sayanthan

E39 M5 rod bearing shells and conrod bolts question

16 posts in this topic

I recently read a very good post written by Mr Vanos covering this. Apparently ARP bolts can be used in the M5, and certainly do no harm, however he said that the standard ones are more than up to the job and have proven themselves to be reliable even in superchanged applications.

 

ARP do not list the E39 M5 however, the M3 ones are the correct length, pitch etc so they are used for those who insist on them. The post is on his FB page if you are interested to read the full write up.

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1 hour ago, Jameswsb said:

I recently read a very good post written by Mr Vanos covering this. Apparently ARP bolts can be used in the M5, and certainly do no harm, however he said that the standard ones are more than up to the job and have proven themselves to be reliable even in superchanged applications.

 

ARP do not list the E39 M5 however, the M3 ones are the correct length, pitch etc so they are used for those who insist on them. The post is on his FB page if you are interested to read the full write up.

+1 ! 

 

Stock bolts are more than up for the job 

 

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I have zero experience withe the BMW engine so can't comment on that but I suspect the OEM bolts are fine, but I can say the tightening procedure is different. I used these back in the day and you don't torque them down you tighten them until a given stretch, it was .005" on a steel crossflow rod, there is a tool you cam buy with a DTI but I just struggled with a mic.    

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On 13/04/2017 at 11:21 AM, Jameswsb said:

I recently read a very good post written by Mr Vanos covering this. Apparently ARP bolts can be used in the M5, and certainly do no harm, however he said that the standard ones are more than up to the job and have proven themselves to be reliable even in superchanged applications.

 

 

 

 

Bang opposite to the information to gave my mate Mike who took his M5 there for the vanos doing - When mentioned that there was an ESS charger ready to go on, Mr Vanos was insistant that he had ARP bolts fitted..........

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How odd, if it was a while ago maybe he was erring on the side of caution before the stock bolts had proven themselves to be capable under such conditions. I think I would insist on them if I was fitting an FI setup simply because they aren't that expensive and would be worth doing 'while you're in there'.

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5 hours ago, sayanthan said:

I'll probably go oem. Too many factors to consider with ARP

Sent from my iPhone using Tapatalk Pro

What set are you going for? RK, Evolve?

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More HP doesn't stress bolts. Higher RPM or constant high RPM and harsh off throttle work does.

I read somewhere that as the tightening procedure is different to stock bolts it could deform the cap.

I am going supercharged and I've used stock bolts.

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tightening procedure has nothing to do with distorting caps, purely rod stretch, for which you need a stretch gauge, failing that there is a torque setting specified, I'm only using ARP's in my 240 bhp 2.2 Citroen as they came with the rods :D

 

the rod distortion is common as many neglect to clearance the rod with a chamfer and sometimes a larger counterbore is required to clear the slightly larger shank under the head of the bolt, many oem bolts don't have this shank and radius.

 

 

unless you are pushing well beyond the design spec of the oem bolt then oem will more than suffice, this is highlighted with RPM not boost, boost compresses the rods, rpm stretched rods and bolts, if the bolts are the same as the S50 then a standard 7k limit of the S62 is well under what they can go to safely (7700+ afaik)

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If you over tighten the bolt I'm pretty certain you can start to oval it?

When you say rod stretch what do you mean by that?

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I think he meant bolt stretch. You can definitely distort the rod bore by overthinking,anyone who has the ability check and resize rods will tel you that. That's why we use a boring plate when boring a cylinder to simulate the amount of distortion the fasteners create, the same applys to a rod.    

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OEM ones would be fine. I had my bearings done on my e39 M5 by CPC at 48k and they used stock bolts. More than up to it.

 

cheers

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