I recently” inherited” a 1982 Corvette. It's clean with no fluid leaks and only has 60k miles on it. I was told there was a "drive line" problem.

When the car is in drive (700R4 Automatic Transmission) there is a terrible grinding sound when rpms are above idle. While the car moves forward, the grinding sound does not stop until placed in Park or neutral. The same thing happens when the car is put into reverse however the car will not move in reverse. It’s almost like the differential is locked up. One other thing is that when the car is in Park, it will still roll forward. (Not backwards. The car does not want to move backwards at all!)

I was told by a friend who owns and races Vettes that the problem sounded like the spider or side gears in the differential. I removed differential this past weekend and everything there was clean and tight. The problem was the same, even with the driveshaft removed so I know it’s not the differential.

The transmission drops into gear just fine but it sounds like someone threw it into park while it is still moving whenever you increase the RPM’s past idel.

Any help out there from the pros?

Thanks

 

Someone probably put it in Park while still moving.

Take it to a transmission expert.

 

It could be a tail shaft bearing but you have to get it up in the air and narrow down where the sound is coming from. If its the trans or rear? I would just replace it instead of nickel and dime it.

 

Correct....update it to one built from '88 up, the early 700 trans has a poor reputation, you want one with an aux valve body, and when you rebuild it, you need install a TRANS GO shift kit, no other.....

 

Thanks...I dropped the tranny pan last night and it's full of metal shards. The tranny is toast. I need to replace. Do you have any information I can get my hands on as to how I go about this. Do I need to pull the engine to get to the trann or can I drop the tranny seperately? Any help is appreciated!!!

 

The trans will come out the bottom- no need to pull the engine. Pull the flexplate cover, 3 bolts that hold the convertor to the flexplate, driveshaft, crossmember, drop the rear of the trans a little, remove the TV cable, dipstick tube and cooler lines on the right sidem left side the sift linkage and the wires to the convertor clutch, then the 5 remaining bolts around the engine to trans. IF you're doing this on the floor with a jack and stands, make double sure the stands are solid. And use good stands- not those sheet metal ones that come from the discount places..

 

I did an R & R on my transmission when it failed 10,000 miles after a rebuild so I could same some money so soon after I had paid for an R & R. It is estimated to be a 6 hour job it took me 9. I am not terribly gifted as a mechanic and don't do it enough to be efficient in my processes and am a wee bit methodical. After the free rebuild following the failure, it lasted another 10,000 miles before if failed again. This time I took it to a reputable business well recognized in the area.

My tranny was missing a clutch and after rebuild they added back that one and two more. Put in a shift kit, replaced plastic parts with aluminum parts and it was worth having it done correctly.

I did use solid jack stands but always felt a little uncomfortable while underneath. Borrowed a tranny jack (necessary I believe) but my stands were not quite tall enough to pull the trans out from under the car without hitting the side. Eventually maneuvered it around and got it out. Two of the top bolts on the bell housing may be hard to reach and will have to tilt the engine slightly (as I did ) to reach them. (Once the transmission is out, it is important to support the engine so as not to stress the mounts). Had a three foot extension on my socket wrench to reach these bolts and it worked out OK.

When I replaced the transmission, I made some guides using about 3 inch long bolts and cut the heads off, rounded them and it worked great. Once in place I removed the guide bolts and replaced.

As I recall, (This was a long time ago...seven years...who remembers) and it is real important to make sure the converter is mounted flush to the fly wheel (again testing memory) to insure that no future problems are created.

My original rebuild was a bad one and often tell people that one must be cautious of friends who tell you with hand covering mouth that "they have guy who can fix your transmission cheap."

I was fortunate that there is a really reputable business nearby. I love the 700r4 and think it a great tranny. It does need a modern update though.

 

Thanks for hour help and advise! I'll be getting my hands dirty this weekend!

 

FWIW: Your original transmission can probably be rebuilt. It may not need to be replaced.

 

I had to have my transmission rebuilt in 1997 or so at about 80K miles. Rebuilt to current standards and now have 230K miles on car and tranny is as solid as ever. Rebuild much cheaper.

 

I've heard it's not as complicated as I may think but I've never done any auto-tran work previously. My concern with a rebuild is the amount of metal shavings and schards that were in the tranny pan. I sould think those shavings would cause damage to almost everything. Please advise if you have thoughts. Like I said, I'm a rookie with transmission work.

 

Metal in the pan is NEVER good, no matter what....

You need get with a local trans parts house, like we have here in Jax Florida, and hopefully they can help you with a ATSG guide and some personal advice.....like I said above, the later 700's are much better design, and so to do a TRANS GO shift kit...no other.....

the metal means you need a new converter.....trash in there all clodded up in the veins.....

 

Im a trans go fan but not there hd 2 kits i use there sk700 kit in my rebuilds provides firm but not harsh shifts but improves drivability and durability

 

As MR Vette said- get the ATSG trans book- almost as good as the GM book and way less $$. Not all that tough to rebuild, just takes time and patience. As far as tools, the books list all of GM's special stuff, but you can look at their tool in the book and figure out how to build a work around tool. You will need a good pair of snap ring pliers- the ones with a 90* bend on the tip, designed for a solid snap ring. Not the ones for the rings with holes in them.

As far as parts, if you have to replace the rear planetary, use one from an 88 or later. Same fit, just a better oil system. Past that, a 10 vane pump minimum, and keep it all hospital clean on the inside.