Re-Using Arp Rod Bolts
 

Hello,
According to ARP, you can re-use their rod bolts.

Do you guys re-use them?

If you torque to full spec to check clearances, do you re-use them?

Les

Les,

Yes, you can. But it's best if you have a historical baseline measurement for uninstalled and installed length when they were new, so you can be sure there's been no deformation or yielding. They're meant to be re-usable, unlike factory rod bolts, but that doesn't mean that it would be a good idea to reuse bolts that have an unknown history.

They also have very specific instructions about torque and stretch procedures, as you probably know. I have reused mine, and torqued them a number of times to do clearance checks and such.

There's been quite a bit of discussion about this in the Pelican Engine Rebuilding Forum. I suggest you do a search.

Rob

Hi,
I did not measure stretch. I just torques them to spec as per the instructions that ARP supplied. I may not have to mess with them. I was just wondering and heard someone say no matter what arp says, don't re-use them.

If you use stock bolts to check clearances, do you replace them with fresh stock bolts for the build?

Les

Les,

There are many people who have reused ARP rod bolts. I've never heard of a problem, but then again, I might not have. Anyone who says "don't reuse them, no matter what ARP says" is acting on fear, not logic or data. In fact, the ARP instructions tell you you must torque them several times *before* you use them in final form. I believe this is to burnish and settle the threads so you have a reliable clamping force, but to be sure, you should talk to them. There may be a danger in reuse is if you don't have any information about their prior condition (and they've been damaged somehow). But again, you're likely to be fine.

I found (and others have found) that the using the torque wrench tends to "understretch" the bolts slightly, as compared with the stretch measurement method. To my knowledge, this isn't a serious problem, because the vast majority of people have had good performance from using just a torque wrench. Again, do a search and you'll find more about this.

If you use stock bolts, which are designed only be torqued once, then you should do all your fitment and testing with the old bolts that you don't intend to use again.

Rob

Hi Rob,
It's been a while since I put them in. Now I remember the torque up three times or whatever. They definitely torque smoother each time after cleaning up the threads with each torque. Thanx about the tips above!!

Les

Before re-using mine, I called ARP (re-used head studs). They said by all means, re-use them. The torque procedure they told me was to condition the nuts and the threads by cycling the torque 5 times before setting the final torque. Worked for me as all studs were spot on 1500 miles later.

When i used the re-torque method i did originally check the size of them..
When i fitted them without splitting my crankcase i developed a method of checking the stretch of them in place and found they stretched pretty much bang on size what they recommended!!
If you know the original length you can get a set of digital calipers in there just...measure them and hit the zero button or hold button on your calipers,,doing this confirms the size you have stretched them to and when you are trying to carefully remove your calipers without disturbing the set size you have taken if you move them on the way out it does not matter because you have hit the hold or zero button on your display!
Being a toolmaker/engineer i know that a dial indicator/clock gauge is more accurate but defo if used correctly you can get your measurment within 0.001"(1 thou)

I would probably go ahead and re-use them also!!

Hi,
Good idea on the caliper. Tips and Tricks of the trade!!

Les

Les, I run my car with re used ARP's at 7500 rpm and they came out of a 9,000 rpm car making 860 horsepower. I dont know if anyone has had a sour experience but my car is still rock solid.

Thanx for the info!

Les