well, my trans torque mount seems to come loose even gracking it down around 100ft/lbs, and that's just a 12x1.5 (yup, banjo thread, thanks vw) into the aluminum trans case
maybe I should try the in/lb torque wrench instead
Most VW/Audi fasteners/bolts are not TTY (torque to yield)
- Thread starter philosopher1313
- Start date
maybe I should try the in/lb torque wrench instead
turbocharged798
Veteran Member
Yep as soon as insults start flying I leave. OP was given factual information why TTY bolts stretch and need to be replaced and he resorted to name calling. Not exactly a good way to win an argument.
Ol'Rattler
Top Post Dawg
ugh. I think i just developed a brain tumor......................
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Ol'Rattler
Top Post Dawg
Never argue with a fool. They will just pull you down to their level and beat you up with experience.............
mk3
Veteran Member
other members have repeated this same correct answer, stated in post 5. I came here to read all of this because I got this question posed to me at work just now.
I specified a torque + angle on a design that I made and which will be produced halfway round the world at a factory in China. I worry that the torque wrenches will not stay calibrated or that any number of other factors will change that change the friction on the surface such as a change in surface treatment of the parts.
With Torque + Angle the tolerance stack-up is better because angles are very easily seen and measured while friction coefficients are difficult and nebulous to measure and control. What I am after is a certain amount of stretch on the fastener so that it preloads the joint to the correct amount of force (pressure).
The factory doesn't like the torque + angle because it is harder for them to do so at each stage of pre-production the question gets repeated to me whether they can be allowed to convert the spec. to a pure torque. I always say no of course.
on my car I always replace the bolt if I am asked. It is a very small percent in $ compared to the rest of the service cost.
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GEFP
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Well this thread explained to me a few of the questions I had. I was of the opinion that the only reason VW specified TTY bolts was so that they could soak a person more for the job. I had also thought that I would just buy regular bolts for an ALH clutch change and forget about the bolts from VW. From what I gather from the links shared here that's not necessarily a good idea. Thanks for the info.
Fahrvegnugen
Veteran Member
What I've noticed about the green vw bolts is that they don't rust when contacting dissimilar metals. If there is rust on them, it is where they have been threaded onto another metal. They aren't expensive in the long run, compared to what happens when an ordinary or reused bolt rusts in place.
eddie_1
Veteran Member
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There's not a single timing belt kit for the ALH & others in Germany that includes all the motor mount bolts. Talked to a couple of mechanics and they said these bolts are not replaced. These elaborate tb kits seem to be exclusively a north american phenomenon.
German Kit:
German Kit:
Andyinchville1
Veteran Member
HI,
Interesting thread .... I'll definitely keep my eye on it since I have always wondered why so many bolts on the VW are one time use.... not that I'm complaining because so far my VW has been my by best car so far so I won't deny it new bolts if needed or recommended...
I personally never seen bolts like the first pictures in person but if I do will know now why they are funny looking.
I have followed instructions as far as strange tightening patterns (like front axle nuts .... torque in stages / back up, back off, tighten again to a certain amount then an extra 60 degrees ....wow ...
Maybe sometimes the instructions are not so much to torque things to yield BUT rather make sure things are seated properly and maybe once you reach a certain torque things get inaccurate so that is why you have funny things like torque to 100 ft lbs then an additional 1/2 turn ? (it would seemingly be better to say torque to 135 ft lbs and be done with it than to say torque to 100 ft lbs then rotate "x" degrees more ??).
I have some old chilton / haynes manuals and many of those books have standard values to torque the various bolt sizes to (even charts breaking it down to different grade bolts (of course you have to be careful if tightening a steel bolt into something like aluminum since the aluminum may strip w/ too much tightening).
Anyways, maybe if you tighten to the numbers in the charts, then the bolts won't stretch and can be reused but if you go more then you may have stretched them too much and hence need to replace them? (i.e.If the bolt stays in its "elastic" range it can recover and be reused again BUT if you go too far (to the "yield" point) then you HAVE to replace it since it won;t "shrink" back ?
one disadvantage I see with just tightening things once is that tightening a new fastener once and forgetting about it can result in things falling apart ....
Once I had new wheel studs put on my trailer ( I don't remember the exact reason why but I had all 5 replaced). Anyways, the shop tightened up the wheels using torque wrench and I was on my way .... problem was when I arrived at my destination, I was 1 wheel assembly short !!
