: Tranny question on my other vehicle-90 Chevy Pickup

02-12-10, 09:31 AM
Ok so my daily driver is having some issues and making me drive the caddy on muddy roads :helpless: which I'm not a huge fan of but it gets me to work.

1990 Chevy C1500 pickup, 2WD, 5.7L with the 700-R4 4 speed automatic, probably around 180k miles, the odometer stopped over 5 years ago. The 1-2 shift was getting a little sloppy and I knew the tranny fluid/filter handn't been changed in over 4 years so I did it, not a big deal once I got the pan off. Changed(not flushed) fluid and filter, filled back up with Dexron III and off I went. For the first couple days the 1-2 shift was happening at a slighly elevated speed(about 25 mph instead of 18mph-ish) but it disappeared pretty quickly and I didn't think anything else of it. But yesterday about 2 weeks after the change the tranny decided it didn't want to shift into 2nd until 33-35 mph and the RPM's were up in the mid 5K range at least(no tach). Checked fluid and it was where it needed to be, it did this at every stop sign and light, once I got out of town the 2-3 shift was slightly elevated but the final shift was about where it belonged.

I'm planning on dropping the pan next week once I get the garage put back together and can pull the truck back in, can anyone point me in the right direction as to where to start looking? I don't have a ton of experience on tranny's other than having a general understanding of the operation and to respect all the little parts in them. From what I'm seeing it appears to be isolated to the 1-2 shift which makes me wonder if I need to replace the bands....but again my hands on experience with tranny's is limited however I would like to do this myself as I feel I'm perfectly capable and have the tools necessary. Probably also going to break down and buy the $105 Helms shop manual set for the truck as I don't have it and can't find it used anywhere.

02-12-10, 03:22 PM
On a 1990 you have a TV cable attached to the throttle that determines shift points. Might want to look at that.

02-15-10, 08:08 PM
Well finally got the truck in the garage after spending all weekend putting the garage back together. After taking a brief look before supper it appears that the kickdown cable is attached and feels like I would expect. I still need to crawl under the truck and check the transmission end of the cable but at least from the top side it feels good. I did find a cracked line(emissions sticker calls it the purge hose) off the throttle body to the vapor canister, but as far as I know that shouldn't impact a thing on the transmission. I'm heading back out to the garage to do a bit more investigating this evening and see if I can find anything else, otherwise I'm probably dropping the pan tomorrow after work.

02-15-10, 10:08 PM
Well Aron appears to have been right, after getting more familiar with the cable(its not just a kickdown cable like on other vehicles I've worked on) and adjusting it(took about 1 a minute after finding instructions) it appears to be shifting right where its supposed to. Another road test on the way to work tomorrow and hopefully I can mark this down as fixed. Thanks!