8L90 BUILD PARTS LIST

• MASTER KIT (BONDED PISTONS, CLUTCHES, STEELS, OVERHAUL KIT)
• Sonnax Shift Zip Kit Valve Body Correction Kit
• Sonnax TCC Zip Kit Valve Body Correction Kit

Updates Details:

• Converter Feed Limit Valve Kit
  GM 8L45 and 8L90 units may have TCC apply and release problems. Bore wear or a stuck converter feed limit valve can result in converter overheat, incorrect TCC apply or release, inadequate lube and cooling and converter over-pressurization. Installing Sonnax drop-in converter feed limit valve kit 154740-19K will restore proper valve function, resulting in proper TCC apply and release, regaining control of lube and cooling.
• TCC Clutch Control Valve Kit
  Burnt clutches, poor shift quality, overheated converters and TCC apply or release issues are common complaints with GM 8L45 and 8L90 transmissions. These issues can be caused by worn clutch control bores allowing valuable clutch apply fluid pressure to leak, reducing the force needed to apply the clutches. Sonnax S2/S3/S4/TCC clutch control valve kit 154740-11K is a drop-in valve with an added seal at the signal apply end and lengthened inboard spool at the clutch apply end that seals worn bores and restores proper function.
• O-Ringed End Plug Kit
  OE end plugs are designed to prevent critical pressure loss by capping the bore, while also functioning as a spring or valve stop. Repetitive spring motion, valve impact and fluid pressure variations cause wear between the end plug and bore mating surface, allowing vital fluid to escape the circuit. Wear at various OE end plugs in GM 8L45 and 8L90 transmissions allows critical leakage at the following circuits, default override, lube flow regulation, and converter lockup/release. These pressure losses impair control of clutches, effect lube flow regulation and critical converter control.
  We Put an end to leaks, restore hydraulic integrity and renew shift operation by installing Sonnax O-ringed end plug kit 154740-17K.
• Pressure Regulator & O-Ringed Shuttle Valve Kit
  Vehicles with GM 8L45 or 8L90 transmissions may exhibit high or low line pressure that results in harsh shifts, burnt clutches, loss of cooler and lube flow and overheating of the transmission and converter. These problems may be caused by wear of the pressure regulator bore casting at the VFS signal port area and/or at the shuttle valve sleeve. Wear at the inboard port of the pressure regulator bore allows VFS (throttle) signal pressure to leak, preventing proper action of the pressure regulator valve and potentially allowing it to remain in the high line pressure position. Wear of the shuttle sleeve due to continuous oscillation of the shuttle valve creates a path for balance line pressure at the pressure regulator valve to exhaust, resulting in excessive high line pressure.
  Sonnax pressure regulator and O-ringed shuttle valve kit 154740-29K restores hydraulic integrity to the lineup by addressing wear that subjects the transmission to either excessive high or low line pressure with upgraded materials, O-ringed sleeve, and unique designs. The pressure regulator valve has been designed with a lengthened spring pocket spool at the VFS signal port area, which provides over double the sealing capability to this critical end of the valve and allows it to operate in unworn portions of the bore. The length of the critical shuttle valve diameter has been significantly lengthened to provide better sealing and durability of the assembly.
• Pressure Relief Ball Valve Spring
  The GM 8L45 and 8L90 transmissions are having a recurring problem where the typical ball and spring seat is not opening and relieving pressure effectively. The OE spring design needs to see 400+ psi in order to open and relieve line pressure. As a result of this high pressure not being relieved, damage/cracks to the worm tracks can occur.
  Sonnax pressure relief ball valve spring 154740-18 allows line pressure to exhaust between 300–325 psi which will prevent future cracking of the worm tracks and restore proper function of the blow-off ball and spring.
• Signal Accumulator Piston Kit
  GM 8L45 and 8L90 transmissions often suffer burnt clutches, shift concerns, low line pressure and/or converter apply complaints due to excess wear in the signal accumulator piston bores in the control solenoid valve body casting. This wear allows valuable VFS signal pressure to exhaust, preventing proper shift control, line pressure regulation, and/or converter clutch apply. The Sonnax drop-in signal accumulator piston kit 154740-06K allows bores to be reconditioned quickly and easily with no reaming required. The hydraulic integrity of the VFS signal pressure circuits are re-established, and future wear prevented with positive sealing and wear resistant components.
• S1/S5 Clutch Control Valve Kit
  Burnt clutches and poor shifts are common issues with GM 8L45 and 8L90 transmissions. These issues can be caused by worn clutch control bores allowing valuable clutch apply fluid pressure to leak, reducing the force needed to apply the clutches. Sonnax S1/S5 clutch control valve kit 154740-13K is a drop-in valve with an added seal at the signal apply end and lengthened inboard spool at the clutch apply end that seals worn bores and restores proper function.
• 1-3-5-6-7 Accumulator Piston Kit
  In GM 8L45 and 8L90 transmissions, the 1-3-5-6-7 accumulator piston is utilized during apply of the 1-3-5-6-7 clutches to smooth engagement. Wear at this bore allows 1-3-5-6-7 clutch apply oil to exhaust resulting in ratio codes, harsh or delayed application of the clutch pack, burnt clutches and slipping/flares. Installing Sonnax 1-3-5-6-7 accumulator piston kit 154740-15K eliminates leaks to restore normal shift operation and feel.

At Shift Rite Transmissions, we’ve got you covered with our standard 1-year 36,000-mile transmission warranty when you purchase a new torque converter, giving you peace of mind from the start. For even greater protection, we offer upgraded warranty options: a 2-year, 50,000-mile warranty and a 3-year, 100,000-mile warranty, available for an additional cost. What’s even better? You don’t have to decide right away! You can upgrade your warranty at any time during your original 1-year coverage period. Stay protected for longer, on your terms.

At Shift Rite Transmissions, we want to ensure your transmission performs at its best! Our warranty covers everything under normal use, but it won’t cover damage to cases or shafts caused by misuse, abuse, or burn down due to operator error. For the warranty to remain valid, all warranty-related work must be completed at our facility in Kankakee, IL. The vehicle owner is responsible for shipping the transmission or vehicle to us for any necessary repairs. Please note that any unauthorized repairs made to the transmission will void the warranty. Please note that our warranty is non-transferable. We’re here to support you and keep your transmission in top shape!

Buyer is required to pay the core deposit up front. Core must NOT have any internal hard part damage or case damage, otherwise there will be additional charges deducted from your core deposit for the damaged hard part(s) or case. Initial shipping cost only covers one-way shipping. Return shipping cost for the transmission core is not included. Return shipping cost is deducted from your core deposit refund, after returned core passes inspection. All Cores must be returned within 30 days from date of purchase. Please visit our Core Return Section for more details.

Majority of units are in stock, in the unlikely case we do not have one in stock, they are quickly available, in most cases, as little as one business day. There are many different variations of this transmission model available so please make sure we get a VIN number when or after you place the order.