LS Swap Used Vs New TTY VS ARP Bolts test

[@savagenomore]

I asked an old engine builder once "when should I replace my head bolts" he said "when they break"...

[@illduitmyself]

grampa never crammed 20lbs of boost into his small block...

[@postmortemspasm]

@@illduitmyself doesnt change the answer

[@peted5217]

Grumpy Jenkins of SBC fame said OE SBC head bolts can be reused for ever [or til threads look sketchy]

[@nsboost]

Grandpa never used TTY bolts either. Or made 1000hp. Lol You can use whatever you want. As long as your ok with saving the money knowing is could cost you time

[@matthewstorm5188]

The problem here is that, when they break, you often have a bigger problem than simply buying new bolts.

[@seanmoore9713]

Videos like this have given me the confidence to go out and give it a try for cheap instead of always thinking what if.

[@dwaynejohnson1159]

I've been reusing head bolts for 30 years and never had a failure. Thanks for sharing scientific proof though.

[@jamesbond7380]

Is this for reals?? I reuse them on heavy diesel and i did today on my first gas engine "LS"... the guy that gave me the job flipped out and got all mad that you never reuse torque to yield bolts i was bro its ok i do it kn heavy diesel and those heads hold and are way hi in compression...

[@foxreviews2292]

@@jamesbond7380 how do u know if they are still ok?

[@TheDrivewayEngineer]

Because they're in a running engine

[@foxreviews2292]

@@TheDrivewayEngineer i mean when looking at them, is there a way to know

[@TheDrivewayEngineer]

@@foxreviews2292 how do you know brand new ones are good by looking at them?

[@evopwrmods]

First off.......Thank YOU....I foudn your channel about a month ago and have been watching alot of your videos. Being a car guy that owned his own performance shop; I was the type to always get the best and run the best parts etc. But now that Im almost at retirement and have lived a few decades since having my own shop. I have become very frugal and now money to me is to tight-wadded and not spent on anything but necessities. I now Re-Use, Re-Cycle, and Re-Purpose everything that I come across. I am about to do an LS swap into an 4x4 OffRoad RV that I am designing and fabricating from the ground up. After finding your channel I am now in heaven with all the Great and Awesome Frugal information that you are laying on me. The LS series of engines is such an awesomely engineered mechanical device. Where old skool push-rof single cam; is better than new skool dual OHC setups. The simplicity is just insanely awesome. Such as with life also. we all could learn much from looking back to what the old timers ran in their hotrods and seeing if that might also work for us in today's hectic fast paced cruel world. Again Many THANKS for laying all this frugal-ness upon me. Not many channels go this route, you should do very well !!!!!!

[@TheDrivewayEngineer]

Yeah, the old hot rodders would run a ball hone through an engine, maybe put rings on it and send it lol. Manufacturing processes have improved greatly, materials have improved greatly, and probably most importantly, any modern engine is fuel injected and overdriven. They idle down the highway at a perfect AFR for the most part, it's really not surprising they don't wear.

[@firstplacelegendgamingmore9800]

The stockers can be reused ,I wouldnt stretch them again with the tty process as the new bolts require. Just 65ft lbs of torque on a used tty bolt works great

[@deankay4434]

Thank you for taking the time to film the work the other guy did. This is what ASTM would do to test or certify a product. Yes, the alloy in the bolt / stud means something to the end results, but the overall thinking of engineering is driven by marketing. No more grease zerks on factory suspension or steering components either. Look, aluminum expands and contracts in all directions 2:1. when bolted to iron or steel. So multilayer gaskets allow for some movement but imports have done this for decades. While at room temp, break 1 head bolt at a time, then re-torque it every 30k. LS exhaust bolts always break at the end so elongate the hole in the manifold / header, place a flat washer over it and it will never break again. It is not rocket science it is a bolt. Sure, grade 8 is stronger but things are not that complicated in basic engine fasteners. 35+ years an ASE Master Tech Retired Great job to everyone envolved!

[@DaDeCodeIsTruth]

Take it how y'all want to. But back when I replaced and relocated the sub frames in my 05 GTO I did extensive research on tty bolts. And after lots of reading and forum searching, the best I could get from a couple of claimed 'gm engineers' on the LS1 GTO forum; was tty is more about the factory torquing process than particulars to the bolt. And YES they can be reused. I ended up replacing mine with standard metric equivalency grade 8 bolts (accident necessitated subframe work) because the factory ones were stupidly priced.

[@Johnny-jr2lq]

Thank you for putting honest information out there for guys who actually have fucking bills to pay and are just starting out everyone don’t have money to burn and throw away

[@dustybeers]

True that x 10!

[@OGbqze]

Fucking preach!!!!!!! I absolutely hate MFS who live with thier parents being handed 10k a month by daddy and make videos about how thier Lamborghini heads only have the top quality stuff and everything else is pointless.

[@stevenhzoll7057]

Studs may allow the maximum thread engagement in the block,very important especially in aluminum.Bolts, if stretched may bottom before achieving the desired clamp load. One must be careful when pushing the limit. I guess it depends how far you want to go and what reliability you need. Thanks for the post.

[@christophergaston5620]

Steven H Zoll agreed. aluminum block is why I went studs, not for extreme strength 🤷🏻‍♂️

[@myoneblackfriend3151]

I saw when Matt highlighted this test. Great work commenting on it, J.R.

