Hello my name is Ryan I just recently acquired a 1991 Montero LWB. The previous owner delivered it from a couple states away and he stated somewhere on the journey he lost the overdrive. I replaced the temperature switch since it was only $14, and also bought an OD relay (which was not $14). The internet told me the relay was on the drivers side but best I can tell it is on the passenger side and buried behind a fair amount of stuff. My question is what should the RPM's be at 60-70 mph? I cant tell if the overdrive is working or not, I do not know the vehicle well enough to know what RPM I should be running. At 65 mph I am at about 3600-3700, at 70 mph almost 4000. Is this normal? Would like to verify OD is broken before I continue attempting to fix it. Thanks, -ryan
91 Monte Overdrive
- Thread starter Waters
- Start date
off-roader
Expedition Leader
Definitely abnormal. IIRC you should be between 2.5k & 3k @ 70mph but it's been a few years since I had a gen I much less tires smaller than 33".
Doorplease
Explorer
Feel for the shift your od is 4th gear
Rpms @ 70 hang at about 2800-2900
Rpms @ 70 hang at about 2800-2900
plh
Explorer
What are the gear ratios of the automatics, and I assume the 91 has a lock-up converter? I'll add these ratios to my gear ratio calculator. For instance with 28" height tires and the V5MT1 5 speed the RPM at 70mph would be 3223 in 5th (overdrive 0.829 ratio) and 4th (1 to 1 ratio) is 3889 assuming 4.625 rear gears.
Oh and note: the factory tach - like all the factory gauges in these vehicles - are not very accurate especially after 20+ years.
Speed in Gear Calculator (Excel or OpenOffice) https://www.dropbox.com/s/7zm17sl60376ppy/GearRatio_Truck.xls
Oh and note: the factory tach - like all the factory gauges in these vehicles - are not very accurate especially after 20+ years.
Speed in Gear Calculator (Excel or OpenOffice) https://www.dropbox.com/s/7zm17sl60376ppy/GearRatio_Truck.xls
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