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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Mon, Nov-05-2018, 01:36:48 AM   #1
warpig12354
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Default Torque vs. stretch on ARP bolts

To start this off I've done bearings on S54 and several S65s. It seems with the S54 (online anyways) it's more frowned upon to use a torque spec, thats provided by ARP with the bolts, over a stretch gauge. But with BE bearings/bolts on S65s for example most people I've had experience with are using the specified torque value (as I have been doing) with no issues. Is there a particular reason for this? I have no problem using a stretch gauge as thats what I did on my last S54 but like the convenience of a one time torque.

Last edited by warpig12354; Mon, Nov-05-2018 at 01:40:38 AM.
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Old Mon, Nov-05-2018, 01:44:05 AM   #2
terraphantm
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Default Re: Torque vs. stretch on ARP bolts

IIRC a few people here found torquing the ARPs to get inconsistent results. And I believe Lang found that even when the correct stretch was achieved, the ARPs provided less clamping force than OE bolts. So I'd refrain from using the ARPs on these cars altogether personally.
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Old Mon, Nov-05-2018, 03:58:00 AM   #3
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Default Re: Torque vs. stretch on ARP bolts

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Originally Posted by terraphantm View Post
IIRC a few people here found torquing the ARPs to get inconsistent results. And I believe Lang found that even when the correct stretch was achieved, the ARPs provided less clamping force than OE bolts. So I'd refrain from using the ARPs on these cars altogether personally.

When I was researching before my rebuild I read from a thread here which he measured the roundness of the rod ID w/ the bearing IIRC and w/ the supplied torque value 70ft lbs it was getting ovaled, he then used the stretch method and it was still too much force. he reduced the torque to 65ft lbs and he got almost a perfect roundness on the bearings IIRC or maybe just the rod/caps.

best way I guess if you really want to be 100% sure is to measure the roundness first. even OEM bolts will probably have some "inconsistency" problems but depends on how much tolerance BMW gave it.
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Old Mon, Nov-05-2018, 04:02:46 AM   #4
terraphantm
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Default Re: Torque vs. stretch on ARP bolts

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Originally Posted by erickrayos View Post
When I was researching before my rebuild I read from a thread here which he measured the roundness of the rod ID w/ the bearing IIRC and w/ the supplied torque value 70ft lbs it was getting ovaled, he then used the stretch method and it was still too much force. he reduced the torque to 65ft lbs and he got almost a perfect roundness on the bearings IIRC or maybe just the rod/caps.

best way I guess if you really want to be 100% sure is to measure the roundness first. even OEM bolts will probably have some "inconsistency" problems but depends on how much tolerance BMW gave it.
He had to go beyond the recommended stretch spec to get them round. The resulting torque was ~70 lb-ft, which was significantly beyond the recommended 50: http://www.m3forum.net/m3forum/showp...8&postcount=72
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Old Mon, Nov-05-2018, 08:16:30 AM   #5
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Default Re: Torque vs. stretch on ARP bolts

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Originally Posted by terraphantm View Post
IIRC a few people here found torquing the ARPs to get inconsistent results. And I believe Lang found that even when the correct stretch was achieved, the ARPs provided less clamping force than OE bolts. So I'd refrain from using the ARPs on these cars altogether personally.
That's what I hear as well + never heard of af failure on the OE bolts, so they are good to go to me. Don't worry there are many other areas where BMW f**** it, but not this one.
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Old Mon, Nov-05-2018, 02:19:29 PM   #6
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Default Re: Torque vs. stretch on ARP bolts

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Originally Posted by terraphantm View Post
He had to go beyond the recommended stretch spec to get them round. The resulting torque was ~70 lb-ft, which was significantly beyond the recommended 50: http://www.m3forum.net/m3forum/showp...8&postcount=72
The M10 version of the ARP rod bolt yes, the M11 one seems closer, recommended was 70 and got the roundess at 68 which is the one I have used on my rebuild.


Then again not sure what's BMW's tolerance in terms of roundness but the rounder the better right.


in terms of failures haven't heard anything from both OEM and ARP.

I guess as long as you check for roundness, should be fine.
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Old Mon, Nov-05-2018, 07:17:27 PM   #7
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Default Re: Torque vs. stretch on ARP bolts

The OE bolts get better roundness than you can achieve with the ARPs without measuring for roundness, and you can't measure for roundness with the engine in the car. The OE bolts also have more clamping force and are significantly cheaper. The OEs also are not a failure point, pretty much ever (I've never seen one posted here), so not a ton to gain.

Soooo... not a ton of reasons to move off stock, especially if you're replacing the bearings without pulling the engine.
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Old Mon, Nov-05-2018, 09:08:49 PM   #8
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Default Re: Torque vs. stretch on ARP bolts

Not a huge fan personally. A few years ago I was building an S54 E36 and experimented with both stretching and torquing.

ARP specs called for either 0.0065 to 0.0070 of stretch or 50ft-lb of torque; yet when I'd torque to 50ft-lb I'd measure ~0.0080 of stretch.
That just bugged me. And yes my Snapon techangle was properly calibrated and the ARP lube was applied where prescribed.

As far as I'm concerned there are no issues whatsoever with stock rod bolts so no reason to use ARP. Just grab some new OE M10 bolts.

The only time I use ARP now is when I'm looking at an early recalled S54 with M11 bolts that the dealer kindly rounded off or mangled in some way. You're supposed to reuse those but sometimes you just can't.
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Old Mon, Nov-05-2018, 09:18:17 PM   #9
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Default Re: Torque vs. stretch on ARP bolts

Quote:
Originally Posted by erickrayos View Post
The M10 version of the ARP rod bolt yes, the M11 one seems closer, recommended was 70 and got the roundess at 68 which is the one I have used on my rebuild.


Then again not sure what's BMW's tolerance in terms of roundness but the rounder the better right.


in terms of failures haven't heard anything from both OEM and ARP.

I guess as long as you check for roundness, should be fine.
Your 04 had M11s?
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Old Mon, Nov-05-2018, 09:31:33 PM   #10
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Default Re: Torque vs. stretch on ARP bolts

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Originally Posted by kaiv View Post
Not a huge fan personally. A few years ago I was building an S54 E36 and experimented with both stretching and torquing.

ARP specs called for either 0.0065 to 0.0070 of stretch or 50ft-lb of torque; yet when I'd torque to 50ft-lb I'd measure ~0.0080 of stretch.
That just bugged me. And yes my Snapon techangle was properly calibrated and the ARP lube was applied where prescribed.

As far as I'm concerned there are no issues whatsoever with stock rod bolts so no reason to use ARP. Just grab some new OE M10 bolts.

The only time I use ARP now is when I'm looking at an early recalled S54 with M11 bolts that the dealer kindly rounded off or mangled in some way. You're supposed to reuse those but sometimes you just can't.
This. But we also just give in and replace the rods most of the time. If you have one rod that needs to be replaced, finding another rod that can be weight-matched is real PITA.

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Discussing Torque vs. stretch on ARP bolts in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)