Took my 75 convert for a nice 30+ mile ride this 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 so didn't have a chance to jack it up and start checking. Any thoughts on where to start?

 

Parking brake sticking? They do do better in reverse than forward.

 

I never use it. Live in a real flat area. But I'm wondering if something let go that is causing the parking brake shoe to lock when I'm backing up?

 

Does it FEEL like it's trying to pull in reverse? Or just in reverse and not doing anything?

If it's not doing anything, the intermediate sprag is possibly broken, or the servo that applies the band is done. Either way, get ready to pull the tranny.

 

Had a new grand daughter and had to go out of town a couple days!

No, it goes into reverse and starts backing up normally. No slipping or odd noises.

 

As your going back does the rear of the car sorta rise a little?

 

I didn't notice that. Felt normal.

 

Usually I notice if the parking brake is hanging up in reverse the rear of the car rises a little.Not sure if it does that if the caliper is hanging up...you could have one of the rubber brake hoses causing the caliper to hang up.

 

I replaced the calipers and soft lines right after I got the car w/ SS sleeved units from Vette Brakes, and about 1.5 years ago one of the fronts started having a problem which resulted in the car pulling to the opposite side. Ended up pulling both fronts and having VBP rebuild them after I tried replacing the soft line. That could be the problem here, but I didn't have a pull to one side or the other when I drove the car.

 

The automatic tranny in my truck failed a while back and the symptoms are like you describe. There would be absolutely no reverse gear after a long drive. Let the truck cool down overnight and it would back up. It worked for a week or so and then the forward gears started to go.

You may consider dropping the pan and check to see if you have a mess in there.

 

 

I'm going to try a number of these suggestions this weekend. Think I need to at least eliminate the parking brake as the culprit before I turn to the trans, differential, etc. I can fix/rebuild the parking brakes where the car sits. The trans will be another question!

Thanks for all the good input.

 

put it in reverse then get it rolling backward , then pop it into neutral just as it starts rolling, if it still stops then it is a brake problem, if it continues to roll backward then it is a tranny problem..
or.. push it backwards and see if it stops while car is in neutral..
or .. disconnect drive shaft and push it backwards.. see if it stops

all these will tell you if the tranny is forcing the stop, or the brakes..

it could be bad gears/clutch packs or binding bearings in the rear end, where thay work OK one direction but bind up in the other direction..

just thinking out loud here, good luck...

 

CONGRATS ON THE NEW GRAND DAUGHTER!!

Keep us posted on the car, good luck!

Dave

 

Dave, thanks for the congrats - she's a sweetie! I did make some progress on the '75 this weekend.

Put the rear end on jack stands, drilled the rivets out of the rotors, pulled the rotors off and out came broken actuator springs along w/ the rivet remains. I figured Ah Ha, got it! I gutted the parking brakes. Nothing else was amiss but the broken springs could easily be causing the problem. After 33.5 years it's probably about time to do the trailing arms, but short term I should be able to get the car where I can move it w/o them. But there is still resistance rotating the spindle backwards - may be because I have the half shafts in a bind since the car is supported by the frame. Ran out of time, but my next step is to jack the half shafts up to about level and see if the axles rotate freely both ways w/ the trans in neutral. If not, next step will be to disconnect the driveshaft, run the car and try the trans in all gears to see if anything is going on there, and see if the differential/axles rotate freely when not connected to the trans.

As an aside, I'm taking this opportunity to get the rear calipers freshened up. When I bought the car in 1996 I pulled all the calipers and took them to Carlisle looking for the best deal. Bought a complete set w/ hoses, master cylinder, and calipers from Vette Brake Products. Last year I had a problem w/ one of the front calipers and sent those back to be rebuilt, so figured the backs are about ready also. I'm going to get the rotors turned today.

Thanks again for the interest. I'll let you know if that was the problem, or if the adventure continues!