ARP Fasteners - Head studs and main bearing cap studs

[Bean]

Hi guys,

I've contacted ARP with the possibility of spec'ing out head studs and maybe some main bearing cap studs for the N9TE engines.

I'm not particularly fond of head bolts in a performance engine - especially boosted, so my hope is that they can spec out something from their existing stock.

If that's the case then it should be a worthwhile mod.

I have the form that needs to be filled out with the dimensions and such, so once I find out about availability, there might be an opportunity for a group buy to lower costs even more.

So this is just a feeler at this point.

Rabin

[N9TE]

I am in. I'm going to be rebuilding a N9T motor this summer.

Kindda curious about the "re-torque procedure" which the general consus is a cannard method and if it would be required after good fastners like ARP studs. I was shocked that such a POS procedure was actually spelled out in the factory manual.

I'll do it if I have to, but everything about it screams wrong wrong wrong.

[Bean]

Everything I've read so far is that you chuck the factory specs for tightening, and use what ARP recommends for the studs. I've also read to make sure you use their thread lube while tightening.

So all the BS should be out the window with ARP's, and they're re-usable as well. So while my plan is to build up as well - these will go in my runner right away. Figure I'll remove the coolant, and then remove head bolt at a time and replace with the ARP stud after throuoghly cleaning the holes and lubing the stud.

Once I get the monster bottom end finished, then I'll either just get another set, or re-use these out of the runner engine.

Rabin

[N9TE]

What was the final word on this Rabin? Were they open to the powerhouse better known as the N9T

[Bean]

I know two N9T's running ARP's - so they won't have to be made. ARP sent me a form to send them measurements from the head and block, and then they'd match it up to something they had in stock. I've never done that yet however - so I don't have any part numbers.

Nick got some - but I'm remembering that they didn't actually have part numbers for it - they just called in and an "old guy" knew what they needed. Again - totally from memory. Hopefully Nick will post up and clarify.

Rabin

[Bean]

BTW - If you get a set done up - please post specs as I'd like a set or two myself. I'm sick and tired of the coolant leak on the my car and I'm tempted to pull the engine and do a reseal and top end rebuild.

Seeing Tama's post again is making it really hard not to just pony up and do the full on build on a spare motor and drop the whole unit in as well. Limp mine on for a while as is - either way though I'll need at least a set of head studs.

Rabin

[billbranch]

I hope my results are not indicative of what we may be in for. I ordered a set for what I had hoped would be my last engine repair on this '91 SW8. Right off we had bubbles. The head has been checked once, and the machine shop owner is doing it AGAIN to be sure it is not the head. It is nice to deal with people like this.

Regardless, the studs have two different threads. The finer threads screw into the block, and, oddly, the end going into the block can be tightened with an Allen wrench. The coarser threaded end does not have provisions to be tightened with the wrench. It seems the intent would be to screw those studs in all the way and then torque using the more finely threaded end and nut. I do not know if anyone else (besides Nick) has ordered these parts. I used his paret list. It would seem torquing specs would change with a coarser thread. When Roger pulled the head, he said he was able to loosen nuts with a small ratchet.

Any comments or suggestions?

[N9TE]

Oh wow, i'm sorry to hear of this mess.

Clearly, the studs were not torqued down with enough force. Studs, by their nature are better at clamping than bolts. The fact they were removed by a quick turn of a small ratchet tells me that there wasn't much if any torque left.

You have to determine exactly how assembly went. what could cause this?

1. Interference at the thread level. Were they dirt or otherwise compromised. What might seem like a reasonable torquing could have been something interfering with the threads
2. Interference at the head gasket. Of course things were hospital like clean? Something interfering with at the headgasket level would cause a mis-torque.
3. Sloppy assembly.

You could chase your tail, but at the end of the day, the studs were not torqued down worth a piss.

what gets me is that straight-away you saw bubbles. Meaning that they just weren't torqued down right initially.

Damn. This sucks. Again, sorry to hear this. I wouldn't think it was the head. Your smoking gun is how easily the nuts came off.

My suspicion. incorrect assembly.

What's the plan going forward?

[billbranch]

This discussion is pretty much part of it. This machine shop also expressed disbelief that the torqued nuts had a greater pitch than the studs screwing into the block.I'm hoping we can come to some kind of consensus here. Roger is sick of working on this engine, and we're all trying to understand what went wrong.

[N9TE]

Well, if we forget it's a cursed Peugeot for a moment and just figure its like one of countless iron block/aluminum head engines ARP makes bolts and studs for. With that in mind, although the pitch is different than the block threads, That pitch is probably used on a number of other stock-application studs that they sell for Toyotas, Nissans, Porsches, etc.

The studs were run down in an incremental fashion starting in the center and going outwards in a clockwise fashon?

What did they torque them down to?

[billbranch]

I vaguely remember a conversation with Roger and he said there were directions in the package.

I also remember an e-mail or exchange with Nick about this.

I certainly will have to ask Roger. I know we had no problems with layout or sequence: I think his questions were do we bottom out the studs, and what's torque value? Do we re-torque? Right now, I am wondering if all of this information is in the directions.

