RACEWARE HEAD STUDS

[DVST8R]

This is an intresting topic, that I have read a lot about, but don't know that much about. I was recently in the mall waitng for the wife to buy somthing or other, and I picked up an issue of hot rodder, or somthing like that and in there they had an article on setting "torques for hi- performance engines" and in this article, they said that the only true and correct way to "torque"is by mesuring the stretch with a dial indicater, and then they went into examples of oem head bolts as well as arp headsutds were they torqued them to the "spec" as per instructoins pased on lube or oil or dry, and none of them came even close to what they should have been via the streach numbers, due to the incosistincy in the friction level between the block and the stud. Moral of the story if it isn't set via strech number it isnt set right. This is how it is done in F1, indy, cart, baja, nascar, nhra, ihra, ect... The other thing that I read was from a builder or custom copper head gaskets, in regards to torquing and HP that you make the most HP with the least possible torque that still seals the head. so ? well I am confused, but I would probabley be inclined to go with the strech version myself :wink:

[fspGTD]

This is an intresting topic, that I have read a lot about, but don't know that much about. I was recently in the mall waitng for the wife to buy somthing or other, and I picked up an issue of hot rodder, or somthing like that and in there they had an article on setting "torques for hi- performance engines" and in this article, they said that the only true and correct way to "torque"is by mesuring the stretch with a dial indicater, and then they went into examples of oem head bolts as well as arp headsutds were they torqued them to the "spec" as per instructoins pased on lube or oil or dry, and none of them came even close to what they should have been via the streach numbers, due to the incosistincy in the friction level between the block and the stud. Moral of the story if it isn't set via strech number it isnt set right. This is how it is done in F1, indy, cart, baja, nascar, nhra, ihra, ect... The other thing that I read was from a builder or custom copper head gaskets, in regards to torquing and HP that you make the most HP with the least possible torque that still seals the head. so ? well I am confused, but I would probabley be inclined to go with the strech version myself :wink:

Generally speaking, the way I understand the "pros" IE: (F1 engineers) set the torques of their fasteners is they determine the torque at which the fastener yields and torque to a certain percentage, IE: 80-90%.  The way they determine this is either by looking up on a table and/or calculations based on size, thread pitc, materials, and lubrication, or they can actually buy extra (they've got enough money, right?) and torque a fastener until it yields, then remove it, replace it with a new one of the same type, and torque it to a little bit less.

I think I understand the train of thought of the guy who said the least amount of torque is best for power, but I think I disagree with his recommendation.  He is probably saying that because of more clamp load, there is more strain (movement/distortion) of the head/block assembly, and that a block with cylinders that is strained will have the cylinder-shape bores change into oval-shape bores.  The piston will rub unevenly and seal less well on an oval bore and therefore, will make less power when the bores aren't perfectly cylindrical.  I think I agree with all that (although I'm not sure how big of a factor it really is.)  But undertorquing goes against the other good practice rules with ensuring a good head gasket seal, IMO.  Based on what I've read, more bolt load is generally better; and the VW head/block seems plenty stiff.  The recommended practice in eliminating the "oval bore" syndrome is rather than reducing bolt load, is to machine the bores with the stresses of the head and head fasteners at full torque simulated.  Very good machinists will have fixtures called "torque plates" that bolt onto the engine block, sort of like a "simulated head", but with big holes in them for the boring/honing tool to reach through and machine the bores.  They will bring the simulated head fasteners up to full torque before doing machining the final bore/honing operations on the cylinder.  Then the perfectly machined cylinders will in theory remain cylindrical when the real head is bolted and torqued up on top of there.  Using a torque plate is one of those little machining tricks that makes the difference between an econo-rebuild suitable for street use, vs a high quality blueprinted type of engine rebuild.  Some machinists have torque plates and use them for rebuilding VW motors, others don't.

A danger with undertorquing is if the pressure on the cylinder head exceeds the bolt load, the bolts can then see a dynamic loading where they stretch and relax a little bit with each cylinder fire.  This can lead to failure of the fasteners, even though they may be installed at a load far under their yield or tensile strength!  You might think, there is less chance of failure of the fastener if it's torqued less?  Well it sounds weird but it is not necessarily true.  Over time small amounts of stretching from dynamic oscillations of an undertorqued bolt can lead to metal fatigue of the fastener material.  (Not to mention the head gasket will have a tough time sealing when the surfaces pressing against it are moving!)  As a result of this, the general practice is to specify fastener torques that comes as close as possible to the yield strengh of the fastener, assuming the material being fastened is adequately rigid and there is adequate thread engagement, etc.

I think you are right about lubricant effecting torque readings drastically.  When I torqued head bolts with only oil lubricant as specified by bentley, it can be felt how much friction there is and the lack of "smoothness" when torquing the bolt because of all the friction.  But when I lubricated the threads with moly lube, boy did they torque up smoothly.  It would be very difficult to measure the lengths of installed head bolts/studs as they are threaded into blind holes!  A bolt that had both ends exposed, that wasn't threaded into a blind hole, might be measurable however.  What you could do is measure the length before/after installation of the bolt though, to see if it has permanently stretched at all.  If it has permenently stretched, it was torqued to above it's yield strength.

[Centurion]

DR D - cost of the stud?

I cannot reach my email - to get a message off to the gang!

Thanks! - C

[Dr. Diesel]

i think they're around $145 U.S for the set.

