in the block now, is of no concern. The goal is to get them out, without damaging anything else.
User avatar
By N_Jay
#46829
Build a jig to center drill the stud.
Then put nut on it for support and use a screw extractor to unscrew the stud.

Find out if the used thread locker, and if so you will need heat also.
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By Scott at Team Harco
#46835
N_Jay wrote: Sat Jan 02, 2021 4:09 pm Build a jig to center drill the stud.
Then put nut on it for support and use a screw extractor to unscrew the stud.

Find out if the used thread locker, and if so you will need heat also.
Build a jig to center drill the stud? I don't think that is feasible. Maybe I'm missing something. Please explain how this is done for a reasonable cost and with just basic shop tools.

Screw extractor? I think you may be missing something. These are M12 block/head studs. I have yet to achieve a success rate better than 5% with a screw extractor. What's your secret?

Let's assume thread locker was used. I have resigned myself to this possibility.
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By worf
#46849
You guys need to visualize the block with the head removed; there will be several inches of exposed stud. Scott is simply showing that with the head in place, unbolted, that the studs are about 5/8” too short.

More after dinner.
User avatar
By worf
#46869
Scott at Team Harco wrote: Sat Jan 02, 2021 3:46 pm All good questions. All solid advice. The shop I sent my block to was through 928motorsports (US Chrome).
Hmm...

Scott at Team Harco wrote: Sat Jan 02, 2021 3:46 pm The question remains. What are good options for getting the studs out?
Here's what I would do:

1) Contact US Chrome. Tell them about the issue, that you have new studs on the way, and that you need to remove their too-short studs. Ask them what removal process they would recommend. In particular I'd want to know if they used one of the more-ridiculously strong Loctite (-like) products.

2) Do a search on Rennlist (ugh... hate to validate TOS, but it still is what it is for a while) on the 928 forum and find the threads on head stud removal. In particular look for threads with posts from GregBBRD.

3) If the internet and US Chrome disappeared this evening here's what I would do tomorrow:
call my machinist and ask him.

If he got hit by a meteor:
- devise a way to evenly heat the block. My arm would get too tired with a torch and I'd want to heat it evenly and slowly over the course of 30 minutes or more. I'd want to avoid locally over-heating the block. So, the heat source can't be super-hot like a MAPP gas torch. How heavy is a 944 short block? Probably too heavy to move around I guess even at half the weight of a 928 short block. I'd want to have the block at about 200°F, but not hotter, to get some expansion of the Alusil. Any core temperature increase will help if there's no good way to target 200°F.

- gather up 20 new (disposable) nuts. Using my Bolt Buster induction heater, I'd get each stud dull-red warm at the top and then counter-tighten two nuts on each. When the stud cools, it will tighten the nuts even further.
- heat the base of a stud with my bolt buster to break loose any locking compound. Not as hot as at the top though. I'd use my industrial contact thermometer to get an idea of how long it takes the BB to heat the base to 2xx°F (The temp at which Loctite Red breaks whatever that is after looking at the bottle.) At that temp, then...
- attempt to turn out the stud.

If you can weld a big-assed nut onto each stud, then that will work better than double-nutting. But, I'd still want that stud hot at the base and the block warm too.

If they used one of the "green" Loctite variants that doesn't loosen at less than 300/400/500+°F then I wouldn't attempt removal; I'd send it back to them and tell them to remove their own too-short studs and then correct any block dimensional issues resulting from removal. And that would piss me off since I'd have to take apart the block (again.)

That's my two cents.
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By Scott at Team Harco
#46870
OK - we're getting real close to convergence on this. I thought about welding a nut on the end of the stud, last night, when I was supposed to be sleeping.

That will be plan C. Also the one with the highest chance of success.

B is vice grips, and A is double nut.

I'll be sure to post updates...

Image

The head thickness is about 75 mm. As you can see, there isn't enough margin for full thread engagement and loading. This became obvious right away.

There was a reference in the WSM regarding later heads being 20mm thicker in this area. That extra 20mm in stud length, would seem to be just about right. We'll know right away, when my order of 944.101.197.03 shows up.
Last edited by Scott at Team Harco on Sat Jan 02, 2021 6:41 pm, edited 1 time in total.
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By N_Jay
#46872
Scott at Team Harco wrote: Sat Jan 02, 2021 4:25 pm
N_Jay wrote: Sat Jan 02, 2021 4:09 pm Build a jig to center drill the stud.
Then put nut on it for support and use a screw extractor to unscrew the stud.

