727 shift probs

[Garys1969RR]

The car: 1970 Super Bee, 383 engine, 727 Torqueflite with reverse manual valve body. Put this trans in about 3 years ago. It worked fine for a couple years, then began to slip in reverse. All other gears work fine. So we pulled the pan and adj the low/reverse band, backed it off 1 1/2 turns. Now reverse works good, but the trans tries to lock up briefly during the 1-2 upshift. Seems that the low/reverse band isn't releasing completely before the kick down band is applying. So thought I would back off the low/reverse band adj bolt about 2 turns to see if that helps, without losing reverse again. Does anyone have any other suggestions as to how to fix this? Thanks

 

[miller]

When you pulled the pan, any sign of metal, in the fluid?
Thinking maybe junk in the shift body, hanging up a valve, or two.

Do you have any idea what shape your bands are in? I've seen some of them take alot of heat, and try to come apart, flat getting wore out.

Past that, if all looks good, just a good band adjustment.

 

[Garys1969RR]

No sign of any friction material or metal in the pan. Fluid is clean and no burnt smell.

 

[PDFROGMAN]

who made the reverse manual VB? from your description I am assuming it is low band apply VB
I have used Grinner in some if the units I have done there ae some mods to the low reverse servo
does it have a transbrake?

 

[Garys1969RR]

No trans brake. And yes, the low reverse band does hold in first. Because when I let off the gas in first, it holds. Dont know who made the V/B as we got it with the trans. Does have a deep alum pan on it.

- - - Updated - - -

I realize when the stock trans shifts automatically from first to second, the over running clutch holds until the K/D band applies. This is the case when it is in drive. If you put the selector in first, then the low/rev band is applied, allowing it to hold under decelleration. Then the low band has to release just before the K/D band applies. It seems that both bands are applying at the same time for a split second. So I will start by backing off the low/rev band a little more.

 

[PDFROGMAN]

The only low band apply VB I have installed and used is made by Grinner, I am not sure who else does a low band Apply MVB
I would give them a call and see how they ID thier VB and see what there solution is.
Like I said earlier there are some mods to the L/R servo, I am sure a heaveir return spring and some shims
been a while since I did one

 

[miller]

Good deal on it being clean.
Have to admit I've never fooled with a reversed pattern shift, so not familar with the mods done. These old Torqueflites have been messed with so many dif ways, kinda mind-boggling.
You didn't build the 727? But, heck, you said it ran fine for awhile.

Past something hanging in the shift body, back to the band adjustment thing. Wish could help more. Kinda simple, but not over-torqued filter screw. Out of ideas for now.

 

[Garys1969RR]

I think the heavier return spring in the servo may help. I may try that along with a looser band adj. Thanks for your help.

 

[PDFROGMAN]

I think the heavier return spring in the servo may help. I may try that along with a looser band adj. Thanks for your help.

would be a good investment to swap out for a billet servo the stock ones tend to crack or cock in the bore