Piston Slap: Lubeguarding Against Ford Tranny Shudder?

by Sajeev Mehta

Updated: May 16th, 2014 Published: March 26th, 2012

piston slap lubeguarding against ford tranny shudder

Dan R writes:

Hello Sajeev,

I have a transmission related question that I was hoping you may be able to assist me with. I have a 2003 Mustang GT, 4.6, Auto. 110k. (3rd owner) The car has the occasional classic Ford “AOD trans shudder” at lower RPM under load.

It does not really affect the overall drivability of the car but is an annoyance and I’d like to take care of it. As far as I know this car has never had a trans service done. I’ve heard mixed reviews on weather to do a trans flush or not.

Would it be advisable to take it to a shop to do a “power flush” or whatever they are calling it, or should I do it myself? I normally do all my maintenance myself. I have no problem dropping the pan and making a mess, I just want to make sure it will clear up the fluid in the converter.

So, any advice is appreciated, thank you!

Sajeev answers:

I have yet to officially choose a side in the battle between power flushing and the normal fluid/filter change. I like power flushing since it blows out fluid from the torque converter, and you have no other choice. Why? Because the bean counters at Ford “thrifted out” the torque converter drain plug (circa 2000) but still left us the rubber access grommet for no good reason…other than being too cheap to thrift that part out, too.

And for classic Ford tranny shudder, you need to change all the fluid, including the converter. I personally know Ford transmission shudder, as I moderate the best Lincoln forum on the planet: a place where Lubeguard Red was/is mentioned regularly. I used it for a Ford tranny shudder many moons ago, and it worked like a charm.

Even at this high-ish mileage, a fluid/filter change and adding Lubeguard Red is a good idea. And now I cursed it: with my luck, my advice means that new fluid will burn out the (excessively worn?) clutches and make things much worse.

Fingers crossed that I didn’t screw the pooch. I hate automatic transmission problems.

Send your queries to sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.

#4R-70W #Additive #AOD #Ford #Lubeguard #Mustang #TorqueConvertor #TransmissionShudder

Sajeev Mehta

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2 of 12 comments

Blowfish on Mar 26, 2012

ya is very true, when car is new, u can run the OD/ 5th gear from a dead stop, but after a few yrs it may not be able to handle the extra torque. One dude told me he never run his 90s F250 dsl on OD while in city, it does make sense esp when the OD is being upshifted early as to save fuel, but u maybe inadvertently using the premature wear of auto box ( which lead to earlier rebuild ) to pay for it! Is OK as long as u trade her in every 3 yrs, just leave her in the D pos and let the computer to do all upshifting.

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Moparman426W on Mar 31, 2012

Like a couple of others said, in city driving just put the shifter in drive instead of OD. That was how my mom drove her Mark V11 for 12 years Never had a problem with shudder driving it like that, plus it saves alot of wear and tear.

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