Master overhaul kit of frictions, steels, gaskets and seals for the Mitsubishi V4A51, R4A51 and V5A51 4-speed autos in Montero Sport, Pajero, L200 and Triton, 1999-2011.
Mitsubishi's longitudinal four-speed automatic, the V4A51 in four-wheel-drive form and R4A51 in two-wheel drive, sits behind the V6 and diesel engines in the Montero Sport, Pajero, Pajero Sport, L200 and Triton. When one of these trucks starts flaring on the 2-3 or 3-4 shift, drops out of overdrive under load, or slams into gear on a cold morning, the clutch packs are usually done. This master overhaul kit gathers the frictions, steels, gaskets, washers and rubber and metal-clad seals for the job, and the listing covers the V4A51, R4A51, V5A51 and R5A51 tags.
These boxes use a torque converter feeding planetary gearsets, with each ratio held by a hydraulically applied clutch or brake. Gearboxlist puts V4A51 production at 1996-2016 and lists the Pajero 2 and 3, Pajero Sport 1 and 2, L200 3 and 4 and Space Gear among its applications, with ratios of 2.842, 1.495, 1.000 and 0.731 in a 2000 Pajero Sport 3.0. It is rated for engines up to 3.8 liters and about 400 Nm, so the hard parts are stout; what wears out is the friction material and the sealing. Gearboxlist notes that the reverse and overdrive clutch packs wear fastest. Once their facings thin and the piston seals harden, line pressure cannot clamp the pack, the overdrive clutch slips on the 3-4 shift, and the control unit is left commanding gears the hardware cannot hold. A master kit replaces every friction facing and steel in those packs, plus the gaskets and seals that keep oil where the pistons need it.
Several common faults mimic worn clutches. Gearboxlist lists failing speed sensors and the inhibitor (range position) switch as frequent problems, and both can upset shift timing without any internal damage. It also warns that neglected engine coolant corrodes the transmission heat exchanger, which can let coolant into the fluid. Read the codes, check the fluid for a milky look, and confirm line pressure with our line pressure testing guide. The slipping diagnosis guide walks through separating a true clutch slip from a sensor or valve body fault. If the unit still slips with good pressure and good signals, it needs this overhaul.
The listing lists the Montero Sport 1999-2004 (3.0L and 3.5L V6), Montero XLS 2001-2002, Pajero and Pajero Sport 2000-2011, L200 and Triton 2000-2011, plus the Challenger, Strada and Pajero Wagon. In the United States the first-generation Montero Sport was sold only with a four-speed automatic, so a US Montero Sport tag should read R4A51 or V4A51. The full-size Pajero and later L200 and Pajero Sport were also offered with the five-speed V5A51, which the listing says this kit also covers; read the transmission tag on the case before you order, and send us your year and VIN if the tag is missing or unreadable. For the Montero Sport specifically, we also stock an R5A51 family master kit for the Montero Sport, and the rest of our overhaul kits are in the rebuild kits category.
This kit does not include a torque converter, bushings or a filter, so plan for them. Sonnax notes that Mitsubishi does not sell the pump bushing separately for these units and that the pump halves have no alignment pins, so mark and align the halves carefully when you rebuild the pump; our pump bushing wear guide shows what to measure. Sonnax also calls severe accumulator bore wear very common in this family, a cause of soft or harsh shifts that new frictions will not cure, so inspect those bores. Soak the frictions in fresh fluid before assembly, use a clutch spring compressor for the piston return springs, and set each pack clearance with a feeler gauge. Refill with Mitsubishi ATF SP-III or a licensed equivalent; gearboxlist lists about 9.7 liters total capacity. Flush the cooler and lines so old clutch debris does not return to the new packs.
| Type | Master rebuild / overhaul kit (frictions, steels, gaskets, seals, washers) |
| Transmission | Mitsubishi V4A51 / R4A51 / V5A51 / R5A51 4-speed automatic |
| Vehicle applications | Montero Sport, Montero XLS, Pajero, Pajero Sport, L200, Triton, Challenger, Strada 1999-2011 |
| Drive | Rear-wheel drive / 4x4 |
| Replaces part numbers | V4A51, R4A51, V5A51, R5A51 |
| Addresses | Clutch slip, 2-3 and 3-4 shift flare, harsh cold engagement, loss of overdrive |
| Kit weight | 7.04 lb |
| Does not include | Torque converter, bushings, filter |
US-market first-generation Montero Sports were built with the four-speed automatic, so a 2002 should carry an R4A51 (2WD) or V4A51 (4WD) tag, both covered by this kit. Confirm the tag on the case or send us your VIN.
No. The listing states the kit does not include the torque converter, bushings or a filter. The pump bushing for these units is a separate aftermarket part, so inspect it and order one if it is worn.
Mitsubishi ATF SP-III or an equivalent that carries that approval. Total capacity is about 9.7 liters, though a rebuild with a drained converter and cooler will take most of it. Set the level hot.
In this family the overdrive and reverse clutch packs wear fastest. Worn facings and hard piston seals let the overdrive pack slip on the 3-4 shift, and the control unit then drops out of fourth. Check sensors and line pressure first, then overhaul with this kit.
Yes. Old coolant can corrode the transmission heat exchanger, letting coolant into the fluid, which destroys clutch facings. If the fluid looks milky, replace the cooler and flush everything before installing new frictions.
