924Board.org

flosho · Posted: Sat Jul 12, 2008 4:29 am Post subject:

Dan, do you have that coupon code? I didn't see that, but maybe i'll call them and see if they'll take 30 dollars off my order.
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ideola · Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI

Just placed my order.

Flosho, I think the coupon code is personalized. The flyer I received has the following info above my name and address:

T253 P3
ZF30657675

The lower number was the "coupon code" I entered, so I doubt that it will work for anyone else. I would simply recommend that you call Summit and ask them if they will extend the special to you.
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erstwhile owner of just about every 924 variant ever made

flosho · Posted: Sat Jul 19, 2008 6:36 am Post subject:

So what are the torque values for the ARP head studs? Do we use the OEM specs or some other?
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ideola · Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI

That's a good question, Flosho. My box arrived today, but I'm jumping in a cab momentarily and can't check to see if they packed instructions or not.

In any event, I was going to post that I confirmed earlier that there is absolutely NO issue with fitment, as Steve attested earlier. These are the cat's meow, especially for $130.
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erstwhile owner of just about every 924 variant ever made

bass gt · Posted: Sat Jul 19, 2008 7:14 am Post subject:

Torque up to 85ft/lbs in 3 steps. say 40 then 60 then 85. make sure you use the ARP assembly lube and not motor oil. then recheck once after running the engine and cool. back to 85ft/lbs. And believe me, you won't get better.
Thanks and renumeration to................

Steve
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Smoothie · Posted: Sat Jul 19, 2008 8:09 am Post subject:

flosho · Posted: Sat Jul 19, 2008 11:35 am Post subject:

So, I tried to install the head today, got everything lined up but the back bottom head stud wont fall into place, I'm thinking its because of the head centering bushing?? It was the only hole that had the little extra piece on it. It was on the cylinder head actually and not in the block? Any tips on this subject? All other 9 went in fine?? I haven't put the nuts on yet, could be that if i twist the nut on down that one it will continue to thread in?
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bass gt · Posted: Sat Jul 19, 2008 7:25 pm Post subject:

From memory there is no issue with the little had locating clips, unless yours is deformed slightly and wont let the stud throgh. Don't wind the nut on until you have bottomed the stud.
I have actually stopped using the rear locating clip. I now fit the stud into the block in the top left end, fit the gasket, use the front clp to locate it all. Then with the head swung up, slide it down the rear stud, then as it is close to the block, swing it down and locate it on the front clip. This means you are not juggling the head around trying tpo find the two clips to locate the head. Then drop in a couple of studs to hld the head, and you're set. All in all, much easier process. Of course, you need to have the inlet manifold removed et, but it is well worth it. Make dropping the head on a snap, as opposed to sliding it around to find the lugs, realising the gasket has dislodged and starting again

Smoothie, 85ft/lbs is 85 ft/lbs. You don't use lower torque values. As you say, the ARP studs have a fine pitch on the top thread. This allows a greater tensional force to be applied. It also allows the stud to stretch in a more controlled manner. But the clamping force is that which you apply via the top nut. And if you wind the ARP studs to 85, or the stock nuts to 85, you are still applying 85. The ARP studs can take significantly more than 85 though. Also, there torsional strength is much better, so the posibility of the head lifting under high boost/compression is greatly reduced. If you look at the torsional strength values of a stud vs a nut vs a bolt&nut, the stud is way ahead on strength. The advantage of these studs is that a more controlled clamping force can be applied, the studs stretch is a more quantified amount, so there is less likely hood of head lift, and as they are significantly stronger than the stock item, an additional 5/10ftlbs can be applied if required. But, all studs must be bottomed evenly to ensure equal loading. If one stud is only 2/3rds down into the block, this will put unequal strain on the bottom thread pitches of that stud and change it's stretch characteristics. So before you fit these studs, make sure you run a tap down the hole to clean the thread, and test fit each stud into a hole so that you can confirm that they all bottom equally. And use LOTS of the AP aasmbly lube. I would recommend buying an additional 4oz pot, to be on the safe side.
In this picture, you can see i have fitted the studs into the block, and am ready for tightening down. I even wound them down to an equal torque of 15ft/lbs with the integral allen socket and then measured each one for it's height off the deck. Then when i fit the head, i repeat this process, by torquing down the stud, and taking a measurement from the washer seat in the head to the top of the stud. Details, details, details. The devil is in the details. of course, this is only necessary if you are building a high HP motor, but it is best practice, so i would recommend it to all. And remember, NECER snatch or tug at the torque wrench to get the click. Use a steady, even pull to set the value. Repeat 2-3 times to be sure, but NEVER, EVER snatch or tug. And for these nuts, buy yourself a good quality 12 point socket. And use LOTS of lube!!!!

