Thread: Getting my rebuilt trans back from warranty work

Ok, so after three weeks I should be getting my car back on Monday... The guy at the shop (Scott) said that the band in the transmission broke because there was too much pressure in the transmission and said that I need to install the stock tune with just the gears being changed. I have a diablew tune and have not heard of any complaints from him so its making me wonder if this guy blowing smoke ?

it all depends on what pressure setting where in the TCM im sure lew wouldnt have defaulted your pressure settings to max line pressure but anything is possible. i would contact dave@triple edge as well get his opinion

If a band broke, then that isn't pressure related. Reason being is the piston that actuates it will only move as far as the bore allows it. Therefore it moves forward and stops, in the process it pushes on the band. It can't surpass the bore, it shouldn't do much by applying faster based on higher pressure.

Was this the forward apply band? If so, likely he inspected it and reused it. Which..in a trans known for snapping the stock one over time.. let's say.. it shouldn't be reused for the cost of a new one.

The band did not necessarily break but was loose. It was shaking/slipping under moderate/heavy acceleration in first gear only. Thanks for your input bill its much appreciated and I will also call Dave and see what he thinks. Also scott at my transmission shop said to put the pressure back to stock. Would a shift kit be a good idea? if so what one?

I still don't buy that it was caused by pressure. Let me elaborate though, because w/o having been inside of a trans, you are at the mercy of those telling you what causes things.

The way our bands sit in the transmission: There is a piece on the band with a hole in it (on right of picture). This hole is set over a solid pin in the trransmission. This does not move, however there is a bit of wiggle room to the bands in general and they are not adjustable like some other transmissions. The piece you see sticking out from the band on the left side is pushed by the pin on the end of the servo aka hydraulic piston that engages the band. Like any hydraulic ram, there is a limited amount of travel allowed and this piston/servo moves the full travel each time it is engaged.

4T65E-RevBand.jpg

There is really no "loose" for the band to be. Stretched? I am unsure...but again it should have been replaced and new shouldn't be stretched.

Let's go a bit further, ask Scott if he followed the Sonnax sure cure info and or if he drilled the feed holes as it outlines
http://www.sonnax.com/system/new-ins...65E-LB1-IN.pdf

In the case where this kit has been used and feeds enlarged, you wouldn't want/need pressure increased through the tune. What is being done by the kit/enlarging feeds is feeding the clutch apply pistons faster, which is what you do via raising pressure. Although doing it via pressure settings puts more strain on seals as they then have to hold more pressure.

With that said and mentioned, we can see that if he's done these things in your trans, that it would be best for pressure to be stockish.

Thanks a ton for the information again bill! So I went there today and put the stock tune on and he did a pressure test on the transmission after the stock tune has been applied and it is still showing max pressure in park at idle. The engine load is also at 20-25% just idling after defaulting the stock tune, but If I raise the engine RPM's up to about 2000 the engine load drops to about 16% at about 20% throttle... I am so confused... I am headed to a dealership soon to get a reflash... IDK where to go from here. They did go through all of the transmission when they had it on the bench and tested all of the solenoids it all came back good. But when the trans is in and he scanned it, it showed high pressure at idle.... Is the tune wrong? is the PCM wrong?

Also he wanted me to pay 800 for the labor and parts EVEN though it has a 18 month and 18k mile warranty, but because he accused me of abusive driving/tuning that it would not be covered... OR I could have it all covered but lose out on the rest of my warranty which is about 1 year 12k left on it.

Sounds like a pretty shady trans shop. I would be thrilled to have a customer have tuned trans pressure and not cry about harsh shifts. Faster shifts = less burned friction materials. He should have just bit the bullet and fixed it without whining. he most likely reused the original band because the surface looked fine and then the lug broke, he gambled and lost.

as far as max line pressure at idle. That is probably not tune related. Was that read with a mechanical gauge on the test port? What was the pressure actually at? Max pressure would be like 180-200+. It could have the pressure regulator stuck or something else in the valve body which would be his fault anyway. If it is actually at max line it should bang into gear at part throttle and it probably will break something else or wipe out the pump quick.

Yeah I agree with you, I went to this shop off of local recommendations. I also think they did reuse the band, when I asked to see it he said he could not find it....

Originally Posted by Anthony Smith

Was that read with a mechanical gauge on the test port? What was the pressure actually at?

Yes I watched him scan it with a Snap-On scan tool , Not sure I think it was around 160ish?? but don't quote me I will get an exact number tomorrow. Like you said if it was at max pressure it should bang into gear maybe ill bring that up tomorrow and see what he says.

Thanks Andy for your input!

Max line pressure is 147 psi and for the record never ever admit to having your car tuned if your car is warrantied at that shop

Sent from my MB886 using Tapatalk 2

My tuner was in my car when I took it in. Their warranty never said anything about it being voided if it were tuned or not. I got it tuned so the transmission would last longer and not shorter

Most warranties have some type of weird worded clause saying hey if you're car is modified to produce more power etc.... They won't be held liable for damages. Granted we know tuning the trans helps but when it comes to what they need to know about your car always plead the fifth.....unless its a dyno operator

Sent from my MB886 using Tapatalk 2

Max pressure read with a manual gauge per the ATSG book and GM ESI FSM's is around 173psi. Not that I had some max line pressure issues on a car once, so we'll just pretend I did a lot of reading up on it. Some of us happen to have a manual test gauge for oil and trans pressure. Awesome tool when you have a question.

I can see both sides of the disagreement on the tuning. Do your best to keep the warranty, but tell him to eat it on abusive driving. A GXP with abusive driving is capable of crapping out a trans super fast. He is unfortunately unhappy about pulling everything apart for that forward band, sorry pressure still isn't to blame for that.

Did he test the soleniod for resistance? Most of them can be tested externally this way to gauge if there is an issue. This is one way of checking the internal harness and soleniod w/o opening the case back up.

Thanks again bill for all the insight! Now that I have my car back I remember about a week or 2 ago I got a TCM code of p0717 (Turbine input sensor) being bad or something. When that code popped up and when I tried to downshift into 2nd or first the downshift would be extremely harsh. If I forgot to mention this car does have tap shift. Would this be a culprit to the forward band breaking? The code would go away if I tuned the car off and on again and it did not happen again. here is a picture of the band that was pulled from my car

http://i.imgur.com/ppQq5y1.jpg

well the p0717 would cause it to go into max line pressure and a downshift in either 2nd or 1st gear will feel like its trying to rip itself out of the car. and no doubt a serious shock to the drivetrain maybe it caused the band to break but wait on bill's input see what he has to say. think you can post a copy of your tune file?

A culprit of the forward band braking is either defective part or old worn part. Line pressure has zippo to do with it IMO. Anthony rebuilds these things all day, since he liked my explanation etc and suggestion that it wasn't pressure, I'd like to think he's on the same page. Anthony, am I off on my thoughts?