Torque decrease for lubricated bolt

http://arp-bolts.com/pages/tech-arpultratorque.shtml
http://arp-bolts.com/pages/technical_installation.shtml
It is worth reading the info above from the ARP web site on assembly lube, and differences in tension in a bolt that has been used once or 10 times. ARP bolts are generally used in critical areas such as conrod cap bolts. A set of conrods that I recently purchased had specific instructions that the ARP bolts should be tensioned and removed at least 3 times prior to final assembly.
What is also clear is that if the same bolt is tensioned dry, oiled, or lubed with arp ultra torque, that with the same torque wrench reading the bolt will exert a different clamping force in each case.
ando

Ok I give too wakeup, where we can not measure the fastener stretch a T-wrench click or strained joint crackle both work about as well on Commandos, ie: both will need re attending to many times and each new twist polishes up the twist friction vs stretch ratios into similar ranges of uncertainty. One of the downsides of my education is lack of trust in indirect measuring methods, until error range gained by pure trial and error with a back up direct measure or a destructive level reached.

While on this subject the small front barrel bolts and the front down ward head studs give me the willies to nip up to stay sealed and not pull through.

I agree! dependant upon lube factor's
Plus a vairable clamp pressure if the bolt underside head is dry or oiled , also if a washer is used. and the speed the wrench is used...it goes on

If a Bolt requires 2% stretch ,i would guess 1.5% -2.5% for most is "Good enough" yet the differance will be differant on a torque wrench. Last week i installed a slew ring, M16 cap heads,the old threads where worn, it had come loose at sometime , so i set the wrench lower, 200 newtons/metre , after a tightening a decided to change the setting to 225 newtons , the wrench clicked off with no increase in turning,[10% more on the scale]] i think the original tightening from scratch had gone behond the original setting, i bet most engine builder's have seen this :?:
It's the law of motion, once a body is in motion the force to keep it moving is less than the force to start it going again. So when you have torqued up your flywheels you need a "lot" more pressure to move the bolt" just a wisker more"

ando said:

http://arp-bolts.com/pages/tech-arpultratorque.shtml
http://arp-bolts.com/pages/technical_installation.shtml
It is worth reading the info above from the ARP web site on assembly lube, and differences in tension in a bolt that has been used once or 10 times. ARP bolts are generally used in critical areas such as conrod cap bolts. A set of conrods that I recently purchased had specific instructions that the ARP bolts should be tensioned and removed at least 3 times prior to final assembly.
What is also clear is that if the same bolt is tensioned dry, oiled, or lubed with arp ultra torque, that with the same torque wrench reading the bolt will exert a different clamping force in each case.
ando

Click to expand...

Well I guess Im the idiot that started this so perhaps Im allowed a final say.
Looks to me that the subject has been well aired and good points scored all around.
Perhaps there is some amount of old school v new boys too. Today, powerful diagnostic
electronic tools are the heart of a tool box, in my time leading edge was a timing
light and a bore scope. Im sure some guys dont need a torque wrench but then having
it isnt a drawback, rather an additional tool in your arsenal. Experience always helps
but so does training and book learning.
My torque wrench is one of the first pricey tools I bought and Id never torque
without one.
The Norton has to be one one of the worst thought out stud and bolt layouts on a bike.
The center front lower stud has very little purchase on the alloy and a lot of fine threads
above. The head studs dont come from the factory with inserts. Im with hobot on
this at least!
Oh and the allen bolts on the 850: buried away so you get to torque them only once.
Suppose that is why they are 30 pounds.....

If you want to find out what tension is actually being applied when tightening a fastener you need a strain gauge of some sort. The rest of this thread is just farting in the wind.

+1 - and the usual suspect(s) is producing the most stench...

JimC said:

If you want to find out what tension is actually being applied when tightening a fastener you need a strain gauge of some sort. The rest of this thread is just farting in the wind.

Click to expand...

An interesting subject. Years ago when I was in the fastener business one of the tools I used was a Skidmore model P strain gauge. It showed the actual force applied to a bolt when a specific torque was applied. A high strength bolt and nut was torqued to the recommended spec and the gauge registered 9,000 lbs. If the assembly was loosened and re torqued it would register 6,000 lbs. This was due to the threads in the nut becoming distorted. Loosen the assembly again and reverse the nut and you were back to 9,000 lbs. Using a higher strength nut lessened this effect. Here we are today using questionable fasteners in cast iron, steel and aluminum that is forty to fifty years old and perhaps even older in some cases and expecting to get consistent reliable results! I personally use a torque wrench but still like to get a feel for the force applied. Many aspects of a complicated subject have been touched on in this thread but it still often ends up, when working on old bikes, tightening until it feels right and fingers crossed it doesn't strip and need further repairs.

JimC » Tue Jul 30, 2013 6:50 am
If you want to find out what tension is actually being applied when tightening a fastener you need a strain gauge of some sort. The rest of this thread is just farting in the wind.

Click to expand...

Yep sir nothing beats objective direct measure of what matters most in fasteners. In my defense of my shade tree attitude how many like me have graphed torque reading vs stretch in rod and flywheel bolts? I try not to poop in my pants in public by mistaken ignorant conclusions. Can anyone else off their cuff quote the variable stretch measures seen as torque is stepped up to full stretch, after first backing off before running back up, till click? I await others objective measures to compare mine, that do not depend on T-wrench as main indicator.

My awareness of mis leading t-wrench variables has increased by at least double by reading the reports, which of course is a bit crazy making on which logically valid points to actually depend on. What matters to me besides not over stressing is the best all around clamp mating that I can get while putting a T-wrench on to calibrate it directly for each fastener's effect in its area and on others some distance away.

So I pinged these guys and have 3x5" samples on the way but too small to cover whole head, so we'd need to collect $150 and get decent sheets of it to spread around and really learn something. Ping em for your own sample too.

Thanks for speaking with me. I mailed 2 samples, Super Low 70-350PSI and Low 350-1400PSI for you to try. I have also attached information on film analysis, you can return the samples for a free analysis. Last I have attached information on Tactilus. Let me know how the samples work, and if you have any questions, please call.

Best Regards,

Bob Budney

Application Specialist

Sensor Products Inc.

300 Madison Ave.

Madison NJ, 07940 USA

Phone: (973) 884 -1755 ext. 5966

Fax: (973) 884 -1699

bbudney@sensorprod.com