Thread: Looking for Trans Rebuild Info

Since your question and post title was specifically about the trans, I'll move this over to the tranny section.

Welcome to the community.

Hi Rem, is your car stock or will it remain near stock? There are a lot of upgrades for these transmissions and a lot of different ways to build them. There are also quite a few common problems with them and parts that should be looked at during a rebuild whether you had issues or not. The link below is one to my website that has a lot of usefull info on this trans.

4T65E Transmission Info

You will need to get a trans tech manual to walk you through the process but it isnt going to tell you the common stuff to look for. As a minimum you should replace all the solenoids, get a hardned 4th clutch hub as the stock ones strip out over time which makes you lose 4th, replace the clutches and steel plates, gaskets, seals, molded pistons, inspect and replace if needed input clutch piston, inspect bands for wear and burning, Transgo shift kit which includes an upgraded boost valve and new accumulator springs, and also you should replace the torque converter with a reman one. This is a basic list and the rest depends on the condition of your transmission after you tear it apart. If you have any questions along the way ask away

That kit will give you the "soft" parts so to say for a rebuild and is a good quality kit at a reasonable price. That kit does not include ANY hardparts such as gear train, drums, sprockets, chains, shafts, bushings, bearings and those are things that will need inspected once it is apart to determine the need for replacement. You also need to replace the 4th clutch shaft with a hardened one. There are a lot of great converter companies out there, and there are also bad ones. I have used a number of different ones and here are a few to help your search.... Precision-I currently use these, CVC, Dacco, ATC, ACT and there are a few others I have used over the years but any of those are good quality converters. Again there are many more out there but I cant speak for them, well I know a few bad companies but I will leave that out. I would stay away from a Napa or Autozone converter if they would even sell one and go straight to a trans shop or I could sell you one if that helps out.

The hardened 4th clutch shaft should be mandatory regardless of what the old one looks like, it WILL go bad at some point which leaves you with no 4th gear. The other hardparts all need to be inspected before replacement as there is no sense in wasting money on parts you dont need. As far as the converter you should replace it with the same code that is on the original converter unless you want a higher stall speed. They dont rate stock converters as you would expect, or like what aftermarket companies advertise them to be. Mix N Matching original torque converters is trial and error unless you know of one that will give you a desired stall speed but I always replace them with the exact same code unless you want a higher stall speed and every car will respond different so it is hard to say an exact number.

Not sure which companies you are referring to but the ones I have mentioned use the colors you say to beware of, most companies use silver or blue paint on reman converters. I have also never seen a pump shaft break on these transmissions. I have seen incorrect installation ruin the splines and also splines wearing on the converter side after very high miles on some cars. In the 10 years I have been building I am yet to see a reman converter from the companies that I have used fail on GM fwd transmissions. Aftermarket performance converters.... That is a different story and you get what you pay for.

Yeah unfortunately that is all a lot of converter builders do, cut it open, clean it, weld it back together and paint it. They have $5-$20 in rebuilding a converter and sell it for $100, its a goldmine company but once you make a bad reputation it is hard to change that. I havent used Dacco converters in a long time and mainly used them for performance upgrades as they offered a great line of inexpensive quality converters but they had a lot of limits as to what they would do and it just wasnt in my interest to continue using them anymore.

Originally Posted by JoeMama

OK, another question.....

What does it mean when the 4th Clutch Hub is "Hardened at the Splines"? While i'm no engineer, I have some experience with metals, and it seems to me that we'd want the whole part hardened? Maybe it's cuz I just don't know how they normally come.

Hmmm, thats a good question. Im kinda interested in the answer myself. Though, as I understand it, the splines are so small that they are easily stripped and thus why that is the only part that is hardened

Hardened is just the fancy slang for it, it is heat treated on the splined end which gives it the bluish black color There is a pic I posted in the carnage thread that shows what the non heat treated shafts will eventually do

Trannyman, if I may hijack this thread for a moment, is the heat treatment sufficient to overcome the stripped spline condition or is there more that could be done?

Also, according to GM, ~03-04 newer hardened 4th clutch shafts were introduced from the factory. This true?

Originally Posted by Sabrewings

Also, according to GM, ~03-04 newer hardened 4th clutch shafts were introduced from the factory. This true?

Thats a good question since Dave recently saw the inside of my transmission.

The 03/04+ 4T65E transmissions did come factory with the hardened 4th clutch hub. Lee, yes yours does have one in it so you dont need to worry about it. Scotty I have never seen a heat treated one fail, even with well over 100K miles on them. I use aftermarket shafts and have also seen used ones from one of my suppliers as they will sell the used hardened shafts and I a didnt even see any of those that looked worn.

Yeah the older 440T4s and 4T60Es didnt see this near as often and was the clutch end that would get chewed up more. One thing I have noticed on the 65s if that the minivans and 60deg V6 cars go through these shafts more often. Its one of those gray areas but I always felt that those cars cyclined in and out of 4th under load a lot more frequently which is going to hammer on the splines more and cause them to fail sooner. Regardless the newer shafts seem to address the problem and I havent seen one come back nor have I had anyone tell me about one failing.