Reams the worn pressure regulator valve bore in GM 6L45, 6L50, 6L80 and 6L90 valve bodies so the oversized PR valve seats and line pressure comes back.
This is the reamer and guide you need to fit the oversized pressure regulator (PR) valve in the GM 6L45, 6L50, 6L80 and 6L90 six-speed automatics (2006-up). The PR valve rides in an aluminum bore in the pump, and on high-mileage units that bore wears oval. Once it wears, line pressure bleeds off and you get low pressure, soft or delayed engagements, slipping under load, and burnt clutches on a unit that otherwise looks fine.
The fix is to machine the worn bore back round and oversized, then drop in the matching oversized PR valve (WIT/TransGo 6L80-PR-OS, sold separately). This set is what does the cutting: a US-made alloy-steel reamer plus a heat-treated steel guide sleeve. The sleeve indexes off the existing bore and keeps the reamer dead straight, so you get a concentric cut by hand on the bench.
The big advantage over the older approach is that no expensive valve-body holding fixture is required. Clean the pump, slip the guide over the reamer, run the bore, flush the chips, and install the oversized valve and spring. The reamer and guide are reusable, so once you have them on the shelf you can recover every worn 6L80/6L90 pump that comes across the bench.
Manufactured by TransGo (part number 6L80-PR-TK). Pairs with our 6L80/6L90 pressure regulator valve kit to complete the repair.
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