hard clunk in reverse??

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ltrripp11

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good morning.

ran across this site recently and signed up. what a nice site. sorry i missed it all this time. with all the knowlege on this site i have a question regarding my 727/8/34 driveline in a 1972 duster 340. the tranny has 2 quirks. the first is when cold (bellow 40 degrees ) it will not go into reverse until warmed up. the second is a very solid clunk when i put the car into reverse. this is only reverse. now im not sure if that is a rearend clunk or tranny. hard to tell. the u-joints are brand new and the car is rock solid with a ground up resto. what do you guys think on both?? thanks for the input and glad to be here.
 
Welcome aboard, you've come to the right place for A-bodies. :) Regarding the tranny not going into reverse when it's cold, those tranny's won't fill the torque converted with the selector in Park, so you should always run it in Neutral for a little while to get the fluid circulating and warmed up. Also ensure your fluid level is correct, and it probably wouldn't hurt to have the fluid and tranny filter replaced if both are old and especially if the fluid smells burnt at all. As far as the clunk is concerned, I doubt it is comming from the tranny. First, check your u-joints, front and rear, to make sure the problem isn't there. Next, check rear end for play by putting the rear in the air and, with the trans in park, move one of the wheels forward then backward with a little authority to see if the noise can be isolated. Hope this helps.
 
oldvart

thanks for the quick reply. jacking the car up is a good idea and i will try that. the fluid and filter is all new and the u-joints as well. im leaning towards rearend myself on which one is the culprit. i also did not know about putting the car in neutral on these trannys for the tourque converter to fill. it would seem it would do it in the forward gears as well though if that was the case?? ill find out. well thanks again. bill.
 
Old Vart is correct about them not filling the converters in park. I have seen a few torqueflites clunk when going into just reverse though. I can't say what causes it though. My 93 Dakota did it slightly and my friend's mom's 78 Diplomat did it real bad. In my Dakota I installed a Trans-go shift modifier kit which included a different manual valve that allowed it to fill the converter in park and it cured all the problems associated with reverse along with making it shift allot better. Man would it turn heads when it slammed 2nd gear.

Now you say yours don't go into reverse until warmed up. If I read that correctly that is more than just filling the converter. Filling the converter just takes about 30 seconds or so after placing the car in gear. If it takes longer than that to get reverse it's time to drop the pan to inspect things.
 
sounds like a worn frt pump, some times a trans gets rebuilt, the rebuilder may inspect the old pump, throw in some new gears. sometimes they don't check the gear housing for the proper clearence. i always start mine in neutral anyway, just so the fluid will pump. if you look at your trans dipstick, you will notice, ck hot while idling in neutral. this is not uncommon in older units, just keep an eye on fluid condition. as far as the clunk, i just thought it was a normal mopar trait. i have found if you apply the brakes firmly, it will lessen this.
 
I had two cars that did that. My 72 scamp w/ a 318 and my 75 Dart. I just thought it was a mopar thing. Something to think about when I have my other transmission rebuilt.
 
ah.........the 727. Your pump seal is gone. When car sits overnite, the fluid drains out of pump. It will last forever like this..but I would always cold start car in neutral to make it last a little longer.
 
appreciate all the replys fellas. it gives me some direction. again the delayed reverse is temperature sensitive. in warm weather or when the car is driven its as normal. the neutral trick should help.
 
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