Torque to yield, head bolts...

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Abodybomber

Abodybomber

Breaking street machines , since 1983.....:)
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Doing a,2006 Ford Ranger head swap...First time I experienced "torque to yield " ,head bolts.. Just looking for a definitive reason ,to explain this.... As I guess," pre-stretch the bolt,seat it ..and then torque it,by degrees "... Not complaining, in any way,just looking for logical.
 
Aluminum heads on a cast iron block. They expand and contract at different rates. That's the theory anyway. The reason I always read and hears was the TTY bolts allow for a little movement.
 
RustyRatRod said:
Aluminum heads on a cast iron block. They expand and contract at different rates. That's the theory anyway. The reason I always read and hears was the TTY bolts allow for a little movement.
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Thank You....
 
the heads need to slide, like the exhaust manifold of a slant. so you get MLS gaskets and TTY bolts that offer a more consistant clamping force. Of course, they are a one and done (sort of, you pre-stretch them to a small percentage once then retorque. Crazy stuff. I ask the same of rod bolts: You torque them once to set the plasti-guage then you torque them again for the final load, so is that reusing? Then you get some ARP's and they say to resize the big end with new fasteners. Dang machine shops are making a killing.
 
Yeah, I remember when a buddy called me when he was putting new head gaskets in a Mercury. He asked if I ever heard of the procedure. I told him it was bullshit and to just torque every bolt to 100 lbs.
(No I didn't)
 
TTY bolts are found in all sorts of materials/assemblies including same old cast iron to cast iron. What it really is ,,, a fancy engineering way to cut cost, use cheap chit for hardware. Real quality steel hardware costs too much. The end user will add new hardware to his shopping list if/when.
If my memory serves, Fords 1.9 Escort engine was their 1st use, 86 maybe?
 
Did head gaskets on a ford 3.8 supercharged, aftermarket bolts failed in the torquing process, ended up using oem original bolts i removed. If they arent bent or necked down they can be reused.
I think it also has to do with no retorquing. I wouldnt want to go back into a ford 5.4 to retighten head bolts...double the thousand dollar job.
Dont care for it,leaves me wondering if its going to let go.they do break.
 
Tooljunkie said:
Did head gaskets on a ford 3.8 supercharged, aftermarket bolts failed in the torquing process, ended up using oem original bolts i removed. If they arent bent or necked down they can be reused.
I think it also has to do with no retorquing. I wouldnt want to go back into a ford 5.4 to retighten head bolts...double the thousand dollar job.
Dont care for it,leaves me wondering if its going to let go.they do break.
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I had to break loose a TTY cam bolt on an Intrepid 3.5L v6. I had a 3 or 4ft cheater on my breaker bar, and it was all my buddy and I could manage to break it loose. I thought for sure the bolt would shear or the drive would shear on my wrench, but thankfully neither failed. I swear that bolt must have been wound like a clock spring, before it loosened.
 
1980 VW rabbit used TTL head bolts. I replaced a diesel head gasket (3 notches) on my sisters and found that out when I looked at them and they were hour glassed....oops, time to hit the VW store again.
 
rustycowll69 said:
I had to break loose a TTY cam bolt on an Intrepid 3.5L v6. I had a 3 or 4ft cheater on my breaker bar, and it was all my buddy and I could manage to break it loose. I thought for sure the bolt would shear or the drive would shear on my wrench, but thankfully neither failed. I swear that bolt must have been wound like a clock spring, before it loosened.
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Been there done that. Three years at a dodge dealership. Bought a 1-7/16 wrench,stuck it in vise, heated it and bent it to hold cam. Nothing i hate more than damaging a new tool.
Ford cam phaser bolts too.
 
rustycowll69 said:
I had to break loose a TTY cam bolt on an Intrepid 3.5L v6. I had a 3 or 4ft cheater on my breaker bar, and it was all my buddy and I could manage to break it loose. I thought for sure the bolt would shear or the drive would shear on my wrench, but thankfully neither failed. I swear that bolt must have been wound like a clock spring, before it loosened.
Click to expand...

Tooljunkie said:
Been there done that. Three years at a dodge dealership. Bought a 1-7/16 wrench,stuck it in vise, heated it and bent it to hold cam. Nothing i hate more than damaging a new tool.
Ford cam phaser bolts too.
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I'll bet those bolts were thread locked and that's why they came out so hard. TTY won't have that problem. Like Ford pick up driveshaft bolts. 12mm 12 point head Locktighted in with 50,000 miles on the clock. I warranted a lot of wrenches and 3/8 drive sockets before I discovered the 1/2" drive Nissan head bolt socket. A1/2" impact will take them loose!
 
