View Full Version : Any way to cure the infamous auto clunk into OD?

09-25-2014, 09:46 AM
Hey guys, I've had 2 auto SC's and both have the clunk into OD. My 89 I have now only has 47k miles on it. My dad said its just the way they were. Is this true? Or is their a fix?

I plan on having the trans flushed soon. Dont know if that'll help.


09-25-2014, 10:15 AM
I have never had a clunk 3 autos in my 89 till I got one with larger od band and bigger gears with shift kit 1to2 servo bands removed.

09-25-2014, 11:45 PM
After a while you learn how it shifts and you'll find yourself lifting the gas pedal slightly w/o even thinking about it and it'll be smooth as glass. Its not really a problem until you notice it in traffic and then it gets to be annoying... My advice... shift into "D" and drive until you're on open road again. :cool: Its caused by the timing/rate of the OD band apply. There is a shift kit fix for it. The kits try to shorten the rate.

09-26-2014, 12:10 AM
I've always found that fresh fluid takes care of the problem. Though Ford says atf in an auto is a life time fluid it really needs to be changed regularly. Once you get fresh fluid in you should notice a difference.

09-26-2014, 11:48 AM
I think it was always a bit of a problem. In fact, there is a part in the AOD called the "anti-clunk spring".

It may be exacerbated by worn transmission mounts or slop in the rear end gears.

09-26-2014, 01:02 PM
The best way to fix the "OD Clunk" is replace the direct drive AOD converter with an open/non-lock converter. Every AOD I have ever owned experienced this OD issue. Now both of my AODs have non-lock style converters and no more clunk into OD. With the non-lock style converter you will sacrifice about 1MPG on the highway but no more clunk is worth it IMHO. Plus by installing a non-lock converter you gain torque multiplication in 3rd gear. The 3 best improvements to an AOD IMHO are... non-lock converter, Lentech electronic OD delete valve body, 2" OD band + associated AODE upgrades.


09-30-2014, 12:45 AM
Even when my original trans was singing its swan song, I never had this issue. My new one is firm but no clunk. It is a 5.0 mustang trans with a few parts swapped out of my SC trans. but it shifts like a champ minus the 2nd to 3rd but im getting used to that.

09-30-2014, 12:17 PM
Thanks guys for the info! This car is gonna get very limited drive time. Maybe 500-1000 miles a year if that. Or atleast until I get the $$$ to get the upgraded head gaskets. The other 2 SC's I had blew head gaskets right at 150k. This one only has 47k so I have about 100k to go, but I will replace the head gaskets before it has a chance to blow.