[@davenelson1571]

I once saw a comparison of assembly lubes for head bolts & that effected the torque reading causing wrong numbers. Would you care to comment on the effect of lube in the bolt torquing process?

[@TheDrivewayEngineer]

To put it simply, what you're trying to achieve when tightening a bolt, is a certain amount of stretch in the bolt. The bolt will try to shrink back down to it's original size, and that's what provides the clamping force, the head of the bolt and the nut trying to draw back together. When you torque something, there's tables that say, at this much torque, you get this much stretch, therefore this much clamping force. So that's how an engineer sets a torque spec, just column a, row 3 on a table equals x stretch. There are variables though, no lube, straight 30w oil, or like, moly lube all provide different amounts of friction. So then the torque table goes out the window, because with no lube, vs moly, the moly is going to give more stretch at the same torque because of less friction. ARP provides a ARP lube spec, or a 30w spec because of this. However, it's all really mental masturbation, none of us are Jack Roush, and to the guy in his driveway, regular oil and the recommended torque spec is perfectly fine.

[@hal2655]

​@@TheDrivewayEngineer When you are torquing a head 'bolt', you are turning it at the same time you are increasing the load on it. You are twisting the entire length of the bolt. Lube reduces the force required to over come the friction of the thread on thread action and the area under the bolt head, and is important for reaching the clamp load an engineer specifies it for. Dry torque vs wet torque is not mental masturbation, hence the call out.

[@TheDrivewayEngineer]

@@hal2655 So you've repeated the same thing I already said lol.... I didn't say dry torque vs any other spec is mental masturbation, I said use oil and follow the recomended spec. Not get off into ARP's super secret squirell lube and alternative spec nonsense.

[@jasonnielsen2125]

I have always reused the used head bolts and main bolts unless new ones are supplied or customer stipulates. I use them for my own engines as well as I’ve always suspected that the used bolts would harden up due to many heat cycles imposed on them through out an engines life. Thank you for this video and keep up the great work.

[@jpskiskate2000]

What about rod bolts? I'm contemplating on re-using mine

[@keysautorepair6038]

I knew something was going on I have always reused headbolts the one time I didn't the gaskets failed in 3 months 20 plus years turning wrenches.

[@Antonio-so1cv]

Only reason I see to use studs over bolts is if you’re frequently disassembling your engine. I’m talking about disassembling it every other week or more for maintenance since continuous threading and torquing may damage the threads of the mating part where studs stay on the block. And the degradation of the both since they not only experience tension force but also twisting where as the studs only experience tension force. Studs are just impractical for regular performance engines.

[@jacobrecord82]

You should do a video on torquing the head bolts. I was always confused with torque to yield bolts.

[@deankay4434]

@jacobrecord82 Depending on which part, year & engine, the specs due change. I will use the “KISS” explanation. Ding the torque specs for your job. Start in the middle as if to smash a pancake outward. But first pass is low, in the middle, rotate in a circle until all have first torque sequence. Required on most you have a second level of tightness. Adjust your torque wrench for second round. If like many newer LS engines, require only two times, place tape or spray a liquid little red paint or uses a drawing. Repeat starting at center, go in a circle pattern, stop. If the next part is “Angel” write it down. In or out of a vehicle, place the handle where you can get on pull. Remember, 1/2 of a circle is 180 degrees, so 1/2 of that is 90. No reason to buy an angle meter, just make a sober attempt to achieve a single 90 degree pull to final tightness. If only 70 degrees, then stop short. Remember, this is like pointing on a circle, just in pie cuts. It is not that hard. ASE Master Tech-Retired

[@liveandletlive2894]

@@deankay4434 anyway to simplify that?

[@1Patient]

Ya, great info, good video. I like how you give your sources credit, and let the viewer decide. Take care bro.

[@TheDrivewayEngineer]

Have to give credit where it's due, I'm just not that type of guy, thanks for watchiing!

[@EnduroTainment]

What I wonder is that if you're still angle torquing the used bolts with the initial 22ftlbs, you're still going to elongate/yield the stock bolts again and they will likely be fine a few times since they hold the same force while yielding for a little bit. But, I'm guessing after a couple uses it will run out of yield and get closer to potential failure. I am still curious as to why the max load on the used bolts are superior. Heat cycles after the stretching almost forges the new grain? Who knows.

[@sea_bass21]

I'm building a 4.3 v6 and, considering the typhoons and syclones used that engine under boost, I feel a lot better about building a roughly 300hp naturally aspirated 4.3

[@KillSwitchNY]

This guy is a hero. I am so glad I kept my seasoned head bolts.

[@mikef-gi2dg]

Now that's DYI information I can use! This TTY bolt stuff was a big mystery until now. I personally will splurge and go ARP head bolts and reuse them at least once if it comes to that. My 99 l31 2500 gvan 350 had one strange bolt problem. The light weight intake manifold bolts, and 5 of the 12 exhaust manifold bolts, heads just popped off, replaced with ARP intake bolts and old Grade 8 bolts, problem solved. This info lets me know where I am at with stock thru aftermarket, thanks.

[@rc3831]

Thanks for pointing this test out that Sloppy Mechanics did so unless you going for the extreme boost it looks like it is best to save some cash and reuse stock head bolts. This is another reason that LS engines are the best bang for the buck.

[@TheDrivewayEngineer]

Yeah, advanced manufacturing techniques and tighter tolerancing really make the difference on these.

[@sterlingwitherspoon5709]

Doug Mullen people will take you to court to prove that u can’t reuse those studs. Even if you have to remove new studs immediately people recommend not using them. I must say I’m still scared to find out. Lol.

