Tensioner stud replacment ideas, bolt replacment etc.

[malibusst]

how about Allen and anyone else who needs these fasteners send me a PM and i will price them on every fastener they need

[JD74]

how about Allen and anyone else who needs these fasteners send me a PM and i will price them on every fastener they need

Wish List:

- Fancy Water Pump Hex's
- Fancy Oil Pump Hex's
- Tensioner and Idler Upgraded Fasteners
- Hex's for anything and everything you can get them for, external.

[NismoS-tune]

Hold on. They use grade 8 bolts ALL OVER heavy hauler trucks with thousands of HP and hard usage (400 ton payloads 24/7 operation) and you're saying an IDLER on a GTR that have been fine with the standard bolts they come with for the last 20 years of use suddenly shear them now?

[r3gill]

Hold on. They use grade 8 bolts ALL OVER heavy hauler trucks with thousands of HP and hard usage (400 ton payloads 24/7 operation) and you're saying an IDLER on a GTR that have been fine with the standard bolts they come with for the last 20 years of use suddenly shear them now?

I didn't wana say what you said just because some of the sponsors that deal with automotive stuff would know more about cars. But when we use a grade 8 on a tractor's exhaust manifold which glows red hot when under full load at steep incline you would think its strong enoogh for automotive use.We're talking about 600+ hp and 2200ft/lbs of torque. Not trying to be smart here but sometimes people seem to over think this stuff.

[malibusst]

or you dont see that most of us "sponsers" have seen problems, or have had problems, and are just trying to make everything better.... i speak from experience.....


- first off, the mounting stud is taking a lot more load than an exhaust manifold stud, you cannot compare the two... the mounting stud is taking an agressive load from a tensioned belt. What ive had happen to me, and have had happen on customers cars is the stud will not completely snap, but ive had almost 75% bend, JUST A BIT... even thought it makes no difference, its still a problem to me and id rather have a fastener in there that doesnt bend.....

also, my personal car, i pulled the stud out, measured... it was stretched about .077" .... yeah....

THE ONES THAT SNAPPED......

- i had many snap on me, heres my reasoning...

-First one that i saw was on a 2.6 high rev motor... we're talking 10,000 rpm's. either the shop who assembled it over torqued it, or it was a faulty fastener....
- then i had a whole batch that kept cracking on me while trying to torque them down... they were all Brand new nissan parts... either the studs had a defect, or i was superman that day....
- customers car with 157,000 kms, had to have his car towed in from sudbury.... his snapped clean against the block...

[R32GT-R]

12.9 is a good grade then? more tear, shear and bend resistant.
not just 12.9 > 8 so must be better.

[r3gill]

or you dont see that most of us "sponsers" have seen problems, or have had problems, and are just trying to make everything better.... i speak from experience.....


- first off, the mounting stud is taking a lot more load than an exhaust manifold stud, you cannot compare the two... the mounting stud is taking an agressive load from a tensioned belt. What ive had happen to me, and have had happen on customers cars is the stud will not completely snap, but ive had almost 75% bend, JUST A BIT... even thought it makes no difference, its still a problem to me and id rather have a fastener in there that doesnt bend.....

also, my personal car, i pulled the stud out, measured... it was stretched about .077" .... yeah....

THE ONES THAT SNAPPED......

- i had many snap on me, heres my reasoning...

-First one that i saw was on a 2.6 high rev motor... we're talking 10,000 rpm's. either the shop who assembled it over torqued it, or it was a faulty fastener....
- then i had a whole batch that kept cracking on me while trying to torque them down... they were all Brand new nissan parts... either the studs had a defect, or i was superman that day....
- customers car with 157,000 kms, had to have his car towed in from sudbury.... his snapped clean against the block...

Speaking from experience sounds good. I may not have given a good example by saying exhaust manifold bolts. but how about a conrod bolt...?? they're still grade 8 in my trade. When you're saying agressive loads you should also consider the vibration caused by diesel engine. There's many factor that goes into this but my point is you cannot say "GRADE 8 WILL SNAP" Sorry I cannot stand by that.

[disrupt]

Some food for thought.

