<VV> PG upshift flare - vac modulator?

[don jennings]

I have had the same problem with several cars. I have found that the
band needs to be adjusted. With the bad modulator the trans had high
line pressure and made the shift firmer so you never noticed the
flare. The last one I did I only backed the band adjust out 3 turns
instead of 4 like the shop manual says to do. Powerglides are good
transmissions but being 40+ years old there is bound to be many
internal hydraulic leaks and the band about worn out,the last one I
have messed with is getting a rebuilt trans installed next week.
Corvair powerglides don't use adjustment screw in the modulator.

On 3/21/13, Frank DuVal <corvairduval at cox.net> wrote:
> An odd question, but if you look into the vacuum port or the mechanical
> action port, do you see a screw head? If so you can adjust the spring
> pressure. I haven't seen one in years with a screw, but I have seen them.
>
> Try disconnecting the vacuum line (plug it) and see if the flare changes.
>
> Did you see ATF drip from the hose when you removed the old modulator?
>
> Frank DuVal
>
> On 3/21/2013 10:11 PM, Bryan Blackwell wrote:
>> Hi folks,
>>
>> So here's something interesting.  A couple months back I reported a
>> problem with smoke in the exhaust and low PG fluid on our '62 102/PG
>> wagon, which I was told pointed to a bad vacuum modulator.  I picked up
>> the new part from Clark's (improved! just for Corvairs! it said) along
>> with the special wrench and installed it.  Took the car out and sure
>> enough, no more smoke.  Great!
>>
>> However, now it flares on upshift - that is on the low to high shift, the
>> engine momentarily revs higher, like it's low on fluid.  I double checked
>> the fluid, it's ok.  The trans worked fine before, and other than the
>> flare it works fine now.  So, did I get a bad one?  I found a few reports
>> of this, but it's not clear if there's a better modulator than the one
>> from Clark's.  Any other things to check - perhaps this has uncovered some
>> other issue?
>>
>> As usual, thanks for any clues.
>>
>> --Bryan
>>
>
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