Finally my wreaker delivery the courier diff yesterday,this arvo I removed the springs,wheels,checked the brakes and worked out the ratio,4.4:1 which will be good for take offs,being a track car only this will be good and I might get to use 5th now.
Its an open wheeler,when I get the axles modified for the escort PCD ,I will weld the centre,but I am als looking for an LSD centre for it as well.I got some info which you guys might find helpful cant remmeber where I got it,could have been here??????


Differential 2004/11/16

US Ring & Pinion Ratios
Vehicle Years Ratio Notes
616 '71 4.111 automatic only
61x, 1x00 All 3.700 boinger sedans
RX-2 '71-4 3.900
RX-3 '72-5 3.700
RX-3 '76-8 3.727
626 '79-'82 3.636
RX-7 12A '79-'85 3.909 & 6-speed Miata
RX-7 12A '84 3.933 part year
GSL-SE '84 4.077 thru 11/84
GSL-SE '84-5 4.083 12/84 up
B-xx00 Pickup '87-8 4.444 4WD M/T
Miata '94-7 4.100 & 99+ automatic
Miata '99- 4.300 M/T only
1600, 1800, 616, 618, RX-2, RX-3SP, SA & FB RX-7, RWD 626 and '86-up Mazda "B" series pickup truck third members (also aka pig or pumpkin) are interchangable. 1984-up models use larger axles, so the side gears in the differential are correspondingly larger-splined and must be swapped for correct gears if substituting into an earlier housing with smaller axles. Pre-SP RX-3s can use the later third members if an SP driveshaft is substituted along with it. Some pickups had 4.44 ratio gears, but never in conjunction with limited slip. The Mazda part number for the 4.44 pickup ring & pinion gearset is M054-27-110A. As the chart shows, '94-up Miata gearsets are also interchangable. See Randy Stocker's Miata Drivetrain Interchange page for more information. See Driveshafts for related differential flange issues. See Rear Axles for additional related issues.


Driveshaft
RX-3:Because later RX-3s use the same type differential center section (pig) as RX-2s and RX-7s, use of the longer later style RX-3 shaft facilitates straight drop-in of the pigs with shorter gears and limited slip found in RX-7s.
RX-7: Except for 4-speed automatics, which used a 5 cm shorter shaft, all 1st generation RX-7's used the same length driveshaft. 1979-1982 shafts have different differential companion flanges than 1983-1985 shafts. 1979-1982 shafts have normal U-joints, while 1983-1985 shafts have non-replaceable U-joints. By using the matching differential flange, fasteners, and seal, either group's shaft can be substituted to the other. Most driveshaft rebuilders are not competently capable of replacing the non-replaceable U-joints, which means some are, but they are hard to find. Replacement 1983-1985 shafts with replaceable U-joints are available from Mazdatrix. Good driveshaft shops can build replacements from scratch if you provide the old one for dimensional comparision. All NA rotary transmission yokes are the same spline and length. RX-2 and RX-3 differential flanges and seals are the same as 1979-1982 RX-7. The later flanges use through bolts with nuts. The early ones use cap screws that screw into the flange. Those threads help one to distinguish between the two types.
RX-7 Turbo: Transmissions for production turbo engines use a larger output shaft diameter and thus a larger driveshaft yoke. The length of a turbo driveshaft is the same as the length of the NA driveshaft for the same generation cars.

CHEERS

Dave

mine are from 1982/83 models!

Nigel,

The PCD of the courier diff is 6/139.7


Shaun

http://www.roh.com.au/pdf_docs/ROH_Australia_applicationguide_2004.pdf

its been such a great read, any further tinkering to the diff interested to find out if it works.

kris what brakes did you use on you rear alfa? and what calipers

Kris, sent you an email, can you please check if you got it

I am yet to see a 8 bolt unit(8 crown wheel bolts?), all my centres are 10 crown wheel bolt and 10 bolt to the housing

Ok sweet as, but do you have any info on what diffs are in late couriers and mazda b series?