Last Word On Loctite

New 9/23/05

hi to all i am exploring ways to fix my cams and i all about the welding but what about locktite? why not use that? its so much easier and i can do it myself? please everyone give me feedback

thanks glenn

It doesn't work.

Rene Carlos Cruz

Since you're new, I won't say anything nasty. :-)

Loctite has been tried, exactly as recommended by Ford, and it failed miserably. It's not even worth the $5 for the Loctite, let alone the $$$$$ for a new engine once it fails!

Dan

Not to be disrespectful of Ford, but it won't hold. If the original swedging (sp?) won't hold, there is no way locktite will. Locktite on a bolt's threads has a huge surface area to work on, at least compared to one of the V8's camshafts.

Greg

Well, the Locktite would only POSSIBLY be a viable prevention if it were applied BEFORE the cams were assembled, but then it seems that Ford has done that recently on a few replacement cams according to reports of some sort of green-goo between the sprocket and tube. Of course to understand the structural design and loads that are being incured on this component it becomes glaringly obvious that no amount of "goo" or Locktite is going to prevent the inevitable from occurring.

Let me see if I can explain this in a short paragraph: The engine has four camshafts. Two of these camshafts reside above each cylinder head. One of these camshafts (now referred to as the "primary" camshaft) on each head is driven by a common chain connecting them to the crankshaft. The other cam on each head is driven from the "primary" cam by a "slave" sprocket and chain. When the engine is accelerated the crankshaft "pulls" on the primary chain shifting the primary driven cam in the direction of the chain. The secondary camshaft is not "pulled" in the same downward and forward motion by the physical location of the drive sprocket at the outside of the bearing surface, but rather is pulled to the other side since the sprocket is "craddled between to bearings. This movement forces the primary cams slave sprocket forward while the secondary cams slave sprocket is driven in the opposite direction. This puts opposing axial loads on the sprocket making it "wobble" as it were until the knurled-swedge joint can no longer securely hold the two parts together. Adding any liquid that will harden like glue will come nowhere near bonding these two materials any better then bubble gum.

Imagine an old bicycle with worn bearing on both the pedal sprocket assembly and the rear wheel. The loads will try to draw them tighter together but on opposite axial plains causing the chain to come off. In our case though the tensioner will not allow the chain to come off, just twist the sprocket from the axle.

Carter Fuji

Loctite does make bearing retaining compounds that will fill voids of up to .020" successfully, but even they'll tell you it is an emergency repair, temporary, and results are not guaranteed. Most times, this compound (and others like it), is used in industrial applications that need to keep running or face thousands or millions of dollars in lost production because the equipment is down. It's a bandaid repair, and it's understood that it won't last forever. Usually, at the next feasible time period, the equipment will be repaired permanently. Industry can afford to do this, and it's done this way to minimize impact on the bottom line.

In the case of the cam sprockets though, there's a lot of things working against you. There are axial and radial (rotational and side-to-side) forces acting upon the sprocket/cam assembly, and the Loctite is not very good at dealing with axial loads. Also, remember the cam/sprocket assembly is contaminated with oil. It's easy enough to clean the oil on the outside of the sprocket for a weld, not so easy to clean underneath the swaged surfaces so that the Loctite adheres.

Simply speaking, pinning or welding is preventing the sprocket from walking sideways and rocking, causing the sprocket to spin, and the dreaded cam failure. Pinning is not really a good option, because hardened dowel pins as used by SHOShop initially are not very good at taking side loads. They're more of a locating pin than a part of a mechanical assembly.

This leaves welding as your best option for preventive maintenance. Different welders use different methods, however the key is to have someone who is familiar with welding dissimilar metals do the job. TIG, MIG, and flux core wire are the most popular methods, each has their advantages and disadvantages.

I, for one, can understand a new guy's dilemma in deciding what to do. Finding out you have to dump a lot of money into a car you just bought, for a failure you didn't know about, can't be easy to take. Take the advice of the rest of the list, and get welded before you do anything else.

As far as your choice of welders, it seems like it comes down to what makes the most sense financially for you. FPS is obviously excellent at anything to do with the SHO, and pioneered the idea of welding the sprockets. If they're close to you, that's the way to go.

Kirk has also welded a lot of cars, and has done a lot of camfests. He is also a good choice, and keep in mind that camfests require him to travel. With the rise in fuel prices, that has to be factored in, which may be driving the cost up.

Good luck with whomever you decide to go with, but whatever you do, give yourself the peace of mind of having welded cams!

-Bob

Actually a while back I asked someone to do the calculations, in theory Loctite should extend the life of a V8 cam shaft by about 10%. So if you have a 120k cam shaft you may get another 12k. It is worth the small change to Ford to extend the life an extra few miles if it causes a failure to occur after warranty coverage. But if you had a 3 mile cam shaft Loctite would help you get only another 1500 ft. That is all assuming that you have no relative motion or noise from the cam shaft so far. From the owners point of view, if they intend to keep a car, get the cams welded. Because welding extends the cam life by a million miles or so it is still the recommended solution.

Buford

Contact Information