Hey guys-
First draft here, please comment/correct/suggest etc.
Thanks
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Basic differential/locker info
Differentials are torque equalizing devices that allow wheels connected to the drivetrain to transmit power at different speeds. This Wikipedia article is excellent and in more detail than I'm going into.
Erik's Toyota truck diff information page. (Also the first Google result for "Toyota Differential". Remember, Google is your friend too.)
Lockers (when active) defeat the torque equalizing nature of differentials, preventing wheelspin and forcing torque to the wheel that is turning more slowly or not turning.
Mechanism basics
Open - This is a regular differentiating mechanism, as found on most production vehicles and as described on the Wikipedia page. Can result in one wheel spinning freely, as on ice and the opposing wheel not turning. Great for on pavement handling and tire wear.
Spool/welded - This is a speed equalizing mechanism. Both sides of the axle are forced to turn together at the same speed. In a welded diff, the planet gears (usually called spider gears) and the side gears are welded together. Peterson's 4wheel write up A mini spool replaces the spider and side gears and performs the same action. A full spool replaces the entire carrier. This mechanism will see increased tire wear and turning radius whether in front or rear. This is preferred by many, especially in the rear, for predictability and cost. Downsides are minimized off-pavement.
Selectable - These mechanisms allow the user to choose either open or spooled operation, activated by electric motor, compressed air, or cable. The pricier and more complicated installation of the options listed here, this is preferred when cost matters less and the truck will be driven on and off road.
Automatic - These lock the differential automatically by allowing one side to spin faster than the carrier (as in an on pavement turn) but not more slowly (as in a one side traction loss). Lunchbox lockers replace the spider and side gears. The Detroit replaces the entire carrier. These are very popular and affordable and there are a range of manufacturers from which to choose. Some people complain about banging and chirping at low speed turns and others find them to be excellent.
LSD - Limited Slip Differentials - This is not a locking mechanism, but deserves a mention. Turning radius, track width, and tire size describe the maximum amount of differentiation between sides of an axle that can be usefully expected. Open diffs allow unlimited differentiation (speed difference, here called slip) and lockers (when active) allow none. Limited slip diffs are intended to allow a certain amount of slip but not more. More here. Mechanisms are usually clutch pack requiring a special diff oil, helical gear style also called Torsen style after the manufacturer, and viscous coupling like in a torque converter. Some LSDs may require some finessing to activate, i.e. feathering the brake or may allow unlimited slip.
Availability
Most 4x4 Toyota trucks came with open/open diffs. Check Erik's page for the info on our trucks.
Spools/welded
I haven't heard any reviews of different spools. I assume this is because it is easy to make a cheap reliable spool and many people would rather weld their open diff than buy a spool. I believe there is no commercially available mini spool for the 8".
Selectable
The Toyota rear Elocker is widely appreciated, and there are many write ups on installation in a minitruck rear. Some links-
https://forum.ih8mud.com/79-95-toyota-truck-tech/204094-elocker-wiring-switches.html
https://forum.ih8mud.com/79-95-toyo...ng-trd-elockers-fzj80-elocker-ecu-switch.html
E-locker
Outdoor Recreation Network - Off-Highway, Jeep, & 4x4 Fun
The Toyota FJ80 8" High pinion elocker will fit in a minitruck solid front axle.
ARB makes a widely used compressed air activated locker. I believe they make the only selectable locker for the 7.5" IFS front diff.
Worth mentioning;
Eaton, maker of the Detroit, has been talking for a long time about making an electric locker.
Auburn is making very cool a LSD selectable locker, but not for Toyota applications.
Ox makes cable operated locking diffs, but not for Toyota.
Automatic
Aussie is what most people seem to like. They seem to be constantly pushing back the date for the V6 diff application, but you can stick the I4 locker in a V6 diff with minor work.
Lock Right
Detroit soft locker no longer available?
Full Detroit link? Eaton's website sucks.
Who else did I miss?
LSD
1986.5-1992 MKIII Supra LSD can be installed in a 8" axle
4x4Wire - Retrofitting A Supra LSD
supra lsd install
supra lsd install
1982-1986 MKII Supra LSD for the 7.5" IFS
http://www.4x4wire.com/forums/showf...&page=0&view=collapsed&sb=9&o=14&fpart=1&vc=1
Detroit Trutrac; Torsen style helical gears
Eaton also makes a clutch pack type LSD, possibly for our trucks but their website sucks.
Center diffs
The 79-95 trucks do not have center diffs, but they deserve a passing mention. The driveshafts turn at the same rate, and this is what makes our trucks part time 4x4s. Full time 4x4 and AWD vehicles have center diffs that allow the front and rear to travel different distances (as in a turn) and can be open, selectable as in LC80s, and LSD as in modern 4runners. Our trucks do not have center diffs, which is why you will get driveline bind and tire chirping on high traction surfaces in 4wd. On our trucks the transfer case lets you disconnect the front output, leaving our trucks in 2wd for pavement operation.
-------------------------------
I'd like to get some feedback before this makes it to the FAQ. Not limited to, but specifically
Anything wrong
Options I missed
Necessary tricks
Links to relatively objective reviews of lunchbox lockers
Links for commercially available spools
Funny limericks
I seem to remember some good tech from KLF on the elockers, links to the good thread(s) would be great.
First draft here, please comment/correct/suggest etc.
