Hello,

Currently having some issues with my transmission. Car is a 1996 LT1 401 CI Stroker
Here is the List:
1. Slipping in OD under heavy acceleration after prolonged driving on the highway. RPMS will increase, car not move, will accelerate slow if i let of throttle No slipping if I have not been driving long. Example in town , no slipping, 1 hr drive=slipping.
2. Trans temperature 266 after 1 hr drive
3. Trans fluid is burnt, can smell it from inside car with windows down sometimes, had a transmission shop quickly verify from dipstick. Can smell only after a long drive.
4. Car will pull in drive, but heavy vibration under the car and it will be slow. This is during prolonged driving and around 3.5 RPM and up
5. Around town driving, the car will pull fine and not have heavy vibration. Will only happen when car and oil have been drivin for a while and warmed up for a prolonged time.
6. Transmission was rebuilt a little over a year ago, 5-6k miles on car since then. Transmission was rebuilt because 401 stroker destroyed transmission.
7. Car shifts gears fine, just at high rpm at prolonged driving causes issues and trans temp to be high.

If i mess around and do some pulls withing my 10 min -20 min road trip around town, i have no issues. But once fluid gets too hot, seems that everything goes down hill quickly.

Transmission shop recommended a rebuild. I am wondering if you believe one is in order or should i attempt a fluid and filter repair first, before footing a expensive build.

Thank you for all the various inputs that will be coming.

Ryan M.

 

I will drop the pan and look inside for debris and burnt clutches parts.Bad smell of burnt coffee is a clear symptom.You are loosing your 3-4 gear,they are a weak part on the 4l60E.You can try an oil and filter change as "extrema ratio", but that smell means just one thing...burned 3-4 clutches.

PS i see now your nick,i think you are "our" Jake son,Are you?If so,I remember with respect your father,great man and corvette expert,we lost a great friend here

 

I think it's time to start shopping for a new trans. Fresh fluid is not going to fix it. Make sure you install an extra cooler with a new trans, especially if you are running a stroker. Cooling is critical to keeping those things alive.

 

I absolutely agree with a cooler.What is the water temp after a long drive and before

 

Yup, get ready for a rebuild and add a cooler if you want it to last. GL

 

Coolant temp was 205 at highest

 

You should add a cooler.A stacked type of cooler which is more durable.I have no rubber hoses on mine.They are all metal lines a few inches from the condenser at an angle to get good air flow.I have the Dewitt's radiator that has a larger cooler then the factory radiator hooked up in series with the additional cooler.It works well and fluid looks good.I try to siphon 2 to 3 qts a year and replace.I had the trans pan dropped once and filter was replaced but it is hard to do because I have a vert and the x supports had to be removed to change the filter.I don't use the car too often but my fluid is always clean.good luck with your trans.

 

..... Sounds to me like its the torque converter clutch slipping ... the 3-4 clutch pack has no tolerance for slippage and will never re-hook once it slips ... you cant hurt anything but your wallet with a filter change ... you might try disconnecting the TCC for a while and see how that works out ... what stall speed converter are you running ? ...........

 

Currently a 2800 stall. Owner at shop. Said to try a new valve body, and he will put it on for free if i purchase the part. If it doent work he will look into a torque convertor. He stated, since im barely out of warranty he wants to help me out as much as he can and keep cost down as much as possible, since it was just rebuilt.

Ryan

 

Can you data log it?
I know that when I roached my 2800 stall converter I could log the slippage with datamaster but I have a 95 with OBDI, I also could track when the converter was locked and unlocked.


Mike

 

Well the issue is, it only happens after i have driven car for a while and trans temp has climbed. I don't leave the city or drive around too often to get it above 200, but if it happens again i will pull my scanner out and get the freeze frame data for when the code sets. Hopefully when shop changes valve body, I wont have to. However, knowing my luck it wont.

Ryan.

 

Well the trans shop chanfed the fluid, dont know if it was all of it and did and 20-25 mile test drive with no problems. However, the problem still exist, playing around hard on the highway cause temp tonrise to 222, sitting at a very very long red light cause temp tonincresse to 255, and still rising. Once i moved a little it dropped to 251, but rose once again at stop. Coolant tempmwas at 219. Have a 401 lt1 stroker. Shop wants to take a look at trans cooling lines. I thinking its the tc, get a weird grinding under the center while idiling periodically. All checks are free, for now, so no sense on taking the car there and back over and over, since its right across the street.

Ryan

 

When I was having trans problems I was driving around with a trans oil pressure gauge taped to my windshield. I found that the trans pressures go WAY down when the fluid gets hot.

I had the same symptoms as you -- OK when cold, slipped a lot when hot. A trans rebuild fixed it. There were some broken parts in my trans.

 

Thanks for the info.

 

Installed a tranmission heat sink to try and keep the temperatures down, but it seems to just delay the symptoms, hasnt got too hot yet, but saw temps get to 207 after some driving around town and messing around on road. Just going to drive it around till $$ frees up for rebuild or new one. Is it possible or a decent idea to fet another 4l60e from another gm car or are there matching up issues....temporary fix ofcourse.

Ryan