At my wits' end with this trans...

BrianG

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I'm just looking for some confirmation or some other theories on what is going on this this thing. I've been driving my 91 L67 swapped GP since the 4th of July. It's been shifting super harsh and I keep getting a TCC stuck on code. I realized on Sunday that if I cleared the DTCs that it would run great, nice crisp but not jarring shifts, and the TCC lockup would act normally. After a couple shutdowns and restarts however, the TCC stuck on code would come back as well as the incorrect gear ratio DTC. I've got 3.29 gears and I've set the drive sprocket ratio to 1.000, so I don't understand why I keep getting either of the codes. Anyways, last night I get home, park it on the side of the street for a moment to get the garage open, and when I went to pull it in, I had almost no power being sent to the wheels. It would just slip and creep forward. I found that if I drop the shifter down to 1, that it would engage just fine. Researching the issue, I've read a few times that the issue is probably a slipping or broken forward apply band. Could it be ANYTHING else? Can I confirm it for sure easily?

The really crappy part is that I was planning to finally get it back to the track this weekend. I might just go thrash it this weekend anyways if manually shifting it through gears is just as effective as being in Drive. Will that work? I'm so sick of this damn thing.
 

timboku

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Sounds like a broken forward apply band, however putting it into first apply max pressure as well..could be fluid issue...I'd drop pan and look for clutch material or metal...your tcc soliniods could be clogged as well with debris sending tripping your code..filter could be clogging up as well, not applying enough pressure to the apply band...also dropping thr pan yiu can inspect the apply band as well.
 

BrianG

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Sounds like a broken forward apply band, however putting it into first apply max pressure as well..could be fluid issue...I'd drop pan and look for clutch material or metal...your tcc soliniods could be clogged as well with debris sending tripping your code..filter could be clogging up as well, not applying enough pressure to the apply band...also dropping thr pan yiu can inspect the apply band as well.
Thanks for the quick response. I'm going to try and drop the pan later this week. I don't suspect any clogging because it's all fresh fluid as of 4th of July weekend, having previously had the trans completely ripped apart for repair. It's probably got less than 150 miles on it since getting put back together. Also, from what I've been reading, the incorrect gear ratio DTC can trigger max TCC, which then throws that code, so they seem connected, especially because clearing the DTCs relieves the TCC stuck on code, which would not (could not) happen if it was a mechanical clog issue.

I'm about to set this thing on fire and roll it down a hill.
 

timboku

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These are what I changed in my gtp..drive sprocket is thr main one and I don't thin the others will effect operation.





 

BrianG

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As far as I know, the VSS pulses/mile has to do with tire size, not gearing since the VSS is based off of a reluctor on the output. I don't think that has to change. Mine is set to 24,296 and I haven't modified that value in HPT. Anyways, at this point I think that is all moot now that I have hardware problems again.

Why does it engage in G1, but not in OD/D? What happens once it gets to 3rd if I shift manually?
 

timboku

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What value did you punch into hpt for gear ratio...iirc you need to punch in 3.67 to convert to 3.29 in hpt..I use dhp but I remeber reading about that issue in hpt.
 

timboku

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I had a similar issue after installing a chain set and a TEP valave body..it wouldn't move under 3k rpm in D..put it in 1 and it would act normal and I was able to shift through the gears...however trans temp rose quickly...pulled that trans out for now and rolling in a lumina trans with 3.29s till I can get it sorted out...what year 65e are you using and what was rebuilt?
 

BrianG

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What value did you punch into hpt for gear ratio...iirc you need to punch in 3.67 to convert to 3.29 in hpt..I use dhp but I remeber reading about that issue in hpt.
I used 1.000. Stock 2.93 uses a value of 1.121. It looks for the ratio of the chain sprockets in HPT.
 

BrianG

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I had a similar issue after installing a chain set and a TEP valave body..it wouldn't move under 3k rpm in D..put it in 1 and it would act normal and I was able to shift through the gears...however trans temp rose quickly...pulled that trans out for now and rolling in a lumina trans with 3.29s till I can get it sorted out...what year 65e are you using and what was rebuilt?
It should be a 97 trans. It was "built" by C-Ya Racing about 6 years ago and I've had nothing but problems. It's got 3.29s with 7/8"chain, hardened input, some wild 7 friction input clutch pack, what turned out to be a 4T60 TC for "stall", and who knows what else he did to this thing. The frictions I looked at seemed fine, this last time around I didn't pull the forward band. I had to rebuild the input/3rd sprag and replace the 2nd roller clutch with new elements.
 

timboku

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Oh man..mine is a 97 trans to..been nothing but issues with it since I opened it up!!! Wanted to burn car..got a 65e non HD for free through it in and it's fine..I'm sending my valave body to TEP as he redid it but I think 97s are funky with channel plate and valave bodies...damn 97s...hoping to get it sorted out as it maybe going in my l32 swapped 95 cutty.
 

BrianG

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I thought hpt auto calculates everything when you punch in gear ratio?
I haven't previously noticed that calculator feature in HPT. I'm playing with it now on a stock 99 GTP tune, but the "starting" numbers keep showing 3.29 for the final ratio while the Drive Sprocket Ratio shows 1.121?! Not sure what this calculator is doing...
 

timboku

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I haven't previously noticed that calculator feature in HPT. I'm playing with it now on a stock 99 GTP tune, but the "starting" numbers keep showing 3.29 for the final ratio while the Drive Sprocket Ratio shows 1.121?! Not sure what this calculator is doing...
Not familiar with hpt, but thinking that's why you need to put in 3.69 to get it to 3.29 ratios..dhp we enter them manually, hpt calculates it but when researching my swap I read alot about that hpt thing...try it out see what it does.
 

