4L70E problems. Again!

[zach_carver]

Ok guys I need some help. I have a 65 C10 with LS2 and 4l70e from a trailblazer SS. I'm having terrible trans problems. I have pulled and reinstalled 3 times in a month. I'll start from the beginning, had trans rebuilt before installing in truck had 100k miles on it. Headed on a trip with it and I lost 3rd and 4th gears. Removed trans builder said 3/4 gear clutches gone again. He fixed it, reinstalled drove 60 miles died again. This time it was as he said "welded togther". He was unable to get planetarys apart. So tired of fooling with what I thought was a crappy builder I call GM and order a new crate 4l70e. Well now I've driven it 3 4 days solid great running shifts beautifully. Noticed today trans was starting to get a little hot after a pretty good little trip it was 199. Then it started slipping, flailing shifts. I'm afraid I'm gonna smoke this new trans. My truck has a cooler thru the aluminum champion radiator only. And I'm using rubber high pressure trans cooler lines. Any help/insight is greatly appreciated.

[Clyde65]

Dude, holler at Clienbarger here on the forum, he rebuilds trans' for a living.

[zach_carver]

Originally Posted by Clyde65

Dude, holler at Clienbarger here on the forum, he rebuilds trans' for a living.

I probably need to. I amcurrently in the process of installing a new trans cooler, but still not real sure what my cause is. I mean it's a new GM crate trans. These problems shouldn't be happening lol

[clinebarger]

Originally Posted by zach_carver

Ok guys I need some help. I have a 65 C10 with LS2 and 4l70e from a trailblazer SS. I'm having terrible trans problems. I have pulled and reinstalled 3 times in a month. I'll start from the beginning, had trans rebuilt before installing in truck had 100k miles on it. Headed on a trip with it and I lost 3rd and 4th gears. Removed trans builder said 3/4 gear clutches gone again. He fixed it, reinstalled drove 60 miles died again. This time it was as he said "welded togther". He was unable to get planetarys apart. So tired of fooling with what I thought was a crappy builder I call GM and order a new crate 4l70e. Well now I've driven it 3 4 days solid great running shifts beautifully. Noticed today trans was starting to get a little hot after a pretty good little trip it was 199. Then it started slipping, flailing shifts. I'm afraid I'm gonna smoke this new trans. My truck has a cooler thru the aluminum champion radiator only. And I'm using rubber high pressure trans cooler lines. Any help/insight is greatly appreciated.

199 Degrees itself will not harm the transmission, But doesn't leave much room for error, You need to add an Auxiliary Stacked Plate Cooler.....After you figure out what is going wrong with your unit!!

Has Line Pressure Rise been verified with a Pressure Gage? Needs to bump 180-200 PSI at WOT with a stock .471" Boost Valve.

What Dipstick & Tube are you using? Are you 100% sure the ATF is at the PROPER level? a empty 4L60E with a factory deep pan & 300mm Converter should take at least 13 Quarts of ATF.

[zach_carver]

The truck has the factory dipstick and pan. The trans came from GM and was supposed to of been empty of fluid. However I started removing plugs from it and fluid come pouring out. Before starting up I pulled the stick and it showed over full on stick in bright red fluid. We started the truck while checking fluid we added 4 qts of fluid. Checked multiple times and was perfect in hot when it had been driven some. But let me add this, when the trans is 180 to 190 degrees it shows maybe .5qt over full above HOT on the stick. I noticed today when truck started acting up it was 199 degrees and I was pulling out of parking lot nice and easy. It was the 1-2 shift that flared/slipped. Before hand the 1-2 shifts had gotten very firm. Only the 1-2 shift. All others were fine. How do you adjust pressures?

[solidaxel]

Sub. to this one!

[izzy_Britton]

yep, sub'd.

[clinebarger]

Originally Posted by zach_carver

The truck has the factory dipstick and pan. The trans came from GM and was supposed to of been empty of fluid. However I started removing plugs from it and fluid come pouring out. Before starting up I pulled the stick and it showed over full on stick in bright red fluid. We started the truck while checking fluid we added 4 qts of fluid. Checked multiple times and was perfect in hot when it had been driven some. But let me add this, when the trans is 180 to 190 degrees it shows maybe .5qt over full above HOT on the stick. I noticed today when truck started acting up it was 199 degrees and I was pulling out of parking lot nice and easy. It was the 1-2 shift that flared/slipped. Before hand the 1-2 shifts had gotten very firm. Only the 1-2 shift. All others were fine. How do you adjust pressures?