In 1982 GM used TTY bolts on there "new" diesel engine. Of course it was just a Olds engine made to run on diesel. Had head gasket problems! Imagine that!
 
Mopar Tim said:
In 1982 GM used TTY bolts on there "new" diesel engine. Of course it was just a Olds engine made to run on diesel. Had head gasket problems! Imagine that!
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I remember those days. I was a advisor at a Buick/GMC dealer back then. Head gasket issues from 2 different directions. The article I posted the link to explains the clamp force needed for a head bolt. More is needed for a high compression Diesel for sure.
 
TTY bolts are used in many places in an engine now. I see them used in main caps, rods, heads, cams , intakes, etc.. We were using them back in the 2.2 and 2.5 heads back in the 80's. Some are replace every time, some can be reused if not necked down. When we were doing Neon heads all day long our dumpsters would be weighted down by head bolts.
 
Mopar Tim said:
In 1982 GM used TTY bolts on there "new" diesel engine. Of course it was just a Olds engine made to run on diesel. Had head gasket problems! Imagine that!
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I remember those cars well. Most problems didn't involve the engine itself......although they certainly did have their problems. The most I saw were transmission problems, because when the engines ran right, they had too much torque for the transmission and usually broke them. Diesel Grand Prixs used to be a dime a dozen because most were sittin in somebody's yard with a bad transmission.
 
toolmanmike said:
I'll bet those bolts were thread locked and that's why they came out so hard. TTY won't have that problem. Like Ford pick up driveshaft bolts. 12mm 12 point head Locktighted in with 50,000 miles on the clock. I warranted a lot of wrenches and 3/8 drive sockets before I discovered the 1/2" drive Nissan head bolt socket. A1/2" impact will take them loose!
Click to expand...
regarding the 3.5L cam bolt, it may have been loctited, but I think the length of the bolt had something to do with it. IIRC, it was about a foot long, because the female threads were in the MIDDLE of the camshaft, reached through a deep counterbore/rifle drill in the front of the shaft.
 
RustyRatRod said:
I remember those cars well. Most problems didn't involve the engine itself......although they certainly did have their problems. The most I saw were transmission problems, because when the engines ran right, they had too much torque for the transmission and usually broke them. Diesel Grand Prixs used to be a dime a dozen because most were sittin in somebody's yard with a bad transmission.
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When those ran they ran well. I drove a demo Century on a couple vacation trips. 35 mpg but they only had TH125 trannys I believe. Not a beefy transmission for a diesel. When GM came out with the 6.2 and then the 6.5, the 700 R4's just came out. Of course they put them behind a turbo 6.5 in a 4 wheel drive. The salesmen would sell them to a farmer that would use it like a grain truck, pulling big wagons of shelled corn in overdrive. Glad I don't work there any more.
 
RedFish said:
TTY bolts are found in all sorts of materials/assemblies including same old cast iron to cast iron. What it really is ,,, a fancy engineering way to cut cost, use cheap chit for hardware. Real quality steel hardware costs too much. The end user will add new hardware to his shopping list if/when.
If my memory serves, Fords 1.9 Escort engine was their 1st use, 86 maybe?
Click to expand...


Straight poop right here^^^^^^^^^^^ it's cheaper which it was drives 95% of everything they do at the factory.
 
toolmanmike said:
When those ran they ran well. I drove a demo Century on a couple vacation trips. 35 mpg but they only had TH125 trannys I believe. Not a beefy transmission for a diesel. When GM came out with the 6.2 and then the 6.5, the 700 R4's just came out. Of course they put them behind a turbo 6.5 in a 4 wheel drive. The salesmen would sell them to a farmer that would use it like a grain truck, pulling big wagons of shelled corn in overdrive. Glad I don't work there any more.
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I was given an 80 sedan deville that started life as a conversion diesel , 65k warranty swap , 135k (60k new ) warranty swap , GM and the dealer teamed up and made the original owner take an olds 350ho gas motor instead of another diesel . I got it with 195k on it and sold it with 335k .Car had a metric th250 trans that had finally given up and nobody in the Lansing area wanted to touch it due to lack of local parts .But the motor still ran like a champ .
 
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