Talked to two different transmission rebuilders and both said to get rid of the shudder add a small bottle of friction modifier designed for rear ends. After replacing the fluid several times and the torque converter too all to come back again i tried this yesterday and it went away within 10 minutes of driving..Iwas worried about adding this stuff in but as a last resort i tried it and it works. Anyone else heard this? It nakes sense because the converter sticks and releases causing this shudder and positrak rears will do the same thing without it.

 

Transmission manufacturers drive lubrication additive companies nuts with requests for 'foo-foo-dust' additives in automatic transmission fluids to resolve driveability issues with their automatic transmissions.

Some transmissions need 'stickier' concoctions as the transmission ages, while others need 'slipprier' fluids.

Transmissions 'tuned' for aggressive drivers show up wierd quirks when used by those who 'baby' their transmissions.

It's not at all unusual for your particular recommendation to resolve your issue -- much like changing fluid causes shift-quality changes that are noticeable by many drivers.

There's a lot of 'stuff' going on in those slush-boxes -- and the fact that they shift at all is just short of miraculous -- given the many compromises in material and clearances.

 

I had the same problem in my 95'. I did the same thing the ford dealers mentioned about the friction modifier, and it worked for about 90 days then the same old shudder comes back. What type of additive did you use? I'd like to see if that is different than the one ford gave me to use. This is my second tranny service in less than 12 months. I also am using the Mercon v that the dealer recommended. Thanks for your help

 

So, I also have this problem. What is the consequence if I just live with the problem ?

 

I'm living with this problem as well. Changing the new fluid at 8K and going with Mobil1 really helped!

Going to look for a friction modifier. What about Justice Brother Transmission additive? Thats a friction reducer? I've used it in other vehicles with high mileage and trans probs... It worked!

Let us know what FM you used...

 

I used to have the shudder.

It started at around 3000KM (2000 miles) It quit this July after a vacation. During the vacation we towed 7000lb for 2000 miles and it shuddered once or twice the first day. Nows its one of those things that I did not notice that it went away. The truck now has around 14k miles and it has not done it in the last 3000 to 40000 miles. I don't know whether I really broke it in or changed the charactristics of the oil with load and heat. Now I wonder if it will come back if I put new oil in the trans and or rearend? I will change the tranny fluid this fall at the end of the summer towing season.

By the way when it shudders pulling the trailer (7000LB) it is amplified. We pulled out of a campground with a stop sign at the top of a hill. We had to start from a stop on a steep hill. Wow did it shudder. It felt like I was going to break something. But that was this spring and it doesn't do it anymore.

 

Go to a NAPA Store and buy the Kendall brand friction modifier. It comes in a 6 or 8 ounce (i think) transparent plastic bottle. Add this to your fliud and drive. after 3 miles you should notice a difference. Mine was almost immediate. Not sure about justice brothers but this is what was recommended to me by aftermarket tranny builders and they have had no failures due to this.

 

I too dealt with this years ago, at 30,000 miles and again at 55,000 miles on my 97 XLT supercab 4.6. I changed fluid at 30,000 to have the shudder reappear at 55,000 miles. I have been shudder free since 55,000 and now have 113,124 on my truck. The secret? I installed an auxillary tranny cooler to take care of the problem, along with fluid and filter changes once a year. I pull a pop-up camper three to four times a year, up to 1500 miles a trip. My drive to work daily goes up and down Signal mountain here in Chattanooga. No shudders at all since the addition of the 22,000# cooler from B&M. Bought it locally at Advance auto parts for about $55.00. Best investment I ever made. Just wish I had installed a temp indicator at the same time.

Oh well, Still have about another 150,000 to go. Maybe I will get to it.

Jim

 

My '97 Lariat 4.6L started shuddering when shifting up or down between 3rd and OD. It got pretty bad. Then I tried the Kendall Positraction Additive. It eliminated the shudder and slippage. But I suspect it made things more slippery and actually masked the real problem. The bolts holding the transfer case adapter to the transmission had worked loose over time. I expect the shudder and slipping I experienced when shifting was because the output of the transmission was binding with the loose transfer case assembly. I took it to the local Aamco Transmission shop. By that time I was leaking fluid rather quickly. The guys at Aamco pulled the transfer case out. Fortunately no cracks in either the transfer case adapter housing or the transmission housing. A couple of gaskets replaced and some lock tight on the adapter housing bolts and no more shudder or slippage. No more friction modifier. I trust these guys at our local Aamco. They advised me I shouldn't have to use friction modifiers (snake oil). I believe that now. They suspected some of these friction modifiers may end up gumming up the valve body. However, I have seen that Valvoline sells a brand of Dexron/Mercon fluid for "older transmissions". Valvoline claims to have added friction modifiers to this brand of fluid.

I wanted to share my experience and hope it will benefit someone else.