Crank thrust - End play

[Jerryl]

Fresh motor/short block, on the stand, never even turned the crank on the stand. . . . . and because I no longer trust anyone, I decided to measure the crank thrust.

Here is my procedure;
1-Set-up a dial indicator on the back side, and make sure it is as close to parallel to he mains and as close to the center of the crank as possible.
2-Hit/tapped the snout with a dead blow hammer into the block, towards the indicator.
3-Pry the crank in the front with a little pressure, thrusting it back into the block, with a small pry bar.
4-Zero'd the indicator.
5-Take a pry bar, and pry the crank forward, read the dial indicator - 0.009"

Repeated this about 5 times with the same results. (At least it's consistent )
I asked the machine shop specifically, to make sure they looked at the end play, since it was at 0.014" when I dropped of the motor.
Now I get 0.009 on a fresh motor?
(They have build quite a few 109's for the locals)

I am now questioning the polishing of the trust bearing surface.
I am thinking to call the shop and return it for correction closer to 0.004-0.006"

Anyone second my thoughts or too picky/concerned?
Do I need to get the thrust side of the bearing coated for a tighter dim, or are they available off the shelf?

 

[m233roller]

That's alittle more than I like to see but it's ok. I built a buddy of mine's engine 2 years ago and it had 10thous. end play and is still running great. I would'nt worry about it. GM says 003 to 011.

 

[87action]

end thrust

Do you weld up the crank thrust area if it is too worn or toss another crank to the recycling bin!

 

[turbofabricator]

Jerryl, The clearance is FINE! Stick with it. The only thing I would double check is the finish on the thrust surface of the crank. If they "touched" it with the grinding wheel, it'll have a saw-tooth pattern that can and WILL cut it's way into the bearing. I hand polish the thrust surfaces and have since reduced thrust problems to almost nothing. Before I started hand polishing the journal, it was almost 50%. I tried alot of differnet ways to keep the thrust bearing alive, and hand polishing the surface is the best, by far, way to keep the bearing alive. Look closely at a dressed thrust surface, and it looks just like a saw blade. Smooth that out, and it'll do wonders! I use to hand machine a groove in the main bearuing to spray oil on the rear thrust face. That didn't help much. Now I don't do that anymore. Just a 1/2 hr with 500, 600, 1500 grit and make it SMOOOOTH. Best 1/2 hr you'll spend. (unless it takes you a 1/2 hr. to install an intercooler in that POS '85 Hot Air you have.)

 

[turbofabricator]

87 Action, You just grind the journal to accept a .010" or .020" oversized thrust bearing.

 

[m233roller]

Iv'e got a 10 over thrust bearing in my engine that's had the crap run out of it for 6 years now and still going strong!!!!

 

[Jerryl]

Jerryl, The clearance is FINE! Stick with it. The only thing I would double check is the finish on the thrust surface of the crank. If they "touched" it with the grinding wheel, it'll have a saw-tooth pattern that can and WILL cut it's way into the bearing. I hand polish the thrust surfaces and have since reduced thrust problems to almost nothing. Before I started hand polishing the journal, it was almost 50%. I tried alot of differnet ways to keep the thrust bearing alive, and hand polishing the surface is the best, by far, way to keep the bearing alive. Look closely at a dressed thrust surface, and it looks just like a saw blade. Smooth that out, and it'll do wonders! I use to hand machine a groove in the main bearuing to spray oil on the rear thrust face. That didn't help much. Now I don't do that anymore. Just a 1/2 hr with 500, 600, 1500 grit and make it SMOOOOTH. Best 1/2 hr you'll spend. (unless it takes you a 1/2 hr. to install an intercooler in that POS '85 Hot Air you have.)

Yeah, I have read those post before about your advice.
As we discussed . . . you would not belief (Maybe you would ) how many have advised me to swith to the 87 set-up. Sometimes I wonder . . . .
My intercooler AKA PAC takes me a LOT longer to install, but I am S-L-O-W-E-R than most, but in my efforts to get this thing done, and at the track.