SAE (society of automotive engineers) fastner grade.

typically you can tell the grade by radial marking on the head of the bolt. but they choose to make that not simple. a grade 8 fastener will have 6 marks and a grade 5 will have 3. marks plus two equal the grade.

grade 5 has an ultimate tensile strength(uts) of 105,000 - 120,000 psi depending on the thickness.

grade 8 has a uts of 150,000 psi

Metric fastener grade.

typically the fastener head is marked with a number 8.8 9.8 10.9 or 12.9

the first number indicates the uts in mega pascals.

8.8 equals 800 mpa which works out to be around 116000 psi. same as a sae grade 5

10.9 is 1000 mpa which works out to be around 145000 psi same as a sae grade 8

12.9 is stronger that a sae grade 8. around 174,000 psi

So far all the strengths have been ultimate tensile strength which is in tension or pure pulling force the fastener will stretch or deform (yield) and fail if the stress reaches this number.

Yield strength is lower than uts typically by 20% but this percentage varies from material to material and process to process how it is made, heat treated, etc (this is a huge topic)

So yield strength is the allowable stress that the material can be subjected to with out damage.

things to think about with bending forces. bolts in bending should be smooth or not threaded across the entire length. no threads typically means the shaft is a little thicker and also doesn't have valleys for a crack to start in.

this is just the tip of the ice burg when is come to engineering and manufacturing.

I hope this helps a bit. I am hung over so i hope it makes sense.

[r3gill]

very good info. On another note lower grade bolts are used on things such as frames just because they do need some marginal movement for two parts attached by a fastener. Higher grade risks of shearing the bolt completely of because of tensile materiel and wont allow movement. So that's another thing to think about.

[NismoS-tune]

why not get some ARP L19 or aerospace studs for the whole car? I'll be ok with the studs the Mine's, tomei, hks cars use since I'm not putting my car through nearly as much strain. At most, I would do a grade 8 bolt unless a cheap upgrade kit came around.

I wonder what the driveshaft bolts are... yep, not even grade 8, better change those too.

[R32GT-R]

when you are running 280 deg high lift procams you want a little extra room for error.

why chance 2 dollars vs 5 when a 12,000 dollar motor is at stake.

[NismoS-tune]

when you are running 280 deg high lift procams you want a little extra room for error.

why chance 2 dollars vs 5 when a 12,000 dollar motor is at stake.

Sorry I was lost. Didn't know the camshafts affected the Idler . You're running L19 headstuds or better? Will you be using better bolts for the cam gears too? Just curious, maybe I should drop $100 worth of grade 12 bolts in my car since it's old.

[R32GT-R]

sarcasm is the lowest form of wit

[mcfly]

why not get some ARP L19 or aerospace studs for the whole car? I'll be ok with the studs the Mine's, tomei, hks cars use since I'm not putting my car through nearly as much strain. At most, I would do a grade 8 bolt unless a cheap upgrade kit came around.

I wonder what the driveshaft bolts are... yep, not even grade 8, better change those too.

L19 suffers from hydrogen embrittlement, since you recommended it you should use one on your engine, let us know how it goes.

[NismoS-tune]

L19 suffers from hydrogen embrittlement, since you recommended it you should use one on your engine, let us know how it goes.

Since I don't know much about cars, I am using L19 headstuds based on research from the top GTR sites (SAU/GTROC) unless I find something better. I'll be happy to see 20,000km before the next rebuild. Lots of the worldwide GTR guys use them which is good enough for my wee build.

ARP's L19 material (comparable to A1 Technologies H11 Tool Steel) is a premium steel that is processed to deliver superior strength and fatigue properties. L19 is a very high strength material compared with 8740 (standard ARP headstuds) and is capable of delivering a clamp load at 260,000 psi. It is primarily used in short track and drag racing applications where inertia loads exceed the clamping capability of ARP2000. Like most high strength, quench and temper steels - L19 requires special care during manufacturing to avoid hydrogen embrittlement. This material is easily contaminated and subject to stress corrosion. It must be kept well-oiled and not exposed to moisture.

I'm not manufacturing these so I don't have to worrking about special care there but is moisture and not so well oil a regular issue on a summer street/track car? I'm learning so I ask.

Just so I understand, you're using stronger studs on your high powered car or simply the ARP2000 ones? According to some of the GTR gurus on SAU, head lift does happen after 700hp with 2000s and they go to L19.

Maybe I'll just kicking a few bucks for some ARP Custom Aged 625+, I recall Allan saying those were better for street and he works hard for what he learns unlike my lazy ass.