| Trans shifting problems revisited |
Subject: Trans shifting problems revisited by Matatk on 2012/5/17 23:15:43 OK, a little background: 1989 Corvette (duh) rebuilt 383 stroker 400+ est crank hp. 700r4 trans, stock style rebuild with transgo 2+3 shift kit (manual vb optional) and 2400 stall. 6600 miles on package, trans fluid and filter were changed at 1000 miles. You may recall the last post I had on the trans with a bogging issue. The consensus was my stall with a low mph shift into 3rd was causing it, which I agreed with. If you recall, I also mentioned a harsh 1-2 shift at that time. It was pretty much always present since the rebuild. The other night I backed into the driveway instead of pulling in. When I left in the morning and pulled straight forward, I noticed the 1-2 shift was very "soft" compared to normal. It was pleasant, and quick. Normally the 1-2 shift is hard and there is about a 1/4 second delay before it kicks in. I just chalked it up to the shift kit. There are no hard shifts from 2-3 or 3-4. So yesterday I was able to do some testing in a parking lot. I was able to recreate the results about 90% of the time. Slightly more pronounced when the fluid is cold, but still there when it's warm. If I back up 20 feet in reverse then put it in 1, the trans and car "jerk" forward a bit. Start driving with mid-throttle and the 1-2 shift hangs and bangs. Put it in park for about 15 seconds, then go forward and the 1-2 shift is softer. Trans still loads up a bit and jerks forward in 1. If I put it in OD, the jerk isn't as pronounced. I was reading and possible causes I found with similar complaints were a worn reverse input drum, broken accumulator spring, worn accumulator bore. I don't think the spring is broken because that usually causes no 1-2 shift at all. It seems likes something inside is binding...like a clutch band, bore, spring, etc. I don't know enough about transmissions to make an accurate assessment at this point. Once I get my garage space back I think I'm going to pull the 1-2 accumulator housing off and inspect the bore and spring. Any thoughts are appreciated! Matthew |