[@TheDrivewayEngineer]

😂😂😂😂 pretty much

[@marcmo7138]

I like the studs because I can torque them without getting out my torque angle gauge. I snapped a main bolt trying to get to 80 degrees.

[@TheDrivewayEngineer]

The torque angle is 90 lol, I feel comfortable I can eyeball them lol

[@marcmo7138]

@@TheDrivewayEngineerNo its 80 degrees on my 5.3

[@TheDrivewayEngineer]

80, 90, close enough :D :D

[@marcmo7138]

@@TheDrivewayEngineer 220 221 whatever it takes. That's from a movie.

[@TheDrivewayEngineer]

@@marcmo7138 Mr Mom lol

[@rockroll9513]

I just compromised; I went with the ARP head bolts instead of the head studs. Saved some money and can re-use the bolts. Best of Both Worlds.

[@TheDrivewayEngineer]

The best solution is to keep your money lol

[@chickenfishhybrid44]

I would like to know how the ARP bolts would test. If someone is guna buy something I think the ARP bolts are a good option. A shop in town uses then on like ever LS build they do under 1000ish. I've used them in the past but can't say that stock stuff wouldn't have also worked in those applications

[@TheDrivewayEngineer]

They test better I'm sure, they have a much higher tensile strength and can provide much more clamping... Stock stuff isn't a failure point though, so beefing it up is money wasted.

[@chickenfishhybrid44]

@@TheDrivewayEngineer I would hope and assume they would test better.. just would be cool to know. Again, like I said if someome is going to buy something I think the ARP bolts are a good option.. some people are going to replace the bolts regardless, even with at least new stock ones. For most people's builds they definately don't need the studs so mine as well save the money and buy the bolts.

[@LittleOldBoat]

I just Reused my torque to yield on my 2.3 L Ford Lima , I cleaned & bristle brush the Blind holes lub the bolt with high pressure chassis grease. Use the big Snap On breaker bar torque the shit out of them , reminded me of piano string's ! What a great engine, The original boost engine!

[@jasonscott6731]

I am a tech with 27 years exp, we were always taught to only use torque to yield bolts once as the torque, due to the stretch, was less every time they were reused. In saying this I work at a dealership (16 years) , we average 6 engines a week and unless there is damage (threads , rust, stripped etc) we always reuse the head bolts(torque to yield) as this is the manufacturers recommendation and new bolts are not supplied. The only failure I have ever seen was due to improper torque sequence (dumb tech) not the fault of the bolt. Keep using them, unless you are continuously boosting over 20psi these bolts are not your weak link.

[@TheDrivewayEngineer]

Yeah I see alot of people leave crap down in the holes and fail to get them actually tight as well.

[@TheGuruStud]

Reusing is stupid. Head bolts stretch, then stretch even more with boost. Dealerships are cheapskate criminals. This test is flawed. It's a one time load test. Running an engine is a NONSTOP load. This why the bolts continue to stretch, then you get a HG leak. Sure, they'll be tighter right after you reinstall...until they continue to stretch, b/c you just retorqued em.

[@MadMaxGarage]

Aha, Matt from Sloppy always questions the status quo and wants proof..well there it is. Nice work. Now I have a crate load of of used bolts I’m going to sell😂

[@ImNotHereToArgueFacts]

At lot of unknown factors reusing these TTY bolts. The tests referenced were probably not well documented as to the life cycle of the bolts used and the torque specs/methods used during each install. Was the block and head steel or aluminum? What was the max temp ever reached on the engine(s)? If it's a junkyarder in a weekend hoopty, it might be different than if it's your reliable work truck used for hauling. I wouldn't reuse them blindly.

[@oktoberchest]

Hey, I replaced headbolts and the manual says *torque to 75nm *loosed all bolts *torque to 20nm *90° *90° I only did step one, torque 75nm only found out later i had to do all steps. I now have driven 160 miles without problems. Should I complete the steps, loosen them and then 20nm and the steps, or just leave it?

[@oktoberchest]

I'm in a mental split here, sir

[@oktoberchest]

My old timer neighbour says he never did the steps, he says to just leave them. What do you say?

[@TheDrivewayEngineer]

If it ain't broke... I'd roll with it

[@oktoberchest]

I loosened them and retighten them one by one. But my torquewrench starts at 40nm. So I did 40nm and 2* 90° somewhat, maybe a little less. Maybe they are too tight now I don't know, I checked every bolt at 75nm and it clicked right away. I drove 85km You think it will explode and leak again? You have some faith? Its a little 1994 lancer 1.6 four banger

[@ryanjarrett5933]

Keep up the good work bro, i was an engineer for Delphi for till 08 when they filed bankruptcy....i used to have little "WTF" discussions with the main choads bout shit like this on the reg! I love letting these little "secrets" out

[@Ninja-es3fi]

With constant heat soaking I'm not surprised if they didn't harden a bit

[@lucysmith4242]

I was waiting for someone to question why the old bolts held more force. Could be that the new tty bolts weren't from the same manufacturer or the same batch of bolts. Also could be that the used tty bolts experienced some strain hardening. We need materials engineers and metallurgist to take a look at these.

[@ImNotHereToArgueFacts]

Link no more workie. Was that tensile testing done on the threads? Where is the bolt yielding? If it works, it works until it doesn't. I'd suggest measuring the bolts. Cleaning the block holes very well (perhaps chasing) and using a torque wrench that will show torque after angle is achieved. Low torque at required angle is a good reason to reject a bolt. I found these numbers somewhere. I'll comment to this with info if I can relocate it.