The wheel flew off sometime in the dark .... I did learn later that you tighten new studs to spec then retighten after 20 or so miles .... THEN if really paranoid check them again after 30 or more miles etc.... ( I was so paranoid after losing a wheel I checked it at 50 mile increments for 200 miles ... interestingly the first few times I had to tighten more .... I guess they needed to be torqued more but not to yield ....
Anyways, because of that incident, I would almost like to torque to yield most times BUT for things like wheel studs that would be too much of a hassle so I guess you just have to cycle them enough times until they don't keep stretching....
In a sense old bolts (provided they have not been torqued to yield) and are in good physical shape (good threads, not a lot of rust, heads not rounded off etc) are the best BUT I guess can lose strength if fatigued...
Overall I try to follow "the book" .... strange tightening procedures and all including buying new bolts if need be because I prefer to do a job once and not worry about it ....
speaking of which I just installed a RSB and the instructions call for checking tightness after 100 KM but not more than 200KM ... I guess I'll just cruise around for 125 KM and recheck them during the daylight ( I drive at night typically and would hate to have to do things in the cold of night somewhere)....sigh
Good thread!
Interesting thread .... I'll definitely keep my eye on it since I have always wondered why so many bolts on the VW are one time use.... not that I'm complaining because so far my VW has been my by best car so far so I won't deny it new bolts if needed or recommended...
I personally never seen bolts like the first pictures in person but if I do will know now why they are funny looking.
I have followed instructions as far as strange tightening patterns (like front axle nuts .... torque in stages / back up, back off, tighten again to a certain amount then an extra 60 degrees ....wow ...
Maybe sometimes the instructions are not so much to torque things to yield BUT rather make sure things are seated properly and maybe once you reach a certain torque things get inaccurate so that is why you have funny things like torque to 100 ft lbs then an additional 1/2 turn ? (it would seemingly be better to say torque to 135 ft lbs and be done with it than to say torque to 100 ft lbs then rotate "x" degrees more ??).
I have some old chilton / haynes manuals and many of those books have standard values to torque the various bolt sizes to (even charts breaking it down to different grade bolts (of course you have to be careful if tightening a steel bolt into something like aluminum since the aluminum may strip w/ too much tightening).
Anyways, maybe if you tighten to the numbers in the charts, then the bolts won't stretch and can be reused but if you go more then you may have stretched them too much and hence need to replace them? (i.e.If the bolt stays in its "elastic" range it can recover and be reused again BUT if you go too far (to the "yield" point) then you HAVE to replace it since it won;t "shrink" back ?
one disadvantage I see with just tightening things once is that tightening a new fastener once and forgetting about it can result in things falling apart ....
Once I had new wheel studs put on my trailer ( I don't remember the exact reason why but I had all 5 replaced). Anyways, the shop tightened up the wheels using torque wrench and I was on my way .... problem was when I arrived at my destination, I was 1 wheel assembly short !!
The wheel flew off sometime in the dark .... I did learn later that you tighten new studs to spec then retighten after 20 or so miles .... THEN if really paranoid check them again after 30 or more miles etc.... ( I was so paranoid after losing a wheel I checked it at 50 mile increments for 200 miles ... interestingly the first few times I had to tighten more .... I guess they needed to be torqued more but not to yield ....
Anyways, because of that incident, I would almost like to torque to yield most times BUT for things like wheel studs that would be too much of a hassle so I guess you just have to cycle them enough times until they don't keep stretching....
In a sense old bolts (provided they have not been torqued to yield) and are in good physical shape (good threads, not a lot of rust, heads not rounded off etc) are the best BUT I guess can lose strength if fatigued...
Overall I try to follow "the book" .... strange tightening procedures and all including buying new bolts if need be because I prefer to do a job once and not worry about it ....
speaking of which I just installed a RSB and the instructions call for checking tightness after 100 KM but not more than 200KM ... I guess I'll just cruise around for 125 KM and recheck them during the daylight ( I drive at night typically and would hate to have to do things in the cold of night somewhere)....sigh
Good thread!
IndigoBlueWagon
TDIClub Enthusiast, Principal IDParts, Vendor , w/
This thread started 3 years ago, but I find the amusing part is where the OP states that he's surprised that no one has brought this up before. In fact a lot of people have brought this up over the years.
I've heard enough stories of engine mount bolts failing when reused that it seems silly to try and save a few dollars by not replacing the bolts. $30 in bolts every 100K miles won't bankrupt most people. Other bolts, like suspension bolts, I think can be replaced based on condition, especially for people in rust belt states. But if a strut bolt fails you're not gong to destroy the engine or get killed, most likely. Lower risk.
