Thread: TC lockup/unlock problems? tranny rebuild ?'s trannyman step in!

so this past week has been the hottest set of days consecutively i can remember in a long time (90-98 all week). i was on my way home from ed's shop in cleveland (about a 50 mile drive for me) and i started up a hill. i dont use cruise control too often, i can get better milage with my foot. so anyhow i give it some light gas going up the hill and the rpms start bouncing between 2000 and 1700 rpms, in what i believe was 4th gear. pretty sure that means the TC wouldnt lock up/unlock.

now granted it was 95*, i just drove 90 miles, and the fluid is the original 130k mile stuff, so it pretty much has no viscosity whatsoever when its hot out. if im driving in 3rd or 4th with the TC locked up and i give it partial throttle i can make it do the same thing. it was 95* today also. it also sometimes shifts kinda hard between 1st and 2nd.

i have a new filter, so im gonna drop the pan, change the filter and fluid, and maybe do another pan drop in a few weeks and replace some more fluid. that might help, it might not. im not that concerned. ive been doing a lot of racing at the track, and i know thats hard on the tranny, and i know that increases my chances of it going out massively. ive been prepared for that. if i have to rebuild/replace thats fine, i can build it with better parts.

my questions are

1. is it infact the TC causing this trouble?

2. could the old fluid/filter be causing this?

3. what parts should i start buying to rebuild with, keeping in mind i love going to the track? ed iis closeby, i could buy a transmission case and star putting it together and just wait for this one to go out.

4. i obviously have a gtp. what if i got a 3.29 double roller chain? what would that do for me? (besides better burnouts and steeper gearing?) could i use an HD differential with the 3.29's? i know i would have to reprogram the pcm, would anything else be involved?

5. is there anything else i should consider?

-Kyle

Hi Kyle, with that many miles and the trans has likely never been cracked open I would definately consider a failing pressure control solenoid being that you also have a harsh 1-2 shift sometimes. That old of fluid surely isnt helping matters any but your trans does have a lot of miles on it. The TCC rpm surging is somewhat common and a number of things can cause it, including a bad pressure control solenoid. Sometimes a complete pcm reflash takes care of this but the problem will often come back after a few weeks. Below are some answers in order to your questions....

1. The torque converter likely has little to nothing to do with your problem and along with what I mentioned above valve body and internal trans wear really plays a larger role in this behavior.

2. It would be a good idea to service the trans just as you mentioned because of the mileage, drop the pan and replace the filter, but likely it isnt going to help your problem

3. There is not a set list of parts you need any wont know until the trans is apart, but below is a list of commonly replaced parts during a rebuild
-Master rebuild kit which includes new clutches, seals, gaskets, etc.
-Hardened 4th clutch hub
-Thrust washer kit
-All new solenoids and or a rebuilt/upgraded valve body
-New input sun gear
-Replace bands as needed, there are 3
-filter
-Shift kit
-Hardparts as needed
-12.9s or faster and you should upgrade input shaft
-mid 12s or faster and you should upgrade to a single chain setup

That is a rough list of common parts but again you wont know exactly what you need until the trans is apart, but above is pretty much standard that will need replaced

4. The stock drive chain setup is a dual chain, the upgrade is to go with a single chain which is stronger and will handle more power and stronger launches with sticky tires. GTPs come stock with a 2.93 overall ratio and an HD diff. The actual diff ratio is a 3.29 and the ratio change is made by changing the drive chains sprockets. There are other diff ratios but not in the HD diffs. You arent going to get better burnouts with an HD diff than a non HD diff, and since you have a GTP then you already have an HD diff. It is more durable than the non HD diffs but will still work the same as they are both open style differentials.

