changed fluid shifting hard now

[84cucv1ton]

didnt flush it.. dropped the pan. filled it.. its not a neck snapping shift, but way harder than it was. fluid is at the right level.. its a stock th400.. any ideas? this never happen to me before thanks

 

[armytruck63]

M1009's shift with a "bump" when everything is working fine, almost like there is a shift kit in the transmission. This concerned me when i first got my M1009. Remember you have the HD Diesel version of the TH400.

My guess is your old fluid was worn out and allowing some slip on shifting.

 

[84cucv1ton]

fluid was ok. had about 16k on it.. shifted real smooth before.

 

[MichiganMudder]

Trans fluid is mostly detergent. So, your trans probably had some build up in it, that the trans got use to dealing with. Once you put the new fluid in, it probably flushed some of that crud out, and now the trans isnt use to it.

 

[Barrman]

Mine shifter harder after a fluid/filter change. It also downshifted on slow hills when before it wouldn't. I would suggest another filter/fluid change in a few thousand miles.

 

[84cucv1ton]

ok im thinking about flushing it now.. thanks

 

[84cucv1ton]

i was given oil from the wrong drum.. i mixed the standard atf with synthetic atf. from what i know. cant do that.. will be flushing it now

 

[twomorestrokes]

My 1008 barks the tires when it shifts. I test drove two when I purchased. The other one just kind of slipped into gears and was mushy.

 

[lindyp38]

my shifting problems went away when i found an old cracked rubber modulator hose........

 

[Cucvnut]

My M1008 barks second gear also I love it.

 

[WARWAG]

I dont think your transmission cares if it has some Petrolium based oul mixed with synthetic based. BUT if it makes you feel better then go ahead and change it out. When I first brought my truck home it shifted REALLY hard like a competition shift kit. Turned out to be a vaccuum leak. You may have bumped that little vaccuum line on the passenger side of the trans. Its about 1=1/2" long and get very very dry rotted and is usually the first leak to occur. When your down there I would just change it out and it should be good for another 20 some odd years. If its not leaking yet it sure will be in the near future.

 

[84cucv1ton]

all the vacuum hoses are new.. so it doesn't matter if there mixed?

 

[Blue2actual]

my old 1009 shifts really firm. Mine did the same thing when I dropped the pan and replaced the filter. It shifted really firm and I never had any problems with it. Most of the CUCV's I have driven have shifted pretty hard. I wouldn't worry about it!

 

[dburd72]

hard shift

If you are talking about Dex6 it is backwards compatible with all fluids and will not cause a hard shift as per GM it is fine to mix Dex3 & Dex 6

 

[Mainsail]

Thanks for the info dburd. I was wondering about that since I changed the fluid/filter in mine and all the BX had was VI. Since you're really only changing the oil in the pan I intend to use my electric vacuum pump to pull the oil out through the dipstick tube and refresh it with some new. I figure a couple cycles of that will result in *mostly* new fluid.

As for shifts, they don't seem any more firm than before the change, but I have no idea when the filter was changed last in mine as I am the new owner. I still get an occasional slow shift that's firmer than normal, but not bad.

 

[donalloy1]

This an excellent thread! Had always wondered about how my 09 has shifted pretty hard. Thought maybe transmission had been beat? You would think that the hard shifts would not be good for rest of drive train?

As for barking tires going into second. Apparently my Power Pack is a complete DOG! There is no way I could muster that. Do you have Supercharged variant???

 

[Cucvnut]

Don i think it only happens in the trucks with lockers.

 

[84cucv1ton]

one thing i never changed was the modulator. got one from my friends work for 14 bucks and its adjustable too. ****s great now.. nice and smooth.. didnt think modulator went bad

 

[max1008]

Just changed my filter and the trans shifts a little bit later and harder then before. After reading this thread it seems like that is normal?!

 

[84cucv1ton]

i dont thin think its is. if its shifting hard there is a reason real easy to figure out just take a little time