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Lost all forward gears. Gained them back after cooling down. Pan is clean段sh
1995 z28. LT1 with a 4l60e
Trans was built in 2006, has a yank 3200ss and a cooler mounted dope style. (installed 2021). about 50k miles on this rebuild total.
Was driving around, and the car started behaving like it was in neutral. At first it felt like it would coast forward but wasn稚 quite fully in gear.
I still had park reverse and neutral. I eventually went from creeping forward with my foot off the gas, to zero movement.
I added PRNDL status to HP tuners in case the linkage was disconnected (I have my wideband sensor zip tied fairly snugly to it). PRNDL status was being reported correctly.
I towed it back home. The next day I could move it forward again. I moved it in and out of the garage. I did not street test it.
I took a video to see if the linkage moves freely. It does.
I attached pictures of my pan after I dropped it. It all looks fine to me.
is there anything else to check? The 4l60e failure chart shows that the forward clutch would affect all forward gears. I find it strange it would start working again out of nowhere though.
Sounds like the filter is clogged or sucking shut possibly. Need to read pressures when it is doing it to confirm. Or, since you have the pan down I would try a new AC Delco filter and see how it does.
As mentioned I would change filter, I have run into cases where the filter appearing normal , had actually bunched up inside at the inlet and clogged a small area. I kinda wish they made a screen type filter for the 60e .
__________________ Frank formerly of Performabuilt, Now just me, What can I build for you today? Call or message me. Click sig pic for my facebook
As mentioned I would change filter, I have run into cases where the filter appearing normal , had actually bunched up inside at the inlet and clogged a small area. I kinda wish they made a screen type filter for the 60e .
Did you test to see if you had gears in manual 1 or 2?
If you never lost reverse as your post suggests, I'd have a harder time believing filter clogged issue
I've seen an input sprag that was bad *attempt* to hold when cold. It's not common at all but something I've seen before so don't count it out as a possibility. (I would not bet $ on this being your issue if I were a gambling man)
Sounds like you have a leak in the input drum shaft. More common than people realize. I've fixed other peoples (shops) constant failures (trans failing in 6 mos or less) because the input shaft had a pressure leak. Press shaft out, loctite, press back in. I do it to EVERY SINGLE trans I build. I've had the shaft fall out of more than one when going to press it out.
last one I fixed went back to the builder three times. He could not find anything wrong with it. So he put it back together and it did the same thing. they brought to me, and thats when the shaft fell out of the input drum with one pump from my press. This is a very important but often overlooked failure point. This has got to be one of the reasons that 4l60's have a bad wrap.
Sounds like you have a leak in the input drum shaft. More common than people realize. I've fixed other peoples (shops) constant failures (trans failing in 6 mos or less) because the input shaft had a pressure leak. Press shaft out, loctite, press back in. I do it to EVERY SINGLE trans I build. I've had the shaft fall out of more than one when going to press it out.
last one I fixed went back to the builder three times. He could not find anything wrong with it. So he put it back together and it did the same thing. they brought to me, and thats when the shaft fell out of the input drum with one pump from my press. This is a very important but often overlooked failure point. This has got to be one of the reasons that 4l60's have a bad wrap.
Saving this quote for my builder. The guy who is likely rebuilding this trans is the best/most reliable around, but I will make sure he sees this info (just in case)
Saving this quote for my builder. The guy who is likely rebuilding this trans is the best/most reliable around, but I will make sure he sees this info (just in case)
I壇 be interested to know if he does this on every build. I知 in the middle of building a unit right now. It痴 actually a fairly fresh rebuild from this past October (ish) and the forward clutches are smoked and one of the check ***** is permanently wedged in the separator plate. That痴 also another mistake builders make. They reuse steel check ***** and usually do stuff to raise the pressure and that (my guess) helps to beat the check ball into the plate worse than it did from the factory. I use torlene check ***** which do not do that.
I’d be interested to know if he does this on every build. I’m in the middle of building a unit right now. It’s actually a fairly fresh rebuild from this past October (ish) and the forward clutches are smoked and one of the check ***** is permanently wedged in the separator plate. That’s also another mistake builders make. They reuse steel check ***** and usually do stuff to raise the pressure and that (my guess) helps to beat the check ball into the plate worse than it did from the factory. I use torlene check ***** which do not do that.
There's a ton of rebuilders to pick from, but only one person who no one says anything bad about locally. I'm dropping it off in a few days.
04-28-2024, 03:58 PM
Lost all forward gears. Gained them back after cooling down. Pan is clean段sh 
