GotTransmissions.com received a question recently that deserves a post of it’s own.
If you have General Motors brand Chevrolet Astro Van or Suburban, or a GMC Safari Van with a harsh 1-2 shift, you have company. This is a fairly common problem with these vehicles and in most cases easy to cure. These vehicles use either a T-700R4(4L60) or an 4L60E automatic overdrive transmission.
Technically speaking the wrong second gear shift accumulator spring was put in many of these vehicles, causing them to shift to hard from first gear to second gear. It was a factory manufacturing flaw not deemed serious enough to warrant a bulletin from the factory for a fix. Most people who inquired were told that’s the way they shift, nothing we can do about it.
For those who want to know what an accumulator is: it is essentially a shock absorber for a shift. It takes the shock and harshness out of a shift. The bigger the accumulator the softer it will shift. The smaller accumulators shift more solid or harsh. The basic paradigm is easy. Essentially, the vehicles that received the too small accumulators from the factory shifted to hard.
You can fix that problem. A few companies now make a repair kit for it. I used the TRANSGO brand kits. The SK 4L60E-Jr is for the 4L60E and the SK700-Jr is for the earlier 700R4 trannys. They (Transgo) have been around since about 1959 making upgrade kits and fix-it kits and suppling repair and diagnostic information to professionals since their inception. Basically they are a research and development company for automatic transmission problems.
FYI, they make hundreds of kits, you can download a free PDF file catalog from the TRANGO site.
Here is the deal, if your transmission is relatively healthy and clean then one can install the bulk of the kit including upgrading the accumulator system without a transmission removal. It is way more common to install the entire kit while your transmission is being rebuilt. In my shop there was no choice, every T-700R4(4L60) and 4L60-E had an SK-Jr installed in it, as a matter of fact, if TRANSGO made a kit for the transmission we were rebuilding at the time, it got it automatically, no pun intended.
Don’t forget that if you do it yourself at home to be extra safe when you jack up your vehicle. Also you will need about 8 quarts of synthetic automatic transmission fluid and a transmission filter and pan gasket.
GotTransmissions.com Blog is presenting this fix as an answer to the question we received, send more questions. You can find more money saving fix-it tips by reading our blog. Enjoy.
PS. Your transmission does NOT need any extra additives. ATF has everything it needs in it already..