[okumaguru]

After reading this thread, I want a set of raceware.  Where do I get them?  I couldn't find them on Jack's site.  Could be I wasn't looking in the right place.
Thanks in advance.
Tim

[2mn2]

After reading this thread, I want a set of raceware.  Where do I get them?  I couldn't find them on Jack's site.  Could be I wasn't looking in the right place.
Thanks in advance.
Tim

http://www.raceware-fasteners.com/photo.htm

m alexander

[Pat Dolan]

Doc:

Just for referrence, here is a complete list of SAE and ASTM fastener grades.  As you will see, there is no such animal as "grade 12".  While I am tempted to say YEB is blowig smoke up your rear, the truth is that few people ever bother to learn anything about fasteners and live by old wives tales, industry slang, and so on.  Even in fastener stores, one will often hear of "grade 10" bolts (that the manufacturer has decorated with more than the usual number of grade-code markings on the head) - which, as I said, don't exist as a standard.

Now, if you (or anyone else) has some later information that SAE has added some new standards, I am all ears (and eyes).

http://www.americanfastener.com/technical/grade_markings_steel.asp

What I found interesting when I searched out this table for you is that the ISO grades shown at the bottom are strangely missing 12.9 (which is closer to what Raceware and ARP studs would be).

To those referring to measuring stretch as a legitimate method of torque measurement:  very true - for rod caps.  You can also do so by measuring how much the main caps grow (if you were to use studs).  However, for a head, you have the little problem of a gasket below that will crush and not allow you to have a "zero referrence" point from which to measure.  The fact that it is a blind fastener is not a big deal (since you assume that the other end is not moving at all, so you measure the increase in length with a dial indicator on the free end).

BTW:  thanks for this thread.  I have been agonizing over the ARP/Raceware issue for some time (building another high-ish HP 1.9).  Don't know if I am decided one way or another, but I definitely have a lot more good information upon which to base my decision.

[theman53]

that link also left out socket head bolts which are alloy for the most part anyway. I have been working on somthing for Myke_W for about 2 months and haven't had a good enough answer to get back to him, but after reading this I think I will try it on my next turbo. I sell these SPS Unbrako bolts that are in all sorts of industries...I can get them at my cost and offered them to Myke first. But I don't want to give somebody something that doesn't work or work correctly for this application. I haven't heard back from SPS what the torque would be for VW diesels and I don't think I will since it is a small market for them. I need to get my turbo engine bored and put back together before I can tell you it they work or hold up. Here's the link for the some of the stuff I sell.
http://www.spstech.com/business_groups/unbrako.html

[Rat407]

 50ft-lbs as recommended by Raceware, with non-synthetic oil, and with a beam-style torque wrench not a less-accurate "clicker", has worked well for me and everyone else I know of who has run them in VW Diesels.

Raceware makes it pretty obvious in their instructions/literature they send out with their vw diesel head studs by the way, not to use factory torque specifications but to use theirs for their bolts.  Along with the added requirements of not using synthetic oil to lubricate the threads (but rather non-synthetic) and also not using a clicker torque wrench but an accurately calibrated beam-style.  They are really quite fussy about proper torquing!  .

Interesting thread, my question is if the beam-style is better than a "clicker" torque wrench, I wonder why the military doesn't require all torques to be accomplished with a beam-style only. All we use in the Air Force is "clicker" except for the altra light 4 to 20 inch pound torques where we use a beam style.  One other thing is you hear that if you use a "clicker" not to double click it but just go with the first and only click, but you see it on national TV on HorsepowerTV putting an engine together and hearing them double click.  :?

[Pat Dolan]

It's back to the same thing:  people just don't pay enough attention to fasteners and fastening tools, and "go with the flow" of what is around them.

While bending beam torque wrenches have SOME advantages, reading a wiggling needle on a shaky scale, trying to correct for parallax (since it always reaches value somewhere almost out of sight!) is a real PITA.  I have ONLY ONE of 3/8" (MAN I wish I have bought the 1/4" and 1/2" drive when I could - but I was doing only air cooled then, and didn't need them) Repco bending beam torque wrench with a little wedge on it that slides along to allow it to hit a trigger that releases a pin at the pre-set torque.  It if audible (barely), visible and tactile (fires against your thumb) and meant for aircraft work.  The wedge is very soft, and the trigger point is very hard and sharp.  After releasing the pin, a bit more deflection puts a mark on the ground face of the wedge.  

As I understood it when I got it (over 30 years ago) workers would engrave their name on the wedge, and the QA/QC crew would collect them at the end of the day.  Mark up your wedge, and your work (and you) would be re-doing the day's stuff.  Another feature was the drive was removeable and available in calibrated torques - that is they would break if taken beyond their marked value (a great way to protect really expensive stuff).  Needless to say, if a mark got you called on the carpet, I imagine a broken drive was a pink slip.

Why do I mention all of this stuff?  Because THAT is how fastener tension should be treated.

[theman53]

These are what I am going to experiment with.
http://www.spstech.com/aero/products/sde_studs/sde_studs.html

After more and more digging here is a competitor of mine that sells the stuff in just our kind of usage.
http://www.aaa-aircraft.com/pdf/sps_racing_brochure.pdf

[jtanguay]

does anyone have the torque specs for the racewares lying around??? i had the sheet but now i can't find it!!!  

[914turboford]

I bought a newly rebuilt engine with Raceware studs. One was missing and one was untorqued. If I relax them all then retorque to Raceware specs should this be good enouogh?
Brian

[jtanguay]

well i dont think you have any other options... i would just do it and hope for the best... except for the missing one.  maybe you can order just one?

[saurkraut]

does anyone have the torque specs for the racewares lying around??? i had the sheet but now i can't find it!!!  

I have the sheet somewhere.  I'll dig it out and post the values.

Best I can remember:

20
35
50

lets see how close I come to whats on the sheet.

Actually the final torque is important, and as long as the lower torque steps are more or less evenly spaced, you should be OK.

Heck do 16.67 ftlb stages to 50.