Greetings all - quick question :
flexplate to crankshft - blue or red locktite?
Big pulley at front of engine attached to crank: blue or red?
Torque convertor to flexplate? blue or red
Anyother places anyone can think of where I'll need locktite while assembling theengine/attaching the trans?

 

I have put thread lock on VERY few nuts and bolts. If you use the red it's almost impossible to get the things undone.

The trucks survived very well when they were made without "LocTite"

I wouldn't (and didn't) use any at all on any of the things you listed. Use new lock washers, nuts and bolts on these assemblies.

 

When I do use LocTite I use blue. I never but things together forever.

 

I vote blue also. The red is permanent and was developed for mounting cylindrical parts.

And Julie, I don't agree with you this time. Locktite has solved a problem that has plagued threaded fasteners since their invention and that is loosening due to vibration. I think it was 1975, or thereabouts, Indianopolis racecars were made to use locktite through out their assembly and thats the first year they found NO nuts or bolts after the race.

 

RED on everything!

 

If i decide something needs locktite, it goes like this ,if you can put a wrench on it, red.
if its a machine screw fastener, blue.

 

There's more than one "red" and "blue", but I assume you mean #271 for Red. It isn't really "permanent", but they caution that heavy duty wrenches or even heat could be required for removal. It is commonly spec'd for flywheel and flexplate bolts -- and anything else you really, really don't want falling out. I've never had to use heat myself to remove flywheel bolts that I've used #271 on.

I'm not sure what engine you have, but I'd be cautious about using red on the front snout bolt. On flat V8's they are hard enough to get off with clean threads. On the other hand, older Chev V8's are pretty famous for that bolt loosening.

 

I really hate that stuff. A properly torqued fastener of the proper size will not loosen because the fastener stretches as it is tightened and the tension generates friction sufficient to keep it tight. The only time I EVER use Lock-Tite is on problem fasteners that vibrate loose. With that said, I can't remember the last time I used it - and I wrench for a living. I maintain a "very precise" German printing press and those yokels used that crap on every single fastener. I always take a hammer and chisel with me to disassemble their "precision machine" when I have to work on something because I can always count on stripping the head out of at least one socket head cap screw.

An Indy car I can understand when the crank is swinging at 15K RPM. But our old trucks? Nah!

 

No sweat - that's why we are here is to offer different ideas and rationales.

Based on the experience I had with the red stuff on a few nuts, I'd be afraid of twisting the studs off the torque converter if I had it on there.

I had a moderate drive train (395 net HP) vibration problem due to pinion angle excess. I drove it like that for almost 10K miles not realizing it wasn't natural to the truck - never lost a nut or bolt.

I think something like this is a matter of individual preference.

Unfortunately many people in the course of their restorations accept the mind set that they will never have to take this stuff apart ever again - and that's a mistake!

 

If you tighten a bolt (or a nut on a stud) to the proper torque (with clean good threads of course) you should not have a problem with loosening. But if you expect a lot of vibration, a thread locker can help. Speaking from experience, the Loctite 242 (it is one of the blues) is what I use on anything 3/8" thread and below. I use Loctite #262 (one of the reds) on all larger. There are a few others I use - Loctite #272 (another red) for high temperature (above 300°F) areas. Do not go by color only, the number is important. And some of the other brands use name designations. One I am familiar with has a product called LocksStuds - equivalent to Loctite #262, and another called LocksNuts - equivalent to Loctite #242.

 

All good advice. I use red on anything that is "mission critical" that does not use a lock nut or lock washer such as steering components (I recently recommended it here on steering shaft U joint set screws and pitman shaft nut). and blue or anything else that I feel might vibrate loose. That is not often, I have never actually emptied a small tube, but replace it every couple years because it makes me feel it's the right thing to do or I've misplaced what I had.
Should I find the need to undo a fastener that I have used red on, I gently heat it with a propane or butane torch to the point it "sizzles" when a little saliva is applied as a temperature test, that's usually hot enough to break the seal.
I prefer to use nylock type nuts on bolts that I want to stay tight. If you use lock washers, make sure you use high quality ones of the same grade as the bolt and nut. Re: engine fasteners, I use whatever fasteners were originally used, replacing any that were originally torqued to 80# or more with high quality replacements of the same type. I also clean any fasteners I am reusing in solvent and chase any threaded holes with a tap before reassembly. If I am replacing headbolts or other parts that are threaded into a machined surface, I lay a fine toothed file flat on the surface and slide it lightly over the holes to be sure that metal has not been pulled up around the holes. If the file "catches", I give it a couple more (gentle) passes until the file slides smoothly across the entire surface.

 

There is a thread on an engineering forum I frequent on the value of lock washers. The consensus, from guys who design engines etc for a living, is that they are useless, and was supported by tests. My Porsche doesn't have any lockwashers on any engine components. On the other hand, all the fasteners are a @#$%%^& to remove. If you've ever worked on a japanese motorcycle with cross-head screws (phillips) you know what I mean.