First questions on my 727 rebuild journey

[AR67GTX]

Good thought on the joint line of the bushing. I'll have to watch that. I'm going to study the pressure diagrams on the servo seal. This is the outer piston in the servo to the front (front band - low band?) (Edit: this is wrong - it's the rear case servo for the low and reverse band.) so I don't see how there can be any pressure from the pan area acting on the exposed side and the lip should go to the inside - but I'll double check.

 

[dvw]

Good thought on the joint line of the bushing. I'll have to watch that. I'm going to study the pressure diagrams on the servo seal. This is the outer piston in the servo to the front (front band - low band?) so I don't see how there can be any pressure from the pan area acting on the exposed side and the lip should go to the inside - but I'll double check.

 

[oldbee]

If I remember on the lip orientation the press. is coming towards the "cupping" side of seal so it's naturally pushing the seal outwards a little; previous posts probably said it better than me. I've only did 3 rebuilds but never had a problem with any of them(first 2 were 'race only')manual valve body,hemi drum,etc. I didn't know what I was doing either, but the FSM is a godsend.

 

[AR67GTX]

I apologize for confusing everyone including myself. The seal question pertained to the rear case servo (low & reverse) and not front. The piston end goes in the bore bottom with the lip facing into the bottom of the bore.

 

[oldbee]

Ar67- yup that's where the pressure is coming from; I wasn't confused,I don't think!

 

[AR67GTX]

Ar67- yup that's where the pressure is coming from; I wasn't confused,I don't think!

I kept saying it was the front servo in error. I could confuse anyone.

 

[dvw]

Before long you'll be building transmisions for your buddies.
Doug

 

[miller]

Yeah, I was thinking 'back the horse up' thing, too.

Good to hear you got it figured out. Next time...with your eye's closed!

 

[AR67GTX]

A bunch of parts rolled in today so tomorrow I'll be back in the reassembly process.

Question - I got what appears to be a proper 10 inch pattern, stock flexplate from Mancini - but it still has 3/8 inch bolt holes. The stock 5/16 inch bolts are lost in them - but they are definitely smaller than 7/16 inch. So what accurately centers the converter on the flexplate - just the engine dowels? I didn't spend a lot of time looking at the crank when I pulled everything apart - does the crank center the converter snout in the bushing recess that closely? Seems sort of imprecise.

Got their yoke too and it slips on just fine.

Thanks for the accumulator spring Doug - looks brand new.

Didn't realize until I got some seals and rings from TSR racing that it's Carl Monroe's company. No wonder they were stocking his rebuild book.

 

[oldbee]

AR67- heckuva question. My guess is a little of crank recess & bushing in the oil pump. If I remember right there was always a little "slop" when putting in the conv. bolts. Converter would always move a little "sideways" in the holes; but it's only moving in a circle around it's center. Probably a bad explanation.

 

[AR67GTX]

AR67- heckuva question. My guess is a little of crank recess & bushing in the oil pump. If I remember right there was always a little "slop" when putting in the conv. bolts. Converter would always move a little "sideways" in the holes; but it's only moving in a circle around it's center. Probably a bad explanation.

I was ready to blow off dialing in the transmission case to see how close it is. I may go ahead and do it now. No wonder they named them flex plates.

 

[oldbee]

LOL, I think the "flex" is fore&aft. Marine Corps, Dept. of the Navy.

 

[dvw]

Do not use the 3/8" holes for 5/16" bolts. Get a different flex plate or drill 4 new holes accurately, pretty tough w/o a rotary table.
Doug

 

[AR67GTX]

Do not use the 3/8" holes for 5/16" bolts. Get a different flex plate or drill 4 new holes accurately, pretty tough w/o a rotary table.
Doug

Doug - I bought three different, supposedly all 727 flexplates and all three were drilled with 3/8 inch holes at the 10 in. diameter pattern. Even the old flexplate seems drilled oversize as the bolt is a loose fit when I stick it up there - but I haven't put a caliper on it yet. What's the deal with this - Chevy corruption of the Mopar parts industry?

If I can find something to use as a dowel that is pretty snug in the crank register, maybe I can overlay the new and old flexplate and mark a pattern for offset 5/16 inch holes.

Another possibility is using Chevrolet 3/8 inch flexplate bolts and drilling and taping the converter lugs out to fit. Not sure if there is enough depth in the bolt plates on the converter to tap deep enough though. And then I might have to shorten the bolts.

 

[493 Mike]

Concerning "hooking end" sealing rings: slip the ring with the ends hooked into the corresponding bore and there should be clearance between the hooks. You should not have the hooks touching if the size is correct.
Decades ago Transgo offered a racing/corrections handbook with tips on many brand transmissions. I found it very helpful. I don't know if the book is still available but, if it is you might want to own one.
Mike

 

[AR67GTX]

OK - pretty much have all the component parts back together. With 30 psi the rear clutch activates pretty soundly and seals up well.

The front clutch seemed to leak quite a bit so I took it apart again. The outer seal seemed good but I put another one on it. I actually reinstalled the original inner seal as it seemed better than the replacements and was in like new shape. I was careful seating the seal and used Door Ease from TSR Racing (which seems to work well). Leakage seemed less although I get a little. Kind of hard to tell as I have to hold a finger over the one hole while shooting air in the other one with the air gun. The clutch pack activates OK.

Does this sound normal?

 

[oldbee]

Sounds good to me, I'm sure 'dvw' will chime in. Great job, don't get "on it" real hard at first after install. Kinda like brakes,clutches,etc.

 

[AR67GTX]

Today was not without challenges. I overlooked installing the linkage for the rear clutch band and may have to pull the planetaries back out to get it in - or maybe just the front one.

And the damn e-clip on the governor cross shaft slipped and shot off into the abyss of the garage while trying to engage it. That gave me a break to clear out half the garage to sweep it down trying to find it. After I gave up and moved everything back in - I found the clip laying on the wooden dolly I have the transmission sitting on. At least I didn't have to go hunt for a replacement in the end.

Almost forgot - my less than stellar quality 1/4" torque wrench fell apart. Got it back together but have n" idea how close to the scale it's reading now. Before it was probably within 5 or 6% but now who knows. So probably head down to Sears tomorrow for a new one.

 

[miller]

Does this sound normal?

Going to say probably, on the front drum, considering you used door-eze on the seals. Think that stuff is a little thick, and can be holding the seal off a little, making a hole. That's exactly why I prefer a light wipe of vasoline. Don't worry about it, though. Only a little running, will let it all settle in. One hint on installing o-ring type seals is to take any twist out, once in place.
Hard to think why the problems on the flexplate/converter bolts. You know those bolts are special, right? Did you have the correct ones, when you pulled it down? If so...both the flexplate, and converter 'should' take the same bolts. Time to step back?

 

[AR67GTX]

I was only testing the clutch packs with 30 psi also - that may not be enough to fully seat the seals.

I need to roll the car out from under the GTX and take a look at the old flex plate still on it. Trying to reach around and under there yesterday with a caliper - I'm not too sure the holes on it aren't even larger and I think it's probably an old factory one. The holes on the new one measured .395 inch.

Yes, I do have the shallow bolts for the flex plate. They look like AARP bolts. The PO didn't use any thread locker on them but I will when I go back together.