81 Automatic. Shaking in Reverse Only
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 7,032
Likes: 2
From: Newburgh NY
81 Automatic. Shaking in Reverse Only
Was at a friends today trying to diagnose a problem with his 81. The car runs and drives great in forward. However, in reverse, after slowly backing up about 10', the whole rear of the car starts to shake so bad the exhaust tips start flapping around. Even at speeds so slow it is barely moving.
The car had sat for several months off and on. I jacked it up and the wheels spin freely on both side. Parking brake doesn't seem to be hung up in anyway. Ujoints, and drive/half shafts look fine. I'm thinking it's the posi clutches and perhaps and drain and refill with some new posi additive might do the trick.
Anyone see this before or have a suggestion? I don't think it is the tranny as it was rebuilt not that long ago and the shaking definately appears to be coming from the rear.
Thanks
The car had sat for several months off and on. I jacked it up and the wheels spin freely on both side. Parking brake doesn't seem to be hung up in anyway. Ujoints, and drive/half shafts look fine. I'm thinking it's the posi clutches and perhaps and drain and refill with some new posi additive might do the trick.
Anyone see this before or have a suggestion? I don't think it is the tranny as it was rebuilt not that long ago and the shaking definately appears to be coming from the rear.
Thanks
Drifting
Joined: May 2000
Posts: 1,952
Likes: 6
From: Palos Verdes Peninsula California
TTT for you. I am curious what it is as I have an 81 auto also. I am by no means an automotive expert, but could it be in the transmission? This is where I'd look.
If it was the rear (like if something got bent or misaligned), wouldn't it shake all the time? Can you feel anything coming from the trans as you are reversing?
I took a look through my shop manual for you but didn't find anything in the troubleshooting sections that matched what you are experiencing.
If it was the rear (like if something got bent or misaligned), wouldn't it shake all the time? Can you feel anything coming from the trans as you are reversing?
I took a look through my shop manual for you but didn't find anything in the troubleshooting sections that matched what you are experiencing.
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 7,032
Likes: 2
From: Newburgh NY
Thanks guys...
It does not feel like the tranny but I haven't ruled that out yet. A couple of mechanics I talked to today do not think the posi unit has anything to do with it. My original thought was the parking brake but on jackstands the wheels spin freely forward and backward.
The car is coming over to my shop on Saturday so I'll get it up on the lift and take a look. I plan to pull the rotors and calipers anyway just to take a look at the Pbrakes.
You have to see/feel what's happening to believe it. It's very strange. The only thing that the car has had happen to it in the last year or so is it sat for a few months. Last year I changed the heater core for him and a few other things but he had driven the car since then.
Thanks again!
It does not feel like the tranny but I haven't ruled that out yet. A couple of mechanics I talked to today do not think the posi unit has anything to do with it. My original thought was the parking brake but on jackstands the wheels spin freely forward and backward.
The car is coming over to my shop on Saturday so I'll get it up on the lift and take a look. I plan to pull the rotors and calipers anyway just to take a look at the Pbrakes.
You have to see/feel what's happening to believe it. It's very strange. The only thing that the car has had happen to it in the last year or so is it sat for a few months. Last year I changed the heater core for him and a few other things but he had driven the car since then.
Thanks again!
