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    AWD front, 188 and 210mm rear questions

    Working on AWD project, some of you are already familiar.
    After initially swinging toward a TR-6060 based driveline, my needle has swung back to a BMW driveline using a franken GS6-53BZ with ATC-700 T-case from E70 X5.

    The TR-6060 with 0.56:1 sixth and 3.64 diffs gave a fairly nice highway cruise gear with 2.04 overall ratio. Engine will be S62, so low rpm torque will be plentiful. With stock diameter tires, this should result in 1700 RPM at 60 and 2300 at 80. Not bad. Not as good as an LS1 Camaro, but not bad.

    To get the same overall ratio with the GS6-53BZ, I'd need to run 2.35 diffs. Even if I can use a diesel 6th in the gas transmission, I'd still need a 2.56 or so.

    *Maybe* if I can track down ZF service information for the transmission, I *might* be able to swap in the diesel 6th gear. The gas sixth is 0.87, while the diesel 6th is 0.84. That doesn't sound like much, BUT the diesel box likely has a shorter input to counter shaft ratio, which could make the actual 6th gear mesh much taller once swapped into the gas box. But that's not something to count on until I have tooth counts.

    Since I have to split the transmission ANYWAY to put the V8 bellhousing on the AWD 6 cylinder transmission, it would be handy to swap the gear, if feasible. For now I'll continue as though I'll have to keep the gas 6th.

    Since I'm running an S62, I have to use the E53 AWD oil pan. Using the E53 pan means I have to use the E53 front diff case. Euro E53's had ratios down to 3.07. The 3.07 diff uses the "tall ratio" case which has more clearance inside for a larger pinion. This case will be necessary in order to use the taller ratios I'm looking at.

    Also in my possession I have the large case 2.93 LSD from an E23 745i turbo. It bolts up to the E30 subframe.

    Is service infomation (pinion depth, preload torque, etc.) available for the front diffs? Shims? I @$$ume I'll be able to get new bearings and pinion seal based on part marks.

    Option A):
    E53 3.07 front case + 2.35 E46 front gears (+ Quaife?), ordered from ebay.de or ebay.co.uk
    2.35 rear end... not sure this was ever put into an E30 style case.

    Pros: Tall enough top gear for good cruise, yet first gear still >10:1, so maintain good low speed acceleration and holeshot.
    Cons: I want a 210mm rear
    Requires: Two front diffs and a 188 rear diff shipped from Europe; building a front diff with no service information.

    Option B):
    E53 3.07 front case + 2.93 E46 gears (+Quaife?) + 2.93 large case rear already in my possession.
    This results in a 2.55:1 overall top gear. That's 25% more RPM on the highway than the 2.04:1 benchmark. With stock sized tires, that's 2150 at 60mph, which is pretty short. That's 2900 at 80. I already drive that in my V8 Fiero... it's gross overkill and wasteful, especially with a 6 speed.

    Pros: cheap, only ship two diffs from Europe; large case rear
    Cons: Way shorter gearing than I want
    Requires: shipping two front diffs from Europe; building a front diff without service information and setting up axles for 94mm rear CV joints.

    Option C):
    E53 3.07 front case + 2.64 gears from a later model car with N series engine + a 2.65 large case rear. These aluminum case front diffs come from the same era during which BMW started welding the ring gears to the carriers in the rear diffs. I don't know if the ring and carrier are welded in the front diff. I don't know if the ring & pinion will transfer to the older case, and I don't know if I might have to do something crazy like machine the gear off the carrier and drill/tap it to bolt to the older carrier.

    Pros: better ratio than option B; 210mm rear
    Cons: Huge technical unknowns; may not be feasible/possible
    Requires: Shipping two front diffs from Europe and finding a 210mm 2.65 gear set stateside; building a first of kind front diff with no service information


    Option A sounds the most reasonable as it gives me the gears I want, and the 188 rear diff with the 94mm CV's is actually strong enough for the power I want to put through it. I'm just into overkill and like the unbreakable 210mm, plus the oddball large case that bolts into the E30 appeals to me, just because it's a weird rare part.

    Thoughts on front diff parts? gear options? anything else?
    Last edited by The Dark Side of Will; 02-04-2017, 01:07 AM.

    #2
    Interesting document on the E70 X5 powertrain:



    It also has links to many other systems.

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      #3
      Snagged a 2.35 rear for 50 Euros from Lithuania. Cost more to ship than I paid for the unit. Still less than some other diffs on ebay.

      Comment


        #4
        Boy, we're spoiled with inside diff and gearbox parts for the earlier cars, aren't we?

        It's more than mildly depressing to see just the diff as an assembly on realoem,
        no shims, no bearings, no crush sleeves, no nut'in.

        My limited experience with older diffs is that the shims are not marked- you just
        measure them and order the thicknesses you think you need.
        But if it's a 'replace as a unit only' box... bleah.
        Racing places like Bimmerworld, I guess, huh?

        Good luck- I was surprised how much the X5 driveline setup is like the E46 and later
        sedan xi's...

        t
        now, sometimes I just mess with people. It's more entertaining that way. george graves

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          #5
          The hardest part will be getting the pinion depth right. I suspect as long as I keep the inner pinion bearing shims with the case in which BMW installed them, I'll be pretty darn close.
          I'll probably go for a Quaife, so I might or might not have to change the carrier bearing shims anyway.