[@ImNotHereToArgueFacts]

Couldn't find it again. I'll continue looking, but not confident.

[@daviddenman7479]

I’m still not looking at my cam bearings🤣

[@foreverendeavors6210]

I have seen them Flake and cause low oil pressure..

[@james10739]

Did you see that ls vs coyote and they blew the head off at like 1800 hp or something im pretty sure that was stock head bolts but i guess thats when you go to bigger head studs

[@TheDrivewayEngineer]

Seems like a solid reason to spend the money lol

[@Brooklyn-bn5go]

I have a feeling that the twisting force has an effect on used bolts, also @bdd1469 makes a good point. I guess if you can get the heads bolted down with enough clamping pressure to seal them to the block, and have not broken any of them it's worth it.

[@SteveAddis]

This is really interesting info. I noticed auto parts people do not try to sell the TTY bolts for bearing assemblies. Now I just found out that the late Chevy I have needs TTY and of course I would need a angle gauge just to install. Just crazy, yet I suppose it has its purpose (connecting dissimilar metals). Would TTY be an improvement over standard, who knows? Thanks for posting!

[@uncagedperformance2096]

I re-use headgaskets and head bolts lol. This is some great info, and proves that you dont need $300 head studs.

[@TheDrivewayEngineer]

Too bad people don't listen lol.

[@uncagedperformance2096]

@@TheDrivewayEngineer and we junkyardist are the dumb ones lol. After being disappointed with a 8k race engine, i pledged to never go back to building a race engine never again. I will continue to use junkyard stuff and thumb my nose at the ones that thinks im crazy.

[@TheDrivewayEngineer]

@@uncagedperformance2096 I've learned the hard way myself, 23k into a 2v 4.6.... got 6k when it was t boned. 4800 bill at the machinist for a 363 302 based short block... That's when I started spraying 250 shots on SBEs lol... I finally learned.

[@sKid-ts7hr]

I bought a set of tty felpro bolts for my 4.6 ford engine. But after this video im thinking of using the old ones but do i have to use same torquing and angle steps !!!

[@TheDrivewayEngineer]

Just torque them like normal, make sure the holes are clean

[@brianawd]

The off the shelf ARP 8740 are garbage. They have been for years. I have lifted a head running them in the past at 28lbs on a 4g63t. It was a known issue back in the day to just run a stock head bolt or Swapped to L19s and never had an issue after.

[@TheDrivewayEngineer]

I forgot about that, I haven't seen a 4g63t in years lol.

[@sxs4l245]

Also. Doesn't ARP pull the stretch out of the bolt/stud, heat treat and box them? That's what I'm to understand. But I'm no engineer either. Thanks again.

[@TheDrivewayEngineer]

Not exactly. They heat treat the raw material, then do all their operations. Heat treat only goes so deep into the material, unless they specifically go through the center. They roll the threads, which is stronger because it smashed the material in instead of removing it like a cutting die would. Mostly the are stonger because the base material has a higher modulus of elasticity, which is the point where it will stretch and not return. The force required to do that directly correlates to clamping load. SO basically, since you can crank them down harder without them failing, they clamp tighter.

[@sexyfacenation]

@@TheDrivewayEngineer just to add to that virtually all bolts and studs have rolled threads, that's not really a specific arp feature.

[@brandonleon795]

Quick question .. I'm building a 5.3 and had my heads milled .030 do I need to get shorter pushrods?

[@Rippee42]

Can you make a video on drivelines? I have a 4l80e for my 62 Nova with a 65 Nova rear 8.2. Junk yard drive line? How to know what yolk and all that. Thank you for your consideration

[@TheDrivewayEngineer]

That's a great idea!

[@garymaya1767]

I guess the only time I would not reuse the bolts is when you buy a used vehicle and rebuild. Cause there’s probably a chance this could be the 3rd time around.. maybe there is a test on the 3rd use?

[@michaelangelo8001]

Very good. Be interesting to see tests of rod and main bolts also...

[@dave0z96]

I’ve reused torque to yield connecting rod bolts on a John Deere 6068 and it was fine . 12 thousand hours later .

[@amindnew527]

Love all your gr8 CONTENT!! old skool wrenchers, even on New LS 4 EVER!!!

[@MichaelWittner]

What if turbos are going to be used is this still ok to reuse the bolts

[@TheDrivewayEngineer]

Absolutely, they'll still provide the force you need.

[@Johnny-jr2lq]

Further more I love the guys that spend all that dam money on crap they don’t need and there hobby doesn’t get finished it’s just a motor sitting in the garage because they ran outta money for the rest of the build

[@TheDrivewayEngineer]

See it all the time, then they're trying to sell it for 1/2 the cost lol.

[@ericmartin3415]

i love the guys that walmart their stuff together , and think they are ballers ...they dont win car shows , dont win races . but they got their money to buy their beer . you stay cool guys

[@mattgemfran]

When reusing bolts do you tighten to a total torque spec or Low torque spec and series of quarter turns. I rescued on a k series Honda and it just didn’t feel even and went more than quarter turns all round. It hasn’t failed yet

[@TheDrivewayEngineer]

I go for a torque spec

[@poet99999]

wouldn't the use bolts have less elongation because they are ALREADY elongated? or is that 5% measure against a NEW untouched bolt? or was it a combined 12% over a fresh bolt

[@pedrocontrerasavendano8578]

The Driveway Engineer, after reading all the comments i still haven't figured out one thing, when reusing the bolts, should i just torque them to oem spec without the degrees or torque them to oem spec with the degrees?

