Problem with APR rod bolts

[Lugnut28]

I am having problem with APR rod bolts stripping the threads out of my rodson the 3rd time you to tourque them. They will torque OK the first 2 times but when you back them off for the 3rd time some are really stiff to turn and they are the ones that strip.. I turqued then to 40# and then to 50. The ones that strip torque OK to 40# but strip before you get to 50#. I took a rod a to the machine shop and they checked my torque wrench and it was dead nuts on. They checked the stretch and it only stretched .005 at 50#. APR recomends .006 to .0064 nstretch. To get that much stretch I would have to tourque them way more than 50#. Is anyone else having this problem?

 

[tc86gn]

I think you are torqueing them too tight. I have ARP's and the machine shop recommended torqueing to 40. Why are you torqueing them 3 times? Or is this just in increments?It is my understanding that after they have been torqued 3 times they should be replaced anyway.
Also I am confused a little. Are you saying that you are torqueing them till you get a specific stretch?
QUOTE
APR recomends .006 to .0064 nstretch. To get that much stretch I would have to tourque them way more than 50#. Is anyone else having this problem?

 

[Lugnut28]

A quote from ARP webpage"The friction factor changes from one application to the next. That is, the friction is at its highest value when the fastener is first tightened. Each additional time the fastener is torqued and loosened, this value gets smaller. Eventually the friction levels out and becomes constant for all following repetitions. Therefore, new fasteners should be tightened and loosened through several cycles before applying final torque. The number of times depends on the lubricant. For all situations where ARP® lubricants are used, five cycles are required before final torquing.

The Documentaion that comes with the APR bolts give you spacific directions on how to torque them. 3 torque cycles. APR recomends measuring bolt stretch rather than torque specs. .0062 -.0066 stretch or 50# each time

 

[tc86gn]

Let me know how much torque you have to put on the rod bolts to get this specific stretch. Never heard of torqueing a rod bolt to a specific stretch rather than a specific torque. If they are stripping out then the procedure is suspect.
Save some money and time and torque to 40 or some guys go 45.
I think I remember a post where REDS Hot Air torqued his to 45.
He runs the hell out of his and I don't think he has a problem.
I have never torqued rod bolts like that way you described and I am a 20 year experienced heavy equipment mechanic and garage junkie after work and never had a problem yet.
It does not matter what you have read. If they are stripping out then they are being torqued too much. PERIOD.
Get some new rod bolts and the lube of your choice and torque to specs and not to stretch.

 

[HellOnWheels]

Problem with ARP rod bolts

What lube are you using? If you use ARP's lube-typically the torque is considerably less than using oil.

HellOnWheels

 

[Joe Tiano]

Hmm...i've used ARP rod bolts in a few motors..1.70 arp rod bolts torqued to 50# with arp lube..never stripped a rod.....do you have the 1.50 or 1.70 uhl???..somthing is not right here! joe

 

[REEDOG]

Using a stretch guage is the recommended way to torque a rod bolt. The torque value is far less accurate than measuring actual bolt stretch. In most situations the threaded end of the bolt cannot be reached with a guage therefore a torque wrench would be the only method in which to put the proper amount of stretch on a bolt. ARP recommends fully tightening and loosening the fastener (considered a cycle) 3 times to "break in" threads. I would suspect the accuracy of the torque wrench. I have mine callibrated at work, we find some that are more than 20% out. Maybe try a different wrench?

