ARP Head Studs - Opinions

[Arith2]

I literally have both so as far as cost is concerned, I already have the studs. I bought a stock set through my parts department just in case. From what I've learned, the nuts will secure the head better and prevent any lifting. This really isn't an issue already but I prefer the way studs apply force rather than stretch bolts. Install may be easier with studs as well. The cost of bolts are significantly cheaper and I would think that's why BMW went with them. Once again, it hasn't been an issue. My only real concern is heat cycles causing them to lose torque. Everything else seems like a plus.

[nahvkolaj]

Slightly off topic here.

Can anyone site a specific link or piece of information that says the ARP bolts aren't a good choice for S54 rod bolts?
I have done a few rod bearing jobs on the S54 engine and used OEM bolts as I don't like to deviate from the factory hardware unless there is a known benefit as talked about above. I've already got OEM rod bolts for when I do my own rod bearings.

I imagine the same holds true for an S85, the reason I ask about the ARP's is I'll be doing my S85 rod bearings over the winter and the OEM fasteners I imagine will be a pain in the ass on my 4 post lift at home with a big 1/2" techangle torque wrench on 10 cylinders vs. 6 at opposing angles as well.

I'm not much in the S85 online community but it would seem a lot of those guys use ARP rod bolts, I'll likely just use OEM but some real data or personal experience on the issues of less clamping force and/or bore concentricity would be greatly appreciated.

Slightly off topic here.

Can anyone site a specific link or piece of information that says the ARP bolts aren't a good choice for S54 rod bolts?
I have done a few rod bearing jobs on the S54 engine and used OEM bolts as I don't like to deviate from the factory hardware unless there is a known benefit as talked about above. I've already got OEM rod bolts for when I do my own rod bearings.

I imagine the same holds true for an S85, the reason I ask about the ARP's is I'll be doing my S85 rod bearings over the winter and the OEM fasteners I imagine will be a pain in the ass on my 4 post lift at home with a big 1/2" techangle torque wrench on 10 cylinders vs. 6 at opposing angles as well.

I'm not much in the S85 online community but it would seem a lot of those guys use ARP rod bolts, I'll likely just use OEM but some real data or personal experience on the issues of less clamping force and/or bore concentricity would be greatly appreciated.

Lang Racing essentially states that the ARP bolts can be a little tricky to get to the right, but they don't outright discourage them. S54 Rod Bearing and Bolt Replacement with ARP Fasteners - Lang Racing Development

That said, there doesn't seem to be much reason not to use stock.

[Slideways]

The piece of information most people are referring to is what Lang Racing said about the rod bolts. I believe it’s actually mentioned on their website for the late style M10 bolts. They claim the ARP m11 distorts the bore.

fwiw, if you have the early m11 rod bolts it seems the answer is less clear and the use of those ARP bolts in that case is less frowned upon. I actually used ARP bolts in the m11 case, but I did so bc I couldn’t trust my stockers any longer for a variety of reasons. Since BMW doesn’t sell them I didn’t have much of a choice.

I’d echo Obioban and use stock bolts whenever you can. They’re extremely critical and there are no known issues with the stock bolts. So, they’re the best known quantity.

From what I remember, Lang tested the ARP M10s and said they can distort the bores. On the other hand, the ARP M11s don't and those are a good option on the early engines as you can no longer get new bolts from BMW.

[Slideways]

I literally have both so as far as cost is concerned, I already have the studs. I bought a stock set through my parts department just in case. From what I've learned, the nuts will secure the head better and prevent any lifting. This really isn't an issue already but I prefer the way studs apply force rather than stretch bolts. Install may be easier with studs as well. The cost of bolts are significantly cheaper and I would think that's why BMW went with them. Once again, it hasn't been an issue. My only real concern is heat cycles causing them to lose torque. Everything else seems like a plus.

Installing and removing the head seems like it would a pain with studs. Bolts are much easier to deal with especially if you need to remove the head in the engine bay.

[tlow98]

Installing and removing the head seems like it would a pain with studs. Bolts are much easier to deal with especially if you need to remove the head in the engine bay.

The studs actually come out very easily. Technically, they’re only hand right and the have an allen head on them if you need to back them out that way.

With a stud the torque is meant to be applied by the nut, not the threads in the block. The stock bolts are the opposite. ( I don’t Know if that’s technically the right lingo, but that’s how they work)

But yes, removing the head with them in would certainly not be fun.

[Obioban]

Lang Racing essentially states that the ARP bolts can be a little tricky to get to the right, but they don't outright discourage them. S54 Rod Bearing and Bolt Replacement with ARP Fasteners - Lang Racing Development

That said, there doesn't seem to be much reason not to use stock.

If you have the engine out of the car and can measure the rods for concentricity, the roundness is not an issue. Most people are doing rod bearings with the engine in that car, so that's not an option.

Clamping forces is less with the ARP rod bolts than stock either way.

[tlow98]

If you have the engine out of the car and can measure the rods for concentricity, the roundness is not an issue. Most people are doing rod bearings with the engine in that car, so that's not an option.

