I have a 1995 LT1 Corvette with an automatic transmission and about 140k on her. About 2 wks ago I was on the highway doing about 75 mph, went to change lanes to get around a car, gave her 3/4 throttle and the downshift was not successfull. She revved up to about 4500 rpms while in neutral (due to the downshift of the automatic transmission being unsuccessful). I let off the gas (still coasting at about 75 mph) and about 2 seconds later she banged (very loudly and jolting the whole car) into gear. If I had to explain the sound it might be like throwing a crowbar into a industrial sized shop fan on high... a terrible sound to say the least. I moved into the outside lane thinking I lost her. She's in gear at this point and I am just steady on the gas to keep 70 mph (about 2000 rpms) and without doing anything (no acceleration or deceleration) she bangs again but stays in the same gear (all these sounds seem to be coming from the transmission or possibly rear-end). I pulled off the highway and as I was getting ready to pull onto the main road I noticed she didn't go into gear after downshifting while on the brake and slowing down (still in OD mind you). Then all the sudden while coasting at about 10 mph towards the shoulder she goes into gear. Stopped at the nearest gas station. Checked fluid... levels fine color pinkish brown. Temperature's fine. No troubles for another 500 miles (I was on my way home from vacation so didn't really have a choice but to cross my fingers and drive). After this happened I have not had her over 2000 rpms and have NEVER accelerated to the point where she needs to downshift. Every other trip will be problem free (only driven her about 10 times on short necessary trips since then). Occassionally on an upshift she bangs slightly going into 2nd or 3rd (but never into 4th or overdrive) and about every other trip to work she'll go out of gear for a brief second before banging into the next. Seems to happen most frequently between 2nd and 3rd. When braking to a stop (0 gas, only brake) the downshift will sound a little chunky every once in a while. I am driving her as little as possible and only to work until I find a reputable shop. Also, She seems to engine brake less than before. Might be slight but I have driven her every day for the last 10 years so I notice little differences. Any advice, suggestions, or help you can give me would be much more than appreciated. Also, if anyone knows a reputable transmission shop in the Miami, Florida area that would be great. Sorry for the long read but I wanted to give as much info as possible. Thanks in advance for any info you can provide.
Cheers,
Kirk

 

Unless it is an electrical issue, which I doubt, find a good shop that trans. is toast.

 

Its a similar story you shared with your 1995 Vette as when the original 700R4 trans let go in my 87 Vert at over 100mph.

I lost the rear reaction planetary gearset & Internal ring gear.
Also fried the reaction tube & bushings inside.

The front white nylon plastic lube seal that goes inside of the input drum underneath the input sprag had falied- ripped in 2.
Seals off pressurized line lube to feed down the rifle & cross drilled transmission mainshaft to forward & reaction planetary gearsets.

I upgraded to the modern Viton brown rubber lube seal & GM NOS 5- pinion gearsets in a full kit on my rebuild.

Its time to remove the transmission pan on your 1995 C4 & see what is in the bottom of the trans pan.

Hopefully nothing abnormal.

I prefer to rebuild original GM transmissions Vs. aftermarket rebuilds.

If you don't have the ability, find a good trans shop that can for you.