[Bean]

I've read that you don't want to bottom the threads as they can get seized in the block when the nuts are torqued down which makes sense to me. So bottomed and then backed off half a turn maybe?

Torque value is supposed to be what ARP recommends for the fastener and not the OEM settings - but I thought Nick posted about that as well. No retorque should be necessary. Directions for the fasteners would be the best place to start for sure.

The nuts coming off with a small ratchet is a BIG red flag... Roger installed the head - what torque did he use? ARP is pretty clear in the instructions to use their spec and not the OEM bolt torque specs. Part of the reason to go with studs is the increase clamping force capability.

Found Nick's post: http://www.505turbo.com/forum/index.php?/topic/1152-getting-ready-to-race-45-for-the-first-time/page-14#entry13848 80 ft*lbs is what he posted, that's a bit more than wheel lug torque.

For reference on the bolts he got: http://www.505turbo.com/forum/index.php?/topic/1152-getting-ready-to-race-45-for-the-first-time/page-13#entry13837

Rabin

[N9TE]

And 80 lbs lubed is like 120 lbs dry or something like that.

They should NOT have come undone.

[billbranch]

After a brief exchange with ARP, I have discussed with Roger what we know. The studs sold for use on our cars have two threads: 1.25 and 1.75. The studs are designed for the coarser thread to be screwed into the block, and the finer threaded end should have the nut and be torqued. The person from ARP (Zac) says to use their lube and hand-tighten the stud and then torque the nuts. No re-torque required.

There is no specific application for our cars, nor is there a stud of the same length as ours with 1.25 pitch on two ends. The person who came up with this kit took a stud with on one end the 1.75 pitch, which on the design application is screwed into the block, and on the other end the 1.25 pitch, which on the design application is the end with the nut which is torqued. We reverse this on the N9T, screwing the finer pitch into the block, and using the coarse thread and nut to torque the head.

There are two machine shops whom Roger has consulted on this matter, both concur that the torqued nut should be the finer pitch, as in the original design application, which is why they both say the installation failed. This is not worth retrying. I am going to have to eat this kit, because Zac has informed me that they will not refund/credit if the parts have been installed.

I believe I am being fair to ARP: apparently a $200 set of studs is not worth as much as the bad publicity they are about to receive, gratis from me, up here on the Intertubes.

And once it's up, it's forever.

[andrethx]

bill, i've been following this story, and i've understood everything (pretty much) up until now, but this last post is puzzling to me....if you don't mind, i have some noob questions.

as i understand it, the OE bolts have threads only on the bottom, the part that screws into the block...the top has a hex head, and one screws the fastener in only once, at which time it is torqued (using the correct order of tightening, torquing procedure, etc.).

the bolts that you got from ARP are not like this, they are designed to screw into the block hand-tight, then one attaches the included nut to the upper set of threads and *that* nut is torqued to the proper spec (again, following proper procedure). the two ends of the bolt from ARP have different thread pitches.

from what you've written, it sounds like roger (or some guy at his shop) screwed the bolts in upside-down (i.e., in the opposite direction intended by ARP). it also sounds like the direction specified by ARP is the opposite direction that an experienced mechanic would expect from looking at the bolts. so the bolts were unable to hold the proper torque, causing a leak (at best) and/or damaged threads on the block (at worst). is this correct?

if so, and here's the noob question, how is this possible? wouldn't one know the proper end of the bolt to put into the block, based on the threading of the OE bolts that were used previously? and wasn't the nut threaded to match the "top" end of the bolt? i'm not trying to be a smartass or second-guess roger or anything, i'm just trying to understand what happened...

andré

[billbranch]

André,

Sorry for the confusion. Yes, the OEM set-up is bolts. These run through the head and into the block. Pitch is 1.25.

The studs, this latest thing, gives greater clamping power blah blah. If there were nothing attached to the head or no reason to monkey with it side to side or front to back someone could just screw in the studs and drop the head right on.There are two pitches on these studs, 1.75 and 1.25. My people are all telling me that the torquing nut should be the finer pitch, which is what the original design intent was. But ARP's person 180°-ed these things, putting the 1.25 pitch into the block, and the 1.75 at the nutted end. If there had been a stud available with the 1.25 at each end with the right length, that is what we would have used. There is no application in their book for the N9T engine.

No one installed the parts wrong.

My mechanic Roger is not a high school kid doing his first rebuild.

The machine shop here is paid to work on NASCAR engines.

The third person who says ARP is all wet I can not identify because of his notoriety. Let's just say he's an owner of an automotive machine shop with whom Roger and I have dealt for years.

Bill

[Bean]

My apologies to you Bill, I had no idea the studs that were provided had 1.75 pitch threads on it, and assumed both ends were 1.25 as that would make sense. The fact that they provided the 1.75 pitch nuts to fit the studs is by definition an admission of the error, since 1.75 is WAY too course for any sort of accurate torque application, nor is it suitable for long term.

I'm going to contact ARP as well as I've been singing their praises and if they don't make it right then I'll have no qualms about spreading the word as well.

*Edited after Zak from ARP called me.

