My Thrust Bearing is done. Advice please

Is this the purpose of tapping the crank forwards and backwards during assembly?? I've always done it (just did two days ago assembling my engine), but never really understood the "why". Follow up to that, is there a side you should end on? I've always ended with tapping the rear of the crank, figuring that is the direction of pressure from the clutch/torque converter.

 

Yes, you got it. Give it a bit of forward thrust while the cap is a little bit loose, but installed. The idea is to get this done before any bearing crush occurs due to torquing the bolts.

Devon

 

Yes, you are correct. If the cap is dowled, or registers off the studs tightly, then none of this needs to be done, just checked.

 

Thanks for the input gents.

The block is a 70 SF block .030 over forged speed pro pistons stock rods. One of the previous owners had it rebuilt before he installed the engine. He also had the transmission rebuilt at the same time both were represented to be stock type rebuilds. There appears to be no oiling mods as the main suction lobe is 1/2".The engine/ Trans has maybe 2500 miles since they were installed in 2006ish and i know I've never spun the motor past 4600. Most of the miles I put on on in the last couple years. I had to pull the engine in December 2012 right after i bought it to fix a leaking freeze plug and had no indications of any issues with the converter to flex plate fitment. It was running and driving fine when I pulled it to add the heads and cam and gave no indication that the thrust was going out.

One thing that I keep coming back to is Gary's advice about the Trans cooler. The reason the freeze plug went out was it rusted out. Could the corrosionin the coolant some how have affected the cooler enough that it some how got fouled? I drained and flushed everything back in 2012 and the car cols fine but you can still see barnacles on the radiator tubes. The only time the temp rises appreciably is when the AC is on and you are stopped.

 

Having just been through this, I sympathize. My powerglide was making 110 psi at idle in gear at the converter and then up from there. Turns out it was a faulty pump modification by a nationally well-known builder. The converter generally doesn't balloon but develops forward thrust from too much pressure in the converter or "charge pressure," not to be mistaken with line pressure.

If you're in a bigger city, get the trans put on a dyno at a trans shop so you aren't wasting your time and money building your own temporary dyno out of your wasted engine and the rest of your car. If you're in the sticks, well you're stuck like I am and build away.

Likely already thought of, but put the old cam back in too, you don't want to be putting a bunch of metal though those new roller lifters. If you've got 030 at the end you made a lot of metal in there already and thus the other carnage.

Sorry, man. Like I said I feel your pain, mine was a brand-new engine too.

 

I got back into this yesterday. I followed the thrust clearance setting procedure you outlined and I'm not getting good results. I checked the thrust with just the upper half of the main bearing in and got .009 and then i installed the cap and set it by snugging the bolts. I backed them off checked the end play and got and got .008. What concerns me is that once I torqued everything i got .005. That seems like a lot of change from bearing crush.

I'd really like to give this engine the best possible chance to survive the summer so if anyone can let me know their thoughts on these measurements i'd be grateful. Everything else checked out great the main clearances are .0015 through .0020 and the crank pin clearances with the old bearings are all in the .002 to .0025 range.

 

Did you check the thrust clearance (after aligning the two halves) in a few different crank positions? Maybe the thrust face isn't perpendicular to the mains.

 

I was thinking of that. It was getting later in the day when i finally got the crank set back in the block so i just measured as i described and called it a day. I doubt I'll get to it today as we have a family cookout, hopefully I can get a few hours after work each day to keep plugging away at this.

 

It's not really uncommon for the thrust to change a little with the cap on. All it takes is a slight misalignment on the cap. This could simply be from cutting it for line honing. Sometimes the caps can get a little distorted over time. Even if they are side indexed and the cut on the parting line for honing, just being .001 off can lead to .002" or .003 difference over the height of the cap.
Dye up both sides with machinist's dye or even a sharpie. Spin it over with a little pressure and see where you get a witness mark. You may just have to dress it a touch with 220 paper on a flat plate.

I'd be concerned that .0015-.002 clearance is just not enough to really supply the thrust with enough lubrication. I like to see .001 per inch of journal, up to .003 as kind of a max. I'd shoot for .0025-.003" myself.

