Just count the teeth. Put a marker pen line on a tooth then turn it counting as you go.

My money is on 39 teeth, and 11 teeth on the pinion (from the 39 & 11 marking). Making it a 3.54, which is close to your estimation.

In future there is no need to remove the cover, which is clearly too late here, just lock one axle and turn the pinion until the other axle completes two revolutions while counting the pinion revolutions. i use a tab of masking tape on the pinion/uni joint and on the axle/tyre to keep track of the rotations. Seems you may have done this. I have done it many times and it can be done with the diff in the car, just pop it into neutral and lift one wheel up, it only takes a few minutes.

    dmc

    I didn't know that

    Thanks for the correction

      dmc thanks for that, yeah it has 39 stamped on it, taking the cover plate off gave me a chance to clean it up 👍

      Image description

        The backing plates can be bought new, I have some that came from Skandix I think, a few years back now.

        The later diffs also had the rear wheel speed sensor for the speedo/ECU/cruise control which is located in the rear cover. This does not have it. My guess is the donor car was a mid '80s 244/240.

        The far more common ratio is 3.73:1 which is found in lots of the 240s. Not sure what ratio you are after for your project. If you are after a burnout/better acceleration diff then the 3.73 is one step shorter and the 4.1:1 gears in a 740 twin cam diff bolt right into the 240 diff and are proper short! I have those gears in my 262 and it is REAL short! Sadly still not very quick though :-( The new engine coming may fix or help that.

        Regarding an LSD a few options exist, I think VPW had an Eaton true track for about $500 or so. Plus the 400-500 to have it rebuilt-installed from a diff shop.

          If you want the rear axle to live, it's good practice to have the axles crack tested, then if okay, get them shot peened - by a place that does aircraft-grade work, not some noddy at a speed shop - and all you have to worry about then is lunching the LSD's spider gears. Maybe they could benefit from shot peening, too, especially if you're going to drive it hard.

            dmc

            dmc are there any upgrades that can be done to the brakes on these? I’m going to replace the disks etc at some point before I install it

                Major Ledfoot thanks for that, it will just be a weekender to take out to car shows and the odd cruise around, not driven hard, the Ute only has a small V8 in it

                  The upgrade is pretty much rebuilt calipers, good pads, new rotors, that’s pretty much the best it can be

                  Tiler
                  They’re stronger than a Banjo, weaker than a Salisbury.

                  There’s two versions of the Volvo diff.
                  The earlier type is called a 1030, and is a close copy of the Dana 30.
                  The later type is a 1031 and uses the same 27-spline axles and centre, but has a larger pinion and slightly larger crownwheel.

                  Changeover is the early 1980s. If it has an electronic speedo sender, then it is 1031 - but there are a few years of 1031s without the speedo sender.
                  You might find information about the number of ribs being an identifier (1030 vs 1031), but it is NOT accurate.

                  If you are going to give the diff a hard time, the first thing that will break is the cross pin.
                  If you weld the diff or fit an LSD, then the next thing to break is the axles. I have not tried Ledfoot’s shot peening solution.

                    Should also add that 1030 ratios are freely available as Dana/Jeep parts, including new aftermarket parts.

                    Alternate 1031 ratios only seem to be available from Sweden at considerable cost.
                    Most people who use these diffs in 6-cylinder or V8 cars quickly find that they want a taller ratio (smaller number). The best option is the 3.31:1 from an 86+ manual 240, but they are relatively rare.

                    7 days later

                    ramrod thanks for that, what price do you have on the disks and pads also is it possible to buy new calipers?

                    Also where are you located?

                      rotors and pads are still available at the local parts shop. most likely they will be ordered in. i prefer genuine rotors though many have said aftermarket are readily available. pads come in a vast variety of materials. avoid the genuine pads, they are super dusty.

                      Calipers are no longer available new hence mentioning rebuilding them. Try a brake shop for this or a licenced mechanic or workshop. Berry Motor Group or Voldat in Melbs will be able to help. The do lots of 240s.

                      Interstate workshops do exist, just mention your location here and someone local to you can point you to a recommended workshop.

                        I get 240 pads and RDA rotors online delivered from Richmond Brake & Clutch, their prices are really good

                        9 days later

                        I think there is a shop there called GLT Automotive or something similar. GLT something, a local will know.

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