Find out if the used thread locker, and if so you will need heat also.
Build a jig to center drill the stud? I don't think that is feasible. Maybe I'm missing something. Please explain how this is done for a reasonable cost and with just basic shop tools.

Screw extractor? I think you may be missing something. These are M12 block/head studs. I have yet to achieve a success rate better than 5% with a screw extractor. What's your secret?

Let's assume thread locker was used. I have resigned myself to this possibility.
The jig can be a piece of tubing over the stud with another piece of tubing tight inside of it so this drill stays centered.

once I stopped using cheap screws extractors and got some good ones I've had pretty good luck.

I have not done a head stud but I've done lots of other things for them

I like the idea that other people have putting a bolt on and then welding the inside of the bolt to the top of the stud if you can get a good well that should work.

And I will talk to the shop to put them in and find out if they put them in dry or put them in with a threadlock or what because if it's red you're going to need a lot of heat and it's blue you're just going to need a little bit of heat.
Last edited by N_Jay on Sun Jan 03, 2021 1:35 pm, edited 1 time in total.
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By worf
#46879
Scott at Team Harco wrote: Sat Jan 02, 2021 6:07 pm B is vice grips,
Don't bother. If you double-nut and counter-tighten with all your might (since you don't care about thread damage to the studs), especially if you pre-heat the stud, there is NO WAY that the contact surface area of vice grip on the edges of threads will provide more friction.

Obviously, make sure when you turn, that your engine stand is properly braced and/or that you are turning in the opposite direction of how the block would want to break-off the engine stand.
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By Scott at Team Harco
#47086
Made the effort to get serious with the first stud. Got my longest 19mm wrenches and slipped the lower one past the first nut while still maintaining use of the box-end. Took a bit of work, but I got it out. There was clear evidence of red thread locker.

I'll take my time with the rest, but this is a good step. :beerchug:

There's no hurry, since the new studs are at least a few days out...
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By N_Jay
#47091
Scott at Team Harco wrote: Sun Jan 03, 2021 7:41 pm Made the effort to get serious with the first stud. Got my longest 19mm wrenches and slipped the lower one past the first nut while still maintaining use of the box-end. Took a bit of work, but I got it out. There was clear evidence of red thread locker.

I'll take my time with the rest, but this is a good step. :beerchug:

There's no hurry, since the new studs are at least a few days out...

If it has read thread locker, I would hit the stud near the block side with a torch.
Probably not try to get it read, but something over 500 deg should at least soften the locker.
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By Scott at Team Harco
#47092
You might want to check your spell-checker. :wink:
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By Scott at Team Harco
#47149
I'm an engineer, as well. I find that I still need to communicate effectively with others.

The more effective I am at that, the more likely I am able to get assistance or get others to act on my recommendations.
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By N_Jay
#47169
Scott at Team Harco wrote: Mon Jan 04, 2021 8:18 am I'm an engineer, as well. I find that I still need to communicate effectively with others.

The more effective I am at that, the more likely I am able to get assistance or get others to act on my recommendations.

Yep, I know. Just careless on the forums.
My spelling is bad and my typing worse,.
Spell checking is my norm, but on the phone I use voice if it is over a line or two.
User avatar
By XR4Tim
#47308
maddog2020 wrote: Mon Jan 04, 2021 10:06 am I have these and never hade any issues.

https://www.zoro.com/westward-stud-remo ... lSEALw_wcB

Removing studs is what they are designed for. easy peasy. no need for welding a nut or making a jig to drill it out.
I've had great luck with those as well.
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By Scott at Team Harco
#47380
The stud removal tools look interesting. I can see myself getting one of those kits, one day.

Might not need it for this project though...unless it's also the preferred method for installation.

Got five more studs out today. Didn't even use heat. In fact it was rather cold in the shop. I got the ambient up to about 50F, but the engine was probably no warmer than 35-40.

