Name: How to Check/Adjust Crankshaft End Play SBC (Tech Tip!)
Uploaded: 2025-03-07T23:21:04.000Z
Duration: 12 min 19 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

What is going on guys, Pat on the shop and tonight we're talking about thrust bearings on this small block Chevy crankshaft end plate.

So as I was getting the bottom end together for the YouTube block, I was putting everything together and I realized I forgot to film about thrust bearing because I actually had to adjust the thrust bearing on the YouTube block.

And someone emailed me and asked me about thrust bearing clearance.

So basically what thrust bearing is on a small block Chevy, it's the rear most bearing and if you look at the rear bearing, almost lost it there, this is just a spare one I have.

You'll notice this bearing has this surface on each side of it.

LS and a lot of Fords and stuff will have the thrust bearing in the middle, but on the small block Chevys and big block Chevys, it's at the back like this.

So what this surface actually is, is for the forward and backward movement of the rear wood movement of the crankshaft.

So when the crank is being pushed forward, say with a torque converter or with a clutch, you're pushing on the clutch, the crank is actually being pushed forward.

This bearing surface here against the crankshaft is what takes that load.

So there is an adjustment on how much play there needs to be in that forward and rear wood movement, and it has to be checked and I'll show you how to adjust it if it's out.

So you don't need a fancy dial indicator to check this, I have a dial indicator set up on this one, but I'll show you what you can actually do with just simple feeler blades and get really accurate results.

A lot of guys, you know, a lot of guys, this is just the way they do it.

Not everyone has the feeler blade or the dial gauge with the base, so a feeler blade works just fine.

On a small block Chevy, you want to see anywhere from 3 to 11 thou from pushed all the way back to all the way forward.

And this is typically something you check before the rods are all installed.

As you can see on this engine, it's together, this is already set and this is good to go.

You don't want to have all this together and then check your thrust bearing because if it's out, it's going to be more of a pain for it to adjust for you.

So let's go over how we're going to check this.

So we're going to pretend like we don't have any of the rods installed and pistons and all that stuff.

And we've already checked main bearing clearance and all that stuff and everything's good.

So what we're going to do is we're going to just have, you can have just the front cap on if you want and then have the other bearing shells in there so the crank's sitting where it's supposed to be.

The rear bearing cap, you're going to want to torque to about 20 foot-tons just so it's snug.

And then what you want to do is you want to tap the crank forward just like that with a rubber mallet and you want to tap the crank backwards just like that with a rubber mallet.

That just makes sure that the shells are aligned, like the two bearing shells are sitting somewhat together for when you're checking clearance.

So right in here is this bearing surface right like that.

But if you were to look, this shell right here, this surface is right there, while the top one, if you want to look at it like that.

So that's where we're going to actually check.

So you're going to get your feeler blades out and the spec is three, on a small block Chevy, three to 11 thou.

So what you want to do is you're going to take a screwdriver right in this area between the main cap and the crank and you're just going to pry it forward gently.

And you should hear, you could probably hear, I don't know if you can pick it up on camera, but there is that little bit of movement of the crank going forward.

So then you can simply do the go, no go method where you take the tightest spec, which is three thou.

We're going to take a three thou feeler blade and put it in between the crank and the bearing surface right there.

So we know we have our minimum clearance and we can take our maximum clearance of 11 thou and it doesn't fit.

And then if you really wanted to, you could figure out exactly what you have.

So there's the four thou feeler blade, see how it goes right in and it's just a little bit of resistance.

So it's probably more like four and a half thou right in between there.

So that means the play that we have with the crank moving from all the way back to all the way forward, like that is four and a half thou.

All right, so what do you do if there's not enough clearance?

You go to take your three thousandths of an inch feeler blade, you take your feeler blade and it doesn't fit.

Well, it's quite simple actually, it's called lapping the rear bearing.

And I'm going to show you exactly how we're going to do that.

