Loosening rod bolts

General engine tech -- Drag Racing to Circle Track

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DaveMcLain
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Re: Loosening rod bolts

Post by DaveMcLain » Sat Feb 03, 2018 9:49 am

mag2555 wrote:
Sat Feb 03, 2018 7:29 am
Not a issue as long as you fill the side clearance gap with feeler gauges.
What you really need to be concerned with in a race motor is the fact that once rod bolts have been torqued up 4 times they need to be replaced or you take a good chance of them failing dependant on how much of there ultimat strength your counting on!
Failing after four torquing cycles? Why? I'm calling bullcrap on this one.

340king
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Re: Loosening rod bolts

Post by 340king » Sat Feb 03, 2018 11:26 am

I like others use hand tools to remove fasteners. I like to use long handled breaker bars so I can get a better feel for the torque and smoothness of release. Once broken free, I typically use a speed wrench to finish the removal. About the only bolt I might rattle out is the balancer bolt. I do normally work on Mopar stuff with a 3/4" balancer retainer bolt. So it can be a challenge to hold the crank in place on a low friction racing assembly.

As far as rod bolts suffering from retorquing, If you don't exceed the plastic limit, the bolt should return to pre-installed length and be ready for more service. If you have under designed or over torqued fasteners, then some permanent/plastic deformation can occur making the fastener junk. That is why you should measure overall length before and after each assembly. in theory, as long as you don't exceed the fatigue limiting stress or cause plastic deformation you can use a fastener forever.

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Re: Loosening rod bolts

Post by CharlieB53 » Sun Feb 04, 2018 10:03 am

Prior to ARP Bolts I had read of some builders that would replace rod bolts after only three uses. Period. Cheap insurance.

This may be a good question to ask of ARP. Although I would have to suspect their answer may be inclined to sell more product.

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Re: Loosening rod bolts

Post by jed » Sun Feb 04, 2018 10:56 am

If I rember right ARP used to recommend you torque there rod bolts at least 3 times befor final assembly.
And that was with there old assembly lube.
That might have changed with there new super lube?????
Just Friday I started looking at the ARP bolt threads, under magnification, on the pulling side and on the coasting side, that's a ring gear analogy, and the threads in the rods just to try and understand the thread engagement.
I also looked at the head of the bolt and its mating surface on the rod.
I was looking for gaulding but found none on the rods I was looking at.

I don't like spinning a good bolt 200/300 RPM removing or installing it.

rustbucket79
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Re: Loosening rod bolts

Post by rustbucket79 » Sun Feb 04, 2018 8:54 pm

Unless their rod bolt literature has changed, ARP recommends replacement on any rod bolt that has gained .001" length in its relaxed state compared to when it was new.

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Re: Loosening rod bolts

Post by Morgo » Tue Feb 06, 2018 1:49 pm

If a steel component (being whatever) last some stress 10 million times then it will last forever (that stress).Basic metallurgy fact.
Aluminium has no such a stress level;it fatique every time the stress is applied no matter how small.That's the reason why somewhere like Arizona have thousands of aeroplanes stored there;the hours just are done and the plane must be discarded..
"when uncomptent order unwilling to do unnecsessary the probablity of failure is high"

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Re: Loosening rod bolts

Post by tresi » Wed Feb 07, 2018 1:10 am

hoodeng wrote:
Sat Feb 03, 2018 2:02 am
Fuel motors nearly know their own way back together!! they are assembled every time with torque wrenches and procedure , a lot of critical fasteners will have a designated amount of cycles ,also the fasteners are all high end products.I wouldn't want to be the crew member responsible for a given task, stripping or breaking a fastener and causing a rush no one wants or expects [no beer for him that night]

Cracking fasteners loose on any production engine for overhaul as has been stated by others before can give important information by feel ,all fasteners in a given type of assembly i would expect to crack off or release in pretty much the same manner .Any hanging up or doughy feel needs to be investigated ,for me anything like what i have described would see a change of fastener on reassembly, after they are cracked loose or released and backed off a turn or two a rattle gun set on minimum torque will speed things up a bit, and you can still monitor the speed and sound it back off at in case something tightens up.

Cheers.
I never wanted anyone to get the idea that things were being assembled with a rattle gun on a fuel motor, only disassembled. Fuel is a world of its own. It surprised me on what is considered normal.

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Re: Loosening rod bolts

Post by mag2555 » Wed Feb 07, 2018 6:25 am

All I am saying is that this is what I do to not have any failures , and doing so has worked.

