Hey Guys, I got an LT1 in my car right now with a 4L60 tranny that's shifting from 3rd to neutral or sometimes 3rd to overdrive and then to neutral. I know SOMETHING is wrong with it but I don't know nothing about transmissions.

What would make my 4L60 skipping sometimes the 4th gear ? Sometimes it will be fine...for exemple if I'm driving the car at 70 mph in 3rd gear and then shift it from 3rd to 4th everything is fine and it will stay like that ... but let say I'm at 50-55 mph and I leave the car in 4th, it will try to shift but my engine will start reving and it will hook up for maybe 2 sec, rev again, hook again, rev again and so on ...

Now the other solution :

I got this 1983 TH700 in my garage that's from a Chevy van that had 80 000 miles on it. The van never been at higher speed then 60 mph.

I got a TCI shift kit that I could pop into it...and set it up as a "Street Plus". I also have corvette cerveau from the 4L60 that I could use.

Will a 83 Th700 last behind an LT1 ? What do I need to change in it to make it beefier or stronger. how much can it cost ... Labor would be done by myself.

Also , is it possible to take the main shaft (input shaft ) into my 4L60 and put into the 83 because my drive shaft as 28 splines and the 83, only 26.

 

I don't know much about trannies but sounds like your band clutches (or something like that) are on they're way out. Looks like a rebuild is needed, throwing an LT1 on an old stock 700 probably will decrease it's life.

 

Anyone else knowns why it does that and maybe answer to my question.