 

Well i finally got the motor set back in the car after a few lost weeks, i found that the only day i was able to do much has been sundays and some weeks that hasn't worked out either. Any way i fired it up this afternoon after i got home from work; it was like one of those phony TV shows where they just twist the key and it lights right up. Needless to say i was pretty happy. I've bent up new tranny cooler lines and tee'd them for a gauge which is presently in the lower line (out to the cooler i believe??) and reads about 35 PSi at a 700 RPM idle. Tomorrow I'll get the hood back on and maybe take a short check ride around the neighborhood to see the pressures in the various gears. I can't go too far as the inspection sticker has expired while the engine was out of commission. Can any of you learned gentlemen tell me what pressures i should be seeing in what gears at what RPM's Just some rough ideas so i'll know if i am doing more damage. Thanks!

 

I went for a short check ride just a moment ago (maybe 3 miles) and found that in drive the line pressure goes up to 50 or so as RPM's increase just before it shifts; going down the neighbor hood streets at 30 MPH it is about 35 PSI. If i drop it into second or first i see 85-90 PSI without any applying much throttle at all. I believe this is too high as was mentioned earlier. Can some one confirm what pressures i should be seeing? Thanks for the assistance.

 

Warm it up completely Tom.. if you still have that cooler pressure in manual 1st and 2nd, I would want look at what is going on with the line pressure in the trans, in those ranges.

All your readings are a bit high, the 85-90 is beyond what is normally acceptable. Never want to see more than 60-70 psi in the cooler line.

The last one I checked, would get to 50psi in L1 or L2 with some throttle, but never beyond that. Driving down the road in 3rd was more like 10-15psi.

JW

 

Thanks Jim, I let the engine warm up to normal temps in the drive way but the tranny was still cool, I need to get an inspection sticker before i dare to go too far.
If i still have high pressures when I'm able to get the tranny fully warmed what is the fix I'm looking at? I am assuming the trans comes out and the front pump is getting the converter feed restriction we discussed or am i over simplifying?

 

I have some updates, i drove 21 miles round trip to get my inspection sticker and had the thrust open up a few thousandths. I did some additional checking and found that the line pressures were on the high side of the normal range and my cooler return pressures were half of the supply side pressure. I also found that my converter has 6 mounting lugs, one of which was sitting on the flex plate balance weight.

Yesterday I installed an external cooler to bypass the cooler in the radiator and also put some .125 Wlliams washers between the flex plate and the converter. I drove it 28 miles following these changes and found no increase in the crank endplay. I am cautiously optimistic that we may have found the problem(s).

I'd like to thank everyone who has offered suggestions and I'd also like to offer my deep gratitude to Jim Weise who has fielded multiple phone calls from me and answered several PM's to help me through this with advice. Jim has been very generous with his time and knowledge and i'd like to publicly thank him for all he's done for me.

 

Larry, I was following your thread with great interest, in fact i copied most of your your cooler set up! :TU:. I can stick my pinkie between the converter face and the flex plate bolt heads so i don't think i have an issue there. Jim thinks the converter mounting tab sitting on the flex plate balance weight had the biggest potential to create a problem; in essence by point loading the flex plate in that one spot it was creating a flat spring effect pushing on the crankshaft. The cooler in the radiator was another potential issue so that got bypassed entirely when i installed the external cooler. I just got back from a 30 mile drive that included a couple good blasts down some country roads; I checked the temp going into the cooler and got 158 idling in the driveway when i got home so i am pretty happy with the cooler so far. I'm going to measure the end play this afternoon after i cools and if its still looking good ray: I'm going to go flog the snot out of it and see if it stands up to that.

I do have one question; how are you insuring the trans lines don't get fouled in the front spring? I was looking at this as i slid the lines by the spring yesterday and i see the potential for a problem there. Other than that running the trans cooling lines through the frame is a slick set up.

 

Yes Larry , I am using the same cooler. Its seems to do a great job on its own. I did take another look at the lines where they pass by the spring and it would seem that the biggest threat is when the car is in the air and the wheels are hanging. When the weight is on them it doesn't look like they could fit between the coils; so unless you are doing a dukes of hazard re enactment it shouldn't be a problem.

I measured the end play a while ago and I'm not seeing any more increase so hopefully i can put this episode behind me. Unfortunately all i did was slap new bearings on a crank with some battle scars so I'm thinking it probably won't last very long. There may be a full on rebuild coming over the winter.