First questions on my 727 rebuild journey

[AR67GTX]

Pulled the shaft this afternoon and tested planetary end play per the shop manual and it still came up about .056 inch to the shoulder which is too much. I had a 3-tab shim @ .060 inch installed and found a 4-tab one that's .064 to replace it with. I can make some more up with the .010 shims I bought but I may go ahead and order a thicker snap ring too.

 

[miller]

Sounds like it will take what it takes, going from one assembly, to the next, and getting each endplay in the right range.
Your probably well aware how, and why, with your experience on gear-banging trans. Same thing. Endplay to keep things in place, and free turning.
Just have to make it right. Too many dang small parts!

 

[AR67GTX]

Back to the flex plate. This is what the bolt slop looks like in the new one.


These are 5/16 bolts with .395 inch holes. Old flex plate holes are about the same.

I was able to get both flex plates on the crank register at once and trace an offset hole pattern. Then with a lot of micrometer readings I pretty accurately established centerline.



I feel I could pretty accurately drill off set holes of a smaller diameter. I would probably oversize them a few thousands over a 5/16 inch bolt just to be safe. Probably wouldn't be perfect to a thousand. But in checking the punched holes off of the edge of the center register - it's not that accurate either.

What do you think - give it a try or just use it as it came?

 

[oldbee]

I wouldn't re-drill new holes. You have to "start" all 4 bolts before tightening them down. They 'should' self-center before you go back thru to tighten. The couple I did always had a little slop when inserting the bolts.

 

[oldbee]

Remember that one one hole is offset from the other 3.. Should help center it all up.

 

[AR67GTX]

OK - well, I think I will probably go ahead with drilling the holes. It won't hurt balance and they will either line up or not on installation to where the bolts slip in without interference. If not, I'll just use the punched holes.

I think the proper method is to thread all 4 in loose first and then make sure there isn't any sign of misalignment as I rotate the engine to torque them.

Yes, I'm keeping the old and new plates matched up so the offset hole is properly aligned.

Thanks OldBee

 

[miller]

OK - well, I think I will probably go ahead with drilling the holes. It won't hurt balance and they will either line up or not on installation to where the bolts slip in without interference. If not, I'll just use the punched holes.

If you 're-locate' those mounting holes, it will affect the balance of the crank/flexplate/torque converter. The whole idea of certain holes being offset is, it 'must' be bolted up balanced.
Just a suggestion, okay? For what it's worth!
If your set on using that flexplate, which is okay, I'd consider this...use real thin, hardened steel washers, under the bolt heads, flexplate to converter. For the too big bolt holes in the flexplate...find some right sized 'bushings', that will center the bolt shanks into the bolt holes. Just need to be about the thickness of the plate, to take up the extra, and will keep the balance in play.

 

[Fran Blacker]

They sell 1/32 wall brass tubing in hobby shops. The ones that sell model airplanes and gas powered cars. Only problem is cutting it. Can't use a tubing cutter because of the burr. You buy 5/16" id it will be 3/8" od. just bring a bolt and the flex plate to check fit.

 

[Fran Blacker]

http://www.ebay.com/itm/Small-Parts...247887?hash=item465ade974f:g:9HYAAOSw3YNXbNjj
This is what I'm talking about. I think the id is a few thousands small. What about buying a 7/16" bushing and drilling the center to 5/16" and cut to length?

Edit: Wall is thick on the ebay piece.

 

[Fran Blacker]

http://www.ebay.com/itm/7-16-x-12-B...968652?hash=item58eb4f5bcc:g:IccAAOSwo4pYZulo
Here's another.

 

[AR67GTX]

I'm doubtfull the holes are located accurately enough for a bushing to fit in all locations. When I was micing the holes on the flexplate there was definitely one that seemed several thousands further out than the other 3 (not the off center hole). I'll sit tight for now.

Air tested the clutch packs mounted on the pump with 30 psi and all was well.