Image
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By Scott at Team Harco
#47509
maddog2020 wrote: Mon Jan 04, 2021 10:06 am I have these and never hade any issues.

https://www.zoro.com/westward-stud-remo ... lSEALw_wcB

Removing studs is what they are designed for. easy peasy. no need for welding a nut or making a jig to drill it out.
Many of these kits claim they are also good for installing studs. Can any of you guys confirm this?
User avatar
By maddog2020
#47512
Scott at Team Harco wrote: Tue Jan 05, 2021 8:51 am
maddog2020 wrote: Mon Jan 04, 2021 10:06 am I have these and never hade any issues.

https://www.zoro.com/westward-stud-remo ... lSEALw_wcB

Removing studs is what they are designed for. easy peasy. no need for welding a nut or making a jig to drill it out.
Many of these kits claim they are also good for installing studs. Can any of you guys confirm this?
With the 928 I installed the studs by hand. Other engines I've used these to install studs.
User avatar
By Scott at Team Harco
#47513
maddog2020 wrote: Tue Jan 05, 2021 8:57 am
Scott at Team Harco wrote: Tue Jan 05, 2021 8:51 am
maddog2020 wrote: Mon Jan 04, 2021 10:06 am I have these and never hade any issues.

https://www.zoro.com/westward-stud-remo ... lSEALw_wcB

Removing studs is what they are designed for. easy peasy. no need for welding a nut or making a jig to drill it out.
Many of these kits claim they are also good for installing studs. Can any of you guys confirm this?
With the 928 I installed the studs by hand. Other engines I've used these to install studs.
'By hand'; I assume means double nut?
User avatar
By maddog2020
#47518
Scott at Team Harco wrote: Tue Jan 05, 2021 8:58 am
maddog2020 wrote: Tue Jan 05, 2021 8:57 am
Scott at Team Harco wrote: Tue Jan 05, 2021 8:51 am

Many of these kits claim they are also good for installing studs. Can any of you guys confirm this?
With the 928 I installed the studs by hand. Other engines I've used these to install studs.
'By hand'; I assume means double nut?
the threads should be clean and smooth enough that you should literally be able to screw the stud with your hands and nothing else. If you can't do this the threads need to be cleaned and chased.
User avatar
By Scott at Team Harco
#47522
maddog2020 wrote: Tue Jan 05, 2021 9:16 am
Scott at Team Harco wrote: Tue Jan 05, 2021 8:58 am
maddog2020 wrote: Tue Jan 05, 2021 8:57 am

With the 928 I installed the studs by hand. Other engines I've used these to install studs.
'By hand'; I assume means double nut?
the threads should be clean and smooth enough that you should literally be able to screw the stud with your hands and nothing else. If you can't do this the threads need to be cleaned and chased.
I see. I'll look into that. So you are able to bottom out the stud by hand?
User avatar
By maddog2020
#47524
Scott at Team Harco wrote: Tue Jan 05, 2021 9:32 am
maddog2020 wrote: Tue Jan 05, 2021 9:16 am
Scott at Team Harco wrote: Tue Jan 05, 2021 8:58 am

'By hand'; I assume means double nut?
the threads should be clean and smooth enough that you should literally be able to screw the stud with your hands and nothing else. If you can't do this the threads need to be cleaned and chased.
I see. I'll look into that. So you are able to bottom out the stud by hand?
yep.
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By Mrmerlin
#48039
NOTE only use a head bolt for cleaning the threads in the block cut 3 small flutes into one of the bolts this will make it easy to clear threads without removing metal from the block.

NOTE the block holes are usually longer than the studs SO you must premasure the studs prior to removing them so they can be put back into the same height.

NOTE use a Mapp gas torch to heat the area where the stud screws in this will soften the loctite and prevent damaging the threads while you remove them
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By Scott at Team Harco
#48041
Mrmerlin wrote: Wed Jan 06, 2021 5:48 pm NOTE only use a head bolt for cleaning the threads in the block cut 3 small flutes into one of the bolts this will make it easy to clear threads without removing metal from the block.

NOTE the block holes are usually longer than the studs SO you must premasure the studs prior to removing them so they can be put back into the same height.

NOTE use a Mapp gas torch to heat the area where the stud screws in this will soften the loctite and prevent damaging the threads while you remove them
Item #1 is good advice. I was considering a tap. An old stud modified as you suggest is a good plan.