Rabin

[Bean]

Last night immediately after posting my reply, I went to the ARP website and sent in an e-mail via their contact us form. Today Zach called me at work to set the record straight, as well as offered to help figure out the best way to proceed.

First things first - these numbers that are posted are for items that simply fit, and they were most likely sourced by someone by ARP simply by dimension. ARP has never put together a kit for the N9T** motors, and these numbers were most likely worked out just as a possible solution.

Facts:
The studs listed here are intended to have the 1.75 pitch threads threaded into the block, and the 1.25 threads are what ARP usually provides for their nuts and their torque values.
They do not offer any studs in these dimensions, or even close to these dimensions with both ends being 1.25 pitch.
Since these parts were specifically selected, the use of them is at the owners own risk.

That said:

When discussing my concerns over the pitch differences and how they would affect the accuracy of the torque settings, he said they actually put the studs into their load cell and measured the difference in clamping load while torquing the 1.25 pitch nut versus the 1.75 pitch nut, and the clamping loads varied by less than 500 psi. 500 psi was less than their tolerances between studs. (190 ksi rated).

Possible solutions:

• Use the studs as is, but use some Nord-lock washers to ensure the nuts stay torqued. (My suggestion after seeing Nord-Lock washers work)
• http://www.nord-lock.com/products/wedge-locking/washers/introduction/
• http://www.nord-lock.com/products/wedge-locking/washers/torque-guidelines/
• Drill out the block holes and install threaded inserts so that the studs can be used as designed
• http://www.timesert.com/html/universalheadbolt.html
• http://fulltorque.com/ffbs.htm

*ARP does have studs in similar dimensions that have 1.50 pitch for the head, so this would be a better choice. In Bill's case since he has the 1.75 pitch studs already, he would have to use the 1.75 pitch thread inserts.

** If you look at the universal headbolt kits from Time-sert - you can see there's a kit for M11x2.0 head bolt inserts.

Summary:

From what Zach found with the clamping force generated with the 1.75 pitch nut, even though the stud is reversed, the studs should still work fine. Course thread fasteners are harder to get more accurate torque with, and they would theoretically be more prone to possibly loosening over time - but if installed and torqued properly they should not have caused the immediate failure Bill's engine saw. In my opinion - Nord-Lock washers would be extra insurance insurance that those 1.75 nuts stayed torqued, and would be a minimal cost solution with no extra work. (Zach knew of Nord-lock washers - but could not endorse their use since they've never done testing)

The "proper" way to it, would be to change all the head bolt holes to M12x1.50 with GOOD threaded insert system like the time sert kit (NOT helicoils - too small), and then use the ARP studs as intended and designed.

I'll update with more once I confirm with Zach what the part numbers for the 1.50 bolts would be, as those would be a better stud to use in reverse. Not only is the 1.50 better, it's close enough to not warrant redoing all the head bolt holes with inserts, and if you really wanted security I would then run Nord-lock washers with the nuts and call it good.

Rabin

Edited January 18, 2013 by andrethx
fixed web links

[billbranch]

Rabin,

You know I appreciate all of your efforts. I also have never ruled out the possibility of installation error, and shall ask Roger just how much research he put into these things pre-install, I think he'll catch on. I'll be going over all of these alternatives with him.

It would be interesting if Nick were to weigh in with how his use of the studs worked out.

Bill

[billbranch]

I spoke with Nick's father this morning. They have never installed the ARP studs. They had bought them because they planned on running 18-20 pounds of boost. We, therefore, have no history of success or failure for these parts. He is also of the opinion, having seen the results of welded heads, that the heating of the aluminum might well render the metal softer, and the smaller washers which we use with the studs might "sink" into the metal.

The gang at the machine shop rebuild engines and know ARP very well. In fact, the owner of the machine shop is in communication with ARP today. Maybe we'll get more feedback.

[Bean]

Spent more time researching any other options, and I can't find anybody that makes high tensile M12x1.50 nuts, so that would explain why ARP went with the 1.75 pitch threads - because they have the matching nuts. So the stud you have Bill looks like the only option unless a nut can be found to cope with the high loads.

The only way to use their M12x1.50 ended studs would be to Time-Sert the block to M12x1.50 bolt holes and then use the studs as designed with M12x1.25 nuts up top. If I can get an overall length of the studs it might be easier to find a better price on a complete kit based on another motor, but for now options look pretty limited, and only if you re-do the head bolt holes in the block if you don't want to use the 1.75 nuts.

Rabin

[billbranch]

The head was tested again at the machine shop.

The head was sent to Eriksson Industries and tested Thursday.

No cracks.

We are proceeding with the re-installation of the head using the factory bolts because, as in accord with the verbage above, we proceeded at our own risk and peril in using the studs and achieved the worst possible outcome. As soon as Roger told me how loose the studs were when he broke down the engine, I knew it was installation error or installation error.

I am very certain the head is good because the head came from a car which was junked with four broken pistons; I guess it was running pretty good.

Mr. Holm believes he has a OEM Peugeot head gasket, and all of the parts will be back at Roger's Monday for reassembly.