Hello, glad to be apart of this website. I never had to register before because I can usually search and find what I'm looking for but today I don't think it'll be as simple...

I just bought my first 4th gen f body 3 weeks ago. It's a 99 formula with an automatic LS set up. The first thing I had to do was have the rear main seal replaced so the trans was pulled, while out we noticed an aftermarket torque converter (which I expected after being told it's been rebuilt before.) The trans always felt flawless, trans fluid was pretty clean but I changed it anyways along with the filter (AC Delco filter, dextron 6 fluid), car has a lokar flexible trans dip stick and was always full. We put the car back together and all has been fine for 2 weeks.. Until today..

I came home from work (5-7 miles) and noticed when I turned onto my road my 1-2 shift was very harsh, 2-3 kind of harsh but not as bad as the 1-2. I let it cool down and took it for another spin, shifted nice and smooth, no issues until i looked down and noticed the CEL had appeared in the last 3-5 mins of driving. Probably 6 miles from home. I stopped, checked some fluids, nothing seemed wrong so I turned around to go to advance auto to get the codes. I got up to about 70mph and then the trans slipped. I slowed way down and cruised at about 35mph all the way to advance with no more slippage. I had the codes run and got the p1870 code, along with both o2 sensor codes and a mass air flow (I think this came from starting engine with it unhooked when I put my new belts on). I let the car cool down at advance and slowly made my 2 mile trip back home... Now here I am.

I've searched and read about the TSB and the fix for it but wanted some more advice to know if it's worth doing it or will I be needing a rebuild either way?? Any info is appreciated, I'm not new to f body's but I am new to 4th gens and their 4l60 problems... Thanks guys.

 

I have had two buddies lately with the exact same issue and told them to install this kit. You will need to pull the valve body off and have the tcc valve bore reamed. I think a shop charged them $40 due to the reamer being quite pricey for a one time use.
Take a look at this links
That bore probably has excess wear in turn throwing the slip code but it solved my buddies issues
http://www.sonnax.com/parts/2458-tcc...ator-valve-kit

 

Thanks man. I've been reading for an hour about it lol

Just for giggles I reset the CEL codes and took it for a short spin 4 miles out, cut it off, sit for a minute, then 4 miles back, and it shifted flawless, except it felt like the overdrive (TC lock up) was kicking in really early then kicking back out and in again, almost felt like a surge in the engine. But no CEL or slips.

Going to order that kit I think and just not drive it until I can install it..

Thanks again for the advice, glad I'm not the only one to experience this. When it slipped that once, my heart sank.. Haha

 

Did your friends also experience the slippage??

I feel like because it slipped once, it's ruined. Or will the kit save it as long as I don't drive it (and let it keep slipping?) until I install the kit??

 

His converter would attempt to lock (dropping the rpm's) then unlock causing the rpm's to jump a bit and throw that code. Why do you think the transmission was slipping? Just because of the higher rpm's ?

 

Yes I was cruising along and it was like it went into neutral, just revved, not accelerating then when I let off the gas it dropped down to idle then slipped back into gear, I then slowed down and cruised home with no other slips... The slip rev/drop to idle all happened within 5-10seconds, then went away.

 

One quick slip due to low line pressure should not do any damage. With that being said my experience is amateur as in I rebuilt one transmission and got lucky lol but do have a bit of general knowledge.
There are a couple of members on here, Mrvedit and clineberger who helped me threw my first build who are very smart and experienced and will hopefully poke in here later.
My guess is they will agree with you needing the sonnax tcc valve kit but they will be able to go a lot more in depth as to all your symptoms

 

Thanks brother!

 

http:// http://www.fitzall.com/A74741QA.php

What are your thoughts on this? It doesn't require reaming and there is a video of the guy installing it with the valve body still in the transmission/car. Seems like a "easier" (which I know doesn't mean better or as good as other fixes) option to me.

What do you guys think?