Watch out for high pressure in GM 8L45, 8L90 valve bodies
Hey now! Oh boy, do I have a fun failure to share with you and warn you about today! Have you encountered a crack in the worm tracks in your GM 8L45 and 8L90 valve bodies (as seen in Figure 1, above)? Sonnax has, and wow, is it frustrating. Once cracked, there is no way
TransGo releases S4 regulator valve for 2018-on GM 8L45, 8L90
TransGo highlights its new oversize S4 regulator valve for 2018-on GM 8L45 and 8L90 transmissions. According to TransGo, when General Motors made a change to the S4 regulator valve in both the 8L45 and 8L90 transmissions, the updated two-land design and computer command strategy resulted in significant increased wear, even at low mileage. TransGo says
GM 8L90 #7 Check-ball: The overheat that saved the day
Beginning in October of 2015, GM removed the #7 Check-ball from the solenoid valve control body in the 8L90 transmission (see Figure 1). This was done in conjunction with the elimination of the Lube Override Enable Valve from the upper valve body as shown in Figure 2. When this took place, the Lube Override Enable
Sonnax introduces S4 clutch control valve kit
Sonnax has introduced a new drop-in S4 clutch control valve kit for GM 8L45 and 8L90 transmissions. Sonnax says users can replace worn parts with this kit (part no. 154740-24K) to restore proper hydraulic control and renew clutch apply fluid pressure performance. The company notes that the Sonnax valve in this kit cannot be used
Shift Pointers: Reassembling GM pumps with cam failure
For the past several years, GM has used a binary positive displacement vane type pump. The compact design allows for it to be utilized in off-axis applications such as the 8L90 transmission and the third generation 6T40 transmission. Figures 1 (above) through 4 display a view of this style pump in the 6T40 applications. The
How to fix GM 8L45/8L90 no-move and no-pressure conditions
By now you may have heard of, or even experienced, a GM 8L45 or 8L90 transmission with a no-move or no-pressure condition. Conditions of no movement or no pressure after repair have plagued this unit since its inception. Here’s what you can do about them. Condition 1: No movement after fast learn or programming If
Searching for the source of an unexpected transmission fluid leak
As the installer was pumping fluid into the transmission from the right side of the vehicle, he was having a difficult time getting it full.
The GM 8L90 Stop/Start or Go/No-Go
The Stop/Start feature many vehicles are equipped with today is in my opinion one of the most annoying features a vehicle could ever have. Of course, my opinion doesn’t reflect the opinion of others, but what is undeniably annoying is when the stop/start feature is not working correctly, especially when it is self-inflicted. Take, for
Transtar highlights cooler flow bypass kit for GM, Allison
Transtar highlights the TransGo cooler flow bypass kit for GM 6L80, 6L90, 8L45 and 8L90 models as well as Allison 1000 transmissions. Years covered range from 2014 to 2022. According to the company, features of this kit include: Provides all-time cooler flow regardless of temperature; Prevents overheating; Reduces transmission fluid temperature; Eliminates thermostatic assembly; Allows
