GM 8L45 Archives - Transmission Digest
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

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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

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

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Raybestos adds new clutches for GM 8L45

Raybestos Powertrain has introduced two new clutch packs for the GM 8L45. The first is a GPZ friction clutch pack (part no. RGPZ-285) for model years 2016 and on of the 8L45. This GPZ complete unit Clutch Pack module features (4) C1 Clutch, (3) C2 Clutch, (5) C3 Clutch, (4) C4 Clutch, (4) C5 Clutch

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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