shift issues

[SYO237]

Looks like im beginning to develop a shift issue.

Putting the truck into OD or D, if I just roll out and accelerate like normal (no launch, no getting into it hard), it stays in 1st until about 4000RPM and then snaps into 2nd. Once it gets into 2nd, it *seems* to go through 3-4 fine.

At a stand still, putting the truck from P to OD or D, it goes into gear, but its seriously bangs into gear harder than usual.

Obvious first thought is to change the fluid thinking there is some crud in a valve....but im thinking that isnt going to magically fix the issue.

Im no trans guru. Any guess what is causing this...or at least the first place to look?

If the answer is total rebuild, I have another built 700 lined up. 4L80 would be nice...but dont have that spare change rolling in my pockets.

 

[Quickstop [UK]]

Re: shift issues

If it's engaging aggressively, is that a valve related issue? How many miles on it?

 

[SYO237]

Re: shift issues

If it's engaging aggressively, is that a valve related issue? How many miles on it?

Yeah, when I go from P to OD or D, its like it has a shit-ton of line pressure...the entire truck shudders and clunks into gear...its not like the small shudder you get under normal conditions...its like someone just slammed into the tailgate shudder The shift into 2nd is a pretty hard jolt too, but its also got 4000RPM behind it to...

Guesstimate on miles....um....between 3000-4000? Its not a stock trans, it was built.

I think I may find a reputable shop around here and see about doing a flush....unless there is a method where I can drop the pan and flush it out myself (I have never taken my truck anywhere, so id rather not start).

 

[Chedarbob90]

Re: shift issues

Disconnect the tranny cooler lines from the radiator and drain it into bucket while the truck is running to get all of it outta the converter. Then once it's all out drop the pan and swap out the filter. If u wanna totally flush it out then pour tranny fluid in the dipstick hole while it's running so it cleans it out better....it's a lot cheaper and does the same thing as a shop would do just w/out the fancy machines...

 

[SYO237]

Re: shift issues

Disconnect the tranny cooler lines from the radiator and drain it into bucket while the truck is running to get all of it outta the converter. Then once it's all out drop the pan and swap out the filter. If u wanna totally flush it out then pour tranny fluid in the dipstick hole while it's running so it cleans it out better....it's a lot cheaper and does the same thing as a shop would do just w/out the fancy machines...

Werd. Only difference is that I dont have lines that run to my radiator anymore... I have -6 braided lines with AN fittings that run to an aux cooler in front of the radiator instead

Im assuming once I see the fluid slow down and stops draining, I turn off the truck.......and when I actually go to fill it back up (after the flush is done) I need to do it running again to make sure the converter fills up right?

 

[Chedarbob90]

Re: shift issues

Yessir. If I were you adam, i would buy a case of tranny fluid and fill it up while its running with the lines off, and when u see ur fluid suddenly change to bright red stop pouring it in and let that stuff drain out.... Then drop the pan and swap the filter. After that. pour in the tranny fluid when the truck is off until it's full. Then fire it up to let it run to the converter and top it off. Then make sure you run through the gears all the way down to first with the truck sitting still and back up to park, let it idle in each gear for about 10 seconds. Makes sure u got tranny fluid throughout ur whole tranny without putting a full load on it...

 

[SYO237]

Re: shift issues

Yessir. If I were you adam, i would buy a case of tranny fluid and fill it up while its running with the lines off, and when u see ur fluid suddenly change to bright red stop pouring it in and let that stuff drain out.... Then drop the pan and swap the filter. After that. pour in the tranny fluid when the truck is off until it's full. Then fire it up to let it run to the converter and top it off. Then make sure you run through the gears all the way down to first with the truck sitting still and back up to park, let it idle in each gear for about 10 seconds. Makes sure u got tranny fluid throughout ur whole tranny without putting a full load on it...

Sounds like a plan to me.

 

[The_Bronze]

Re: shift issues

Just disconnect the return line to the transmission. That way you flush the cooler as well.
The top line at the transmission is the return, so that is the line you would want to remove from your aftermarket cooler. Just add a length of hose to the cooler outlet and aim it into a bucket. ~12 quarts later you should be good.

 

[MikeRenz]

Re: shift issues

i'd drop the pan first, let it drain...clean the pan / get all the grit out of the pan.......pop the pan back on w/ the old gasket and flush as mentioned.....then drop pan again, change filter, refill.

why recirculate all the crap fluid if you don't have to?

 

[SYO237]

Re: shift issues

Lets throw in a curve ball.

I decided to see what would happen if I adjusted the TV cable. Gave it one adjustment and the insane line pressure going from P to OD is gone and back to what it used to be.