There's a few things you're going to need.

First and foremost, you're going to need a really flat working surface.

If you don't have that, a thick piece of flat metal or even a piece of glass will work really well because you're going to need it for a sanding surface for your rear bearing.

The second thing you're going to need is some wet dry sandpaper.

This is 320 grit, so 320 to say 400 grit.

And then you're going to want some fine sandpaper.

I don't unfortunately have a bigger sheet of this, so I normally will like a full size sheet of like 800 to 1000 grit to finish the surface when you're done.

This will do majority of the work and then you're just going to polish it up with that.

You're going to need a gear clamp that's big enough to go around the bearing to hold it all together.

Some WD-40, some brake clean or rubbing alcohol or something to clean the bearing up after.

And a vernier caliper to measure how much you're taking off.

So you want to put the bearing shells together as they sit in the block.

So it sits like this because you want to know what the front and the back are.

So make sure when you put them together that they are indexed the way they would be in the block.

So the idea is you're going to remove material from this face, but you don't want to, ideally you don't want to remove the material from the back.

Because the back of the thrust bearing will actually take the most wear because the crank is being pushed forward against this surface and not so much backwards on the front thrust surface.

So typically you want to leave the back as thick as possible and take from the front surface.

You can take a little bit from each side, but ideally you want to leave the back alone and that's why you mark which side is the back so you know you're only going to be sanding the front.

So we're going to be wet sanding this so we'll spray some WD-40 down.

And then you're going to want to take your verniers and measure the flange thickness.

So you might find it's a little bit different at the mating surface, but you want to find the thickest point.

Now maybe we only had 2 thou clearance before for the thrust surface.

We want to get to 5 so we're going to have to take 3 thou off the back of this.

So once we've got our measurement to where we want it, we have 3 thou removed, this might take you all of 5 minutes to do.

Keep checking because you'll find it comes off pretty quick.

Then you finish the bearing surface with the 800 grit, wet sand it again with your WD-40 just until you have a nice smooth surface.

So now that you've got your bearing surface all lapped and everything cleaned up, brake cleaned, wiped down, make sure you clean all that muck and guck off there, you can go ahead and reinstall this bearing and recheck it the same.

Torque the rear main cap down to 20, hit it back and forth, and then recheck that clearance again and it should be bang on.

If you followed that step and measured properly that flange surface with the vernier and made sure, and then once you get everything in and torqued down the crank fully with all the bearings, just go ahead and make sure you check that again.

Talk about if you have too much crankshaft in place so you go to put the crank forward and you can slide bigger than 11 thou feeler blade in between.

First of all, make sure you really check out what's going on because typically if there's too much clearance, there's something funky going on with either the bearings or often times the crankshaft is worn to the point where it's not usable or has to be repaired.

But what they do make for crankshafts that have been ground, if the thrust surface has been ground, they make bearings, Clevite makes them, probably a few other guys, where this surface is actually thicker to make up for that.

If it's obviously too thick and you can't get a crank in, you can lap it in to take more, but do the same process as we just showed to get it in.

It's a little bit more complicated if you have too much crankshaft in play, but typically what you'll find is that you're usually going to be on the tighter side.

I've had more issues with having to add clearance rather than take it up with too much clearance.

There are options, like I said, get the crank being repaired or replaced or you have to go to a thicker flange bearing.

But if you have too much, make sure you really take a look and see what's going on with the bearings there and really do some investigative reporting because too much is a sign of something's worn out.

So there you go guys, thrust bearings, crankshaft in play, easy peasy stuff, but a lot of guys overlook it.

So make sure you check it if you're doing your engine over, if you're doing a check on your engine.

Pry that crankshaft forward and backwards.

You don't need a dial indicator, you can just use a set of feeler blades.

Everyone should have a set of feeler blades in their toolbox and you can just check it real quick like that.

You'll know right away when you go to pry your crank forward and back.