Transmission issue, or just paranoid? 5.3L w/ 4L60

[jza]

Truck has 82 000 on it, got the transmission service done, had the fluid drained and the filter replaced.

 

I noticed (even before the transmission service), the truck sometimes shifts hard when going from first to second. Sometimes it even does it from third to fourth. I don't know what actually constitutes a "hard shift" but I can certainly feel the truck shifting, but it doesn't launch me forward or anything.

 

I only really notice when I'm accelerating slowly, I usually accelerate a lot harder. Could it be the TCM adapting to "new" driving habits? Am I in for a transmission rebuilt? Is it just a 4L60 thing?

[desrtrat]

first thing i would do is clean your MAF. a dirty one can cause trans shift issues..

[jza]

first thing i would do is clean your MAF. a dirty one can cause trans shift issues..

 

 

I'll clean that, thanks.

 

As I said you feel the shift sometimes, ya, but it's something only the driver will feel, through the gas pedal and what not.

[gmtech4]

i was a tranny guy up north for 3 yrs and i sent more than one out the door doing that and never heard another word about it

 

all shifts are of course electrcal ,the amount of throttle you have at the time of the shift is what the ECM uses to determine how much line pessure to put into the shift

 

there is no nicey slopey sliding gradual(clutch killing)shifts going when a firm shift is goin on ,

 

your right the shift adapts are what happens in a rebuild but yours are "up to date"to pick a phrase,

 

what im gonna sum up and say is ,firm shifts are better than soft shifts and that they are computor controlled ,it would take me forever trying to figure out why a firm shift happened while driving slow,

 

your truck has no TCM,the PCM does it all,Allisons have a stand alone TCM only

 

IDK what to tell ya ,maybe a few minites with a master gauge on the line pessure port and goin for a spin along with a tech 2 scanner

 

also max line pressure is also a default on alot of tranny codes to get your attn,maybe get it scanned for giggles first

 

hope this helps abit

 

 

rambling over lol

[jza]

Very insightful post Govtech, thank you.

[gmtech4]

ty ,i was just barfing old info lol

 

why there is line thru it is another question lol

 

Rob

[00Silverado4x4]

After 54k miles on my previous 04 Sonoma & now 90k miles on my Sierra, they both have acted precisely like you described. I'd not worry about it unless it stops acting like that.

[wilsonz71]

My truck does the exact same thing, only from 1-2 under light and slow acceleration. I do have an iffy mass air flow sensor that needs to be replaced, but I don't think that's it. I try to always have it shift 1-2 at 2000 rpm or higher and it won't do it. I try not to worry about it, think it's fairly normal. Also, it has never done it while towing.

[GMstrong]

rather have firm shifts then softs shifts.Learned that the hard way.

[gmtech4]

rather have firm shifts then softs shifts.Learned that the hard way.

 

 

i bought a 700R4 (4L60 predesseor) SRTA (GM rebuilt tranny) before i was in GM for my 85 "burb" 2wd diesel and i beat the piss out of it draggin a trailer etc and it slammed into gear all the time ,when i tore her heart out and tranny to crush the shell (insert tears here) i took it apart to steal the 3-4 clutches that went for a poop in my 93 C10 i put her engine in and that tranny was as fresh as can be ---it had 250K km on it !!

 

i put a SRTA in my 93 before i left GM for the discount !! 3 yr warranty,,,no brainer

 

im chatty tonight ok ??

 

lol

[jza]

I drove a buddies GMT800 with 4.8L and the 4speed, shifts pretty much the same as my truck. I can feel it a little more in my pedal than I could in his though.