Thread: **HELP** 04 GTP SC shifts but wont drive

Recently replaced axel and now my car will shift in all gears but won't drive when I press the gas... I have to turn the car on and off a couple of times to get it to go.

Changed the axel and forgot to refill trans fluid. Drove around for a day and boom. So, I refilled trans fluid think that's the fix and still no action... Trans fluid is pretty dark so I'm about to drop the whole pan and change filter etc.

Any other thoughts. Felt like I was stripping metal from something when I pressed on the gas. Grinding vibration. That made me check the axel and I found a mess on the passenger side. Thought the grinding was over after I replaced it but nope....

Sent from my SM-N950U using Tapatalk

Yeah... I hate to be the bearer of bad news but driving around all day with no trans fluid will destroy your transmission. You can try changing the filter and the fluid but you're most likely just wasting money at this point. Bare minimum, your clutches are toast, if not most components. My buddy who rebuilds transmissions refuses to even attempt to rebuild ones that have run dry for that long. Too much damage. Sorry for the bad new. Good news is that these transmissions are cheap and easy to come across in the junkyard. Just be careful and look at the fluid color and find one that was in a major collision with lower miles.

Originally Posted by wstefan20

Yeah... I hate to be the bearer of bad news but driving around all day with no trans fluid will destroy your transmission. You can try changing the filter and the fluid but you're most likely just wasting money at this point. Bare minimum, your clutches are toast, if not most components. My buddy who rebuilds transmissions refuses to even attempt to rebuild ones that have run dry for that long. Too much damage. Sorry for the bad new. Good news is that these transmissions are cheap and easy to come across in the junkyard. Just be careful and look at the fluid color and find one that was in a major collision with lower miles.

Appreciate even the bad news ha.. I need all the info I can get right now. Dont even know how to take a tranny out but I can learn how. I got this far in 2months.. You know if it matters what tranny it is, as far as yr/gears? Because I was roaming in the J yard today and found an 04 CompG SC. It had 135K on it. Not in a major car accident tho.... I have 185K on my 04 GTP Supercharged. Got it around 135K and haven't checked or changed the tranny filter in 5yrs and who knows what the previous owner did.. I just figured out what I really had 3months ago and started nodding because blown gasket and warped cylinder heads.....

Put on CNC ported heads, 130# valve springs, oversized radiator, cai, coil pack and wires, also a 180° tstat and alternator voltage booster, new alternator, front plog, 3" Downpipe and 3.5 pulley......... Need to save my bottom end. Just got started loving these 3800's

Sent from my SM-N950U using Tapatalk

Sorry to head about the problem. You have one clean looking gp there! I'd try searching under Billboost as he has a lot of how-to's like this.

It might be "worth" trying the fluid change and filter, but I wouldn't expect anything, and even if it does "work" I would save up for doing a rebuild or replace sooner rather than later.

If you have the 04 gtp non-comp g, you can't use the comp-g trans unless you have the computer flashed for it and install the shifter and paddle shifters. The valve body and channel plate are different as the gearing ratio. I can't remember, but around 04 the transmissions changed the shift selector to internal and the checkball and a few other minor things, so make sure you look around and make sure the one you're getting works since 04 is an odd year.

As far as the general process, you'll need to remove the intake to get to the upper bellhousing bolts. Remove starter (think it's two or three bolts). If you have headers, I usually find it easiest to "feel" the bolts for the bracket attaching the engine to the transmission by reaching down the back laying over the engine. I found it easiest to use a fender brace engine holder to hold everything in place, but you can use a lift or something similar. You'll be dropping it out the bottom, so unless you want to do the engine with it, a jack won't work. I usually unbolt the 10mm dipstick tube and pull out first. Remove all electrical connectors by the intake side and the differential mounted speed sensor. I usually remove the speed sensor so I don't damage it. Remove the two differential bolts attaching the engine to trans bracket. Un-clip and remove all the transmission cooler lines. Unclip any electrical connections and basically anything attached to the subframe. unbolt the trans and engine mounts. Unbolt the power steering rack from the subframe and watch out for any eletrical connections. Unbolt the sway bar. Remove the torque converter bolts by spinning the flywheel with a screwdriver or something and removing bolts one by one (there's three). I usually drop the pan and let the fluid drain out (it's lighter and easier to work with) then use a few screws to re-attach. Remove your wheels with the vehicle jacked up and secured. remove the axle nuts, I usually use a screw driver to keep the rotors from spinning and use an impact. Remove swap bar links. Either wrestle with the ball joint, or remove both control arm bushing bolts and pry the control arm out. Then remove the axle from the hub on both sides. I use the hood with a really long extension or long pole to put top pressure on the passenger axle and hammer on the bottom inner cv joint and it pops out. Driver's axle is the most tricky. Since you're dropping the subframe, check everything is supported again and drop the four main subframe bolts after removing the front little brackets. Now it's easier to get to the driver's axle and pry it out with a pry bar (one on either side works best). My least favorite part is reaching the last bellhousing bolt. It faces towards the transmission and is right under the rear exhaust. "easiest" way to reach it is to have a double swivel connector on a really long extension to an impact and fish it through where the engine to trans bracket went. With the axles removed this isn't that bad. Obviously have a transmission jack under here and have the strap or chain around the top to stabilize it. Remove the last bellhousing bolts, pry on the housing to separate and all you need is to clear the flywheel. Then drop and remove! Installation is pretty much reverse of install, but remember to fill your new torque converter (I don't recommend re-using one from a transmission that has blown like this one). When you get it installed, fill with about half the fluid, double check everything, start the car and dump the rest of the fluid in as quickly as possible. Then drive it till everything warms up and check the fluid again and adjust as necessary. First time I did this it took me a weekend, now it only takes a few hours. Plan more time than you need.