[@TheDrivewayEngineer]

It doesn't matter

[@thegoat5334]

Sounds good to me, I'll reuse mine... thank you

[@ryanaustin1970]

Excellent video , I'm not surprised by the results, used bolts will always stretch less because obviously they've already been stretched some and opposite with new bolts. It isnt a real comparison with the studs versus bolts because of how and where loads are applied . It was cool too see the cheap studs against the go to arp studs . Again not surprised with the results there . Keep in mind studs are designed to be reused . I see the point of this video and your previous regardless as to how I feel about all the info . I will say thou yes arp is pricey but when you spend thousands on an engine I'd prefer to not have reused bolts and wonder..."shit I hope this bitch stays together "as I'm flogging it down the track or some high rev burnout . Cheers

[@andrewmontgomery1763]

But that's also the point with the LS engines in general, that you can buy a 4.8/5.3 for $400, so spending nearly that on a set of ARP head studs (when these engines can reliably hold 700 crank hp with used head bolts) seems silly, unless you're going for 1500 hp, which 99% of people are definitely not.

[@matthewstorm5188]

I have no doubt that a reused bolt will have a higher clamping force. The first tightening work hardened the bolt, which increased the yield strength. Tightening the bolts to the same spec the second time will therefore result in an even GREATER clamping force. The problem here is that work hardening also increases brittleness. By reusing TTY bolts, you increase the risk that a bolt will snap during tightening, which will put you in a world of hurt. This is particularly true if you decide to reuse the same bolt multiple times. The risk of even ONE snapped bolt just isn’t worth the relatively small cost of a set of new bolts, both in terms of monetary cost and stress. At least for me.

[@iamgoat3035]

what is recomended for manifold bolts taking into consideration i have a broken one on each manifold already? i managed to weld a nut to one with threads showing and it came out easily so now im looking for extractor set to remove other one. so i dont imagine i can buy a pair of replacement bolts so should i get stock replacement set or ARP set?

[@TheDrivewayEngineer]

DOn't use an extractor, keep welding to get them out. Dorman makes LS manifold bolts for like 13 bucks a set.

[@ht0093]

This only for head bolts? What about main cap and rod bolts?

[@TheDrivewayEngineer]

I've been reusing those as well, however the test only covers the head bolts

[@kid.0llie]

Love vids like this, true knowledge not just BS!

[@TheDrivewayEngineer]

I appreciate that!

[@David-lr2vi]

I reckon they only came up with TTY to make bolts a consumable item. As long as you don’t over torque the bolts into the plastic zone they should be theoretically infinitely reusable (within reason of course) if they are torqued using a standard torque number. Making the bolts TTY means you can’t reuse the bolts and get the same clamping force using the same TTY tightening procedure (ie: tighten to 20nm then 40nm, turn 45 degrees, stamp your feet twice and look towards the full moon!) which it entirely their plan! By only providing a TTY system they try and force you to buy new bolts but applying some logic to the issue I would say that (me not being a mechanical engineer btw) I would use the torque wrench the work out what the old bolts are torqued down to before removing them and then tighten them back down to that torque setting on reassembly.

[@privatedata665]

This ^

[@Poaf-1]

So what is it saying ? What are the best ones to use? The old tty bolts ?

[@TheDrivewayEngineer]

The ones you got for free with your engine

[@randywilliams4325]

On the used head bolts - could the metallurgy be changed form heat cycling under a load ?

[@TheDrivewayEngineer]

If we wanted to get real engineery, yes, Thermal expansion of the bolt length is: eb = αbΔTbLb. Thermal growth in the clamped members is: ec = αcΔTcLc. Next, length changes due to preloading at elevated temperatures are: δb = (Δb + δ) - eb, -δc = (-Δc + δ) - ec. Initial preload at room temperature is: Fi = kbΔb = -kcΔc. The bolt force at elevated temperature is: Fb = kbδb = kb(Δb + δ) - kbαbΔTbLb and clamped-member force at temperature is: -Fc = kcδc = kc(Δc - δ) + kcαcΔTcLc. Because no external force is applied to the joint, forces in the bolt and members must be in equilibrium - that is, Fb + Fc = 0. Therefore, (kb + kc)δ = kbαbΔTbLb + kcαcΔTcLc, or δ = (1/(kb + kc))(kbαbΔTbLb + kcαcΔTcLc). The new bolt force after the temperature change is: Fb = (kbΔb) + (kb/(kb + kc)) (kbαbΔTbLb + kcαcΔTcLc) - (kbαbΔTbLb) or Fb = Fi + (αcΔTcLc - αbΔTbLb)(kbkc/(kb + kc)). The stiffness factor at the far right is the combined internal stiffness ki defined as: kbkc/(kb + kc) = 1/((1/kb) + (1/kc)) == ki and 1/ki = 1/kb + 1/kc. The expression 1/ki is the compliance of the preloading loop. Therefore, the combined internal compliance of a preloaded bolted joint is the sum of the compliances of the bolt and clamped members. This lets us write the bolt-force equation in a more-compact form: Fb = Fi + (ec - eb)ki. Bolt load after a temperature change is the preload at room temperature and the product of the net thermal expansions and combined internal stiffness. This is similar to the expansion force of a bar blocked from both ends: ΔF = ke = kα(ΔT)L. Thermal effects may increase or decrease bolt load and clamping capability. Use this equation to weigh design options: either reducing the differential thermal expansion, giving the joint more compliance, or otherwise assessing the bolt stress at different temperatures. For example, the condition for invariant bolt load due to temperature is: αbΔTbLb = αcΔTcLc.

