3800 4T80E>4t60/65/hd
- Thread starter Turbocharged400sbc
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I suspect my trans slips in 3rd gear and that I had the problem last year too.
At 20 psi my trap speed was 141 mph. At 29 psi my trap speed was 139mph.
But my ET was quicker because the 1st half the 1/4 mile was quicker at 29 psi.
2nd half was slower.
Eventually I was shifting in 4th before the 1/8 mile because of the slip. Didn't make sense even when I was 3.71 back then. Now I have 3.11 gears.
And on the only 2-3 shift I seem to get full RPM right away (over 6300rpm at about 100 mph in 3rd gear) I don't think my precision torque converter can slip this bad.
I will be lowering boost to 20 psi on each engine until I can prove the trans aren't just slipping all the power away.
Ideal boost profile would be 20 psi off the line then ramp to 29 psi, then right before the 2-3 shift go back down to 20 psi !
At 20 psi my trap speed was 141 mph. At 29 psi my trap speed was 139mph.
But my ET was quicker because the 1st half the 1/4 mile was quicker at 29 psi.
2nd half was slower.
Eventually I was shifting in 4th before the 1/8 mile because of the slip. Didn't make sense even when I was 3.71 back then. Now I have 3.11 gears.
And on the only 2-3 shift I seem to get full RPM right away (over 6300rpm at about 100 mph in 3rd gear) I don't think my precision torque converter can slip this bad.
I will be lowering boost to 20 psi on each engine until I can prove the trans aren't just slipping all the power away.
Ideal boost profile would be 20 psi off the line then ramp to 29 psi, then right before the 2-3 shift go back down to 20 psi !
Fwd doesnt put anywhere near the load... so you should be fine if you stay out of 4th...
I broke the first 4t80e by overboosting off the line. 25 psi brake torque in 2nd gear. Clutches couldnt hold.
2nd one got hurt after much abuse and only when i shifted to 4th. Same with this one.
So i will stay out of 4th and use only 20 to 22 osi max.
I broke the first 4t80e by overboosting off the line. 25 psi brake torque in 2nd gear. Clutches couldnt hold.
2nd one got hurt after much abuse and only when i shifted to 4th. Same with this one.
So i will stay out of 4th and use only 20 to 22 osi max.
Black is the old sick 4t80e
And we just cleaned and painted a low milrs 4t80e that looks perfect on inspection. Looks new inside.
We took out the 3.11 diff with EP LSD fom the old trans and put it in this one...
Also will send back the super loose precision torque for a restall. And use a stock aurora 4.0 torque for now. That should help keep me out of 4th.
And we just cleaned and painted a low milrs 4t80e that looks perfect on inspection. Looks new inside.
We took out the 3.11 diff with EP LSD fom the old trans and put it in this one...
Also will send back the super loose precision torque for a restall. And use a stock aurora 4.0 torque for now. That should help keep me out of 4th.
someone did it....
ls4/4t80e
looks like he's ground enough off the trans that he's right next to the diff cover Oring (probably wanna rtv that as the trans case will probably flex. ground a bit off the block too)
the oil pan looks like it'll be fun
giggity
Where's the rest of the story...
Y U HI DING ??
Ok James.... are we 100% sure the 2005-2011 new style 4t80e with the non viscous converter will fit my setup ?
I'm still running aftermarket shift controllers.
I have 3 I want to buy low miles. Tired of hunting them down, I should have enough for the season and in the meantime rebuild one of them to the highest specs I can.
I'm still running aftermarket shift controllers.
I have 3 I want to buy low miles. Tired of hunting them down, I should have enough for the season and in the meantime rebuild one of them to the highest specs I can.
yes, the major differences are the range/IMS switches and the fluid pressure switches which are diagnostic related.
btw 80e manual lists your no drive problem as likely being the forward sprag. even though the forward band "assists" the sprag in locking the forward drum. the sprag freewheels in coast/decel and holds under acceleration. this is the only sprag in the whole trans that is a ramp/roller style instead of the modern dogbone sprags.
problem is seen in your video....you need to stop pedaling the car during your burnout.
sprag slippage is greatest at high tq while locking up, and it takes 2-3 events before rollers become flat spotted and you end up with less than half the elements holding (as half the rollers are sitting on the flats, and not wedged.
no forward gears and "hard moving in forward" are both related to the sprag/band.
do your burnout and let off without getting back into it and that major issue should disappear. the same problem rears its head on the 65e as well as other tranny's.
maybe you could modify the manual valve to apply fluid to the coast clutch to lock it up but then when you pedal it youll go from acceleration to full engine braking when you let off. so thats probably not the best solution (talk about upsetting the chassis) but it would let you pedal it and make the sprag last a little longer since it'll be harder for it to release and then lockup
btw 80e manual lists your no drive problem as likely being the forward sprag. even though the forward band "assists" the sprag in locking the forward drum. the sprag freewheels in coast/decel and holds under acceleration. this is the only sprag in the whole trans that is a ramp/roller style instead of the modern dogbone sprags.
problem is seen in your video....you need to stop pedaling the car during your burnout.
sprag slippage is greatest at high tq while locking up, and it takes 2-3 events before rollers become flat spotted and you end up with less than half the elements holding (as half the rollers are sitting on the flats, and not wedged.
no forward gears and "hard moving in forward" are both related to the sprag/band.
do your burnout and let off without getting back into it and that major issue should disappear. the same problem rears its head on the 65e as well as other tranny's.
maybe you could modify the manual valve to apply fluid to the coast clutch to lock it up but then when you pedal it youll go from acceleration to full engine braking when you let off. so thats probably not the best solution (talk about upsetting the chassis) but it would let you pedal it and make the sprag last a little longer since it'll be harder for it to release and then lockup
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