Full overhaul kit for the Mitsubishi R5A51 five-speed: frictions, steels, separator plates, gaskets and seals for a 1999-2004 Montero Sport rebuild.
A 1999-2004 Mitsubishi Montero Sport that flares on the 2-3 shift, takes a long pause before it grabs Drive or Reverse on a cold morning, or shows dark fluid full of clutch dust needs more than a fluid change. This master rebuild kit is the complete consumable package for a bench overhaul of the Mitsubishi R5A51 family: full friction plate set, matching steel plates, separator plates, and the gasket and seal package with case, pump and valve body gaskets, lip seals and sealing rings. The listing gives the kit's reference numbers as B124820D, B124880B and W124881B.
These are Mitsubishi's rear-drive and four-wheel-drive longitudinal automatics. The R prefix is the two-wheel-drive case, V is the four-wheel-drive version, and the 4 or 5 is the number of forward gears. The electronic five-speed version runs six solenoids (low/reverse, underdrive, overdrive, second, reduction and torque converter clutch) that steer oil to the clutch packs and brakes, so when the frictions and piston seals wear, the computer can command a perfect shift and the hardware still cannot hold it. A master kit renews every clutch facing, every steel, and every rubber and Teflon seal the oil passes on its way to those pistons. According to the listing, the same clutch stack-ups and case sealing are shared across the R4A51, V4A51, R5A51 and V5A51, which is why one kit is sold for all four.
Sonnax lists severe accumulator bore wear as very common in these units, and that wear causes soft shifts, harsh shifts, delayed engagement and engagement shudder on its own. Inspect all four accumulator bores during teardown, because new clutches will not fix a leaking accumulator.
Pull a fluid sample and check level and smell first. Then rule out the electrical side: on the five-speed, Sonnax publishes the internal harness pin-out, and each solenoid should read 2.7-3.4 ohms at 68 F across its pins. A solenoid out of range is a valve-body or harness repair, not a rebuild. Our guide to testing a transmission solenoid with a multimeter shows the method, and flare versus slip helps you separate a worn clutch from a timing or pressure problem.
The listing fits the 1999-2004 Montero Sport with the 3.0L (6G72) and 3.5L (6G74) V6. Be aware that published specs for the first-generation Montero Sport list a four-speed automatic, so on most US trucks the tag will read R4A51 (two-wheel drive) or V4A51 (four-wheel drive) rather than the five-speed R5A51; the full-size Montero is where the five-speed V5A51 appears. The listing says this kit covers all four, but read the tag on your case and count the plates in each drum against the kit before you throw the old ones away. If the tag is missing, send us the year and VIN. A companion V4A51/R4A51/V5A51 master kit is also available, along with more options in rebuild kits.
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The listing says the kit covers the R4A51 and V4A51 four-speeds as well as the R5A51 and V5A51 five-speeds. Read the tag on the case, then compare the plate count in each clutch drum with the kit before discarding the old plates.
Yes. R in the code means the two-wheel-drive version and V means the four-wheel-drive version with the transfer section. The clutch and seal kit is the same, but the case and output parts are not.
It can be, but Sonnax lists engagement shudder as a symptom of worn accumulator bores in this family. Inspect the accumulator pistons and bores during the rebuild and repair them along with the clutches.
A clutch spring compressor, snap ring pliers, a dial indicator for endplay, and a way to air-check circuits. Plan on a pump bushing if the original is scored.
Use the Mitsubishi ATF specified in your owner's manual for your model year. Do not mix in a generic fluid that does not list the Mitsubishi specification.