Waiting on Federal EX to bring me a thicker snap ring for the output shaft. I inserted 3 - .010 shims and got the planetary end play down to .026. This snap ring should be 5 - 6 - 7 thousands wider which should get it down close to .020. That should be snug enough.

 

[Fran Blacker]

This hole question is being over thought. Ideally the holes should be closer than a 1/16" . The bolts don't need to clamp down like head bolts it's more about shear strength. If you were racing then it would matter more. I know it's a little shamy I'd put the bolts in the way they are. If you went that way, put the first three in a turn loose but turn engine clockwise (direction it runs) when you put in the last one in should be against the edge of the hole in the direction of rotation, Torque it there. Then torque the other three. This will horrify miller and dvw maybe? Can't wait to hear.

 

[AR67GTX]

That's sort of why I'm reluctant to mess with a bushing. If the bushing is less thick than the flex plate and isn't loaded - then it essentially is doing nothing but rattling around in there. I also would not want a bushing that was very slightly thicker than the flex plate as then the clamping force would be on the bushing instead of the flex plate which I doubt would help with shear much and might lead to loss of tension if the bushing compresses.

 

[miller]

Agree with your thinking, unless bushings are in right. Only thoughts are to use them for locating the center of each hole, since their over-sized. Even nylon bushings would do, once the bolts are torqued.
But, it's your party. What you think will work.

 

[Fran Blacker]

That brass tubing if you cut it a little long and annealed it with a propane torch it would crush. Look under the head of the torque converter bolt there is a nice radius to form it. The second ebay tube address should be right.

 

[oldbee]

Overthinking agree. Any make I've ever done all about a 1/2 turn loose,rock the conv. to center and tighten down.

 

[AR67GTX]

Well - after studying my old and my new flexplates, I've decided to go with the old one. The old one is .013 inches thicker material, the holes are .005 inch smaller and it's just overall flatter and less warped than the new one. I'm going to clean it a little and give it a fresh coat of paint, bolt it back in with new bolts and check runout on it once more. Those ears on the stock type plates can be moved very easily with a bit of pressure to make them all line up in the same plane. The one ear that was out before could be seen laying a straight edge over it. It straightened up easily putting it in a vice and giving it a bit of a tug. Of course until it's torqued down tight to the crank I can't really evaluate it for sure.

If anyone wants a stock, repro flexplate cheap I have one.

 

[AR67GTX]

Started back to work today on the 727 despite bad allergies - but quickly ran into another possible worn part I have overlooked. I focused on the front planetary so much that I overlooked wear on the back side of the rear planetary where it rides against the #8 steel thrust plate in the annulus gear. There's a pretty good groove worn there that pretty much matches up with the thrust plate.



It measures a little more than my .035 in feeler gage which probably accounts for most of my excessive end play in the planetary train. I did check the #8 shim thickness and it mics at .036 so it seems to be in shape. So basically the planetary is riding on the annulus case instead of the thrust washer.




Possibly having a bit too much Bubba in my blood I thought about putting one of my .010 metal shims on the rear of the planetary to run on the steel thrust plate.



I cut and bent some tabs to keep it locked to the planetary but I'm not sure this is a sound idea - I'll have steel running on steel?

Other thoughts - my #2 plan is I have a thinner brass shim (.055 inch) but that alone will reduce my overall end play to essentially zero.



My #3 plan is I also have a .040 composite thrust washer I could put between the planetary and the thrust plate #8. That should leave me with about .015 in end play - but will it hold up?

Or, #4 - I could go looking for a new rear planetary.

And finally, #5 is just run it as it is, although I'm wondering if this wasn't a contributor to some of my noise with the planetary case skimming the back of the annulus case.

Thoughts? I didn't really want to get this thing back together today anyway.

 

[oldbee]

New rear planetary would be my plan. Sorry..

 

[AR67GTX]

Well, I do know where I can supposedly buy one for $115. It's curious - that (and the sun gear) seem to be about the only severe wear I've found in the transmission. but that steel thrust washer running directly on the aluminum planetary case doesn't seem like the best approach.