 

[Lugnut28]

I am using 1.7 bolts with APR supplied Molly Assembly Lubricant. Torqueing the first rod seem like a lot of pulling than was expected. I first snugged the bots with a rachet to start, and then I went to torqueing to 40# which was GM spec. On some I was concerned because after torqueing to 40# some took more than 1/4 turn to got to 50# while others were tight at less than 1/8 mure of a turn, all on the 2nd cycle of tightening. The first 3 torqued to 50# but the 4th stripped out. I stopped went to my machine shop for help and had my torque wrench checked there by inch pound device and was 2 inch pounds off at 50# torque. I think that is pretty good for exactness. I checked a Husky that I brought home from work that was just taken out of the box incase mine was bad and that was off 1 # at 20#, 3# at 30# 40# and 50#.
Their concern was with after the 2nd cycle they removed the bolt completely and had to use a wrench to get it all the way out because it had become too tight to take out by hand. When the same bolt was put back in the same hole you could only tighten 2 to 3 turns and then had to use a wrench for acouple of turn and then became easy.

 

[Intercooler]

I guess I will have to get my sheet out again but I thought the spec was 70 ft.lbs.?

 

[FJM568]

What did your machine shop torque the bolts to when the resized the rods???(You did resize your rods, didn't you??? )

If you don't torque them to the same torque that the machine shop used when resizing your rods, then the big end on your rods won't be as true as when the shop did them...Any more torque and any less torque will have the big end slightly distorted than when machined...Also, when resizing, the machine shop should have used the bolts that you were going to use to put the motor together with...

 

[gofstbuick]

What did your machine shop torque the bolts to when the resized the rods???(You did resize your rods, didn't you??? )

What FJM568 says is exactly right. Every engine I have built (and I'm no expert), the machine shop provided the torque spec for my resized or new rods. And I torque the rods with the bearings installed to check the clearance measurements between the rods and crank. I then install the main caps (with bearings) and check the clearance measurements between the main cap and crank. IMHO, I assume you're using snap guages and a micrometer and not relying on plastiguage After verifying the torque and clearances for the rods and main caps, I torque to those specs. Any changes, I would either verify with the machine shop or recheck clearances at the different torque specs.

 

[Chuck Leeper]

Torque problemz??

If these are stock rods, then the torque values shown on an ARP chart most likely are waaaayy too high. I say this for 2 reasons:
1. The stockers are cast and NOT near the thread strength of a steel rod.
2. If the holes on the caps have not been chamfered to accomodate the under head radius of the fastener, then you are wedging the bolt radius into a non-conforming area..NOT good for torque accuracy or for minimizing material displacement.
Failure to chamfer the holes will allow the edge material to be pushed into the hole, thus wedging that matl against the bolt shank...

If the bolts are "stripped", it's most likely that the threads in the rod, [see #1] NOT on the bolt are damaged and the rods are junk...

lastly, the ARP instructions tell us to reduce the torque values when using lubes other than 30 wt engine oil..

My story and I'm stayin w/ it!!

 

[Lugnut28]

The machine shop resized the rods,chamfered the holes, torqued them to 50#. We were just talking that when he torques bolts with oil vs. molly lube the torque vaues are less with molly. The threads appear to be pulled from the bottom of the rod hole. When I back the bolt out all the way the threads come out like a spring, all together.
The directions read" If you do not have a stretch gauge follow these steps using the ARP Molly Assembly lube. After rods are installed into the motor, torque bolts to 50 ft.lbs.loosen the nuts. torque to 50 ft.lbs again. Loosen the nuts and torque to 50 ft.lbs a third and final time. That makes 4 cycles including torqueing to resize the rods. Also what do they mean by loosining the nuts, I have rod bolts???
Am I the only person who has had problems with this, and do others directions say the same as mine about torquing?? The people who have their machine shop tell them what spec to torque to have APR rod bolts and whare do they get their specs from??