          In my effort to get this thing to turn, I'll probably leave the rear open, which means I can "just" drop the 2.35 pinion and ring/carrier combo into an E30 case and go.

          Comment


            #6
            Now that I think about it a little more...

            The front diffs are basically 168mm units.
            I've heard that the Quaife for a Z3 1.9 will fit an E53 front diff, for example.

            The same might be true of the pinion shims and bearings. The carrier shims are different because the front diffs use more or less conventional shims, while the rear diffs use the bearing retainers on the sides of the unit like the 188's and 210's use. I wonder if a pinion depth tool made to locate the pinion face relative to the axle centerline would work the same in both units.

            I think it's likely that if I keep the OE shims with the case they came out of, I won't need to change anything to get the pinion depth right.

            The split case design is a PITA to deal with, but fundamentally it's just more time consuming to set the carrier shims that way.
            Last edited by The Dark Side of Will; 02-03-2017, 09:24 AM.

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              #7
              From my experience with the 168 diffs for 2002's and 320's, and a couple of
              188's from E30's, the pinion spacers, and usually the case spacers, too, stay with
              the gears, approximately. The cases seem not to vary much at all, while the gear setup does.

              That kinda makes sense- the case is just several parallel or perpendicular surfaces,
              easy to set up and easy to measure to make sure the process is correct,
              while gear cutting is complex, and the cutters wear, get resharpened smaller, and
              the machines have to be capable of several axis- motion. And it takes several
              different operations to make the gear, the bearing- mount surfaces, and the shoulders.

              Yeah, I would expect the depth tool to work, if it locates from the bearing cones...
              the variable is that the teeth are not always on the pinion in the same place,
              as in, the nose may not be exactly indexed to the teeth. In extreme cases with
              168's, you can see this externally, as there may be more or less thread sticking
              out beyond the flange nut for the pinion flange.

              And from experience with 4wd trucks, I wonder if a quaife in front will work- a Salisbury in front does
              not, very well. On 'mostly slippery' surfaces, it really fights your steering input.
              Almost everyone who uses something in front uses a locker- and locks it for grip, then unlocks for maneuverability.
              Conversely, a Salisbury in back is an aid, because you can use the throttle to kick the rear
              out, while only one front wheel loses traction, letting the truck pivot on the front wheel that
              is not spinning... just thinking with the keyboard, here...

              t
              Last edited by TobyB; 02-03-2017, 11:47 AM.
              now, sometimes I just mess with people. It's more entertaining that way. george graves

              Comment


                #8
                Interesting. So you think if I keep the spacers with the 2.35 pinion and install everything into the E53 case I'll have the best chance of getting the pinion depth right first try? I'll keep that in mind.

                Probably going to be a while. I'm in Afghanistan for the next several months.

                The 2.35 fronts are pretty rare... They were only available for about 3 years in Euro market E46 330xd stickshift cars. Even the Euro E53 3.0d stickshift 3.07 front diffs are more common.

                ETA:
                Also, I'm building this car for performance on dry pavement... and not for drifting (or ice racing). The helical front diff helps FWD cars turn without lighting up the inside front. Any limited slip rear diff induces understeer because it tries to equalize the speeds of the left and right wheels. With the S62 and great big transmission, the car will be pretty front-heavy and will need all the help it can get to turn. I've heard of Subarus set up for tarmac getting good results with a helical front and open rear as well.
                Last edited by The Dark Side of Will; 02-04-2017, 01:14 AM.

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                  #9
                  So on your way home take leave enroute and poke around in germany and some other countries. The Euro has been weak you might want to stock up on it.
                  https://www.facebook.com/BentOverRacing

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                    #10
                    Lol... They're actually going to send me to Sembach/Kaiserslautern to "decompress" for a week before going back to the States. I am already aware that location is a 1:45 drive from the Nurburgring. If I can take a day without getting into too much trouble, I *will* go hammer on a rental car at the Nurburgring.

                    I'd love to get parts as well, but I have no idea how to find junkyards in Germany.

                    Is there a German equivalent to www.car-parts.com ?

                    Comment


                      #11
                      not that I'm aware of. Ramstein and Baumholder and Spangdahlem all have small junkyards. Rentals are frowned upon the ring because the insurance will not cover them if you have an oops. Sembach is just a housing area these days with some office space.

                      There were a bunch of used german lots over near Saarlouis and Saarbrucken which are not far from Ramstein. In between the two is Hartge and just north of Das Ring in AC Schitzer and Spa
                      https://www.facebook.com/BentOverRacing

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                        #12
                        Google "Nurburgring Rental" and you'll see there are lots of outfits that rent cars for the 'ring. Not saying it's cheap, but since I'm there for free, I can blow a few extra bucks.

                        I'll have to see if I can get Space-A flights to Ramstein once I'm back in the US.

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                          #13
                          Sub'd! I love learning stuff about this. I swear I get more enjoyment learning about BMWs/E30s than driving them.

                          *Also who knows if my ix actually gets an engine swap.
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