The wrong studs are out. Waiting on the proper ones. :beerchug:
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By Scott at Team Harco
#48491
Mrmerlin wrote: Wed Jan 06, 2021 5:48 pm NOTE only use a head bolt for cleaning the threads in the block cut 3 small flutes into one of the bolts this will make it easy to clear threads without removing metal from the block.
Great idea! I did this today. No problems. Cut the flutes, sprayed a little carb clean in each hole and threaded the stud in.

Got it to go in by hand for all but about 1/4 turn. Did the last bit with a wrench on the top jam-nut. Rolled the engine over and blasted each hole out with compressed air.

Now I am ready for the new studs.

Any thoughts on putting a little red loctite on the threads? Oil? I'll try to thread them all in by hand - just want to be sure they all bottom out.
User avatar
By worf
#48497
Scott at Team Harco wrote: Thu Jan 07, 2021 8:26 pm I'll try to thread them all in by hand - just want to be sure they all bottom out.
Review Stan's advice in his first post.
User avatar
By Scott at Team Harco
#48576
worf wrote: Thu Jan 07, 2021 8:45 pm
Scott at Team Harco wrote: Thu Jan 07, 2021 8:26 pm I'll try to thread them all in by hand - just want to be sure they all bottom out.
Review Stan's advice in his first post.
I don't know any of you guys on a first name basis. Therefore I don't know who Stan is, by his handle.

Reading through all the posts, I see nothing specific to what, if anything, to put on the threads at installation. The WSM has no information on this.

As I see it, there are effectively three options:
1) clean off any oil and install dry
2) clean and install with a drop of oil on the threads
3) clean and install with a couple of drops of red loctite

I am leaning toward #3. I welcome opinions of those with more experience in this area.
User avatar
By linderpat
#48592
Scott at Team Harco wrote: Fri Jan 08, 2021 7:57 am
worf wrote: Thu Jan 07, 2021 8:45 pm
Scott at Team Harco wrote: Thu Jan 07, 2021 8:26 pm I'll try to thread them all in by hand - just want to be sure they all bottom out.
Review Stan's advice in his first post.
I don't know any of you guys on a first name basis. Therefore I don't know who Stan is, by his handle.

Stan is MrMerlin.
User avatar
By N_Jay
#48596
I am no expert on the car, but the studs probably should not be bottomed out.
They need about 1.5 to 2 times the diameter to get maximum holding force.
Is there a history of then stripping out? If not 1.5 is probably enough.
Thread locker is just that to lock the threads. Is there a history of them working loose?
If not, it is unneeded, and probably unwarranted.
If the top bolt is torqued dry, then the bottom should be also. If it is wet you will be turning it into the base and "Jacking" the threads out.
Allowing the threads the freedom to move helps relieve any torsional stress on the stud, and makes final tightening a tad more accurate.
User avatar
By Scott at Team Harco
#48600
linderpat wrote: Fri Jan 08, 2021 9:04 am
Scott at Team Harco wrote: Fri Jan 08, 2021 7:57 am
worf wrote: Thu Jan 07, 2021 8:45 pm

Review Stan's advice in his first post.
I don't know any of you guys on a first name basis. Therefore I don't know who Stan is, by his handle.
Stan is MrMerlin.
Ok - thanks for providing that. Unfortunately Stan does not describe, in his post, an answer to my latest question.
User avatar
By N_Jay
#48610
Scott at Team Harco wrote: Fri Jan 08, 2021 9:37 am

Ok - thanks for providing that. Unfortunately Stan does not describe, in his post, an answer to my latest question.
I tried. It is definitely a most certain "It Depends".

Is there a history of;
a) Working loose
b) Threads pulling out of the block
c) Breaking Studs

How many turns of what thread is there between first engagement and bottoming?
How many turns of thread are there on the bottom of the stud?
User avatar
By Scott at Team Harco
#48613
N_Jay wrote: Fri Jan 08, 2021 10:04 am
Scott at Team Harco wrote: Fri Jan 08, 2021 9:37 am

Ok - thanks for providing that. Unfortunately Stan does not describe, in his post, an answer to my latest question.
I tried. It is definitely a most certain "It Depends".

Is there a history of;
a) Working loose
b) Threads pulling out of the block
c) Breaking Studs

How many turns of what thread is there between first engagement and bottoming?
How many turns of thread are there on the bottom of the stud?
a - no
b - no
c - no

Not relevant. Have you seen the most recent photo placed in this thread? That is what I am dealing with, with the exception that all of the studs are now out. I could count threads, but what is the point? There will be more than enough thread engagement. Not bottoming the stud out, makes no sense.