Hope that helps! Feel free to ask any questions along the way. It's not a fun job, but it's better than what the shops charge you for! My biggest hints are to get an actual transmission jack or rent one, and have two regular jacks on hand to drop the subframe (makes lining up the subframe easier on installation).

Also, rebuilding yourself isn't out of the question. It does take time and research and patience. Good luck!

Originally Posted by wstefan20

Sorry to head about the problem. You have one clean looking gp there! I'd try searching under Billboost as he has a lot of how-to's like this.

It might be "worth" trying the fluid change and filter, but I wouldn't expect anything, and even if it does "work" I would save up for doing a rebuild or replace sooner rather than later.

If you have the 04 gtp non-comp g, you can't use the comp-g trans unless you have the computer flashed for it and install the shifter and paddle shifters. The valve body and channel plate are different as the gearing ratio. I can't remember, but around 04 the transmissions changed the shift selector to internal and the checkball and a few other minor things, so make sure you look around and make sure the one you're getting works since 04 is an odd year.

As far as the general process, you'll need to remove the intake to get to the upper bellhousing bolts. Remove starter (think it's two or three bolts). If you have headers, I usually find it easiest to "feel" the bolts for the bracket attaching the engine to the transmission by reaching down the back laying over the engine. I found it easiest to use a fender brace engine holder to hold everything in place, but you can use a lift or something similar. You'll be dropping it out the bottom, so unless you want to do the engine with it, a jack won't work. I usually unbolt the 10mm dipstick tube and pull out first. Remove all electrical connectors by the intake side and the differential mounted speed sensor. I usually remove the speed sensor so I don't damage it. Remove the two differential bolts attaching the engine to trans bracket. Un-clip and remove all the transmission cooler lines. Unclip any electrical connections and basically anything attached to the subframe. unbolt the trans and engine mounts. Unbolt the power steering rack from the subframe and watch out for any eletrical connections. Unbolt the sway bar. Remove the torque converter bolts by spinning the flywheel with a screwdriver or something and removing bolts one by one (there's three). I usually drop the pan and let the fluid drain out (it's lighter and easier to work with) then use a few screws to re-attach. Remove your wheels with the vehicle jacked up and secured. remove the axle nuts, I usually use a screw driver to keep the rotors from spinning and use an impact. Remove swap bar links. Either wrestle with the ball joint, or remove both control arm bushing bolts and pry the control arm out. Then remove the axle from the hub on both sides. I use the hood with a really long extension or long pole to put top pressure on the passenger axle and hammer on the bottom inner cv joint and it pops out. Driver's axle is the most tricky. Since you're dropping the subframe, check everything is supported again and drop the four main subframe bolts after removing the front little brackets. Now it's easier to get to the driver's axle and pry it out with a pry bar (one on either side works best). My least favorite part is reaching the last bellhousing bolt. It faces towards the transmission and is right under the rear exhaust. "easiest" way to reach it is to have a double swivel connector on a really long extension to an impact and fish it through where the engine to trans bracket went. With the axles removed this isn't that bad. Obviously have a transmission jack under here and have the strap or chain around the top to stabilize it. Remove the last bellhousing bolts, pry on the housing to separate and all you need is to clear the flywheel. Then drop and remove! Installation is pretty much reverse of install, but remember to fill your new torque converter (I don't recommend re-using one from a transmission that has blown like this one). When you get it installed, fill with about half the fluid, double check everything, start the car and dump the rest of the fluid in as quickly as possible. Then drive it till everything warms up and check the fluid again and adjust as necessary. First time I did this it took me a weekend, now it only takes a few hours. Plan more time than you need.

Hope that helps! Feel free to ask any questions along the way. It's not a fun job, but it's better than what the shops charge you for! My biggest hints are to get an actual transmission jack or rent one, and have two regular jacks on hand to drop the subframe (makes lining up the subframe easier on installation).

Also, rebuilding yourself isn't out of the question. It does take time and research and patience. Good luck!

Thanks! Took a lot of research to get it done, even if I bought everything backwards.. But man, This is awesome! Appreciate your time and patience to write this detailed description. I did the cylinder head work and etc. Guess I'll have to invest in engine hoist, jack for the trans and Camshaft/RockerArms now. Make use of the ported cylinder heads/130# springs I already have. I'll do my best and I'll definitely be back to ask questions....