So, went for a drive....and it now shifts like normal for what my truck is. Pulled over and for the hell of it, gave the TV cable another adjustment. I felt no change in pressure, shift points, etc. and still not hanging up again. Went out on the road to get up into 3-4 and shifted fine. Again, pulled over and gave the TV cable one more crank. Still no feeling of change in pressure or shift points.

So....now what? I know this didnt fix the issue seeing how it did the same thing with hanging up back in January for a short period of time while driving down to Miami, but seemed to disappear after a mile or 2 down the road.

I still want to pull the pan, change the filter, etc. But should I be paying attention to anything on the valve body and cleaning it or......??????

 

[gkrcr882]

Re: shift issues

Had the same issue in my Ty. Had to let off to get a decent shift point, otherwise it would be around 3500, and it was a jolt. Clicked the TV out one notch, and it shifts as its supposed to. IIRC, under light throttle 1-2 upshift should be at 11mph. The high/hard shift is from high TV pressure, or "downshift command". Governor controls upshifts, TV controls downshifts and line pressure. Its a balancing act in a way. Governor pressure overcomes TV pressure, you get an upshift. TV pressure wins, you get a down shift. Hence why the TV cable is called the kickdown cable. :tup: .

A flush wouldnt be a bad idea at all, I think most of us are due for one ourselves.

 

[SYO237]

Re: shift issues

Had the same issue in my Ty. Had to let off to get a decent shift point, otherwise it would be around 3500, and it was a jolt. Clicked the TV out one notch, and it shifts as its supposed to. IIRC, under light throttle 1-2 upshift should be at 11mph. The high/hard shift is from high TV pressure, or "downshift command". Governor controls upshifts, TV controls downshifts and line pressure. Its a balancing act in a way. Governor pressure overcomes TV pressure, you get an upshift. TV pressure wins, you get a down shift. Hence why the TV cable is called the kickdown cable. :tup: .

A flush wouldnt be a bad idea at all, I think most of us are due for one ourselves.

Sounds like I may have to remove the governor and give it a clean as well possibly?

 

[SYO237]

Re: shift issues

For those following along.

I am narrowing down the problem as of right now to a worn out TV cable. Talking with Rodney and DaveP today, I yanked off the cable on the TB side and took a look at the teeth grooves that help keep the cable adjusted. I have some teeth that are laid down flat on one end that might be causing slippage.

I mentioned that I adjusted the TV cable above and went driving and the truck went back to being "normal". Well, after looking at the teeth and putting everything back together again, I jumped in the truck and put it through the gears again and the high line pressure and banging into gear from P is now back.....all with just removing the cable, looking at it and putting it on. Havent had a chance to go drive it yet to see if its back to hanging in gear, but it seems like Ive narrowed down the prob to focusing on the cable for now.

Im going to mark the teeth with some silver pen and take the truck out and see what happens.

Crossing fingers its a worn TV cable. A $40 fix is mucho better than a few hundred dollar fix :tup:

 

[MikeRenz]

Re: shift issues

i said that foo

 

[SYO237]

Re: shift issues

thread revisit.

I bought another aftermarket TV cable, did the swap and no change in shift patterns when adjusting the cable.

So it looks like I possibly have an internal issue. As a last resort, Im going to drop the pan and see if I can flush out the trans, put new fluid in, get a trans pressure gauge and cross my fingers its just maybe some grime and gunk floating around. I have little hope that it is though.

Trans R&R #4 incoming...

 

[SYO237]

Re: shift issues

thread revisit.

I bought another aftermarket TV cable, did the swap and no change in shift patterns when adjusting the cable.

So it looks like I possibly have an internal issue. As a last resort, Im going to drop the pan and see if I can flush out the trans, put new fluid in, get a trans pressure gauge and cross my fingers its just maybe some grime and gunk floating around. I have little hope that it is though.

Trans R&R #4 incoming...

After taking Harmon for a ride and talking it over with the rest of the FAST crew, there is agreement that my symptoms seem to be that of a possible dirty ass valve body and stuck valves. Looks like im dropping the pan, removing the VB and giving it a good flush out. This should be fun... :tdown: but I guess if it works, saves me from having to do a full rebuild.

 

[MRKING]

Re: shift issues

I have a spare 80e we could do a stock rebuild on and install . I even have the long output that when trimmed fits the tcase . I bet we could do it for well under 2k .

Go buy a junkyard gm 80e tcu , jsm trans mount bar , cheap converter , have adam fix your driveshafts shortening/lengthening and throw that biatch in .