I'll will be applying a small amount of red loctite and bottoming out the studs. Unless - unless, there is a solid recommendation to do something else.

Thanks for the help. :beerchug:
User avatar
By N_Jay
#48621
Scott at Team Harco wrote: Fri Jan 08, 2021 10:15 am
N_Jay wrote: Fri Jan 08, 2021 10:04 am
Scott at Team Harco wrote: Fri Jan 08, 2021 9:37 am

Ok - thanks for providing that. Unfortunately Stan does not describe, in his post, an answer to my latest question.
I tried. It is definitely a most certain "It Depends".

Is there a history of;
a) Working loose
b) Threads pulling out of the block
c) Breaking Studs

How many turns of what thread is there between first engagement and bottoming?
How many turns of thread are there on the bottom of the stud?
a - no
b - no
c - no

Not relevant. Have you seen the most recent photo placed in this thread? That is what I am dealing with, with the exception that all of the studs are now out. I could count threads, but what is the point? There will be more than enough thread engagement. Not bottoming the stud out, makes no sense.

I'll will be applying a small amount of red loctite and bottoming out the studs. Unless - unless, there is a solid recommendation to do something else.

Thanks for the help. :beerchug:
If there is sufficient thread engagement, then "more" engagement does nothing.

If the threads in the block extend further than the threads in the stud, overtreading allows the potential for something (rare case) to get into the top grove and lock the assembly. (Why add potential for future failure.)

Bottoming the studs allows any force the stud exerts on the bottom to be transferred and added to the force from the pull of the stud, so you are raising the force on the threads to no benefit. If the top nut were to catch, any rotation of the stud will start "jacking" the threads out of the block, or start twisting the stud. Best case is to allow the bottom threads the same freedom of rotation as the top threads.

My guess is that the studs and thread engagement are well overdesigned so this is all academic, but each issue uses up a little bit of the engineered margin.

if using any thread locker, I would go with blue locker as the temperature of a water-cooled engine should not exceed its softening point. Red is overkill. (and could result in thread damage if needed to be forced out.)
User avatar
By worf
#48633
Mrmerlin wrote: Wed Jan 06, 2021 5:48 pm NOTE the block holes are usually longer than the studs SO you must premasure the studs prior to removing them so they can be put back into the same height.
Scott at Team Harco wrote: Thu Jan 07, 2021 8:26 pm I'll try to thread them all in by hand - just want to be sure they all bottom out.
Here—-^
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By worf
#48636
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By Scott at Team Harco
#48653
worf wrote: Fri Jan 08, 2021 11:25 am
Mrmerlin wrote: Wed Jan 06, 2021 5:48 pm NOTE the block holes are usually longer than the studs SO you must premasure the studs prior to removing them so they can be put back into the same height.
Scott at Team Harco wrote: Thu Jan 07, 2021 8:26 pm I'll try to thread them all in by hand - just want to be sure they all bottom out.
Here—-^
OK - so that says nothing about any product application to the lower stud threads. It speaks of the depth of stud insertion. This recommendation, as good as it is, assumes the shop that installed the wrong studs inserted them to the proper depth. I can duplicate this depth with the correct studs. If it turns out that the stud has bottomed out, then that's just one data-point. My plan is to bottom them out. I will do the math to see how this correlates with the depth of the wrong studs. But it proves nothing due to screw-up #1.

I'm not trying to make this some kind of science experiment. I'm just looking for suggestions on 'best practice'. Wrapping this in "do your homework" is fine. If no one wants to say use a drop of oil, or use red loctite, or put the studs in dry, that's fine. I'll work this out. I thought this was a simple question. Am I wrong about that?

worf wrote: Fri Jan 08, 2021 11:31 am TDS Loctite Blue

https://dm.henkel-dam.com/is/content/he ... 8-04-09pdf

TDS Loctite Red

https://dm.henkel-dam.com/is/content/he ... 8-04-09pdf

Read’em. Avoid confusion.
I know about Loctite. I have half a dozen varieties and have a good understanding of the appropriate application. I'll save the documents you posted, but I have a lot of technical data from them. I use both the blue and red (and orange (574), and green (609?)) regularly.
User avatar
By Scott at Team Harco
#48683
N_Jay wrote: Fri Jan 08, 2021 1:47 pm
N_Jay wrote: Fri Jan 08, 2021 1:47 pm Do a little more research./ You will find that bottoming studs is never a best practice, and is often specifically recommended against.

http://greenhulk.net/forums/showthread.php?t=262721
image.png
That's good information. There are some conflicting recommendations with respect to the information in the Porsche workshop manual. Specifically, the application of lubricant to the washer under the head nut. I will follow the Porsche manual when it comes to that.

