Thread: Doing 60 at 3 K

Originally Posted by Scimmia

I don't care how many you've owned, you obviously don't have a clue in this case. As for explaining how something mechanical will simply stop, the splines wear away over time and eventually give out. When this happens, the trans will no longer shift into 4th, and that's it. No other symptoms. This is why GM started heat treating them for the 2003 model year, the hardened splines don't wear away. This has come up more times than I can count over the years on the various wbody/bonneville boards that I'm on. Extremely, extremely common.

What "piston" are you even talking about? I can only guess you're talking about the accumulator piston? Not a very common failure at all on these transmissions. Pretty common problem on the 4L60 with the plastic pistons, but that's a totally different setup.

I'm sorry but I agree with this. Its a VERY VERY VERY VERY common issue. There doesn't have to be anything wrong, they splines can just go away without any warning or without any noise. Thats why I'm saying a simple task of just driving on the highway with the car in drove, pull the selector back into 3rd and see what happens. If nothing happens then 4th gear it gone, in which case the most common issue is the splines. If it does go up then you would be correct in assuming its not locking the torque converter.

Lets stop *****ing at each other and just fix the problem, hows that sound?

Try what I said and report back here and we can asses the situation from then.

Ive actually done that as i sated before while driving at 60 mph dropped it back down to third and nothing happen, and popped it back to drive and same thing. so looks like 4th is gone huh, how much to replace the splines? is the rest of the trans shot?

wow i didn't think i started a heated topic, and of course a noob would start it, sorry guys, but thanks for the people who actually wanna help.

wow 50/50 shot, and i bought this car to by my DD to drive 40 miles a day and i thought i bought a dime piece. And i have to have the oil pan replace casue it rusted through. is this a common problem as well? how much would it caost to replace the splines? and is the rest of the trans is good?

Originally Posted by 02GrandPrixIraqVet

If you shifted back down to 3rd manually yes its not getting 4th gear/overdrive. I bet that clutch pistion is the problem not pushing the 4th gear pack in to place. Exactly what went wrong with my last one. No fluid and filter in the world will fix that.

Ill quote myself I did agree that 4th was gone. Ill take the hit for not calling the clutch hub by the wrong name yes I called it a clutch piston earlier, Which apparently is wrong got it. Either way this is the same thing that went wrong with my last one.

no im sure its rusted through i had it on my buddys rack and its rusty as all hell and when you go to touch the spot its all soft, not good, saw it first hand.

let me as you guys this question. my 99 gtp has done the same thing to me 2 times now. i was going to alabama last week end and went up a mountain twards fortpayne and the car downshifted to 3rd while driving up the mountain. once i got over the mountain the car never shifted back to 4th. i tried manually down shifting to 3rd and back to 4th and it never did anything. felt no shift or change in rpm. i figured 4th was gone. said oh well and drove for another 15 miles and got on the interstate running 80 and still in 3rd gear. After about 5 miles it finally went in 4th gear and has been doing fine sence. scanned car and there are no codes. Whats The possible cause.