Steve
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Rasta Monsta · Joined: 12 Jul 2006 Posts: 11723 Location: PacNW

That's interesting. . .I always thought studs weren't supposed to be bottomed. . .
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WeiBe (1987 924S 2.5t) - 931 S3

Smoothie · Posted: Sun Jul 20, 2008 3:03 am Post subject:

Smoothie · Posted: Sun Jul 20, 2008 3:13 am Post subject:

bass gt · Posted: Sun Jul 20, 2008 4:45 am Post subject:

Smoothie,

I was getting my tensional and tonsionals in a twist

Re the ARP studs, i'm prety sure the paper that cam ewith them spec'd them at 85ft/lbs. Perhaps Dan can assist here.
Re the stretching of the studs, i have recorded the lengths of each stud using a didital vernier. When i pull the head, I check the allowed values. Allegedly, the ARP studs will "shrink" back to original length if left without tension for a while. So i have 2 sets that i rotate when i pull the head.

Steve
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flosho · Posted: Mon Jul 21, 2008 7:39 am Post subject:

Ok guys, on the back of the box, it has the specs for all their studs/bolts.

the "12 mm stud" has an option for 77 ft/lbs, 86 ft/lbs, or 96 ft/lbs. This is depending on the "fastener tensile strength" in either 170,000/180,000 psi or 190,000/200,000 psi, or 220,000 psi, respectively.

Meaning, if i want it to hold 200,000 psi, i should torque the head stud nuts to 86 ft/lbs.

All these torque specs assume using ARP assembly lube, they are higher if you use 30 wt motor oil.

I'm just going to torque these things to 86 ft/lbs. I'm guessing if I tighten them more, its going to take a catastrophic disaster to lift the head.
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Smoothie · Posted: Mon Jul 21, 2008 9:30 am Post subject:

Someone please correct me if I'm wrong of course, but I think the tensile strength ratings don't change - they're a set number depending on the strength of a fastener (a characteristic of its' material, size, and hardening). -So a 170k-180k psi ARP stud can be torqued to 77 ft-lb, a 190-200k psi torqued to 86 ft-lb., etc.
I'm pretty sure the tensile strength ratings are at or close to the breaking point, so the actual "tensional force" or "clamping force" you get at the recommended torque is significantly less than the tensile strength rating of the stud (, but still significantly more than you'd get with the OEM head bolts).
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bass gt · Posted: Mon Jul 21, 2008 9:41 am Post subject:

Smoothie,

yes, the applicable torque values depend on the material the studs are made from. There are various "compunds" that ARP supply, and you set the trq value accordingly. So by winding it down tighter wont necessarily be a good thing. However, the values ARP give relate to the studs used in conjunction with their assembly lube. I believe that the values increase if you use normal oil. And from memory, the material these studs are made from, the specs rate the trq value at 86ft/lbs. There is obviously some headromm over this if you use motor oil, which is not as good, and causes the threads to bind a little more than their lube. Hop this helps.

Steve
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Front Wheel Drive is the Devil's work.