Thanks
---------------------------------------
Basic differential/locker info
Differentials are torque equalizing devices that allow wheels connected to the drivetrain to transmit power at different speeds. This Wikipedia article is excellent and in more detail than I'm going into.
Erik's Toyota truck diff information page. (Also the first Google result for "Toyota Differential". Remember, Google is your friend too.)
Lockers (when active) defeat the torque equalizing nature of differentials, preventing wheelspin and forcing torque to the wheel that is turning more slowly or not turning.
Mechanism basics
Open - This is a regular differentiating mechanism, as found on most production vehicles and as described on the Wikipedia page. Can result in one wheel spinning freely, as on ice and the opposing wheel not turning. Great for on pavement handling and tire wear.
Spool/welded - This is a speed equalizing mechanism. Both sides of the axle are forced to turn together at the same speed. In a welded diff, the planet gears (usually called spider gears) and the side gears are welded together. Peterson's 4wheel write up A mini spool replaces the spider and side gears and performs the same action. A full spool replaces the entire carrier. This mechanism will see increased tire wear and turning radius whether in front or rear. This is preferred by many, especially in the rear, for predictability and cost. Downsides are minimized off-pavement.
Selectable - These mechanisms allow the user to choose either open or spooled operation, activated by electric motor, compressed air, or cable. The pricier and more complicated installation of the options listed here, this is preferred when cost matters less and the truck will be driven on and off road.
Automatic - These lock the differential automatically by allowing one side to spin faster than the carrier (as in an on pavement turn) but not more slowly (as in a one side traction loss). Lunchbox lockers replace the spider and side gears. The Detroit replaces the entire carrier. These are very popular and affordable and there are a range of manufacturers from which to choose. Some people complain about banging and chirping at low speed turns and others find them to be excellent.
LSD - Limited Slip Differentials - This is not a locking mechanism, but deserves a mention. Turning radius, track width, and tire size describe the maximum amount of differentiation between sides of an axle that can be usefully expected. Open diffs allow unlimited differentiation (speed difference, here called slip) and lockers (when active) allow none. Limited slip diffs are intended to allow a certain amount of slip but not more. More here. Mechanisms are usually clutch pack requiring a special diff oil, helical gear style also called Torsen style after the manufacturer, and viscous coupling like in a torque converter. Some LSDs may require some finessing to activate, i.e. feathering the brake or may allow unlimited slip.
Availability
Most 4x4 Toyota trucks came with open/open diffs. Check Erik's page for the info on our trucks.
Spools/welded
I haven't heard any reviews of different spools. I assume this is because it is easy to make a cheap reliable spool and many people would rather weld their open diff than buy a spool. I believe there is no commercially available mini spool for the 8".
Selectable
The Toyota rear Elocker is widely appreciated, and there are many write ups on installation in a minitruck rear. Some links-
https://forum.ih8mud.com/79-95-toyota-truck-tech/204094-elocker-wiring-switches.html
https://forum.ih8mud.com/79-95-toyo...ng-trd-elockers-fzj80-elocker-ecu-switch.html
E-locker
Outdoor Recreation Network - Off-Highway, Jeep, & 4x4 Fun
The Toyota FJ80 8" High pinion elocker will fit in a minitruck solid front axle.
ARB makes a widely used compressed air activated locker. I believe they make the only selectable locker for the 7.5" IFS front diff.
Worth mentioning;
Eaton, maker of the Detroit, has been talking for a long time about making an electric locker.
Auburn is making very cool a LSD selectable locker, but not for Toyota applications.
Ox makes cable operated locking diffs, but not for Toyota.
Automatic
Aussie is what most people seem to like. They seem to be constantly pushing back the date for the V6 diff application, but you can stick the I4 locker in a V6 diff with minor work.
Lock Right
Detroit soft locker no longer available?
Full Detroit link? Eaton's website sucks.
Who else did I miss?
LSD
1986.5-1992 MKIII Supra LSD can be installed in a 8" axle
4x4Wire - Retrofitting A Supra LSD
supra lsd install
supra lsd install
1982-1986 MKII Supra LSD for the 7.5" IFS
http://www.4x4wire.com/forums/showf...&page=0&view=collapsed&sb=9&o=14&fpart=1&vc=1
Detroit Trutrac; Torsen style helical gears
Eaton also makes a clutch pack type LSD, possibly for our trucks but their website sucks.
Center diffs
The 79-95 trucks do not have center diffs, but they deserve a passing mention. The driveshafts turn at the same rate, and this is what makes our trucks part time 4x4s. Full time 4x4 and AWD vehicles have center diffs that allow the front and rear to travel different distances (as in a turn) and can be open, selectable as in LC80s, and LSD as in modern 4runners. Our trucks do not have center diffs, which is why you will get driveline bind and tire chirping on high traction surfaces in 4wd. On our trucks the transfer case lets you disconnect the front output, leaving our trucks in 2wd for pavement operation.
-------------------------------
I'd like to get some feedback before this makes it to the FAQ. Not limited to, but specifically
Anything wrong
Options I missed
Necessary tricks
Links to relatively objective reviews of lunchbox lockers
Links for commercially available spools
Funny limericks
I seem to remember some good tech from KLF on the elockers, links to the good thread(s) would be great.
Last edited:
Cave-man simple and reliable. But absolutely horrid on-road performance.