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My car was doing the exact same thing years ago with the codes being thrown and harsh shifting because the gear ratio section on my DHP was wrong. After i fixed that its been great. I do not know what to tell you about the call all the sudden not wanting to move.
 

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Not familiar with hpt, but thinking that's why you need to put in 3.69 to get it to 3.29 ratios..dhp we enter them manually, hpt calculates it but when researching my swap I read alot about that hpt thing...try it out see what it does.
This ^^^^ you need to put in 3.69 as 3.29 is default for stock GTP gears. Might be too late though if you're only getting gears putting it in 1st or 2nd. I think if you try to grab 3rd it'll just free rev or act the way it was acting when you pulled it back in the driveway.

Also, FWIW, in the description of when/how it happens he explains how bad high line pressure is for the transmission and also goes on to say that you'll get out at a gas station, go to start the car back up and you lose D and 3. Just about explains your situation exactly.

From TEP's webpage..

"Regardless the route cause of WHY the band broke, it is broken and needs to be replaced. Below are a few pictures of forward apply bands and how you can tell if yours has broken or not. One picture is of a good band, a fractured band that was on its way to failure, and a broken band. Sometimes you may find about a 1" piece of metal from the band laying in the lower transmission pan when you drop it for inspection. Other times the lug will tear on the band where it is brazed on."



"The next picture shows 3 different Forward Apply bands. From left to right you will see a band with a broken off and missing apply lug just as the above picture shows, next a fractured band, and to the right is a band in good condition."


 

BrianG

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This ^^^^ you need to put in 3.69 as 3.29 is default for stock GTP gears.
Why tho?? Isn't the stock final gear ratio 2.93 because of the 1.121 ratio sprocket set and the 3.29 diff ratio??? Using the 1.000 sprockets gets you to a final ratio of 3.29. It seems that calculator is not taking into effect the sprocket ratio, and the ratio is just a text field to be updated. Do I scale everything by another 1.121 by forcing a final 3.69 and leave the gear ratio at 1.121? Do I scale everything by another 1.121 by forcing a final 3.69 and change the gear ratio to 1.000?
Might be too late though if you're only getting gears putting it in 1st or 2nd. I think if you try to grab 3rd it'll just free rev or act the way it was acting when you pulled it back in the driveway.
That's exactly what I expect. Going to give it a shot tomorrow.
Also, FWIW, in the description of when/how it happens he explains how bad high line pressure is for the transmission and also goes on to say that you'll get out at a gas station, go to start the car back up and you lose D and 3. Just about explains your situation exactly.

From TEP's webpage..

"Regardless the route cause of WHY the band broke, it is broken and needs to be replaced. Below are a few pictures of forward apply bands and how you can tell if yours has broken or not. One picture is of a good band, a fractured band that was on its way to failure, and a broken band. Sometimes you may find about a 1" piece of metal from the band laying in the lower transmission pan when you drop it for inspection. Other times the lug will tear on the band where it is brazed on."



"The next picture shows 3 different Forward Apply bands. From left to right you will see a band with a broken off and missing apply lug just as the above picture shows, next a fractured band, and to the right is a band in good condition."


Yeah, I read that last night. Absolute textbook scenario and symptoms for me. Here we go again...
 

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Yeah, I read that last night. Absolute textbook scenario and symptoms for me. Here we go again...
TBH, your car isn't making HUGE power numbers, you'd probably be fine with a stock trans/shift kit. It's a lot better than taking that one apart so many times only to have something else fail inside of it.
 

BrianG

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TBH, your car isn't making HUGE power numbers, you'd probably be fine with a stock trans/shift kit. It's a lot better than taking that one apart so many times only to have something else fail inside of it.
I don't mind taking the trans apart, and I have too many expensive hard parts in here to just throw a questionable stock one in. I just mind taking the whole car apart.
 

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Well, after you replace that band you *should* finally be in the clear to track it.
 

BrianG

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Well, after you replace that band you *should* finally be in the clear to track it.
LOL! I'm not even gonna cross my fingers this time. If it can happen with this thing, it will happen. Of course that one part is in the deepest darkest part of the trans.
 

SleeperLS

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I have 2 old "built" 4t65e hd transmissions sitting in a garage. They both work, but need tcc solenoids fixed. I am going to try to sell them to TEP at a core cost. If you want one, just pay $350 and one is yours. One has 3.69's and one has 3.29's. 3.69 trans built by intense and the 3.29 trans was built by TEP
 

BrianG

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I have 2 old "built" 4t65e hd transmissions sitting in a garage. They both work, but need tcc solenoids fixed. I am going to try to sell them to TEP at a core cost. If you want one, just pay $350 and one is yours. One has 3.69's and one has 3.29's. 3.69 trans built by intense and the 3.29 trans was built by TEP
I appreciate the offer, and that's a great price, but I'm gonna pass. I've got probably the same upgrades if not some others in my trans, and having a trans ready to go doesn't save me from all the overhead work I gotta do already anyways. Thank you though!
 

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