5. The above parts should cover what you need or at least give you a good start. It really depends what kind of power you will be making and what times you run at the trans as to how the trans should be built.

im planning on running the mods in my sig with a good tune from my wideband, 13's is all im shooting for.

i can make it do it whenever now, it just bounce between a couple hundred rpms, for a few seconds until it shifts, or until i let off/give it more gas.

if i give it about 75% throttle while its doign this and let right off, it kinda jolts, or makes a hard shift, or something.

thnaks, and ill develop more questions as i go aong

Trannyman do you think your bushing kit is necessary, as well as a full bearing kit for, input piston as well, for a typical tranny at 70k

There are a handful of bushings that are very common to be worn and should be replaced. They generally arent worn badly, but worn to the point that they should be replaced, especially if the trans is going to be apart for a full rebuild. The stator support bearing should definately be replaced regardless of mileage as it is a known failure point and not only can cause whining noises but also cause wear on the drive sprocket bearing race. The input piston is a coin toss but likely worn at 70K. I have torn apart 150K mile transmissions with a good input piston, and on the other hand I have taken apart 40K mile transmissions with a badly worn one. If it looks fine then it is safe to use.

also, when its cold, and i put it into or take it out of gear, it makes a groaning noise..

ok, so heres what it comes down to, if im rebuilding im going to upgrade in the process.

-Hardened 4th clutch hub
-Thrust washer kit
-All new solenoids and or a rebuilt/upgraded valve body
-New input sun gear
-Replace bands as needed, there are 3

besides these things, is there anything else i need?

would moving on to a higher stall convertter be worth it? will the car still be streetable? what would i have to do if i ever wanted to run slicks safely?

i also think im goign to replace the axles at the same time. if i do this, i will have replaced every single suspension and drivetrain part on the front end of my car, except the steering rack.

If you plan to stick in the 13 second range then you should be fine. You may also want to consider a new drive chain set depending on how your old one looks. You should also install a shift kit to help quicken and firm up the shifts. Other than a master rebuild kit which will include your gaskets, seals, clutches, it looks like you have the majority of it covered. Use the stock converter or a reman stock converter, there is no reason to go up in stall with an M90 car as the stock converters stall around 3K already and is more than enough.

what is this thing? it says its for all buick v6 engines..

Summit SUM-G1700 - Summit Roller Pilot Bearings - summitracing.com

That is a pilot bearing for the input shaft of a manual transmission to keep the input shaft and clutch centered. It is not used with automatic transmissions.

ahhh. i see.

so, roughly, how much $$ am i looking at for parts? im gonna be doing the swap myself, so labor and shop rates dont apply

Are you asking $$ wise for a full rebuild or just a few parts? Full rebuild you are looking at $600-$1200 for parts depending on what you find inside the trans.

yeah, whats its going to cost me to rebuild the transmission if need be.

is there any way to find out if the presssure control thing you mentioned is going bad?

The only real way to test the pressure control solenoid is with a scan tool and a pressure gauge on the trans to verify operation. Other than that it is just a guess.

ok.

the thing that confuses me is it's not throwing a code or anything, so i cant even get an idea of whats wrong..

You should have your trans properly diagnosed to determine the cause. The pressure control solenoid most likely has nothing to do with your problem if you have TCC problems. All solenoids/valve body repaire requires dropping down the transmission a bit from the bottom of the car as you have to remove the side cover. This is a very involving job and will require some type of engine suppport or engine hoist as the engine and trans need to be help while lowering the craddle from under the car to allow you to drop down the trans. The first thing I would suggest is to check for codes in the code history is likely you will have one or more based on your conditions mentiond.

Engine sensors can certainly have an impact on transmission operation, especially the MAF sensor, and going through a carwash could have picked up some a lot of extra moisture/water in the intake system depending on what you have on your car and can cause the maf sensor to read wrong. The pcm uses MAF signal to determine engine load based on airflow across the sensor and to some extent uses this information for line pressure, but at part throttle conditions it wont have near the effect as WOT conditions. While at very low throttle positions or shifting into gear the pcm has base pressures that it commands to do the job and it an engine sensor or wiring issue likely wouldnt cause slippage, though it could cause max line pressure which would give very harsh engagements into gear and during shifts.