Changed Back to OEM Headbolts

[Brian MP5T]

The Arp Studs are the Leader in racing motor Technology. I have only had them for 3000 Km and they are out.

1st. The OEM Stock bolt is a Allen Head Torque Yield bolt. It does not require a socket to fit around it like the 12 Point ARP. This proves to be a SERIOUS ISSUE as the 12 Point 1/2 Inch Deep Socket simpley does not fit all the bolts. It fits so poorly that the person at Renco, seems to have forced the socket in between my lifter pots (Douche). With the socket unable to fit, there is no wonder why my #6 Stud backed off, there is no way to get an accurate torque. I asked him to use blue thread lock and torque it to 80 Ft/Lb. With heat and the fact that he did not threadlock, they loosened and I got a Major cooling problem. The Head is fine, the Block is fine and I didn't really want to see my pistons again, but whatever. No damage done.

2nd. The OEM Stock Torque Yield bolts act like a spring rather than a stud. They are torqued to a specific rating and then as the head and block expand at diferent rates, they stretch and hold the mess together. If the car had an Aluminium Block and Head, I would say ARP All the way. Mazda must have spent Shitloads on R&D to come up with the bolt. So I'm a firm believer that the OEM is superior in this application.

 

[evilmonkeyMSP]

Dude...

 

[JCell]

good thing it didn't cause any damage

 

[Brian MP5T]

Yeah, It's still "In Progerss" I should have it running witin one hour. What a PITA

 

[hazeXban]

Good thing you keep close tabs on your motor.

Hail Brian MP5T! hehe.

Good luck man.

 

[tekkie]

If you use the right socket there is no problems installing the arp head studs, they have one at sears that fits no problem, when we did Azian6ers it was simple.

 

[Dimitrios]

Agree with tekkie; I blame the idiot at the shop vs. ARP fasteners.

 

[Brian MP5T]

If you use the right socket there is no problems installing the arp head studs, they have one at sears that fits no problem, when we did Azian6ers it was simple.

The ARP is definately a great product for engines. I just think that the stock bolts may be better for this application witht he MLS Headgasket. The ARP would start to crush the gasket each time the engine went through a heat cycle and eventually the ARP would loose tourque.

 

[Mr. Win]

hmm... i thought people had problems with oem streching...

 

[Brian MP5T]

Ummm, focus is pushing for 400 WHP and on OEM Headgasket and Bolts...

 

[evilmonkeyMSP]

weiners

 

[Brian MP5T]

Bump The Top.

 

[WetsuitxNinja]

Good info, sad to see you wasted money on products "superior" to find they sucked. I would hate to be the guinea pig when it comes to that kind of stuff...

 

[Bigg Tim]

I agree, and with what MPNick has told me, they are the best to use on our motors with the stock Head gasket because of what you already stated with their "spring" action characteristics. They provide a great sealing for and he has made over 330whp using the stock head bolts and head gasket.

 

[Brian MP5T]

It's all good. I have the ARP studs holding the Porsche Motor to the stand right now. What a weak job for such a strong racing product..

 

[GNO]

The OEM Stock Torque Yield bolts act like a spring rather than a stud. They are torqued to a specific rating and then as the head and block expand at diferent rates, they stretch and hold the mess together. If the car had an Aluminium Block and Head, I would say ARP All the way. Mazda must have spent Shitloads on R&D to come up with the bolt. So I'm a firm believer that the OEM is superior in this application.

Part of your statement has to be inaccurate, there are some contradiction in terms.

With a torque-to-yield bolt, the bolt is tightened to the yeild point. They are torqued to a specific value and then an additional X degrees, usually 90. I don't have any referance material at the time, so I'm not positive on the value for the FS. The additional turn brings the bolt to the yeild point.

Brian, I'm sure you're aware of most of this. I'm going to define some of the terms so that others can follow.

Referring to a stress/strain curve, a common illustration used to show how materials react while under stress. In this case, we'll be looking at tensile stress, or pulling. The linear portion of the stress/strain curve is the elastic range. The elastic range is where the spring effect you mention occurs. In the elastic range, you can stretch a material (in this case a fastener) and once the stress is removed, the material returns to it's original shape. The material wants to go back to its original shape, so it pulls the two ends together.

If stretched far enough, the elastic properties are lost and the material does not return to it's original shape. This is called plastic deformation.

The yeild point is the on the stress/strain curve at the end of the elastic range when the curve is no longer linear. At the yeild point, metal goes into plastic deformation. This is why torque to yeild bolts are not reusable and why I say there's a contradiction in the terms you've used. With the ARP studs, you should be in the elastic range. . . giving you this spring effect you mention.

If the studs were over tightened, you may fall into the problem with plastic deformation and they should not be reused. Also, if during the heat cycle the studs stretch past yeild, then plastic deformation occurs again, making a loose fit after cool-down. That can be from overtorqueing or poor design/material choice by the fastener manufacturer.

I'm thinking the shop overtorqued and didn't tell you. As for the gap created when crushing the gasket, retorque the nuts. I not positive, but I believe retorquing is also listed in either the ARP or gasket manufacturer procedures.

 

[lcruz64]

I was about to drop $$ on bolts & studs. Reevaluation time.

 

[Brian MP5T]

Part of your statement has to be inaccurate, there are some contradiction in terms....

Well written, I am not an engineer or Mechanic but I am very good with Cause and Effect.

The possibility that the shop went to "Torque Town" on my ARP is slim to nill. I believe that the heat cycle plus the fact that the studs were not thread locked. I believe that the product is a good one, I believe also that the Mazda Bolts are if used properly on this engine will never fail. I think that the ARP are complicated for nothing and with a stock gasket and stock bolts tightened and used properly, the need for ARP fasteners is simply not there for the FS engine.

Believe me I am not disagreeing with you at all, It's interesting and that is what the internet Forum is for...

Thanks For Your Post.

 

[CWiLL]

did u say 12mm 12point>? cuz arp head bolts are 13mm might be y urs dont fit

 

[jeffmsp]

that could have been very bad, good thing you got it taken care of before anything was damaged. Are arp bolts 1 time use or could you try and reinstall them with a new gasket, that thread lock and the tool tekkie was talking about? how many ks before you had the problem?