[@randywilliams4325]

The Driveway Engineer Much more of an answer than I bargained for . I feel like I owe you a beer . Thanks for your time .

[@TheDrivewayEngineer]

Randy Williams just beat in mind, in the real world, none of this matters, the math has already been done, no need to over think it.

[@sheaadams86]

what sealant do i put on my head bolts threads if i reuse them?

[@TheDrivewayEngineer]

LS bolts don't go into water like Gen 1 bolts do, no sealant neeeed

[@sheaadams86]

@@TheDrivewayEngineer whats your opinion on reusing MLS gaskets?

[@TheDrivewayEngineer]

I reuse them with some copper spray

[@sheaadams86]

@@TheDrivewayEngineer i thought about doing that but theres debris(hard oil deposits?) in between the layers im worried about causing a bad seal, how are you cleaning/prepping the old gaskets? maybe do a video on reusing MLS gaskets? 😉

[@TheDrivewayEngineer]

Spray them, install them, don't think about it, live your best life :D kzbin.info/www/bejne/nHqUm3Vvrqd6asU

[@MyLuckyStars84]

when using the old head bolts, do I use factory torque setting or is there a recommended FT lb torque spec to use?

[@TheDrivewayEngineer]

Use the factory spec again

[@gearheadhuff7853]

@@TheDrivewayEngineer so reuse the the tty process of decrees? Are ft/lbs

[@OneBoomBox]

I know I'm a year late on this but what would you torque a used head bolt to 5.3 vortec what I was able to find online was 22 ftlbs then 90 degrees then 70. Is it okay to follow same torque procedure with used head bolts

[@TheDrivewayEngineer]

Yes, that's what I typically do

[@arturozarate1752]

Thanks for bringing this information closer to the "wandering" public. Test results don't lie.

[@kevinhumphrey932]

What do the subscriber's on this channel think about reusing the rod bolts what information I do find is kinda like the reusing the head bolts this is a 2010 5.3 engine I'm building with forced air I'm going to say it'll run around 9-13 lbs of boost nothing to crazy

[@kevinhumphrey932]

It is the aluminum block with the DoD crap being disabled

[@maxgermain]

If reusing the used bolts, should the tty be done or just torque to a certain number?

[@TheDrivewayEngineer]

I usually just follow the factory sequence

[@Airman..]

Great information! How much torque do you shoot for on a used head Bolts?

[@TheDrivewayEngineer]

75 ft/lbs, I don't always get there though. Sometimes I do another 90/90 degree too, depends on my mood that day lol.

[@Airman..]

@@TheDrivewayEngineer i will start using this number, i followed gm specs precisely and ripped head bolt threads near the firewall on an AL 6.2 block, what a pain. Thank you

[@TheDrivewayEngineer]

Yeah, you can feel when they're seem like they're not happy. I usually just leave them if they're close, or replace them if they're not

[@bimmerfab]

Head bolts curing and getting stronger over time very interesting!

[@TheDrivewayEngineer]

Like fine wine 😂

[@jonesy_grows]

Good info, appreciate you taking the time to bring this to your channel

[@wreckerman4691]

I always thought you could reuse the head bolts but everyone trying to make money of what you don't need i did not know that for sure thanks

[@Funtimes670]

What would be the torque amounts. I have seen 22 50 75-80. What do you do them to?

[@TheDrivewayEngineer]

22 ft/lbs then 90 degrees

[@Funtimes670]

The Driveway Engineer 90 degrees 1 time or 2? Do you do the shorter ones the same?

[@CouchHam]

What about connecting rod bolts? Do you reuse them??

[@TheDrivewayEngineer]

Yes

[@davidcollins6164]

what was the point of 'torque to yield' then?

[@TheDrivewayEngineer]

To ensure extra force isn't put on the fastener.

[@jeremydawkins8399]

I bet it has to do with the heat cycles and relieving stresses built up in the metal from the manufacturing process. BMW using to only use 100K mile plus engine blocks they would buy back from customer cars to build their F1 Megatron engines. They said they were stronger because the metal fibers had naturally aligned through the thousands of heat cycles.

[@bdd1469]

The reason the used bolts have higher numbers is because they have been stretched and NOT returned to their original length or elasticity. The reason a stud is preferred is they save the threads in the block from being destroyed from multiple torquings of headbolts on an engine that will be freshened up often. They also offer a more consistent clamping load across the head. The thing you havn't considered is how many times is that paper clip ( 200, 000 mile head bolt) going to bend (stretch), at every start up and flooging, before it decides it doesn't feel like working that day. $45 doesn't even cover a half hr of labor at my shop, I can't imagine risking the huge amount of time and parts involved over a failed bolt to save 1000th of a penny for every mile.......

[@matthemberry]

Pretty cool you make $90 an hour. Some of us are poor. I couldn’t imagine spending money on something I already have. The fact is people have reused tty bolts with a very high success rate. I know I have and never had a failure. From Land Rover to Subaru, Chevrolet. That being said if I was charging for my work and running a shop I’d charge the customer an extra $45.

