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ARP Rod Bolts Group Buy fresh thread
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924RACR  



Joined: 29 Jul 2001
Posts: 8300
Location: Royal Oak, MI, USA

PostPosted: Tue Feb 04, 2020 4:04 am    Post subject: Re: Checking the rod bolt stretch... Reply with quote

Euro924S2 wrote:
924RACR wrote:
Hopefully all can see these:
https://www.facebook.com/vaughan.scott.3/posts/10213319882546400


Cool, does that mean stock torque is still recommended when used with ARP lube?


Not likely; that was merely trying to establish a baseline for stock values...
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 903
Location: Maysville, Colorado

PostPosted: Fri Feb 07, 2020 12:37 am    Post subject: Reply with quote

Emailed in order on Tuesday. I have not heard anything back on installation stretch/torque. I have one of the previous group buy rod bolts so can compare it with the drawings for the new ones. They should be about the same as they are giving it a part/drawing number AR336-2Mod. If someone has the specs for the previous bolts it would really help.

Actually getting all the ARP bolt set numbers and installation installation figures in the Mods/Performance section would be a good idea. I'm thinking rod bolts, head studs and main bearing bolts, maybe flywheel. Any more?
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MikeJinCO  



Joined: 08 Jun 2010
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PostPosted: Wed Feb 19, 2020 12:45 am    Post subject: Reply with quote

Should be getting drawings for approval today. I'm concerned that there might not be the bolt head undercut that was on the last batch. The undercut(radius) decreases the stress riser at the corner plus having it fit in the rod better. I looked up the old threads on the forum and the 2015 batch was spec'd at 65 ft/lb torque with a stretch of .007-.009".

Looking at ARP's catalog of normally tightening rod bolts to 75-80% of yield, it be wise if when reusing bolts that the nuts be replaced as they are made from 8740 with a YS of about 180,000 psi vs the ARP2000 200,000psi. Don't use the original nuts as they would be no better than 12.9 which is a bit lower than the 8740.
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hayeslewis  



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PostPosted: Thu Feb 20, 2020 1:54 am    Post subject: Reply with quote

Can I still get a set?
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MikeJinCO  



Joined: 08 Jun 2010
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Location: Maysville, Colorado

PostPosted: Sat Feb 22, 2020 10:23 am    Post subject: Reply with quote

Got the drawings. The only difference I see is that the new bolt has a head fillet radius of .025-.030 similar to the original bolt where the previous ARP bolts have and undercut stess relief radius.
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MikeJinCO  



Joined: 08 Jun 2010
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PostPosted: Mon Feb 24, 2020 12:56 pm    Post subject: Reply with quote

I have review the bolt drawings and will send in an approval on Monday.

The significant differences are:

1. The used OEM bolt is .010 longer than what I'll call ARP336-1 the 2015 bolt in new condition. The new bolt ARP-2 will be the .010 longer. That might be some permanent deformation as the reduced top neck is .3365 dia versus .3360 on the lower reduced neck.

2. ARP has a reduced neck both upper and lower of 0.336-0.338". ARP-1 measures 0.337. The area difference between the .336 and .338 is approximately .0011" sq

3. The head on ARP 336-1 has a slight reduction to allow a flatter contact area with the rod face. Both the OEM and ARP336-2 have a slight radius between the head and the throat. Specified as .025-.030" radius.

4. The nut on the OEM will not thread up past the end of the threads, ARP336-1 will and I suppose ARP 336-2 will also.

5. With my approval I will comment that it would be nice if it could be changed improve the head face area by changing that radius without decreasing the strength or adding a stress riser. I do not have a rod with me and will examine one of the prior to sending in the approval as it may well not be necessary.
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MikeJinCO  



Joined: 08 Jun 2010
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PostPosted: Tue Feb 25, 2020 8:04 am    Post subject: Reply with quote

The order is placed. The top connecting rod hole is chamfered for the radius and too allow the ribbed section to pass thru so the radius on the bolt is not an issue.
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MikeJinCO  



Joined: 08 Jun 2010
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PostPosted: Sun Mar 15, 2020 11:49 pm    Post subject: Reply with quote

Could everyone on our buy list please send me a PM with information on how to contact you. I really need all this written down in case I should have a problem with coronavirus( I have a compromised immune system) I have heard nothing positive or negative from ARP so we are still on track.
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924-76  



Joined: 05 Jun 2006
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Location: Ontario, Canada

PostPosted: Fri Mar 20, 2020 6:08 am    Post subject: Reply with quote

PM'd
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MikeJinCO  



Joined: 08 Jun 2010
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PostPosted: Tue Mar 31, 2020 7:44 am    Post subject: Reply with quote

I contacted ARP today to find out their status. They said that ARP was still open at the moment and that the bolts are going into thread roll. He also said that they should be done in the next few weeks.
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Moparboy72  



Joined: 29 Jul 2014
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PostPosted: Tue Mar 31, 2020 8:01 am    Post subject: Reply with quote

Thanks for the update Mike!
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924-76  



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PostPosted: Thu May 07, 2020 12:06 am    Post subject: Reply with quote

Any update info?
Thanks
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MikeJinCO  



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PostPosted: Sat May 09, 2020 6:50 am    Post subject: Reply with quote

The rod bolts should be shipping on Monday, May 11.
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924-76  



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PostPosted: Mon May 11, 2020 8:57 am    Post subject: Reply with quote

That'a awesome, thank you very much
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MikeJinCO  



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PostPosted: Sat May 16, 2020 11:28 pm    Post subject: Reply with quote

I received a 15lb box or bolts yesterday. Quite pretty and each in its own protective plastic sleeve. I need to cost out shipping on UPS vs postal today. I'll be getting to people as soon as I find out. If you don't get a commercial discount, the UPS rates seem very high.

I'll send out a note with them with what I know about torque, and stretch and lube.

Basically

I would not recommend not using the standard Porsche rod nuts as they will be made from 12.9 steel(same as rod bolts)which has a yield strength of about 155Kpsi and these bolts need to be stressed to a minimum of 150kpsi That is way too close for use. The ARP nuts #ARP 301-8351 are made from 8740 steel with a yield strength of 180kpsi minimum, so for really serious use one probably shouldn't reuse them either as they would be at 86% of the yield strength and the standard proof load(no permanent deformation) is generally recognized to be about 80%.

I asked the contact at ARP what torque/stretch the bolts should be at several times and never got a reply. The torque that I found recommended for the last group buy was at 65 Ftlbs and a young fellow I have met who is a suspension designer for Fox Shocks who says that bolts are always very difficult to figure out did some quick calcs and came out at 61 Ftlbs. The ARP lube should probably be use while following ARP's installation directions from their website. Supposedly the ARP lube has better repeatability during the recommended multiple times tightening installation process than other lubricants.

I'll try to expand on that in my note.
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