m73m95

What is the size/pitch of the snap on stud extractor for head studs?

I remember the thread containing this most valuable information, but the abyss has swallowed it!

Thanks,

beentherebaby

The OE Porsche 944 head studs have an M12 x 1.50mm pitch thread. Be advised that these studs are held into the block with high temp Loctite so you'll likely need to heat the stud for awhile with a heatgun to soften the Loctite. Folks have snapped studs off trying to remove them with an impact wrench because they didn't heat/soften the Loctite first. You can also damage the threads in the block making for expensive repairs.

Rogue_Ant

Mark, what are you doing? The stock headstuds are pretty good...

m73m95

I need to remove them for the Nikasil.

Rogue_Ant

Ah - I C.

Willard Bridgham 3

The stock head bolts are stretch bolts.

The ASME, AISC, SAE and all Engineering societies who certify fastener strength say not to reuse stretch bolts, ever. They have failed by definition the first time they are used.

xtaC

I had zero issues when I did mine, and I used no heat at all.


https://rennlist.com/forums/924-931-...p+stud+remover

DDP

Yes but in reality people have re-used them plenty with no issues, including myself.

m73m95

That is exactly the thread I was looking for!!

Thank you very much.

beentherebaby

I try to help people help themselves by providing accurate tech info. People are free to use this information as they please or completely discard it.

I'm pretty sure those who have stripped the threads out of their 944 engine block or broken off the head studs trying to remove them, would have preferred to have known before hand that the studs were Loctited into the block and that heating the studs could have prevented the expensive engine damage that resulted?

KuHL 951

I had the machine shop that did up my head remove the OE studs on the block. They used heat once they knew the OE studs were set in Loctite. They also chased the threads with a flat bottom tap after to make sure they were clean and ready for the ARP's. I had heard tales of traces of aluminum being pulled off on the studs when they were removed without heat. I assume the ARP's need Loctite also since a precise stud height above the top of the head has to be set.

Chris White

I usually don’t contradict Willard (‘cause he is usually right!) – the stock head studs are not a TTY (torque to yield) fastener. All bolts and studs stretch when tightened – that’s how they work. TTY fasteners (more common on modern cars) stretch past the point of elastic recovery…they cannot be used a second time.

All that being said – I would replace the head studs if they have been used more than a couple of times and the block is out of the car. The new studs are cheap.

The stud extractor does not work that well. I TIG weld on a nut, give the stud a good whack on the top (the old timers call this ‘waking up the treads”!) and then remove them with a ¾” 1,000ft lbs impact gun. Be careful using a regular wrench with a breaker bar – any sideways force (deflecting the stud) will greatly enhance the chance of breaking the stud off.

Oddjob

Having US Chrome in WI do the coating? What pistons/coating and rings are you going to use?

JohnKoaWood

And that would be why I left mine for you to do!

Ask him (above) as he is the one setting it up for me!

Chris White

“Him above” uses Millennium Technologies….