Repairs the worn control valve bores in an Allison 1000 six-speed valve body that cause harsh shifts, delayed engagement and limp mode.
If your Silverado or Sierra HD with the Allison six-speed slips on the 3-4 shift, drops into neutral when you lean on it towing in third or fourth, gets stuck in one gear, or sets ratio and solenoid performance codes such as P0732 through P0735, P0766 or P0777, this is the kit built for that complaint. It is the TransGo SK Allison-Jr (part number TGOSKALLISON-JR), a Shift Kit Jr. valve body repair kit. TransGo lists it for 2005-2010 General Motors vehicles with the Allison 1000, 2000 and 2400 six-speed, which on the pickup side means the LBZ and LMM Duramax era. It installs in the valve body you already have; it is not a replacement valve body.
The Allison 1000 is a clutch-to-clutch transmission: every shift is one clutch releasing while another applies, and the valve body controls both sides of that handoff. Pressure control solenoids feed trim valves that set how hard each clutch is squeezed, and the shift valves route that oil to the right clutch. When the trim valves and their bores wear, or when the factory pressure simply cannot hold the torque a towing or tuned Duramax puts through it, the holding clutch slips. The C2 and C3 clutches take the worst of it, which is why burnt C2 and C3 plates show up on so many teardowns. TransGo states that with this kit installed, the friction torque capacity of the holding clutches and brakes in second through sixth gear rises by roughly 100 percent when the lockup clutch is off and line pressure is at maximum. The box contains two USA-made hardened steel trim valves, check balls, inner and outer springs, and a drill bit for the required modification.
Pull the codes and freeze-frame data first and check the fluid level and condition. A ratio code with a heavily burnt fluid smell may mean the clutches are already gone, and this kit will not bring back plates that are worn through. Our Allison 1000 valve body testing guide walks through separating valve body faults from solenoid and clutch faults, and the Allison limp mode guide explains the failsafe gear behavior you will see when the TCM detects a slip. If the clutch packs test good and the problem is slip under load, the kit is the right repair, and TransGo recommends putting it in before adding engine power, since it installs without pulling the transmission.
TransGo lists this kit for 2005-2010 Allison 1000, 2000 and 2400 six-speed units. The model year alone is not enough to be sure, for two reasons. First, 2005 is a split year, and many 2005 trucks still have the five-speed. The quick check: the five-speed uses an external manual lever position switch on the case, the six-speed has it inside. TransGo says the kit can go into a 2001-2005 five-speed, but it will not give the added fourth and fifth gear capacity those units need, so it recommends its full ALLISON SK kit instead. Second, the six-speed valve body was redesigned for 2010 and does not interchange with 2006-2009 parts, so confirm your castings against the Transmission Digest identification article listed below before ordering a 2010. For 2011 and later trucks TransGo sells a different kit. If you are unsure, send us your year and VIN, and see the rest of our Allison 1000 parts.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Only if the truck has the six-speed. Many 2005 trucks have the five-speed Allison. The five-speed has an external manual lever position switch on the case and the six-speed has it inside. TransGo recommends its full ALLISON SK kit for five-speed units.
No. TransGo lists this kit for 2005-2010 six-speeds and sells a separate kit for 2011-2019 Allison 1000 and 2000 units. The 2010 valve body was also redesigned, so a 2010 owner should confirm the castings first.
Two hardened steel trim valves, check balls, inner and outer springs, a drill bit and the TransGo installation instructions. You reuse your existing valve body housing and solenoids.
No. The valve body comes out from underneath on most pickups. You will need a new filter and pan gasket and fresh fluid, plus a scan tool to reset adaptives afterward.
It fixes the pressure side of the problem. If the C2 or C3 frictions are already burnt through, the clutches need to be replaced too. Check the fluid and codes before you decide.
Use an Allison-approved fluid. Allison currently lists TES 668 as its recommended spec for the 1000 Series, and TranSynd 668 meets it.
