Transmission problem Update: post rebuild issues

**IffyG** · 05-02-2011

Over the last few weeks I've been having issues with intermittent long shifts from 3 to 4 and difficult 4-3 downshifts on the highway. Yesterday I was merging onto the highway and the it banged through the 3-4 shift.

Today I swapped out my poly motor mounts and brackets with a pair of brackets and rubber bushings I picked up from the junkyard thinking that my mounts might be amplifying the issue. I took it out on the highway and was carefully monitoring the 3-4 shift and the 4-3 shift on both the tach and my Aeroforce. The 3-4 shift seems to go smoothly most of the time aside from the occasional long shift and the bang into 4th I experienced yesterday.

The 4-3 downshift on the other hand seems to be royally screwed. Once the car is cruising in fourth gear (per my Aeroforce), I accelerated to induce a downshift. The RPMs would initially jump with minimal acceleration, the transmission downshifts and the RPMs drop approximately 300-400 before 3rd gear finally catches and the car continues accelerating.

I've been through a few transmission scares, so I have checked everything that caused bad shifts in the past (my trans fluid is full, battery is good, cat is good, MAF is good) and can't come up with anything else easy to check before I haul it to a shop for a diagnostic. Any input would be appreciated.

**L36pro** · 05-02-2011

make, model, year?

**BillBoost37** · 05-02-2011

Can't agree more with L36Pro on the info.

You do reaize that on pre 03 and some 03's that were built late 02, you have a non-hardened 4th clutch hub. By inducing shifts, you load up torque on the weak splines. It's possible you are stripping a bit before the shift. Same going into 4th.

**IffyG** · 05-02-2011

Sorry, forgot I don't have a vehicle section filled out on this forum. It's a 2002 Chevy Monte Carlo with 120k on the clock. Trans fluid was changed 2 years ago and I've only put 12k miles on since then. The fluid still looks brand new.

I'm aware of the non hardened fourth clutch and realize that forcing the car to act up isn't the greatest idea, but without forcing it to have the problem the best I could say was the car wasn't shifting correctly. I figured having a bit more information would be immensely helpful.

**L36pro** · 05-02-2011

it will always look brand new because there are virtually no contaminants in the transmission.

**BillBoost37** · 05-03-2011

And now I completely disagree with L36NotPro. Sorry dude.. trans fluid gets dirty, burnt, and the oil/detergents break down over time.

OP, I wasn't saying that what you were doing was bad. I got 180K and I still go in and out of 4th at WOT. Kinda waiting for it to strip out. And yes, the more info the better. What I was saying is..your issue might be the 4th splines wearing out and stripping slightly as your trans tries to go in and out of 4th. Another possiblility is that the 4th clutches are worn. There's only two actual frictions in the 4th pack.

**L36pro** · 05-03-2011

well never wasnt a good word. i shouldve said that it doesnt deteriorate NEARLY as quickly as motor oil, so in 12k it will still look pretty fresh. i have seen fluid get more and more red as time passes.

**IffyG** · 05-03-2011

And I put that comment about the trans fluid in there because if my trans was eating itself, I would expect the fluid to have either metal particles or a different appearance. Might be relevant, might not. I'm just trying to get a feeler for what might be wrong before I haul it to a shop. I have the luxury of a second vehicle, so the Monte is sitting until I decide what I want to do with it.

**L36pro** · 05-03-2011

if your looking for metal, pull the filter out and bust it open. you wont see it in the fluid itself

**BillBoost37** · 05-03-2011

Originally Posted by L36pro

if your looking for metal, pull the filter out and bust it open. you wont see it in the fluid itself

Its possible. Bad..but possible

**blueguy** · 05-03-2011

Originally Posted by L36pro

if your looking for metal, you wont see it in the fluid itself

Then you've apparently never seen bad fluids...metal sure can be in the fluid...because it looks like clay.

**L36pro** · 05-03-2011

i guess if you blew up the torque converter, but he just explained that he didnt see metal in the fluids.

**blueguy** · 05-03-2011

Not really...considering the transmission is tons of moving METAL parts if anything takes a dump inside the trans that makes contact with fluid it'll be in it.

**L36pro** · 05-03-2011

well he just stated that his fluids look brand new. and ive never neglected my transmission to that point so i wouldnt know.

**BillBoost37** · 05-03-2011

Originally Posted by L36pro

i guess if you blew up the torque converter, but he just explained that he didnt see metal in the fluids.

This is getting silly. There's bickering for no reason. Please stop trying to prove Nick wrong. Soon I'm going to keep count and kick some butt. If the TC blew up, the trans would soon stop working. This is because the TC fluid goes through the VB and it's couple small filters in the middle of it. So you got crap in the valves and those filters get plugged. Got it? Let's cut the crap and stop posting stuff that doesn't apply, doesn't matter and is totally f'n wrong.

OP. sorry for the rant, but you don't need this crap in your thread. Your problem is confusing enough.

**IffyG** · 05-03-2011

Originally Posted by BillBoost37

OP. sorry for the rant, but you don't need this crap in your thread. Your problem is confusing enough.

I appreciate that. There is a reason I don't post on this forum all that often (and it's shown it's ugly head in this thread), but I'm trying to tap all the knowledge sources I can on this one.

Anyways, I was more or less looking to see if anyone else has had a problem similar to mine, since the RPM drop on the 4-3 downshift seems very distinctive to me. I know there can be a problem with the TCC causing some RPM oscillations, but it was my understanding that this only occurs when cruising in 4th and not when downshifting.

**L36pro** · 05-03-2011

tcc will also cause problems in third.

**IffyG** · 05-07-2011

Took the car out this afternoon for a highway drive and everything was fine until the car warmed up. Then it started having trouble with the 3-4 upshift, so I got off the highway. After stopping at the light and getting going the 1-2 shift slammed into gear and I checked my Aeroforce. Sure enough it popped a p1811. I limped the car home and it only had two hiccups on shifting in the 15 miles it took get home. I'll be limping it to the dealer Monday morning for a better diagnosis, but I'm speculating that I'm experiencing a PCS issue of some sort.... thoughts?

**IffyG** · 05-09-2011

Dealer says the PCS is toast. They want 1100 for the job. I called a few independent shops and they want between 800 and 1000 to replace it... now I need to decide if I want to spring for a full rebuild or pay what might be a band aid solution.

**IffyG** · 05-18-2011

I took the car to a shop earlier this week. They deemed the transmission to be toast... I opted to have them rebuild the transmission and replace my forever leaking oil pan gasket while they are in there. Should have it back by the end of the week.