Backing off the stud from bottoming in the block is no problem. It will be interesting to see what that measurement reveals when compared against what the shop did.
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By worf
#48693
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pm OK - so that says nothing about any product application to the lower stud threads. It speaks of the depth of stud insertion. This recommendation, as good as it is, assumes the shop that installed the wrong studs inserted them to the proper depth. I can duplicate this depth with the correct studs. If it turns out that the stud has bottomed out, then that's just one data-point. My plan is to bottom them out. I will do the math to see how this correlates with the depth of the wrong studs. But it proves nothing due to screw-up #1.
The point is that even with longer studs you may end up with too short studs if you bottom them out. So, some experimentation will be required in order to arrive at an acceptable range of stud height above the deck.

If that is obvious then I appologize for misunderstanding your intentions based upon what you wrote.
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pmI'm just looking for suggestions on 'best practice'. Wrapping this in "do your homework" is fine. If no one wants to say use a drop of oil, or use red loctite, or put the studs in dry, that's fine. I'll work this out. I thought this was a simple question. Am I wrong about that?
The 928 shop manual is completely silient on the topic of replacing head studs. It is unclear to me if anyone providing you with advice has replaced head studs in 928 engine blocks. I already told you that I have not.

That said, absent a consultation with someone who has replaced studs in 928 or 944 blocks, I would turn them in dry with blue loctite since there's a lot of thread engagement.

Head bolts are 'lubricated' with a tiny bit of motor oil as per the WSM.

I would probably do the same with the tops of the studs so that the nuts turn smoothly when it's time to torque them.

Last, there's the whole issue that the 928 WSM calls for 3 90-degree turns when there's annecdotal evidence that the new Porsche studs won't take that.

So, in the end, it is kind of a science experiement.

Here's a TOS thread:

https://rennlist.com/forums/928-forum/5 ... ds-12.html

You can start there or at the beginning.
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pm I know about Loctite.
That wasn't for you.

The blue and red loctite have virtually the same release temperature. For applications with a lot of thread length the blue loctite 'is as good as red' since you'd have to heat it up to loosen it anyway.
User avatar
By Scott at Team Harco
#48698
worf wrote: Fri Jan 08, 2021 2:11 pm
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pm OK - so that says nothing about any product application to the lower stud threads. It speaks of the depth of stud insertion. This recommendation, as good as it is, assumes the shop that installed the wrong studs inserted them to the proper depth. I can duplicate this depth with the correct studs. If it turns out that the stud has bottomed out, then that's just one data-point. My plan is to bottom them out. I will do the math to see how this correlates with the depth of the wrong studs. But it proves nothing due to screw-up #1.
The point is that even with longer studs you may end up with too short studs if you bottom them out. So, some experimentation will be required in order to arrive at an acceptable range of stud height above the deck.

If that is obvious then I appologize for misunderstanding your intentions based upon what you wrote.
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pmI'm just looking for suggestions on 'best practice'. Wrapping this in "do your homework" is fine. If no one wants to say use a drop of oil, or use red loctite, or put the studs in dry, that's fine. I'll work this out. I thought this was a simple question. Am I wrong about that?
The 928 shop manual is completely silient on the topic of replacing head studs. It is unclear to me if anyone providing you with advice has replaced head studs in 928 engine blocks. I already told you that I have not.

That said, absent a consultation with someone who has replaced studs in 928 or 944 blocks, I would turn them in dry with blue loctite since there's a lot of thread engagement.

Head bolts are 'lubricated' with a tiny bit of motor oil as per the WSM.

I would probably do the same with the tops of the studs so that the nuts turn smoothly when it's time to torque them.

Last, there's the whole issue that the 928 WSM calls for 3 90-degree turns when there's annecdotal evidence that the new Porsche studs won't take that.

