First questions on my 727 rebuild journey

[AR67GTX]

The existing yoke has some noticeable wear on it. I spent some time on my old Corvette tracing a driveline vibration until I found the worn yoke and transmission bushing and fixed them. And the bushing in the GTX is a babbit bushing and I think the rough places in the yoke have sort of ate it up a little. Interestingly it doesn't really have a lot of slop - I suspect the previous owner replaced the bushing which kind of held the slop in check for now - but while I'm in this far I would just as soon deal with it.

 

[miller]

Yup! Just out of habit, unless the tailshaft bushing looks real good, I replace it. Too much play there, can wear the rear seal out before it's time.
Only takes a little effort to change it...and worth it.

 

[AR67GTX]

Summit was of no help on the yoke so returning it and the combination u-joint and guess I'll look around elsewhere. Replace the bushing now I can always deal with the yoke a couple months down the road if I have to.

 

[Fran Blacker]

Got a drive shaft from this company and 1350 yoke was fine. A1 Driveshaft 414-445-9996 email [email protected] Not sure if 1st a in email address is a capital or not. The yoke was a little beefier than the 1330 yoke I had shaft, worked ok with the extra length but would have order a 1/4" to 3/8" shorter shaft. To do again I would measure from end of output shaft to center of rear u-joint and let them set c to c length with allowance for space for d-shaft movement. I'd buy the large yoke then adapt from there, of course making sure it was possible.

 

[AR67GTX]

Did some Googling around and if you can believe the internet, when the A518 tranny came out around 90 or 92 they changed the spline machining on the output shaft. Still a 29 on 30 design but the cut of the splines changed. Apparently they are making a lot of replacement yokes for the A518 based on the revised output spline machining and trying to sell them as A727 yokes and they don't fit. So now to find an old style slip yoke.

 

[miller]

I had to look up driveshaft companies, to find parts, like the slip yoke I wanted. What u-joint are you wanting to use?
I needed a 29/30 spline, using 7290 u-joints. Spicer itself doesn't list one.

Another thing I ran into was the rear yoke...checked out as a 1330 size wise, ordered two different sets of the needed straps for the u-joint. Did not fit. Tried a set of 7260 straps, and fit perfect! A 1330 is wider than a 7260, so a little puzzling.

 

[AR67GTX]

I sent an inquiry off to Mancini Racing since they listed a bunch of yokes and should know what Mopar takes what (maybe).

 

[Fran Blacker]

Got a drive shaft from this company and 1350 yoke was fine. A1 Driveshaft 414-445-9996 email [email protected] Not sure if 1st a in email address is a capital or not. The yoke was a little beefier than the 1330 yoke I had shaft, worked ok with the extra length but would have order a 1/4" to 3/8" shorter shaft. To do again I would measure from end of output shaft to center of rear u-joint and let them set c to c length with allowance for space for d-shaft movement. I'd buy the large yoke then adapt from there, of course making sure it was possible.

!330 cup dia is 1.0625" 7260 cup dia is 1.078". I would say the straps are the same.

 

[miller]

Straps have different bolt locations, and part #s.

 

[Fran Blacker]

I never checked but seem logical they would be the same, guess not. I'll check out of curiosity when I hit the garage. Have 742 in a five gallon bucket and a 7260 yoke on shelf, live an learn.

 

[AR67GTX]

Well, the Advance Auto flexplate didn't pan out either. It was just a less well finished version of what Summit sent with the same dual pattern and 3/8 inch holes x 10 in. So now I'm giving Mancini a try - both for a yoke and a flexplate. He says he has a 7290 yoke that will fit and it looks like 1330/7290 u-joints are available. They also seem to have a nice looking line of OEM style flex plates with one specified to be drilled on a 10 inch pattern for 5/16 inch bolts. They should know their stuff (I hope).

