Took my 75 convert for a nice 30+ mile ride Saturday afternoon. Car is stock w/ the original L-48, the original TH-400 automatic, and 30,889 miles. I've owned it for a little over 12 years. Parked it in the carport and went out a couple hours later to take it back to where I store it. Put it in reverse and car went back about 3 to 5 feet and then stopped as if I had applied the brakes. No noises, grinding, etc. Put it in drive and pulled forward, back into reverse and same thing. Back about 4 feet and stopped. Gave it a little gas in reverse and again no noises, but no rearward movement. No slipping, just stopped. Pulled forward again & shut it off. Brakes feel and act normal when pulling forward. Had to go out of town so I have not had a chance to jack it up and start checking. Any thoughts on where to start?
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Re: 75 Corvette will not back up
First check the transmission fluid level. If it is two quarts low this is how they act.Lyle
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Re: 75 Corvette will not back up
BILL-
Can you provide some more info regarding your complaint? Can you bring up the RPM's on the engine in reverse and the car won't move? Could be your problem is in the rear axle assembly. With the car only moving 3 feet in reverse and then just stopping with no noise or clunks, sounds strange, but yet moving forward?
MartyComment
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Re: 75 Corvette will not back up
Thanks guys
1. I will check the fluid.
2. I was also thinking along the lines of the parking brake. I live in a real flat area and never use it. Was thinking that perhaps something turned loose and it is jambing in reverse?
3. Nose of the car is about 2' from the carport wall so I can't get it out to test the other trans theories, but during the ride the trans operated normally, both in drive and reverse, no noises, slipping, etc.
4. I have never "ragged" on this car, and again no odd noises, so I think the differential is ok unless something turned loose in there that is jambing?
5. I brought the rpm's up in reverse when it stopped and there was no slippage or movement or unusual noise.
6. The trans seems to be engaging normally in reverse and in drive.Comment
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Re: 75 Corvette will not back up
When In Rev. Does The The Car Feel Like It Engages Into Rev, - (meaning- Does It Feel Like Engagment Into Foward Gear)when You Are In Rev. Does Rpm Seem To Just Raise And Go Nowhere.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: 75 Corvette will not back up
No. When raising the rpm in reverse, and I didn't raise it more than a few hundred rpm, the feel is of solid resistance, not free revving.Comment
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Re: 75 Corvette will not back up
Edward I mis-read your question: "When In Rev. Does The The Car Feel Like It Engages Into Rev, - (meaning- Does It Feel Like Engagment Into Foward Gear"
Yes, when I put the car into reverse it does feel just like when it goes into drive, and feels normal when it starts backing up that 3 or 4 feet until something stops it (and it is not a violent stop).Comment
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Re: 75 Corvette will not back up
Bill My Advise Is To Jack Up One Wheel At Time To See If Wheels Rotate Freely In Netural , It Can Be A Pain To To Jack Correctly Because The Rear Wheels When Jacked By The Frame Already Have Resistance , Try Using A Small Jack Ane Use The Lower Shock Mount. Which Moves The Lower Strut Rod And Trailing Arm Togeather To Put Less Stress On Drive Shafts.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: 75 Corvette will not back up
Thanks Edward, I'll give that a try. It will be this coming weekend.
I'll let you know how it goes. BillComment
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Re: 75 Corvette will not back up
If the bolts fall out of the differental ring gear it won't back up. I had a friend that this happened to but I would think their would be some bad noises.Lyle
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Re: 75 Corvette will not back up
If you have a posi, jacking only one side won't work for you.Comment
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Re: 75 Corvette will not back up
Hmm, smarter heads prevail here than me, I guess, but I fall back on my experiences in this. Why hasn't anyone suggested transmission failure? I had a 77 Buick that had identical issues. Put it in gear, rev the engine and nuttin'. Just engine noise, no grinding, no movement - it was as if I never put it in gear at all. All the forward gears worked just fine.
I resorted to only parking in places that allowed me to pull forward after parking. In the end, I got a rebuilt transmission.Comment
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Re: 75 Corvette will not back up
Bill, just my 2cents. I had this happen to me way back it was the parking
brake. If you can go forward and then into reverse (repeatedly) the trans should be ok. Go for the easy, less expensive stuff first
KenComment
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Re: 75 Corvette will not back up
The turbo 400 is a very good transmission. My original owner 70's turbo 400 has only given me one problem and it was in the first two weeks of ownership. After a 1K mile trip, and just arriving at my destination the turbo 400 would not shift to second or third. Don't remember 38 years ago if I tried to use reverse.
Drove it to the dealership and they put it on a lift. I watched. Only thing wrong was that the rubber hose connector to the vacuum modulator had become disconnected. Easy fix. Have over 165K on it now.
I learned in watching that the dealership placed the rear portions of the lift under each of the strut rods. Yep they bent them. Management did not like it when I demanded new ones. Hope they learned something.
Powerglides were easy to break the back up function of the transmission. Don't remember now what would break, but it did not ruin/destroy the transmission. Drove one for awhile without reverse in my 58 Bel Air. Just never parked it where I would need to back up.
All 70-82 Corvettes have posi-traction, standard equipment beginning with the 1970 model year.Comment
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Re: 75 Corvette will not back up
That's my guess too. From the description of the problem, the transmission isn't loosing reverse and drifting into neutral. It's still in reverse but something is binding, not allowing the car to move further.
IF... one of the parking brake shoes lost a chunk of material and it's floating around at the botton of the drum inside the rotor, it's possible that it's wedging itself between the drum and the other shoe.
It would only get wedged going in one direction but not the other. (which would mean the rear shoe would be the one that lost the lining)
If the back of the car looks like it's trying to "lift" during the lock up event, that would confirm the problem is in the rear drive, spindle or parking brake and not in the transmission. The transmission is trying to do it's job but something is binding somewhere else.Comment
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