I just watched a person on YouTube who had the same problem I have. Said Torque Converter was fried. I'll keep you guys on standby for sure. Once again. Thanks!

Sent from my SM-N950U using Tapatalk

Looks like these are the only cars that is compatible for my Transmission if I'm not mistaken?

Sent from my SM-N950U using Tapatalk

Originally Posted by BillBoost37

FWIW, searching on my name and the word "eas y" without the space will usually get you most any write up you may need on a 3800. Easiest way to do a trans removal possible. How to remove a transmission

WSTEFAN, you are doing some great stuff. Seems that you know your stuff well and are giving back to the community all the time. Thumbs up man! I would mention that pulling the dipstick tube before draining the pan is going to drop about a quart of so of fluid on the person.

Axles are held in the transmissions with c clips. Known as compression clips. The easiest way to remove the axles is to put the axle toward the transmission first to relieve any pressure on the clip then give it a quick hit out of the trans. On the passenger side this is super easy as you can crawl under put a hammer handle against the back of the inner cup and give it one quick smack. Driverside is best done with an angled prybar. My personal favorite tool for this is gearwrench 82248. Don't buy one unless you do a lot of work on a car. But the indexing head and a little practice will make anyone that ever popped an axle out hate your guts. Scottydoggs saw the tool in action and nearly fell over (long way down for him). Other that that.. take a view of the write up I posted and review WSTE's write up and you'll breeze right through it.

Thanks Bill! I've used pretty much all of your how-tos at this point, thanks for taking the time! And thanks for the catch on the dipstick. I was writing that off memory so things may be a bit out of order.... lol plus I'm not the cleanest mechanic....

Hadn't thought of pushing in first on the axle but it makes sense! I'll have to try that next time!

Originally Posted by showtastiik

Looks like these are the only cars that is compatible for my Transmission if I'm not mistaken?

Sent from my SM-N950U using Tapatalk

Those are the ones! That being said, you'll want to look at the top where the shifter attaches. You'll need the one that matches your transmission. One is inside one is out. I think there's a way to re- do the wiring, again bill boost did that write up, but that might only work for the older models. The only exceptions to this are the comp-g and gxp which are specific to those models, though if you have comp-g, I bet you can use regular and just tune the codes out.

The only difference between hd and non is the differential (held on by 4 bolts and a clip).I doubt your stock one is damaged, so you could get one from an n/a and swap the differential making it "hd" if you have a hard time finding good hd ones, plus the n/a ones tend to be driven softer since no supercharger.

Watch out on the gear ratios since some other w- body cars used different gear ratios. If you search the forum on gear ratio it should come up.

Found on that just came in today.. 2005 GTP SC MN7... Its wrecked too, so I might be lucky

Sent from my SM-N950U using Tapatalk

Nice! I have a junkyard removal thread that goes over an easier way of removing the transmission at the junkyard (aka, you can get sketchy to speed things up without having a jack as most yards don't allow them). Good luck!

Originally Posted by BillBoost37

Undo the subframe bolts.. then the struts... bang. Pull what you need lol

FWIW the only SC'd cars that didn't have the 2.93 gear ratio was the comp g. So if it's charged you are good. Now if you had a Riviera, PAU or Bonneville... we'd be talking about ensuring you had the right trans casing to have structural support on the rear of the trans where those cars have a trans mount. All the transmissions fit into the W body though as they all have the holes on the driver side of the casing. Sorry.. some days I know too many silly details.

Thanks for clearing that up billboost! That being said, if you have a few guys helping you, yes, this method is quickest, but you will curse the universe if you do this alone. Just try removing the torque converter bolts with it on the ground yourself. Idk, maybe I'm just weak. I like to remove most everything while it's up in the air before you drop it, then drop it this method. I'd read over my post, study your car, and go from there! Everyone has a different method that works for them. Just take it slow and double check if in doubt! Good luck!

This is lovely info!! All up to me and my tools.. Headache haha

Sent from my SM-N950U using Tapatalk

Originally Posted by wstefan20

Nice! I have a junkyard removal thread that goes over an easier way of removing the transmission at the junkyard (aka, you can get sketchy to speed things up without having a jack as most yards don't allow them). Good luck!

How can I search to find that write up. I was talking to an old guy at the yard telling me it took them the whole day to remove a transmission from a Buick. Told me he will never ever do front wheel drive again haha. Scared me off ha. I need all the cheat codes. I just went to a shop here and they said they'll charge me $3800 for my 3800 engine haha [emoji44]....

Sent from my SM-N950U using Tapatalk

Originally Posted by BillBoost37

Agreed.. taking out the starter and doing the converter bolts would be wise in the air. I think everything else would be ok on the ground. Still going to suck a bit but it can be done. The JY I liked to work from would use their CAT to lift stuff for you. One day I pulled two engines in about an hour. Yeah.. the guy running the loader had worked with me before and he kept cruising by saying.. "ready?"

Now I need that kind of love haha

Sent from my SM-N950U using Tapatalk

Can't seem to find your junkyard transmission right up Wstefan

Sent from my SM-N950U using Tapatalk