I was racing a friend of mine the other day on the highway -pretty much doing a top speed run. I buried the speedo for quite some time but afterward the tranny never was the same. It will no longer shift into OD and the 1-2 and 2-3 shifts occur at around 4000 rpm no matter what engine load. also while driving I noticed that when I let off the gas in 2nd or 3rd the rpms drop down to idle then back up to whatever rpm i was at before when I reapply the gas. I was told that this could be a broken sprag and that some small pieces of it may have gotten lodged in the 3-4 shift valve. whaddya think?

 

I have the exact situation you are having, high speed cruise through the Wisconsin Dells area and now no OD and High RPM shifts in all gears

Check out the responses the my thread "700r4 shifts like a caddilac"

Maybe you can use some of those ideas too.

 

Thanks for replying. my problem may or may not be similar to yours. My OD stopped working instantly when I shut my car off after the drive. I can put the shifter in OD and the car will move just the same as if it is in D. When I step on it there does not appear to be any slippage since I can roast the tires in all but third gear. my 1-2 shift is very firm and 2-3 is similar BUT I do have a strange vibration now when the car is slowing down thru 2nd gear (maybe 1st- I dunno). And it will drop down to idle while Im cruising and I let off the gas in 2nd or 3rd. But it will not shift onto OD. Strange

 

I am having the same problem in my 91 firebird. I took it to a local shop to get the torque converter changed and when I came out my tranny was shifting real hard 1-3 at like 4000-4500 rpm's. When I put it in overdrive and hit the gas it was like I was riding the clutch. I just ordered a remanufactured 700r4 from net gear head transmision for 575 including shipping. With a 1yr unlimited mile warranty. Ill let you know if this was my problem.

 

I found the problem! I had a stuck Throttle valve. After I freed it up I regained OD and my 1-2 2-3 shifts are back to normal. I had to pull the valve body to do it though. I also got a chance to put in my new police B4C 3-4 upshift valve to keep my ride from downshifting from 4-3 at haevy throttle. It works. Really good. No downshift at all.