The Chrysler/Jeep dealer in our area is telling me that they normally don't replace the TTY bolts on the caliper brackets when I did the brakes on my wife's Cherokee. To top it all off, they had 2 of each (front and rear are different) from sets of 4, so I deduce that Cherokee's are going around my area with reused TTY bolts in their brake systems! 🙄 I also couldn't find anywhere the proper torque sequence for these bolts, only a single torque value for the front and rear wheels. Naturally the dealer is no help. Thanks for the great info, it must be spread around. Ignorance will doom us all.
This is great! People are a lot more likely to pay attention to instructions once they know the reasons behind them. Otherwise they may just make up a reason in their head that might not be correct.
I recently rebuilt a ford 2.4 diesel engine and used all new tty bolts, i followed the manuals instructions on tightening and all seemed ok, later when the engine was started i noticed bubbles in the radiator header tank and a solid top hose (failed head gasket) i removed the rocker cover and cam shafts etc to get to the head bolts, before removing them i tested them all for tightness with a torque wrench, the specified tightening sequence was for the big bolts 20nm 40nm plus 90 degrees plus 90 degrees so i started my test at 50nm and worked up in 10nm increments, i got to 90nm and all were clicking the torque wrench apart from one which just went round and round. On removal of the head i found it leaking in the area of that one bolt, the bolts i used were from a supplier who sold me the full kit gaskets bolts the lot, the numbers on the head of the bolts were 10.9 i found out that the correct numbers should be 11.2 so i spent a little extra for branded bolts made in Germany and so far no problems all running fine. My question is the first batch of bolts i used were of unknown origin probably Chinese and i am wondering how close to the manufacturers specifications are these bolts are made obviously it must be a random luck of the draw type thing so for all out there in a similar situation dont go cheap on these things they might come back and bite you. Just add, the bolt in question measured an eight of an inch longer than the rest after removal
Usually when a bolt it torqued with degrees they are torque to yield I can’t say I’ve ever seen one that wasn’t and I do motor work professionally at my repair shop I own, the degrees is when ur actually stretching the bolts u almost always have a low ft lb torque then the last 1-2 steps is degrees.
Almost all "critical" bolts on modern engines use degrees for the final torque step because it helps to get a more consistent result than a torque specification alone. However, it has nothing to do with whether or not the bolt is a torque-to-yield bolt. A very high percentage of those bolts are not torqued to their yield point and can be reused if they are not damaged.
Outstanding Precision provided with clear detail explaining to even the most basic mouth-breathing knuckle draggers why you cannot just assume you can reuse fasteners although I do think it might be still too much to expect the same to understand concept but it was an excellent presentation
There will be small variations in width between any bolts if they are measured carefully enough. What I'd like to know is when exactly a bolt is too thin to be used. What measurement is considered to be out of spec verses acceptable variability ?
The bolt manufacturer will have tolerances that they use in manufacturing quality. The higher the quality of the bolt (as opposed to low quality bolts purchased in bulk from a hardware store), the less variation there will be in size. You could perform your own measurements if you had a large enough quantity of the same bolt that are new (not used).
What about metal bolts in aluminum engine parts. Are metal bolts galvanized so there is no dissimilar metal corrosion? And if you have to remove a part you should always use new bolts?
The other one you need to do a video on is NOTusing a hammer to release the steering joint taper in the steering arm. Everyone thinks it’s ok to keep walloping it until the eye deforms and pops the joint pin out
Hi Justin, I'm a rookie to this engine building, Am I correct that even though I see in the service manual to rotate 90degree (2X) does not mean my head bolts is torqu to yield? So can I reuse the bolts? And yes in the service manual it does not say I cannot reuse the bolts. The bolt part number is Toyata 90910-02121. Your thoughts?
You are correct. All torque specs on modern engine head bolts will include an angle as the final step. This does NOT mean that the bolts are TTY bolts. The best place to check is in the service information. If it does not specify that the bolts must be replaced every time, then they are probably not TTY bolts.