Clamping forces is less with the ARP rod bolts than stock either way.

There is some clarification to this with respect to the M11 rod bolts. When installing the ARP M11 bolts according to the stretch instructions I was getting within an acceptable variance (within 3ft lbs) for final torque vs the stock M11 rod bolt final torque.

As in, I would install a stock rod bolt according to the factory TIS instructions (degree angle) and my digital torque wrench would record a final torque at that angle. Next I’d remove that factory bolt and install an ARP bolt and torque it to the specified stretch settings. That stretch torque setting correlated nearly exactly with the stock bolt final torque.

Conversely, if you install ARP M11 bolts according to the ARP recommended torque setting (70 fl-lbs) you will be pretty far below the torque settings of both the stretch method and the TIS stock method of tightening. ARP suggests using the stretch method for this reason.

If anyone find this in the future and wants all of the numerical data please take a look in my build thread. Hope this helps!

as far as the M10 bolts go, I have no first hand experience, but have no reason to refute Lang’s findings. FWIW, Lang also has a lot more confidence in the M11 ARP bolts and routinely installs them in place of questionable stock M11 bolts.

Cliffs notes M11:
- Stock is good if history is known
- ARP M11 is good if you use the stretch method
- ARP M11 is less good if you’re just torquing to 70ft-lbs

Cliffs Notes M10:
- Stock is best
- ARP M10 appears to be riskier than stock in any scenario at this time

[Arith2]

The studs actually come out very easily. Technically, they’re only hand right and the have an allen head on them if you need to back them out that way.

With a stud the torque is meant to be applied by the nut, not the threads in the block. The stock bolts are the opposite. ( I don’t Know if that’s technically the right lingo, but that’s how they work)

But yes, removing the head with them in would certainly not be fun.

And this is why I considered them. It's just a more robust design. In this case cost isn't a factor at all which can influence decisions. Nothing is at its yield point for the stud. Studs and nuts are more expensive to manufacture than bolts so I can definitely understand why they went with bolts. It's not needed by BMW themselves. I bought the studs with the intent to put them in so I need solid devils advocate arguments. As I said before, heat expansion causing them to loosen is my main worry.

Who here is using the studs and why?

[tlow98]

And this is why I considered them. It's just a more robust design. In this case cost isn't a factor at all which can influence decisions. Nothing is at its yield point for the stud. Studs and nuts are more expensive to manufacture than bolts so I can definitely understand why they went with bolts. It's not needed by BMW themselves. I bought the studs with the intent to put them in so I need solid devils advocate arguments. As I said before, heat expansion causing them to loosen is my main worry.

Who here is using the studs and why?

Me. I’ve given you all of my ‘facts’ above, but here is my subjective arguments based on the people I encountered through my rebuild process. I used ARP studs for all the reasons above and more.

If you tighten them properly you’ll get slightly more clamping force than stock (5% from memory) and they won’t loosen. ARP knows what they are doing with most engjne fasteners most of the time. ARP has been putting this style of fastener on MLS gaskets for decades.

What I did do was talk to what I thought were the shops that had the most experience with these motors. Hack Engineering from the UK was the best combination of having a lot of experience with head gasket repairs (bc euro motors like to go pop) and also being extremely willing to talk about their experience. This gave me a big warm fuzzy. They’ve never had an issue with the ARP studs. They are very thorough. You’ll find more factual info on M3 Cutters than anywhere else regarding privateer s54 rebuilds.

They’ve also had a lot of experience with rings - NPR brand. They were extremely patient with me and answered all of me very bit-picky, but critical tolerance questions and their engine builder were dead-on with their advice for my stock rebuild.

On the other hand, the US shops I talked to (they rhyme with Car-dawn and Fang) were cagey and acted like their trade secrets weren’t worth sharing. They also wouldn’t sell me
single bearings when they multiple on hand and the alternative options would cost me a six week lead time. So, I’m not going to support them and honestly, I don't trust them as much after speaking with them. They just wanted me to write a check for $15k on a un-warrantee’d motor. No thanks.

So, yeah is there 100x more experience with stock studs? Sure.

I’ve yet to see an issue with the ARP head studs so I’m rocking them. If there is an issue I’ll swap them and out another HG on. But I’m betting the likelihood of that is very small.

[Arith2]

Me. I’ve given you all of my ‘facts’ above, but here is my subjective arguments based on the people I encountered through my rebuild process. I used ARP studs for all the reasons above and more.

If you tighten them properly you’ll get slightly more clamping force than stock (5% from memory) and they won’t loosen. ARP knows what they are doing with most engjne fasteners most of the time. ARP has been putting this style of fastener on MLS gaskets for decades.

What I did do was talk to what I thought were the shops that had the most experience with these motors. Hack Engineering from the UK was the best combination of having a lot of experience with head gasket repairs (bc euro motors like to go pop) and also being extremely willing to talk about their experience. This gave me a big warm fuzzy. They’ve never had an issue with the ARP studs. They are very thorough. You’ll find more factual info on M3 Cutters than anywhere else regarding privateer s54 rebuilds.

