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Reverse Clunking Sound


grassfiddler

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I have a 52 Dodge Coronet with the gyromatic transmission. Everything was working well till about two weeks ago when I went to back the car out of the garage. As I was backing out of the garage I heard some loud clunking sounds and the car wanted to stop sunddenly. The car didn't make the sound or the stopping action if I drove in reverse quickly until the car started to slow down. The car would go forward just fine and would shift like it is supposed to.

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    I have a 52 Dodge Coronet with the gyromatic transmission. Everything was working well till about two weeks ago when I went to back the car out of the garage. As I was backing out of the garage I heard some loud clunking sounds and the car wanted to stop sunddenly. The car didn't make the sound or the stopping/lurching action if I drove in reverse fast, until the car started to slow down the clunking would come back. The car would go forward just fine and would shift like it is supposed to while going forward.

   I just went out the garage to drive forwards and backwards to see if I could figure out the problem. As stated above it would make a clunking sound while going in reverse slowly and it would lurch and stop like I was hitting the brakes. It would start out like this but if I hit the gas pedal it would clear up until the car slowed down when the clunking would return. It would do it if I had the clutch pushed in or not, and or if I was using the brakes.

   I shut the car off, put the car in neutral, got out and tried and tried pushing the car by hand. Going forward was no issue but it would barely move while trying to push it backwards. At first I thought it was an issue with the reverse gear but I'm not so sure because when the car gets moving it goes just fine. I have been driving the car like this and it runs out great. It's something while in reverse that is makeing this sound. Also the brakes seem to be working good and the parking brake seems to be working right but I haven't ruled out an issue in those two places. So I don't know if it's in the clutch, the rear end, etc.....

  Any ideas would be greatly appreciated.

Edited by grassfiddler
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Just came in from the garage. Armed with a starting place from Don Coatney, Greg G, and my neighbors help and knowledge, I jacked the car up to get both rear wheels off the ground. I tried to move the drive shaft by hand and even got forceful with it but found no free play. I then spun each wheel by hand to see if there was an issue with the rear end. Each wheel turned freely in both directions but I noticed that the drive shaft wasn't always turning when the wheels turned. So I think this eliminated these things as the problem. Next I started up the car to see if the clunking or binding was happening without any weight on the rear wheels. Forward was fine but the clunking continued in reverse. So with some discussion of the parking brake we theorized that it could be a loose lining or broke return spring. So I barley applied the parking brake, put the car in reverse and the clunking sound and the binding went away! So it looks like I'll be tearing the parking brake a part. I'll post back as I get into this project to let everyone know what it was. Thanks for everyone's help. 

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Transmission parking brake shoes dragging and covered in oil from a rear trans seal leak will cause  your issue.

Parking brake adjuster and tool used to easily adjust it shown. There is a little metal cover plate with two 7/16" hex bolts to remove and then you can look in and see the small shoe adjuster. You really need to pull the driveline off the back of the trans E-brake drum and remove the drum nut to pull the drum off to inspect the shoes and their condition.Shoe adjustment is sensitive. Adjust till they barely barely touch the drum. Just a very slight drag of the shoes-very slight or none!

 Shoes must be free of any oil.

Bob

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Edited by Dodgeb4ya
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Well since you have a gyromatic car, I would suggest you really need the parking brake, as the Gyro gives you no compression braking when parked.  You could temporarily back off the back off the adjustment on the brake and do a test drive to see if that's your problem.  Just remember to chock your wheel when yo park it.

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my 50 with gyromatic did the same thing. I took the drum off the parking break and found the bolt holding the shoe at the top had lost the nut holding it on. I put  self locking nit on it and now it works great. the lose shoe would flop enough for it to try to lock up. Exactly like you said it would do it when backing then when I went forward it would go in place and no problem.

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I haven't been able to get under the car to check out the issue, but hopefully this weekend I'll be able to get it tore down. I'll report back what it is just in case someone else needs to know for there car. After I get this issue fixed I need to pull the oil pan and fix the main seal and replace the pan gasket. Wish me luck.

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