You bought your engine & trans package from a Salvage yard.....Correct? And the Dipstick & Tube are also from the same Salvage yard?? You have too watch these things! NEVER assume you got a matching Stick & Tube, They could have broke the Stick pulling the engine & installed a Longer Stick.

GM ships their NEW automatics dry (Maybe a quart will be in there from assembly), The Converter that come with them is Remanufactured & is also Dry. Yours having 8-9 Quarts means 1 of 2 things.....The Trans was ran on a Dyno OR You got sold a USED unit that was a return.
GM Dynoing their units would be news to me!

I'm guessing the Converter was already installed? (It would about had to have been for 4 quarts to bring the unit to proper level)

1-2 Flare..... A Flare, Cut-loose, Neutralization is a sudden rise/jump in RPM during a ratio change. A 1-2 Flare is unlikely....

In 1st gear...With the shifter in D4, The Forward Clutch, Forward Sprag, & Lo-Roller Clutch are Holding.

The ONLY thing that needs to happen for the Ratio change too 2nd is the 2-4 Band applies & holds the reverse input drum, sunshell, & reaction sungear stationary.

Even if the 2-4 band does not hold/Slow apply....The trans will just stay in 1st, No wild jump in RPM......Unless the Forwards cut-loose, Again....Highly unlikely! I can stack a bunch of steels in the Forward Clutch with minimum pressure & they would hold.

If you just have a Loooong Slow-Slipping 1-2....Well, If the Band cant stop the Drum, That puts us right back to Pressure Rise & Fluid Level.

2-3 Flares/Cutloose/Neutralization are VERY common even with good Pressure Rise & Fluid Level. The Band has to release & the 3-4 Clutches have to come on in Perfect Timing.
Band release too early/3-4's come on too late & you get a Flare....Back to 1st gear ratio because the only Friction holding is the Forwards.

Band comes off slow, Or the 3-4's come on too early, You get a Tie-up.....Or more technically....It goes into 4th between 2nd & 3rd.

2-3 Flare & Tie-up are extremely hard on the 3-4 clutches.

[zach_carver]

I'm not 100% on dipstick/tube. The motor and trans came from an man who had wrecked his trailblazer and was parting it out. I was unsure about GM testing as well when I received it but there was actually a sticker on tranmission case under the GM decal with part# the said TESTED. So once I seen it i assumed it had been dyno tested before shipment. I only notice the flare 1-2 shift when trans was really hot. I added a Hayden cooler yesterday and removed it from the radiator all together. Drove it quite a bit and no issues thus far. However I'm not 100% convinced that it's fixed. I really appreciate all your help.

[clinebarger]

Originally Posted by zach_carver

I'm not 100% on dipstick/tube. The motor and trans came from an man who had wrecked his trailblazer and was parting it out. I was unsure about GM testing as well when I received it but there was actually a sticker on tranmission case under the GM decal with part# the said TESTED. So once I seen it i assumed it had been dyno tested before shipment. I only notice the flare 1-2 shift when trans was really hot. I added a Hayden cooler yesterday and removed it from the radiator all together. Drove it quite a bit and no issues thus far. However I'm not 100% convinced that it's fixed. I really appreciate all your help.

That's a Reman, Not a new unit. You need a pretty big cooler when bypassing the Radiator, As I stated before.....199 is not hot & should not cause issues.
Keep us posted, And good luck!

[zach_carver]

Originally Posted by clinebarger

That's a Reman, Not a new unit. You need a pretty big cooler when bypassing the Radiator, As I stated before.....199 is not hot & should not cause issues.
Keep us posted, And good luck!

Thanks and will do. I got the biggest Hayden cooler I could find. Its half the size of radiator nearly LOL Its pretty big. I filed a claim with GM in case other issue occur. Gonna try and drive it a bunch after work and see what it does. Is 3/8" cooler line big enough for flow? Im running rubber transmission oil cooler lines 3/8".

[compsystems]

Who tuned the pcm? Has anyone changed the transmission settings in the tune?

[zach_carver]

Originally Posted by compsystems

Who tuned the pcm? Has anyone changed the transmission settings in the tune?

Trans was originally tuned by PSI who built the harness and computers for the swap.

So I called GM Performance and they tell me 200 degrees is not anything to worry about with trans temp, and that most likely what I was experiencing was the trans learning my driving habits and that different things adjust at different temperatures. Being that it was just installed few days ago. Told me adding the cooler in front of the radiator was a good idea and would just help transmission live longer. I dont know how much is true but its under warranty and there now is a case# so I should be covered.