Slight Acceleration Shudder

[Mediamonkey11]

Hey all,

I've got a strange little happening going on with my Expy. ALWAYS between 5 and 9mph during acceleration I'll get a slight shudder/wiggle from what seems like the rear end. I just changed the trans fluid, installed a cooler, and a remote filter kit with in-dash temp gauge which did not seem to make any difference at all other than a slight increase in smoothness of shifts (old oil was still very red, just slightly darker than new).

I filled it with Castrol Transmax Mercon V just for reference.

What does this sound like, trans mount, slip yolk, u-joint?

BTW, it does it regardless of turning or going straight, and regardless of how hard I accelerate.

Thanks guys!

 

[Mediamonkey11]

Uh oh, no ideas might be bad! Lol

 

[grayGT10]

I have the exact same thing on my 02 with 96k on it. I also had it on a previous 01. I too would like to know what this is. It does not affect the normal drivability but is driving me crazy! I mentioned it to a technician at a Ford dealer. He stated "it's normal, nothing to worry about". I'm thinking it's not normal. Anyone have any insight?

 

[grayGT10]

As a side note, I do not feel the shudder when I accelerate in reverse.

 

[KWT2000]

is it strait line acceleration? or only when turning doesnt need to be much of a turn

if it is when turning you most likely have a limited slip rear diff and it doesnt have enough friction modifier in it,

 

[BakerEdition]

I have the same in my 2000 5.4, been there since 77k when I bought it and still there 3 years later with 105k....I had this happen in a car one time...it was the U-Joints. I looked at mine last year and grabbed the drive shaft to see if they were loose..but nothing...So I thought I would drop the shaft and pivot them and see if they were binding....but them stupid star headed bolts wouldn't break loose and I didn't want to snap them off...but its in the back of my mind to take it somewhere and have then replaced just because of age and mileage...but i would put in a good joint like a "spicer"

mine does it on acceleration going straight and it don't do it all the time...sometimes I notice it more than others.

 

[KWT2000]

thinking this thru 99 and up are AWD wonder if it could be viscous coupler in the T case?

 

[BakerEdition]

I think they had the problem with the Oldsmobile Bravda..

 

[Mediamonkey11]

It happens when turning or when going straight, it's a little worse the harder you accelerate, the more I think of it. I'll likely change the diff and tcase oils, what do they take? Yes I have limited slip.

 

[KWT2000]

the Tcase takes ATF about 3 qts, the rear takes 85/90 plus the friction modifier, castrol makes a synthetic with the modifier in it for $10 a qt, i got mine from oriley

 

[Mediamonkey11]

Awesome thank you! Interestingly enough, I found out it does it in reverse as well!

 

[grayGT10]

The shudder happens straight line or turning, soft or hard acceleration. It does not do it in reverse.

 

[KWT2000]

with it being all wheel drive or auto 4wd i would start with a tcase fluid change

 

[grayGT10]

I'll give that a shot. Thanks.

 

[Lightnig]

hmmm, interesting.

My '97 does the same thing. In 2 high. Haven't noticed it in any of the 4wd settings, I will have to test that.

 

[KWT2000]

mine has a bad shutter on acceleration while turning so tomorrow the fluids are all getting changed

 

[Mediamonkey11]

Just as an update, I changed both front and rear diff fluids (EXPENSIVE!!!), transfer case fluid, and both ujoints on the rear driveshaft. Still shuddering slightly upon acceleration.

Interestingly enough though, I did find its much worse when in 4wd and turning slightly...

Any fresh ideas by chance?

 

[Zidjan]

It happened to my 02 also...I changed the transmission fluid and add in friction modifier

Dr. Tranny 19610 Instant Shudder Fixx Friction Modifier

It has been 3000 miles and the shudder hasn't been back.

Chances are our torque converter is going bad...but the modifier buys some time before we replace or rebuilt the tranny.

Doesn't hurt to try that $7 fix.

 

[Lightnig]

ummm, ok, maybe I'm just being stupid and asking a silly question

but how does friction modifier in the diff affect the transmission?

They are completely independant fluid systems after all.




Not trying to be a smart A or anything, just want to under the reasoning here...

 

[98eb5.4]

ummm, ok, maybe I'm just being stupid and asking a silly question

but how does friction modifier in the diff affect the transmission?

They are completely independant fluid systems after all.




Not trying to be a smart A or anything, just want to under the reasoning here...

problem is finding out exactly what it causing the shuddering,
sounds like it was the tranny torque converter here rather than the rear

i've got the same prob on a 98, shuddering on initial accel, anyone know if you still use the modifier if your traction lock is shot? worn out? not working? i'm assuming the clutch pack is done in mine at ~ 240k miles+

shuddering seems to be from the rear and i'll be looking at the rear diff soon