Auto trans shifting

[MY1978]

Hello all -

Been absent for a while with my crazy questions.  slowly moving forward on my cab refurb.   Gauges in and working, interior LEDs in place, original seatbelts re-webbed, new fuel sending unit installed, current inspection with one seat and one seatbelt, new retro radio install next week.  Now have to wait for warmer weather in Virginia to put down self stick sound/insulation mat & carpet and also color and reinstall dash pad and interior trim.

Anyway, maybe this is just me (and probably is because I have forgotten how this truck drives), but I feel like after the transmission rebuilt, my truck doesn't shift exactly like it is supposed to - like it shifts late from 2nd to 3rd.  So could it be after the rebuild everything is just "tight" and needs some breaking in?  Am I just spoiled with the smoother shift through 4-6 gears on my 2016 Tahoe?  I also feel like the engine is straining at high speed.  Again, is it just ME and I have become spoiled having those new 4th, 5th, and 6th gears?  I ask my mechanic to check the shift and they say they find no problem with the shift.

I do not have a tach in my truck.  Is there some way to check the shift without a tach so I can finally be satisfied that all is well.

Thanks.

[VileZambonie]

Not enough info to help you. Tell us about your powertrain ... What trans?

[MY1978]

350 V-8, TH350 trans, 3.4 axle ratio

[VileZambonie]

Is there vacuum at the modulator hose connection with the engine running?

[MY1978]

Will have to check.  I would think that is okay since mechanic cleared it.

[VileZambonie]

So you Assume? Let us know what you find.

[MY1978]

RUDE!!!!  But I will reply.   I have faith in my personal mechanic - thank you very much!!!  Although my mechanic says it shifts fine, I have only owned this truck since it rolled off the assembly line so I PRETTY MUCH know it's quirks and how it has run, and shifted, over the 40+ years I have owned and driven it.  I just would like to know the answer to my original question which is......is there a way to check the gear shift timing WITHOUT having a tach or is there a way it CAN be checked like on a dyno.

[VileZambonie]

I was not being rude so sorry if you took it that way (never heard the old saying? So I guess I am guilty of assuming as well) The point was to verify and not assume that someone else validated something just because you trust them.

[bd]

First time I heard that saying was in the 80s.  It became very popular at the dealership and OEM because we were all guilty of making assumptions that we shouldn't, even as professionals.  It got us into trouble and prolonged our agony many a time.  The trap is as prevalent today as it was then.   

Advice to the wise, avoid it whenever possible.   

[zieg85]

Late shifts indicate something isn't quite right.  I guess I am trying to understand the OP question if his mechanic is a stand up guy and all is well.  Maybe a 2nd opinion is required here and since we can't test drive it on this forum, find an established shop with an old timer that knows these basic transmissions well.

[JohnnyPopper]

Well if you have an old school tach/dwell meter, you can run a wire extension to your dist and take it for a ride with the meter in your lap or on the dash. Fixed it for you...

[TheBigHat]

There is NO break in period on an automatic transmission. If it shifts hard to you it's probably because of a fresh actuator spring. Often the rebuild kits have a little bit sturdier spring to them. If you put a softer one in it will shift softer, but understand it is at the cost of faster clutch wear. If it is hitting really hard not just "firm" there may be some other problem the shop isn't owning up to but if you aren't happy with it they SHOULD be willing to make adjustments. I just did this adjustment for a customer on a 4L60E the other day. There was nothing technically wrong other than the customer wasn't as happy as we could make him. He is now 

[JohnnyPopper]

Your Bigness,  I think the original post said it shifts LATE from 2-3rd, like the engine is revving too high in the RPM band.

Since he has no tach (mentioned) he is just going off his gut experience since he has owned it for so long.

All guess work till you apply some science.

Being the first to admit ignorance of Automatic transmissions, my limited experience would look at the modulator. I believe they can be adjusted by an internal screw in the vacuum port.

[TheBigHat]

That's ok, I had the soft spring/hard spring down in reverse anyway! If you want it to shift like a hammer take the spring out! But after re-reading without my prescription beer goggles on I see your point! LOL!

[MY1978]

Hey guys, thanks for all the suggestions.  I think it is just me.

FYI......the "he" is a "she"