Correct shift points (RPM) on ‘82 700R-4

[Flowjoe]

Hello all,
recently had the 700R-4 in our ‘82 rebuilt. Before, it leaked like a sieve and I don’t think it was achieving lock up. Post rebuild it no longer leaks, has nice crisp shifts and seems to be getting lock up, however, it shifts very quickly on the way up (1800-ish or less under normal street driving) and holds onto each gear way too long on the way down (I find myself at 1000 RPM frequently). The motor does not feel happy here - bordering on lugging. This is not how it ran pre-rebuild.

We thought it was just a matter of TV cable adjustment but there is none left in this cable. We’ve got another on the way but before we start adjusting I thought I’d check on where it should be shifting (up & down) and when lock up is supposed to lock and unlock. Having difficulty locating that info (I have the AIM and crossfire service manuals but not the regular service manual).

We also had to go through the rear diff and changed ratios from the stock 2.71:1 to 3.08:1. We did change out the driven speedo gear and read about 3 MPH faster than actual - not that this should mean much to a non-computer controlled transmission but thought I’d throw this info into the mix.

 

[Tom Bryant]

I'm not having any luck finding that info either. You are probably going to have to get a GM service manual although a good transmission shop should be able to tell you where they should shift.

 

[Flowjoe]

We did replace the TV cable but no change. We are now looking at the governor...It was rebuilt but it might not be correct for application (Corvette is apparently different than regular cars in this respect). After that we are thinking valve body. Just a few oversights from an otherwise very reliable builder.

I had wondered if GM designed the shift points for economy rather than performance in that day and age.

 

[douglasamariani]

I had wondered if GM designed the shift points for economy rather than performance in that day and age.

The 82 Corvette was the first year of the 700R4 and the shift points we're very close together for economy reasons. One of the biggest complaints was that the transmission would shift into second gear too early and then 3 and OverDrive. One of the biggest complaints that we had at Chevrolet back in the 80s was the transmission was always hunting for a gear. My 82 collection edition was always looking for a gear which was normal for that year and then they straightened it out in 84. There's only so much you can adjust the TV cable and many people damaged the transmissions with a misadjusted cable.

 

[Flowjoe]

Interesting. A while back I ran across a mention of the shift points as you describe but did not bookmark it and now can’t find it.

As mentioned above, prior to rebuild it did not shift through the gears so quickly nor hold them so long. We used the same valve body and TV cable. Those would seem to be the only two places GM could have engineered different shift points on a non-computer controlled transmission.

The car goes back today to double check the governor and valve body.

 

[douglasamariani]

B&M sells a shift kit that worked very well in changing the shift points. Back in the 80s and 90s we were installing them at the dealership at customer complaint requests. The customers were charged for the parts and labor but we're very happy with the outcome. I was when I installed it in my 82 collectors.

The link is just a reference of what was installed in the transmissions. Other companies had made them but the B&M shift kit was the "go to" kit

B&M 70239 B&M Shift Improver Kits | Summit Racing

Free Shipping - B&M Shift Improver Kits with qualifying orders of $109. Shop Automatic Transmission Shift Kits at Summit Racing.

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