 

[gofstbuick]

During the resizing process, the rods are torqued and resized. In order to get the clearances correct, that torque value should be matched. On my SBC, , I recieved my C/A rods with ARP rod bolts from the machine shop with the rods torqued to 55#. The torque spec for a SBC rod bolt is 45#. But the correct clearance is acheived a at 55#. It was also stated on the receipt and spec sheet (along with other spec info) that I received from the machine shop. Loosensing the rod bolts (to install the bearings and check clearances) was 55# of torque, the same spec I was told by my machinist. I set my rod bolts to this spec. My Buick engine has stock sps rod bolts, the machinist resized and returned those rods torqued to spec and I checked clearances and assembled at that spec (rod torque spec and other important info noted on the machine shop receipt and spec sheet). I assume your machinist torqued your rod bolts to 50# and check clearances, and if so, why did he/she not have a problem. Or what was done differently. I'm not trying to sound like a smart alleck, but just wondering

 

[Chuck Leeper]

Torque??

The first 4 cycles should be done in a rod vise to prevent the caps from being twisted when the torque is applied.
Also, the machine shop should have retorqued the bolts more than just when they were resizing them. A resized rod that is not loosened, checked for out of round and resized again, if not dead on,, most likey will be out of round once the bearings are inserted and the engine is assembled. This will reduce the desired brg clearance,[at the parting line] and that reduction can be the difference in a brg failing or continuing to live.. BTDT!!
When the rods are torqued in the engine, they must be "shimmed' w/ feeler gauges to prevent the caps from being pulled,[twisted] off location and thus mis-aligning the brg shells.
Next.. You may have the WRONG directions... As you said, the inst said to "loosen the nuts" and re-torque.. That is a steel to steel contact and as I said in my previous post, the stockers are cast, and as such, are much weaker in the threads than a steel rod.
The key to the directions being wrong is the reference to the stretch gauge. A stretch ga. is used on a nut and bolt combo, not on a bolt into thread combo.
Did the shop give you the original tech sheet that comes w/ EVERY set of ARP fasteners??
I'd certainly call ARP [805-981-1329 and ask

Bottom line is: these rods are JUNK and using them after the threads are pulled is asking for a membership into the DOTC club!!

 

[Lugnut28]

Last night on an extra rod we torqued the bolt to 50# and took it out.It came out fine,smooth and easy. We put the bolt back in the same hole and retorqued it to 50#. When we loosened the bolt it was much harder to turn then when it was done the first time. When we went to start the bolt for the third time it went in a couple of threads easy and then we had to use a rachet. It seems like the more you tighten and loosen them the worse they get. It seems that after you torque it more than once the threads degrade and get worse untill they pull out. Another crazy thing is that when we had a hard time threading the APR bolt in after second torquing a stock both threaded back in no effort at all.
As far as direction it has the part # right on top so I don't think it is the wrong directions mabey the directions are just incorrect.
I don't want to cause any hard feelings with anyone, its that I don't understand that if so many others use these why is isn't this happening to them with stock rods??

 

[1badTTA]

I used the same bolts on my engine and had no problems, I had to disregard the instructions since they are not for a buick, but a SBC or whatever else. I torqued mine to 30, loosened then 40, loosened, then 45 and I had no problems. To me it almost sounds like someone ran a tap through your rods and removed too much thread and now you are pulling what is left of the thread.

Just my $.02, But I wouldn't be using those rods ever again.

 

[tc86gn]

Lugnut,
You are not creating hard feelings at all. There is a lot of advice on this post to choose from. We are all just trying to help you out.
One thing is for sure to me. If a good rod strips out, and the threads were fine before you put the bolt in,then you are torqueing them too much.
Also I wouldn't be using those rods or bolts. How many times have you torqued them? Too many times.
1 Bad TTA hit the nail on the head. In the end it is your decision and motor.

 

[Lugnut28]

See if this link works http://community.webshots.com/user/lugnut28

Should be copy of instructions

 

[Mike Licht]

How are you putting the stretch gauge on? I just tried and every one I have will not fit the Buick Rod. A Chevy rod uses a nut a bolt where it is very easy to fit the gauge on both ends of the bolt to measure the bolt stretch while torquing (you must use a wrench) FWIW I have always just torqued ARP's to 40 and never had a problem. I use moly lube on the threads and under the head.
Mike Licht