So, in the end, it is kind of a science experiement.

Here's a TOS thread:

https://rennlist.com/forums/928-forum/5 ... ds-12.html

You can start there or at the beginning.
Scott at Team Harco wrote: Fri Jan 08, 2021 12:36 pm I know about Loctite.
That wasn't for you.

The blue and red loctite have virtually the same release temperature. For applications with a lot of thread length the blue loctite 'is as good as red' since you'd have to heat it up to loosen it anyway.
Alright. We're getting somewhere. :beerchug:

I am finding exactly the same thing in the 944 WSM when it comes to information on installing block/head studs. I.e. nothing.

It is clear that the upper end of the stud should be lightly oiled. Further, it is stated that the washer under the head nut should not rotate when the nut is tightened. The torque spec is quite clear. Step 1: 20 Nm, Step 2: 60 degrees, Step 3: 90 degrees.

Blue Loctite sounds like a good answer. I don't want the stud rotating as the nut is being tightened. And if I back the stud out 1/2 turn from bottoming, there is a slight risk of this without thread locker.

I have a plan. Now all I need are the studs.

Sorry this got dragged out for so long. Thanks for all the help, guys. :thumbup:
User avatar
By N_Jay
#48731
This is how we all learn.

You can google wet vs. dry thread torque specs and see all the discussion.

The fact you are tightening by angle and not by torque eliminates some of the variability due to thread lubrication.

Wet (oiled) threads put more force (stretch) on a bolt or stud than dry threads at the same torque.

If it were me, I would do the 20nm in two steps (Maybe 10nm and then 20 nm) to make sure everything seats evenly.
User avatar
By Scott at Team Harco
#48809
N_Jay wrote: Fri Jan 08, 2021 4:04 pm This is how we all learn.

You can google wet vs. dry thread torque specs and see all the discussion.

The fact you are tightening by angle and not by torque eliminates some of the variability due to thread lubrication.

Wet (oiled) threads put more force (stretch) on a bolt or stud than dry threads at the same torque.

If it were me, I would do the 20nm in two steps (Maybe 10nm and then 20 nm) to make sure everything seats evenly.
Good idea. 4 steps.
User avatar
By worf
#48858
Scott at Team Harco wrote: Fri Jan 08, 2021 2:26 pm It is clear that the upper end of the stud should be lightly oiled. Further, it is stated that the washer under the head nut should not rotate when the nut is tightened.
It should not turn when you are doing the first torque to 20 N-m. It's recommended to cross-hatch sand the deck side of the washer to make it rough to help it not turn.

You don't want the washer to turn because the starting/stopping washer can throw-off the torque reading.

However, for the 90° turns, no one has ever been able to explain to me why it matters. See following post on torque and torque-to-angle.

Scott at Team Harco wrote: Fri Jan 08, 2021 2:26 pm The torque spec is quite clear. Step 1: 20 Nm, Step 2: 60 degrees, Step 3: 90 degrees.
It is this last, third, 90° turn with new head studs that is not recommended. See Greg Brown posts in the referenced thread.
User avatar
By Scott at Team Harco
#48860
worf wrote: Fri Jan 08, 2021 8:09 pm
Scott at Team Harco wrote: Fri Jan 08, 2021 2:26 pm It is clear that the upper end of the stud should be lightly oiled. Further, it is stated that the washer under the head nut should not rotate when the nut is tightened.
It should not turn when you are doing the first torque to 20 N-m. It's recommended to cross-hatch sand the deck side of the washer to make it rough to help it not turn.

You don't want the washer to turn because the starting/stopping washer can throw-off the torque reading.

However, for the 90° turns, no one has ever been able to explain to me why it matters. See following post on torque and torque-to-angle.

Scott at Team Harco wrote: Fri Jan 08, 2021 2:26 pm The torque spec is quite clear. Step 1: 20 Nm, Step 2: 60 degrees, Step 3: 90 degrees.
It is this last, third, 90° turn with new head studs that is not recommended. See Greg Brown posts in the referenced thread.
I plan to roughen the head-side of each washer. This is actually mentioned in the WSM.

I'll review the post you reference in more detail.

Please note: the S2 spec is only three stages. There is only one at 90 degrees. Much different from three stages of 90 degrees.
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