[@bdd1469]

@@matthemberry I wasn't saying I make $90 an hr....Any shop in my area charges $80-$125 an hr for labor depending on the size and if it is a dealer. I'm glad you've had good luck, I'm not one to risk my customers car or my time over $45. I don't have much money , but I do put arp studs and bolts in my motors to protect the parts that are actually expensive.

[@TheDrivewayEngineer]

If a used bolt will fail without warning so would a new one, which is also used the instant you tighten it... So from the start your entire premise is invalid. I'm not advocating people do this to unsuspecting customers, and I'm not sure why so many of these discussions take that turn. I do not advocate being dishonest with other peoples property. I merely am presenting evidence for people to make informed decisions with their own property.

[@TheDrivewayEngineer]

I think I'll reply anyway, nothing you said there adds up at all, but do tell us oh wise metallurgist wtf you're even going on about 😂

[@firemanifd]

Nice! This is a great money saver

[@Saddedude]

Curious how 1/2" arp studs woukd compare....

[@TheDrivewayEngineer]

I'm not, since stock bolts have easily held 1500 tire and beyond.

[@SupraBdub]

Nice, looking forward to sharing this with my ls buddy, thanks again!

[@TheDrivewayEngineer]

Thanks for watching!

[@mtotheizatt]

Is this specifically for ls engines or all stock head bolts? I’m about to cheap out on allllll my engine builds

[@mtotheizatt]

The Driveway Engineer thanks for the video. You make awesome content

[@TheDrivewayEngineer]

Thank you!

[@davenelson1571]

I really enjoy your videos! Please keep making them!

[@danielsullivan9865]

Great info you need to rate those Chinese turbos that everybody says don't make any power

[@TheDrivewayEngineer]

I'm working on getting some storage space and engine dyno time to test some of these things this summer. Need to get the ole budget up first.

[@motherlovinsnuffstar]

@@TheDrivewayEngineer I'll be looking forward to that!!!

[@MrBojangles901]

I like it dude. Feels so dumb to throw away what seems like perfectly good bolts. Also, any experienced mechanic will berate you for it. But then again the same oldschool mechanic thinks torquing bolts with angles seems stupid and nonsensical so take from it what you will, haha. I felt so stupid spending more than 100 dollars on BMW crankshaft bolts from reassembling the timing chain multiple times. Throwing those big, heavy, barely used bolts in the garbage. Here's my personal rule. Reuse TTY bolts at least once is fine. When doing the angle part go a little easy on it. So if the spec says 180 degrees maybe do 150. Reason being exactly what this video showed which is that the reused bolt will overtorque with the same procedure so if you reduce the angle slightly you should be in the right spot.

[@johntaylor1947]

Good to know ,I would bet GM and Ford ect. buy pretty good bolts as they don't want warranty returns. When buying new bolts who knows what Quality they are.

[@interceptor0166]

Maybe because they were heat cycled in a running engine.

[@TrackDayMaker]

I’m pretty new to LS stuff in the grand scheme of things, but when I was in Subaru land this was a constant back and forth too. Subaru says they are single use TTY head bolts, but basically every Subaru master tech reuses the ones they pull out.

[@TheDrivewayEngineer]

I pretty much put people in two categories when it comes to this. People who have done it with no problems, and people who just read stuff on the internet 😂

[@TrackDayMaker]

The Driveway Engineer a long time ago a buddy and I were flipping blown head gasket Subies on the side. The one part that always ate in to our profits the most were the new head bolts. We stopped bothering after we found out dealerships don’t bother either lol

[@Sands10welding]

Awesome channel man! Im so happy i came accross this. Building my first turbo ls. Do you know anyone that has lifted the heads with boost on stock head bolts? If so do you know what psi they were at. Btw im shpoting for 600-650 for my build. Thanks for the great content, love the channel

[@TheDrivewayEngineer]

Thanks for the compliments! There seem to be alot of factors at play, I ran 15-16 psi, made 640 HP, didn't have trouble. I've seen people hit them with 28-30, I've seen them fail at 10 lol. I think some people don't get the bolt holes blown out properly and that causes problems for them and confused the issue.

[@patrickhickman8723]

how about reusing rod bolts?

[@TheDrivewayEngineer]

I reuse them all

[@patrickhickman8723]

@@TheDrivewayEngineer thank you for all you do brother, you have been a huge help to me and to so many. This is my first LS, and unfortunately I am starting with an LQ4 that has broken pistons so............ I get to bore it and put in new pistons. This is out of a 2001 Suburban 2500 complete, I have everything like you suggest, the entire vehicle which is all stock. This generation of LQ4 also has the weaker rods so I snatched a set of dimple rods for 150.00 - since I am hanging new rods and pistons should I have the assembly balanced??? I am using 862 heads and ss2 cam, went with 36lb injectors in stock truck intake manifold, shorty headers. I am building a single seat rock buggy on 43" tires with a turbo 400 w/2500 stall.

[@TheDrivewayEngineer]

If I had to do all that, I'd start with another engine. You're going to spend more on all this than punting it and starting over.