Thanks for the feedback. I feel a little better about it.
If I had to weld the crank, I'd just get a stroker for this HA.

Next: How to seal Cometic HG's.

 

[Jerryl]

87 Action, You just grind the journal to accept a .010" or .020" oversized thrust bearing.

. . . . . So, where would a rookie get such a bearing?
PS: Machine shop confirmed that the crank thrust surface was polished.

 

[Pronto]

Jerryl, The clearance is FINE! Stick with it. The only thing I would double check is the finish on the thrust surface of the crank. If they "touched" it with the grinding wheel, it'll have a saw-tooth pattern that can and WILL cut it's way into the bearing. I hand polish the thrust surfaces and have since reduced thrust problems to almost nothing. Before I started hand polishing the journal, it was almost 50%. I tried alot of differnet ways to keep the thrust bearing alive, and hand polishing the surface is the best, by far, way to keep the bearing alive. Look closely at a dressed thrust surface, and it looks just like a saw blade. Smooth that out, and it'll do wonders! I use to hand machine a groove in the main bearuing to spray oil on the rear thrust face. That didn't help much. Now I don't do that anymore. Just a 1/2 hr with 500, 600, 1500 grit and make it SMOOOOTH. Best 1/2 hr you'll spend. (unless it takes you a 1/2 hr. to install an intercooler in that POS '85 Hot Air you have.)

Ken, can you explain your technique for hand polishing the the thrust surface please?

 

[Jerryl]

Ken, can you explain your technique for hand polishing the the thrust surface please?

Sand paper and hand polishing:
500, 600, 1500 grit to finish it off.

 

[V8Killer]

Ken, can you explain your technique for hand polishing the the thrust surface please?

Same way I polished the up-pipe on my GN

 

[LOT]

end play

I would use it BUT if it really bothers you @ .009 and you would sleep better @ .006---.007--send the thrust bearing to Callico Coating (N.C) and have both side coated.

 

[Pronto]

Sand paper and hand polishing:
500, 600, 1500 grit to finish it off.

Same way I polished the up-pipe on my GN

Just wondering how you keep the surface flat since we're talking very small clearances. I've got polishing compounds at work that could put a mirror finish on the surface but I couldn't make sure it would be flat which I assume is important.

Anyone got a picture of one polished?

 

[Lil Truck]

Just wondering how you keep the surface flat since we're talking very small clearances. I've got polishing compounds at work that could put a mirror finish on the surface but I couldn't make sure it would be flat which I assume is important.

Anyone got a picture of one polished?

Did you ever get an answer to this old thread?

 

[ITSAV6]

Mine has .040 and have .010 thrust bearing as thrust surface was cut when crank was ground. Running with it over a decade.

 

[earlbrown]

Just wondering how you keep the surface flat since we're talking very small clearances.

With those grits, you couldn't change the shape if you tried. When it comes to sanding/lapping by hand once the metal gets 'smooth', the media just quits eating. Once the 'mountains' get knocked down, the grit just can't reach down and dig.

I noticed that years ago when I was building my 4.1. I had my crank in the lathe and polishing the journals trying to get more than .0003" on my main clearances. I damn near wore out a belt and the journal just got bigger instead of smaller. Instead of removing metal I was just imparting heat. Let the crank cool off for a few hours and turns out all the extra polishing didn't even remove a 10th. I do have one shiny ass crank though!!

 

[Pronto]

I polish gold and deal with clearances of 8 microns. I can easily lose 2 to 3 microns with the high polish from my final contacts so I have to compensate for that. Of course gold is much softer than the metals that we're talking about here.

 

[earlbrown]

Yeah, I think gold is slightly softer than iron.

 

[Lil Truck]

Yeah, I think gold is slightly softer than iron.

Yes, but the price for some of these Buick parts you would think they are made of gold!

 

[BobbyBuick]

.003 to .011 is in spec .

i Think its fine i like a little Extra not to tight more room for oil .I modify the bearing to let oil get to the rear thrust side of the bearing