Gears grinding

My son was driving his car today, said he heard a "clunk" and then the car don't go no more. The motor was still running. He coaasted to a stop and took a look, didn't see anything out of the ordinary so he started the car again. Car ran fine, when he put it in drive, huge grinding noises from underneath but gears would not engage.

I got home, we towed it back to the house, and I get the same symptoms. I check underneath hoping to find a broken U-joint. I twist the drive shaft and there is a definite clunk in the tranny spline area. Checked fluid, it was low, filled it, same problem.

Did he blow the transmission or could this hopefully be something cheaper? I am a tranny dummy, so any suggestions are definitely welcome.

Thanks in advance.

Bill

 

Anybody? It's a 70 Skylark with 350/350 if that helps.

 

Does it make the same noise in reverse as it does in drive?

 

Yes, and then it gets a little louder when you put it in back in park but slowly fades away.

 

Just how much fluid did you have to add????

I'm no trans expert either, but it sounds like possibly the clutch packs are burnt out. o No: Either way, the trans probably needs to come out for a rebuild, or replacement.

 

Best way to tell if its the rear or the trans is look underneath the car when it's in gear. Is the driveshaft spinning or not. :idea2:

 

Ya,
It does sound like a rear diff failure, if not it is probably an output shaft failure. Trans is turning everything back to the output ring gear, but not the shaft itself from the sound of it.

Part of the grinding noise you hear when you go back to park is the parking pawl trying to engage the still spinning output ring gear. You hear this sometimes in a shop when someone has a car on a lift or stands and is letting it drive the wheels, then they fail to completely stop the wheels before going to park.

 

Thanks for the information. I have never had a tranny apart. Is this a do-able project at home, or should I just eat it and pay a professional? I do not have an engine hoist or a lift.

Is this damage normal wear and tear type stuff, lack of fluid, or a 16 year old foot in it???

 

If the output shaft broke on the TH350 I would say it's not the kids fault. Probably a weak shaft. Not to say he couldn't have been beating on it to accelerate the failure, but the TH350 output shaft is tough and I hoenstly haven't ever seen one broken. I've seen them break inputs occasionally but not an output.

If it's the rear diff, it could be caused by alot of things. If he was cruising at road speed and it quit, not his fault.

 

Here's an online article I have posted. You can attempt it yourself BUT there are alot of things along the way that can trip you up. It requires attention to detail and patience.

http://www.nastyz28.com/forum/showthread.php?t=53671

 

Drive shaft is spinning, so I assume it is the rear diff. Pull the cover and replace everything or is this just a specific part.

Sorry guys - I am sure these are dumb questions, however if I knew the answer, I wouldn't embarass myself with the question.

 

Took the cover off, found a big broken pin, anybody know where I can get one wthout buying a whole new rear end??

 

GM sells pins. I got a replacement from the dealer.

 

Do I hear a nuetral drop at about 5,000rpm's?:spank:

 

Exactly what I said, he said he doesn't burn out - often. Checked all over the place for a replacement, none of the parts stores carry them. I'll try the local Chevy dealer in the morning.

Thanks for all the help, I would have never checked the rear diff and woulda paid somebody to look into it for me. :TU:

 

that's exactly what i was going to say, but didn't want to be the first to say it

and having owned one of these cars when i was 17 (21 now) "not often" means "every chance i get" lol