[@patrickhickman8723]

@@TheDrivewayEngineer probably but I am all in now lol

[@TheDrivewayEngineer]

@@patrickhickman8723 if that's what you chose you are, I'd sell that shit right now and walk

[@adrenalinejunkie126]

Thanks for all the foot work bro. Super informative. My 240,000 mile 5.3 has never been apart. I'll be reusing mine, and probably the rest of the bolts that I removed except for...those damn exhaust manifold bolts🤣🤣🤣 3 were broke off, like everyone else's 🤣🤣🤣

[@TheDrivewayEngineer]

The Dorman bolts are like 13 bucks, mine have been holding a turbo up for 2 years now lol

[@adrenalinejunkie126]

@@TheDrivewayEngineer well then....I should try those. I'm going turbo eventually. Gonna be thumbing through your vids for turbo install tips

[@jsomething2]

I went with Dorman stud kit meant for a Mustang, 10.8 and nice locking nut. gotta get 2 kits, but super cheap and always handy to have M8-1.25 stuff around.

[@adrenalinejunkie126]

@@jsomething2 gonna look into that too. Thanks bro

[@JayDee-bz2ge]

missing a big difference in a stud vs bolt. this test didnt show at what TQ on the wrench = what result at the fastener , how consistent , etc... i prefer studs for the constancy and it's how it should be done if OEM wasn't cheap. and if anyone has an aluminum block.... i cant imagine not using studs.

[@tjt4036]

Great info.

[@rongreen8485]

I can't imagine a gas engine head bolt torqued beyond 120 ft. Lbs. Max. As long as it doesn't stretch you're good.

[@georgiaboy1579]

What about the rod bolts?

[@TheDrivewayEngineer]

I reuse those as well

[@vicvachon859]

What about rod bolts??

[@TheDrivewayEngineer]

I resuse them also

[@adwagner1597]

Awesomely informative thanks!!

[@davenelson1571]

Why do you think that's the case? Does the many heat cycles the used bolts have been through effect the metals grain structure/atomic density?

[@TheDrivewayEngineer]

I believe it's simply from torque cycling them, takes a bit of the yield out of them each time.

[@lucysmith4242]

@@TheDrivewayEngineer look into strain hardening.

[@prancstaman]

Nice video. Ok, back in the day of school LeaRnIgs, loL, I was taught how to build aircraft piston driven and jet engines. Failure was not an option here. So, proper procedure, which you will find interesting, in replacing the important bolts. For example, jug bolts, main case half bolts, compressor section case bolts, and so on. To replace one of these bolts due to failure by to much stretch, or breakage. Yes, you measure the length of the bolt and given specs from the manufacture, anyways not the point. When prepping the new bolts, Yes, there is a prep procedure, you install the bolt and lube torque the bolt or dry torque the bolt, which depends on manufacture procedure and loosen the bolt, doing this 2 to 3 times before finally torqueing the bolt to specs for the install. Now compare this to what everybody is ranting about on those head bolts, Kinda funny, LOL. People at GM grabs a fresh new unused head bolt and torque them in the engine. Come on, that bolt has at least 3 or 4 more times of loosening and retorqueing left in it's life before it is even considered bad. Do a test of these bolts actually failing. Seeing how many times it take to torque and loosen the bolt for it to even be considered bad.

[@TheDrivewayEngineer]

Part of the problem is people don't clean the holes out thoroughly. Combine that with the angle torque method GM recommends, and you get clueless people blindly reefing on bolts because the instructions said so, and you get both new and reused failures. Whenever someone posts a failure, and I can see the bolt up close, it winds up being an axial failure, from over torque, probably from dirty bolt holes

[@BearFulmer]

the new bolts could test lower because of work hardening done on the used bolts

[@TheDrivewayEngineer]

There is probably some truth to that. However, used are hardly throw aways, and 100% of people who break them, new or reused, have left water or oil in the bottom of the holesThe bolts hit the liquid, the liquid can't compress, they get false TQ readings, or break the bolt, and blame the bolt

[@BearFulmer]

@@TheDrivewayEngineer I was just thinking about the metal, look in reusing them until I exceed those specs

[@HomebrewHorsepower]

There's something else going on here. Why would a used bolt be superior to a new one? I'm not arguing that the test results are incorrect, and I'm not arguing that used TTY bolts are necessarily useless. But there's something else going on that isn't captured by this test. I'd be curious to have an explanation from a material scientist or potentially from the GM engineer who designed and specced that bolt setup.

[@TheDrivewayEngineer]

It's a good question, I'd love to see more testing. I'd like to see new bolts tested, torqued, retested, etc etc to failure. But the Ingstrom in my lab is broken and we just send all our stuff out for testing now lol.

[@ryanaustin1970]

@@TheDrivewayEngineer I'd agree we need a super nerd to explain . I would put 100 new bolts torqued loosened retorqued etc would result in the same as the used ones

[@ryanaustin1970]

@Foghorn Leghorn well being as they're both GM bolts ... from probably the same supplier and meet the same specs ... yeah I'd say the quality of bolts us the same , wouldn't you ?

[@ryanaustin1970]

@Foghorn Leghorn oh fuck off ... jesus how much difference do you truly believe there is .... VERY little . Are you going to sit there and try to convince me or anyone that theres some night n day difference between the 2 bolts

[@t.r.bf.t.p3923]

People's comprehension skills are getting very poor to say the least I'll just assume bolts are of same material and quality it's sad to think people actually still use logic like that in 2019 .... Scary they probably use the same logic when voting ...

[@sheldonvanek9791]

Great Info. dude! keep up the great video's.

[@LSCHEVYRYDER254]

they say the proof is in the pudding this would be said pudding lol

[@whoguy4231]

Thanks man.... BEST information out there and it makes sense!!!

[@CatlocosGarage]

Thanks for the info. Good job