On the other hand the new sun gear I got from Makco to replace my chewed up one looks very nice with well machined splines. Even has bushings already installed. Hope to start on some reassembly over the weekend now. All the valve body mods have been completed. Just need to re-wash a few parts and blow everything off good.

 

[AR67GTX]

Is this orange plastic piece supposed to bear on the end of the manual vavle? Mines no where close.



Here's a picture when I first removed the valve body.

 

[oldbee]

No, that contacts the neutral safety/reverse switch..

 

[oldbee]

The metal tabs are for Park,reverse & neutral for grounding the switch.

 

[AR67GTX]

No, that contacts the neutral safety/reverse switch..

That didn't occur to me. Thanks.

 

[miller]

All looks great! Can't tell you on the Transgo stuff, maybe somebody with experience on 'em. Usually on something like that, if the instructions say to do it, there's a reason.

We having fun, yet?

 

[AR67GTX]

All looks great! Can't tell you on the Transgo stuff, maybe somebody with experience on 'em. Usually on something like that, if the instructions say to do it, there's a reason.

We having fun, yet?

The instructions just say file a notch about half way through the bulkhead. It's not fussy. So that's what I did and I figured it's purpose would become apparent to me on reassembly. But apparently not - must be sort of like the neutral switch cam. TransGo has been around since 1959 so I guess they know what it's for. They had a neat little rod they called a mumbly peg that holds the detent ball and spring in place while the shift ratchet is inserted in the mount and then just a simple push down shoves the ratchet into place and the peg out underneath. Pretty trick.

The fun starts with a table full of clean parts - now mostly just installing new seals, rings, gaskets and shoving it all back together.

 

[miller]

Think a 'heck, yeah!' goes here. Know exactly what you mean.

 

[AR67GTX]

Got a fair amount done this morning. The only problem I ran into was the hook rings on the rear clutch input shaft. The new ones in the kit were just too small in diameter to hook and I finally put a piece of wire around them and twisted it tight to pull them all the way in the shaft groove but they still wouldn't snap and the hook broke off both when I tried to hook it with a pick and pull it over. So - I reinstalled the old ones that fit easily and are fairly loose and probably have some wear as the edges are pretty sharp.

What do you think - try to find another set or leave well enough alone? Anyone got a pair from a rebuild kit they didn't use?

Put the planetary's together first:





No issues there except I replaced one washer shim that was getting a bit thin.

Then the clutch packs. I'm re-using the clutches and steels. They look brand new, full thickness and you can still read the printing on the front friction pads. No way to have access to ease the piston seal into the cylinder so I just greased it up good and knocked it in gently with a wooden dowel and small hammer.








I ended up with .080 clearance with wiped down frictions and steels so that seems to be good. It already has the thickest available snap ring installed so I can't easily reduce it further. The fiber washer between the two clutch packs was a little below .060 so I installed a new one of .063 inch.

Then the rear clutch pack. I used a .010 feeler gage blade to work the seal into place and seat the piston.





I ended up with .040 clearances on it with wiped off frictions and steels which I think is good. Then I ran into the issue with the hook sealing rings so I quit for the day after re-washing the case, tail housing and rear shaft and blowing them dry.

 

[miller]

Yes, I would have re-used the steels, and clutches, too, long as no signs of warping. You should 'soak' the clutches in trans fluid, before final assembly. Yup, the end play is the important part in the clutch packs.

Your now getting into the 'will it run' part of rebuilding trans. Kinda hard how to describe how-to on some of it...just like those hook-end rings. That's where you stop, and think about how to do it. Many times the book will give you hints, but still takes actually doing it. (I'd get more new rings, instead of using used rings, unless they are in good shape.)

Getting the piston seals in, is also a matter of deciding the best way. Using a feeler gauge can work, as long as you don't cut the seal. There's times I've worked mine in by using lube, making sure it's going in straight, pressure and rotating the same time. What works for me, might not for you, so find the way that best works for you!
End results is what matters.