They’ve also had a lot of experience with rings - NPR brand. They were extremely patient with me and answered all of me very bit-picky, but critical tolerance questions and their engine builder were dead-on with their advice for my stock rebuild.

On the other hand, the US shops I talked to (they rhyme with Car-dawn and Fang) were cagey and acted like their trade secrets weren’t worth sharing. They also wouldn’t sell me
single bearings when they multiple on hand and the alternative options would cost me a six week lead time. So, I’m not going to support them and honestly, I don't trust them as much after speaking with them. They just wanted me to write a check for $15k on a un-warrantee’d motor. No thanks.

So, yeah is there 100x more experience with stock studs? Sure.

I’ve yet to see an issue with the ARP head studs so I’m rocking them. If there is an issue I’ll swap them and out another HG on. But I’m betting the likelihood of that is very small.

I do welcome arguments against them but I haven't been convinced they're going to fail, it was just a bit of worry. I'll going ahead and use them as there seems to be no apparent downside.

[digger]

unless you plan to have the head off a few times $55 vs $210 seem like a easy decision

[tlow98]

unless you plan to have the head off a few times $55 vs $210 seem like a easy decision

This is good logic, but if you’re doing this for the first time it’s just not that simple.

When rebuilding my engine I made several choices based on cost alone. Some of those decisions worked out, but some did not and it sucked and caused about 3 months of waiting.

If you build these engines frequently, and have all the confidence in the world. Yep, the cost-based logic is a no-brainer.

But if you’re doing this for the first time or haven’t done it in a while there is value in the ability to go back. And also, in the peace of mind that you can go back.

Here’s the scenario. You followed the TIS, which is great and pretty thorough, but you’re lying awake at night wondering the following… did you put the sealant on? Do you want to double check a piston orientation (don’t have a boroscope)? Forget those random O-rings on the timing chain rails? Front main seal - guess what, it decided not to seal. Did you triple check the thinnest part of the walls between the cylinders for debris? On both the block and head and both sides of the gasket?

To know the answer to these the head comes back off.

When you had four hands helping to set the head down and you were holding the timing chain up in the air and expertly placing the 50lb juggernaut down did you get that dowel fitted perfectly or did you slip and mark the soft aluminum head?

You only have 10-15 minutes to get that HG on, apply the sealant, drop the head, and torque 14 bolts in sequence in multiple stages of torque. 42 precise torquing events. In smooth rotations. Did you get them all right every time?

Did you video every step to QA/QC yourself? Nope, well then you don’t really know.

All of that to say… how do you avoid these problems and keep your project going on a decent timeline? (We all know BMWs e46 parts are going NLA more and more all the time)

1) you’re a pro ($55)
2) you’re not a pro but you have multiple sets of stock bolts ($110+)
3) you’re not a pro and have ARP ($2xx)

But just remember, 15 minutes to get it just right the first time. Set up that camera, but if you kick it over mid process you won’t have time to reset it and accomplish your mission.

Tick. Tock.

At least, for one crazy person (me), this is how I thought about it.

[Obioban]

On the other hand, with FCP… replacement stock bolts are free.

[bigjae46]

Shameless plug...I have an extra set of head bolts. $25 shipped.

[digger]

This is good logic, but if you’re doing this for the first time it’s just not that simple.

When rebuilding my engine I made several choices based on cost alone. Some of those decisions worked out, but some did not and it sucked and caused about 3 months of waiting.

If you build these engines frequently, and have all the confidence in the world. Yep, the cost-based logic is a no-brainer.

But if you’re doing this for the first time or haven’t done it in a while there is value in the ability to go back. And also, in the peace of mind that you can go back.

Here’s the scenario. You followed the TIS, which is great and pretty thorough, but you’re lying awake at night wondering the following… did you put the sealant on? Do you want to double check a piston orientation (don’t have a boroscope)? Forget those random O-rings on the timing chain rails? Front main seal - guess what, it decided not to seal. Did you triple check the thinnest part of the walls between the cylinders for debris? On both the block and head and both sides of the gasket?

To know the answer to these the head comes back off.

When you had four hands helping to set the head down and you were holding the timing chain up in the air and expertly placing the 50lb juggernaut down did you get that dowel fitted perfectly or did you slip and mark the soft aluminum head?

You only have 10-15 minutes to get that HG on, apply the sealant, drop the head, and torque 14 bolts in sequence in multiple stages of torque. 42 precise torquing events. In smooth rotations. Did you get them all right every time?

Did you video every step to QA/QC yourself? Nope, well then you don’t really know.

All of that to say… how do you avoid these problems and keep your project going on a decent timeline? (We all know BMWs e46 parts are going NLA more and more all the time)

1) you’re a pro ($55)
2) you’re not a pro but you have multiple sets of stock bolts ($110+)
3) you’re not a pro and have ARP ($2xx)

But just remember, 15 minutes to get it just right the first time. Set up that camera, but if you kick it over mid process you won’t have time to reset it and accomplish your mission.

Tick. Tock.

At least, for one crazy person (me), this is how I thought about it.

did you put the piston rings upside down?