ARP rod bolts for 3,0 ..Torque question

[MaRu]

I bought my ARP bolts some time ago. I wrote down how to torque them, but ...now of course i canīt remember anything.

Does anyone now how to do this? How much NM do the get? Engine is a 3,0 Carrera. (I think the rods are same as SC)

Thank you, regards

Malte

[irobertson]

The instructions are available on the ARP site.
Go to "Instructions" and enter your part number.

[faverymi]

Don't forget their special torquing grease

[911pcars]

This current thread might help:

arp rod bolts?

Sherwood

[boyt911sc]

Here are my data from my last ARP rod bolt installation. First column is at 50 ft-lb torque and second column is the 'stretch' values. You need to apply the recommended ARP grease for consistency. Using the recommended torque, yielded a stretch value very close to spec. Was very satisfied with the results.

@50 ft-lb. Stretch (")
8342----- 0.0101
8356----- 0.0095
8378----- 0.0097
8260----- 0.0091
8323----- 0.0092
8300----- 0.0100
8368----- 0.0101
8359----- 0.0094
8360----- 0.0097
8360----- 0.0092
8247----- 0.0095
8367----- 0.0099

Spec. 0.0095"/0.0100"

Tony

[chris_seven]

These figures show a variation in preload or around 11% which considering that you have torque tightened the bolts is very good.

I would normally expect to see a scatter of around 30% when using torque as the measurement of preload.

Were the bolts new and if so did you run them up to torque 2-3 times to burnish the threads?

I would have tightened the bolts that didn't reach the minimum stretch a little more as they will be just a little 'loose'.

[IXjamesXI]

May I chime in with an ARP rod bolt related question since people who know might be reading this thread? I have a nice new set of ARP 10mm bolts for my SC rods.. but I can not for the life of me get them into the rod end cap.. even using a BFH. It's as if the bore in the rod end cap is just too small or the bolt is too big. The original Porsche bolts are very snug, but at least they can be re-inserted. Anyone ever had to deal with this? does the bore on the rod and end cap need to be honed to get these things to fit? I am sort of at a loss to figure this out!

[MaRu]

Thanks guy, -I found it in the meantime (78 NM I think). My problem was I didnīt had the partnumber anymore. -bolts were new

[911pcars]

Originally Posted by IXjamesXI

May I chime in with an ARP rod bolt related question since people who know might be reading this thread? I have a nice new set of ARP 10mm bolts for my SC rods.. but I can not for the life of me get them into the rod end cap.. even using a BFH. It's as if the bore in the rod end cap is just too small or the bolt is too big. The original Porsche bolts are very snug, but at least they can be re-inserted. Anyone ever had to deal with this? does the bore on the rod and end cap need to be honed to get these things to fit? I am sort of at a loss to figure this out!

Measure the original Porsche bolts you removed, then let us know.

Sherwood

[IXjamesXI]

If I am hijacking this thread, let me know and I will take it up elsewhere.. and maybe I need a micrometer to approach this correctly, but here is what I am up against..

I measure the stock bolt... 67,000 mile engine.. and I get 10.16mm


And I measure the ARP bolt and I get pretty consistently 10.17mm


Now of course, just because my handy digital calipers are "precise" to .01mm.. doesn't mean they are "accurate" to .01mm.. so this difference could well just be the tolerances of the measuring tool I have at my disposal.. But I can't deny the physical evidence that I "feel." One of these things is bigger than the other!

Just as an illustration, I can twist the stock rod bolt about halfway into the rod cap (going the wrong way of course, but just to see and feel the fit of the locating portion of the bolt.) At this point it's just too tight to go any further by hand. It's the same feel when installing the bolt the right way, halfway in by hand is possible and a little tap from a hammer would send it all the way.


Now when I try this little experiment with the ARP bolt.. I get nowhere.. a distinct "no-go" feeling.. I can't even get it to catch in there a little bit. And when trying to assemble the rods the "right" way, I can't tap it in with a hammer.. at least I haven't tried hitting them hard enough to do so, I've already tried to tap them in with an almost more force than I am comfortable with.


So I just don't know what to do. Is this something other people have had to contend with? I thought it would be pretty straightforward putting these things in, but apparently not. Will a machinist be able to free up that hundredth of a millimeter or whatever it is that I need? God forbid I end up with a loose fit in there, I can imagine that would basically mean the end of the rod, or if I installed it, the end of the engine. Does tightening the rod bolt mean it gets thinner as it stretches, but does the bore in the rod and cap also get tighter with more clamping?

[IXjamesXI]

Well a quick followup already.. just went out to the garage and tried it again.. lined it up, wiggled the best I could to set that "shoulder" into the bore as squarely as possible, and gave it a good THWACK or two. Success... it's really darn tight, tighter than the stock bolts I removed, but it's in there. Onward I guess and thanks for looking.

[911pcars]

Originally Posted by IXjamesXI

Well a quick followup already.. just went out to the garage and tried it again.. lined it up, wiggled the best I could to set that "shoulder" into the bore as squarely as possible, and gave it a good THWACK or two. Success... it's really darn tight, tighter than the stock bolts I removed, but it's in there. Onward I guess and thanks for looking.

Good. I was afraid you might have 3.2 rods in your engine (they use 9mm rod bolts/nuts). Trying to install 10mm bolts into one of those might have been interesting.

Sherwood

[AlfonsoR]

Here are my data from my last ARP rod bolt installation. First column is at 50 ft-lb torque and second column is the 'stretch' values. You need to apply the recommended ARP grease for consistency. Using the recommended torque, yielded a stretch value very close to spec. Was very satisfied with the results.



@50 ft-lb. Stretch (")

8342----- 0.0101

8356----- 0.0095

8378----- 0.0097

8260----- 0.0091

8323----- 0.0092

8300----- 0.0100

8368----- 0.0101

8359----- 0.0094

8360----- 0.0097

8360----- 0.0092

8247----- 0.0095

8367----- 0.0099



Spec. 0.0095"/0.0100"



Tony

Hey Tony, what brand and model torque wrench did you use? I too am impressed that your stretch results are fairly tight. I am looking to buy a wrench for this. Have been looking at the snap-on torqo-meter style with indication.

Thanks,
Alfonso

[irobertson]

For comparison, here are my numbers after 3 tightening sequences and measurements.
Position Stretch Torque
Bolt 1A 0.0100 42
Bolt 1B 0.0102 38
Bolt 2A 0.0104 50
Bolt 2B 0.0100 48
Bolt 3A 0.0099 45
Bolt 3B 0.0101 52
Bolt 4A 0.0103 41
Bolt 4B 0.0105 40
Bolt 5A 0.0099 50
Bolt 5B 0.0101 45
Bolt 6A 0.0104 43
Bolt 6B 0.0101 44

[HawgRyder]

My first guess would have been temperature.
It's amazing how two parts that will not go together will go if you cool one and warm the other!
Bob

[ertech]

Purchased the 10 mm by mistake I needed the 9mm ones .pm me if interested
These are new and never used

[Jeff Alton]

Have used both the 9mm and 10mm ARP bolts more than a few times. We install with a stretch gauge. The few times we checked the torque out of interest the 9mm took on average 10ft/lbs more than the torque spec and the 10mm ones within a pound or two.

Get the ARP stretch gauge. It has a very high tension dial indicator that hold easily on the bolt. Have tried a couple of lesser quality stretch gauge setups and the headache is not worth the savings....

Cheers