1991 240 speedometer and differential issue

[okihiro]

hi all,
my 91 240's differential went to hell after the seal leaked out all the oil and the gears pulverized itself. i took it to an mafioso type indi mech as i was stranded in the bronx on way to work. he replace the whole rear end. problem is that he must have used an older 240 rear end as the speedometer now reads that i am doing 120 mph regularly and my mileage is running way fast.

so is there any way to set my speedo to work with the "new" rear end or do i have to 1. change the rear end back to a 89-93, or 2. change my speedo cluster to an older model's.

regards,
chifan

[93Regina]

my 91 240's differential....he replace the whole rear end...speedometer now reads that i am doing 120 mph regularly

"a non-ABS 240 has a 12 segment tone ring cutout. A 240 with ABS brakes will have a 48-tooth diff mounted tone ring"

So, an ABS tone ring came with that installed rear end.

I would unplug sensor at rear end, and get a Garmin GPS unit. Otherwise, find a speedo head used on ABS vehicles, or get the 12 segment tone ring, and install it (lots of work).

"ABS Electronic Speedo - With the ABS 48T diff version, the ABS speedo version has an add-on "daughter board" on the speedo cluster to scale the 48 pulses back to 12 pulses per wheel rotation, (to end up with with much the same resolution as the non-ABS system 12 pulse system)."