We buy a stunning number of bolts at IDParts, all from dealers because we don't want to enter into this kind of discussion about bolt specs. If it's OE we feel we don't have to argue about the suitability of a fastener. And it's really not that much money, unless you're building a car.
We could have similar discussions about other components, like dual mass flywheels, the need for MAF sensors, or rusting turbo actuators. It's a car. Parts need to be replaced when they wear out. That includes bolts.
I've heard enough stories of engine mount bolts failing when reused that it seems silly to try and save a few dollars by not replacing the bolts. $30 in bolts every 100K miles won't bankrupt most people. Other bolts, like suspension bolts, I think can be replaced based on condition, especially for people in rust belt states. But if a strut bolt fails you're not gong to destroy the engine or get killed, most likely. Lower risk.
We buy a stunning number of bolts at IDParts, all from dealers because we don't want to enter into this kind of discussion about bolt specs. If it's OE we feel we don't have to argue about the suitability of a fastener. And it's really not that much money, unless you're building a car.
We could have similar discussions about other components, like dual mass flywheels, the need for MAF sensors, or rusting turbo actuators. It's a car. Parts need to be replaced when they wear out. That includes bolts.
eddie_1
Veteran Member
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This is where the German side is coming from, after talking to a couple of Master Mechanics here. Their take is about tightening things properly and making sure the bolt can hold the torque. Only replace bolt if not torquable.
And your point about things coming loose is very good. I suspect cases where the motor mount bolts were not torqued properly and came loose with vibration but issue was blamed on not using new bolts.
In fact in Germany if you get new wheels/tires, you have to come back to the shop after 100Km to get bolts retightened or sign disclaimer when leaving the shop. Torque spec 120NM.
IndigoBlueWagon
TDIClub Enthusiast, Principal IDParts, Vendor , w/
And here shops just run the air wrench until it stops and call it good.
I still re-torque wheel lugs 1-2 days after a wheels swap.
KLXD
Top Post Dawg
I break them loose then retorque them.
SilverGhost
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I think the term TTY is thrown around and misused, and that was the catalyst for the OP's original posts.
As far as VWAG - there are a lot of bolts requiring replacement for one of several reasons. Whether its lock tight, deform able self locking bolts or nuts, critical use case, or bona fide TTY.
As far as replacing those bolts during something routine - we have lost countless jobs for cost because we quote the bolts while other shops don't. Some we even see back after the resulting carnage.
So I limit replacements to critical use and inspect others for condition and recommend from there. I can put lock tight on my self!
Jason
PS: the wheel bolts/lug nuts sound like a perfect example of why VW recommends torque + degrees of turn.
As far as VWAG - there are a lot of bolts requiring replacement for one of several reasons. Whether its lock tight, deform able self locking bolts or nuts, critical use case, or bona fide TTY.
As far as replacing those bolts during something routine - we have lost countless jobs for cost because we quote the bolts while other shops don't. Some we even see back after the resulting carnage.
So I limit replacements to critical use and inspect others for condition and recommend from there. I can put lock tight on my self!
Jason
PS: the wheel bolts/lug nuts sound like a perfect example of why VW recommends torque + degrees of turn.
IndigoBlueWagon
TDIClub Enthusiast, Principal IDParts, Vendor , w/
Aren't you just starting over if you do that?I break them loose then retorque them.
flee
Veteran Member
Also, this technique works to avoid the false friction of not-ideal condition of the
studs, bolts and nuts. Wheel nuts and bolts can 'stick' in place due to rust and dirt, etc.
KLXD
Top Post Dawg
Lug bolts. You said you retorque them after a bit. I figger they are likely overtorqued, maybe under, so I redo them and I know fo sho.
IndigoBlueWagon
TDIClub Enthusiast, Principal IDParts, Vendor , w/
In my case they're not, because I torqued them in the first place.
Rrusse11
Veteran Member
My guru insists on 85#s with the weight OFF the car. Lower the lift afterI break them loose then retorque them.
work, tire rotation, etc so that the torque doesn't turn the wheel, but NOT
all the way so that the full weight of the vehicle is on the wheels.
They do use an air wrench but with a 50# "stick".
Then final torque by hand, cross torquing the bolts, then a final circular wrenching to double check.
I have my own torque wrench that lives under the back seat.