why does my tranny shift softer when it warms up?

[gabet40]

when my engines cold, right after i warm it up, my 700r4 will by shifting nice and hard and high. then it seems like as soon as all the tranny fluid gets through the radiator and warms up, it shifts soft and low.
the tranny shop put regular, not synthetic, fluid in if that has anything to do with it. any explanations?

[Longhorn Man]

Warm oil is thinner than cold oil, and the thinner it is, the more shock it can take.

[68 with 350 TPI]

The above post is correct.

But here are two things that will really help a 700r4.

1) make sure the TV cabale is adjusted right. (it has to do with shift feel,line pressure,shift timming etc and if its not right it can cause early trans falure).

2) If the trans is not a corvette unit by all means get the corvette servo for it!
The corvette had a much better servo that held much higher pressure and will much inprove the shifting at full throttle and part throttle. (by the way it can be put in with the trans still in the car or truck

[gabet40]

yeah im always checkin that cable but the first screw it had stripped so the cable had been sliding through the throttle screw so much, like 3 or 4 of the cable strands frayed so i had to really wrench down on it but its stable now.
i just thought it was strange that it shifts great when its cold, then softer and softer and lower and lower the more i drive it.
now about this vette servo, do i get this a the tranny shop? wrecking yard? chevy dealer? thanx a bunch

[68 with 350 TPI]

You can get the vette servo at any chevy dealer, trans parts shop, a wrecking yard, and maby a local trans shop if they are good guy and dont sell you a stock 700 part.

[1-PU70]

I had the trany shop put a corvett servo in my 700. $35 + $15 to pu it in. It did firm up the shifts but not that much.

[68 with 350 TPI]

You can put in the part yourself and save some $$$.
Dont expect it to act like a transgo shift kit with just a vette servo though.
It will help to keep the sliping down and if its used with a good shift kit it really makes a nice diffrence.
By itself its still worth getting just to help keep the normal driving wear and tear down.

[chevroletrucks]

Its possible your valve body is worn out, and the warm thinner fluid is not doing it's job like the cold thick fluid does. Had the same problem many moons ago with a C6 in a 79 bronco a shift kit cured the problem re-routing the fluid through different non-worn passages.

[gabet40]

i talked to my tranny guy today, he said that of course it shifts softer warm cuz of the thinner fluid. but he said that vette servos an important asset. about $35 for the kit, then around $150 for the kit, installatoin, lost fluid, labor, etc..
so i think im just going to buy the kit through them then get as much advise from yal as possible as to how to get that old servo off and new on. pics or explanation GREATLY appreciated
he said its very important to watch for the band underneath it cuz if you mess it up, it messes this up, and this up, yadda yadda yadda, just dont mess with the band underneath. and not to get the kit make in Taiwan cuz its cheaper but not made right and itll screw you over in the long run as well

now, since when they built my tranny, they used a shift kit from the get go, should i expect much differnce?

[68 with 350 TPI]

I will take a pic of a 700r4 I have sitting out now for you tomarrow.

I will try to show you where the servo goes and I will tell you how to put it in.
Pretty easy to do in or out but I would take the driveshaft out and drop the crossmember so you can get to it better and see what you are doing.

[gabet40]

id i do that then id have to drain the fluid. then would be a good time to refill with synthetic i guess. i just have to find a couple days where i woundnt have to drive cuz its my only transportation

[68 with 350 TPI]

well here is what you are looking at on the trans. It right next to the throttle valve cable and its on the same side as the dipstick.

[68 with 350 TPI]

servo

[68 with 350 TPI]

you may want to tap it with a hammer to lossen it up a bit.
You will need to push it back into the trans case with a large screwdriver and then remove the outer retaining ring.

Here is a vew of all the parts there so it may help if you get them out of order.

[gabet40]

thats a very helpful diagram, thanx a lot. im sure itll all make perfect sense once i start piecing it out.

[68 with 350 TPI]

Hope it helps.
Let me know how it goes