satx79vette

I just finished installing a 700R4 in my 79 and have noticed a couple of things and wanted to know if they were normal or not... (1.) When I take off, it seems to stay in 1 a lot longer that my old TH350 did. (2.) When it shifts from 1 to 2, it shifts fairly hard, the rest of the shifts are smooth (about the same as the TH350 had). Is this normal or should I be concerned?

Smokehouse69

Is your TV cable adjusted properly? A maladjusted TV cable will definitely effect your shift quality. Also did you put a shift kit in the car? A very quick hard shift is sort of normal with a Street and Strip type shift kit.

timbo79

A COUPLE OF ITEMS FIRST:

1) Did you switch the torque converter?

2) Did you use a pressure test for the gears?

3) Is the tranny rebuilt? shift kit? corvette servo? or just a run of the mill 700R4 (their are literaaly millions of them!)

Answers:

Yes, normal for first to go for a longet period. I have a bit better than stock torque converter and I usually "shift" between 2300-2700 RPM

The shift is harder and you feel it. But you only really feel the "jump" when jumping on it.

As for the other gears, it depends how you have set up the tranny to shift in conjunction with the RPM level. If it shifts a bit too soon (as most of the smog people would want) then you won't feel it. If you have it set to shift in the 3-3500 area then you will feel it and you will also get better acceleration. I am not a pro at it, but I iunstalled it with the assistance of a friend. We reworked it, rebuilt it, put a shift kit and also a NEW servo in it and it works great. My buddy assisted in the pressure for the gears and also in connecting the TV cable.

THE TV CABLE IS CRITICAL>>>

You can also see a neat config at BowTieOverdrive.com the home of .. you guessed it.. Bow Tie Overdrives (700R4)




[Modified by timbo79, 11:27 PM 10/20/2002]

satx79vette

I bought the tranny used (recently rebuilt) and it had a fairly new torgue converter in it. Not sure what is meant by pressure testing the gears. However, I did use Bowtie's instructions on setting the TV cable with a pressure gauge. I'm suspecting that it might have a shift kit in it because of how it's shifting. The price was right on the used tranny (even if I have to have it rebuilt) I'll come out ahead... I've never driven a vette with a 700r4, so I wansn't exactly sure how it would feel.....

Apeiron

The 700R4 has a huge drop in ratio from first to second so the 1-2 shift will feel late and hard compared to a TH350.

mrvette

I have had a 700 with the Superior kit in it, and the 1-2 shift if allmost immediate, holding 2nd for a LONG time, especially if I"m on it at all, and then doing a nice crisp 3rd, and then 4th....but if I put the lever in 3rd gear instead of 4th....the tranny will then hold 2nd for seemingly ever...the 3-4000 region for sure...then of course stay in 3rd.....and of course shifts harder like that too.....
but with the 336 rear gears, first gear I feel is damn near useless....it's as if it's not there at all really.....I suspect it has limited use entirely...maybe if I had a 308 or milder gearset it would be more useful....but that's only a 10% change, not worth making....

GENE

MIKER

It sounds like you understand how to properly adjust the T.V. cable so we can assume that you have done all you can with that.
I don't think that there is a way to describe the "normal" behavior of a transmission that has been transplanted from one type of vehicle to another. For instance, if that transmissions shift calibration was set up for a 5000 lb. truck running a 4.10:1 rear gear ratio, it will perform differently in your 3300 lb car running a different rear gear ratio.
Along with T.V. cable adjustments, the shift points can be calibrated by making changes to the governor (springs and or weights) and valve body (valve springs).

jdunne

Is hard,is GOOD........to paraphrase a commercial over here.......nice crisp shifts keep the heat down,a shift that is so smooth that it can't be felt is generating a lot of heat as slipping must be occuring......john :chevy ;)