Little pilot bearing issue ????
 

Ok, put the 7109 bearing i got from BOP in today, had it in the freezer overnite, when it pretty easy, i have it in the crank all the way, but noticed i can pull the bearing in and out about 1 or 2 mm with my finger., when i pull it out some, its seems tight but a little loose when i push it back in.

Rented the tool to remove but the arms dont fit in the bearing, ending up just using a pick pulling a little at a time on all four side and it came out, im assuming this should be in a little tighter.

Did a search, some say to stake it in, are we talking about putting dimples in the side of the crankshaft to hold this in place, paid a pretty penny for this forged crank, dont think i want to be hammering on that thing.

Any help would be great.

Rich

Get a small tube of green locktite. That is sleeve and bearing retaining compound. It is very low viscosity, like water. put a very thin film on the crankshaft pocket and a very thin film on the OD of the bearing race and install it. Make sure not to overdue it and get any in the bearing itself. Wipe off the excess. That should take care of it.

Next time you have to knock one out:

https://www.tiktok.com/@oldecarrguy/...80978044783878

Done this many times, works great!

Same process but I always used some grease.. then make a sandwich with the bread! ;)

Hey thanks guys, Mike i take it your talking about loctite 620 or 680 as long as its green.

Rich

Locktite 620 would be better if you have a choice because it's thinner. 680 can fill gaps up to .015" and might all get scrapped off when you install the bearing. Would work in a pinch though.

In today's world of substandard cheap parts made with little QA control I would be suspicious of the bearing. Time to break out the micrometer and measure the bearing and the crankshaft and see what is what.

Personally if I found the crankshaft machined oversized I would install a custom bushing instead of a bearing that needed Loctite to keep it from moving around.

Just my opinion which along with a sawbuck will get you a steaming hot cup of Joe just about anywhere. 🙂

Just stake it in a couple of places.

Ok, measured both bearings i have, both are 1.378, inner is 0.590, i see Buttler has a bigger bearing that is 1.379-1.380 with the inner being .593, on there listing is says .002 over sized, but later in the listing it says .007 over, guess i have to call on that one.

I have the flywheel on now , gonna pick up some hf tele scope measuring tools, dont know how well that is gonna turn out for accuracy.

Stupid question, when your talking about staking it , your talking about inside of the crank right where the bearing sits, so you would have to stake it first, then put in the bearing,

Maybe this might be easier, its a Scat Forged crankshaft, you guys with these have to use the bigger bearing, or did you get the 7109 to work.

I’d use the loctite before I would stake it to keep it in there.

If the bearing is staked in place or Loctited down how do you know it has been installed in perfectly alignment with the crankshaft centerline? Do you use a jig or something to hold the bearing in place while securing it that way?

I’m going to make an assumption here. And yes, I know what happens when I make an assumption. Nevertheless, I am going to assume that the bearing moving in and out 1 to 2 mm means a very light slip fit. No more than .0005”. 5 tenths in machinist talk. So, using my assumption, at worst case of .0005”, when the bearing is touching one side the centerline of the bearing would be .00025 off of centerline from the crank pilot bearing hole. If you use green loctite like Mike said, there will be a film of loctite all the way around the bearing until it sets up. Then you are down to maybe.0002” off of centerline or less. I would think that since in the real world of manufacturing where nothing is ever perfect, and that’s why tolerances to size exist, .0002” deviation from centerline would not make any difference in performance.

Exactly, easy way to secure the bearing without any potential slip ups. Staking the bearing in the crankshaft will certainly work. But the OP did not want to stake his forged crank. I think the Pontiac factory service manual says to stake it. My only issue is staking with the engine installed, I always seem to have that errant stake strike that misses a little and can hit the bearing or shield.