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Re: Loosening rod bolts

Post by Warp Speed » Wed Feb 07, 2018 9:37 am

DaveMcLain wrote:
Sat Feb 03, 2018 9:49 am
mag2555 wrote:
Sat Feb 03, 2018 7:29 am
Not a issue as long as you fill the side clearance gap with feeler gauges.
What you really need to be concerned with in a race motor is the fact that once rod bolts have been torqued up 4 times they need to be replaced or you take a good chance of them failing dependant on how much of there ultimat strength your counting on!
Failing after four torquing cycles? Why? I'm calling bullcrap on this one.
It seems you call B.S. on allot of things.
Maybe get out more?!? Lol

DaveMcLain
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Re: Loosening rod bolts

Post by DaveMcLain » Wed Feb 07, 2018 3:13 pm

Warp Speed wrote:
Wed Feb 07, 2018 9:37 am
DaveMcLain wrote:
Sat Feb 03, 2018 9:49 am
mag2555 wrote:
Sat Feb 03, 2018 7:29 am
Not a issue as long as you fill the side clearance gap with feeler gauges.
What you really need to be concerned with in a race motor is the fact that once rod bolts have been torqued up 4 times they need to be replaced or you take a good chance of them failing dependant on how much of there ultimat strength your counting on!
Failing after four torquing cycles? Why? I'm calling bullcrap on this one.
It seems you call B.S. on allot of things.
Maybe get out more?!? Lol
So am I right or wrong? If I run the bolts up several times while checking messing with bearings etc do they then need to be replaced? Does that make sense?

joe 90
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Re: Loosening rod bolts

Post by joe 90 » Wed Feb 07, 2018 3:39 pm

It all depends on whether or not you're running a business that sells bolts.
False information is a good way to maximise sales.

hoodeng
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Re: Loosening rod bolts

Post by hoodeng » Wed Feb 07, 2018 5:19 pm

Hi Tresi , i didn't mean to imply the fuel engines were assembled with rattle guns , what i meant was , the fasteners in the parts trays could almost jump back to where they came from!!
If you put a timer on a fuel engine, the total running time between getting turned around is probably somewhere between two and three minutes.
{ i will stand correcting on that one!}

I probably am from the camp that changes fasteners on recommended maximum cycle count ,be it four or forty uses ,if that helps keep an engine away from a possible DNF ,it's cheap insurance.

On a race bike i worked on ,there were a number of service procedures between rounds that required the removal of various covers , from memory there were around 30-40 odd 1/4 UNC socket head cap screws into billet alloy, what was noticed was that after around 20 or so service cycles there would be random loose fasteners after a round ,the assembly process was the same so what was happening? it was noticed the plating of the fastener had worn off changing the load surface of the thread when in tension ,as the environment was always oily the installation conditions was possibly not ideal.The fix , change fasteners periodically ,,,end of random loose fasteners.



Cheers.

Warp Speed
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Re: Loosening rod bolts

Post by Warp Speed » Wed Feb 07, 2018 7:39 pm

DaveMcLain wrote:
Wed Feb 07, 2018 3:13 pm
Warp Speed wrote:
Wed Feb 07, 2018 9:37 am
DaveMcLain wrote:
Sat Feb 03, 2018 9:49 am


Failing after four torquing cycles? Why? I'm calling bullcrap on this one.
It seems you call B.S. on allot of things.
Maybe get out more?!? Lol
So am I right or wrong? If I run the bolts up several times while checking messing with bearings etc do they then need to be replaced? Does that make sense?
Some high end company's for years have had a suggested torque usage limit. Pankl suggests no more than 4 or so. Other manufactures vary. We set rod bearing clearance and do mock-up with used, cycled out bolts.
Now I know your gonna say that the used rod bolts won't give the same results during clearance checks as new, but it is proven that if the free length of the fastener doesn't change past max spec, they will give consistent results. But May be not in service, hence the recommended tightening cycle limit.

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Re: Loosening rod bolts

Post by Warp Speed » Wed Feb 07, 2018 7:40 pm

joe 90 wrote:
Wed Feb 07, 2018 3:39 pm
It all depends on whether or not you're running a business that sells bolts.
False information is a good way to maximise sales.
Ok :lol:

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Re: Loosening rod bolts

Post by digger » Wed Feb 07, 2018 7:44 pm

It depends how they are "far" tightened.

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