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  • ransom

    June 9, 2011 11:51 a.m. ransom Reader

    I'm trying to fix the 2002's instrinsic shortcomings. One of which is its nose-heavy weight distribution.

    This 2002 opened me up to the notion of moving the gearbox to the rear, but I feel they did it the double-hard way: They stuck firmly to BMW bits, and so kept the separate gearbox and diff.

    I just pinged the adapter folks at Kennedy Engineering to ask whether they'd heard any other rumblings of demand for front-engine rear-transaxle adaptation, but I'm not hopeful.

    My central question is about whether I'm missing anything obvious in my assumptions about approaching this, which are:

    • Use a transaxle which is already used in this configuration (Porsche 944, Alfa GTV, ???), so that it's available with an appropriate cover plate and support for a driveshaft input.

    • That leaves the single biggest hurdle in building a bellhousing/clutch cover/front driveshaft support to match the engine. This probably also needs to provide 3rd/4th engine mounts since the transmission is no longer locating the engine.

    It sure would have been nice if BMW (I'm leaning towards using an M42) had used transmissions that didn't have integral bellhousings... Still probably easiest to start with a dead trans and cut the bellhousing off, I suppose.

  • HStockSolo

    June 9, 2011 12:03 p.m. HStockSolo New Reader

    ransom wrote: It sure would have been nice if BMW (I'm leaning towards using an M42) had used transmissions that didn't have integral bellhousings...
    I am pretty sure the bellhousing bolts onto my Getrag 250 (E36).

  • ransom

    June 9, 2011 12:13 p.m. ransom Reader

    In reply to HStockSolo:

    That's a skosh more than just the bellhousing, no?

    Still, that's a lot better than I recall (trans in storage). If I'm really, really lucky, perhaps the span of that bellhousing-plus-some will allow for two bearings with a little room between them to support the input shaft...

    If I'm incredibly lucky, maybe I'll find that this can be done by trimming the existing input shaft and attaching a guibo joint... At least this part I can revisit the previously linked site for help on.

    Thanks for waking me up!

  • WilberM3

    June 9, 2011 12:13 p.m. WilberM3 Dork

    i forget the numbers of the transmissions, but the e30 M3, e28 M5 and e34 M5 gearbox unbolts from the bellhousings, though i'm not sure what bellhousings are available to adapt, but it might be a starting point.

  • VividRacing

    June 9, 2011 12:14 p.m. VividRacing New Reader

    Just buy a wrecked GTR and toss that bad boy in there

  • pigeon

    June 9, 2011 12:15 p.m. pigeon Dork

    Take the transaxle and torque tube from a 944 and shorten the torque tube and driveshaft if/as needed and make up an adapter from the bell end of the torque tube to the motor? Seems like a lot of work to me when a 2002 like Woodstock can go win Targa Newfoundland. Maybe ring up Adrienne Hughes at Ecksten's Autoworks here in Rochester and ask her what they did to Woodstock to get it to handle?

  • June 9, 2011 12:16 p.m. 93gsxturbo HalfDork

    C5 Corvettes use a rearmounted T56 and diff. Strong, cheap, different ratios available. Separate units bolted together. Clutch is in the front.

    You can get kits to use them without the stock torque tube, with a conventional syle driveshaft or shorten the stock torque tube.

  • stuart in mn

    June 9, 2011 12:21 p.m. stuart in mn SuperDork

    WilberM3 wrote:

    i forget the numbers of the transmissions, but the e30 M3, e28 M5 and e34 M5 gearbox unbolts from the bellhousings, though i'm not sure what bellhousings are available to adapt, but it might be a starting point.

    It was the Getrag 265 that had a removeable bellhousing. It was used in some years for the regular e28 535i, the standard transmission in an M5 was the Getrag 280 that didn't have a removeable bellhousing. I don't know if it bolts up to the four cylinder BMW engines, though.

  • cwh

    June 9, 2011 12:35 p.m. cwh SuperDork

    Sawzall.

  • ransom

    June 9, 2011 12:45 p.m. ransom Reader

    I love this forum...

    @pigeon: That struck me as the most direct appraoch. And they can handle beautifully. I'm just having a blast geeking out on the engineering while I turn a car I love into an even better version. I'm already starting clean-sheet on the front end, and right now I'm definitely having a bout of "while I'm at it..."

    @93gsxturbo: I had no idea. I'll have to look into that. In particular, I'm finding it curious that the 944 arrangement still has a near-full-size bellhousing at the rear for no reason obvious to me. If the T56 arrangement is smaller it might mean less cutting up the floorpan.

    @WilburM3 and stuart in mn: Awesome; those bits of info together deserve some follow-up...

    @cwh: that and a friend with a flycutter on a mill are not an unreasonable answer.

  • WilberM3

    June 9, 2011 12:47 p.m. WilberM3 Dork

    stuart in mn wrote:

    WilberM3 wrote:

    i forget the numbers of the transmissions, but the e30 M3, e28 M5 and e34 M5 gearbox unbolts from the bellhousings, though i'm not sure what bellhousings are available to adapt, but it might be a starting point.

    It was the Getrag 265 that had a removeable bellhousing. It was used in some years for the regular e28 535i, the standard transmission in an M5 was the Getrag 280 that didn't have a removeable bellhousing. I don't know if it bolts up to the four cylinder BMW engines, though.

    that's it, the 265. i thought the m5 had a removable BH too because we put an e30 m3 gearbox in a broken M5 for a customer who didnt want to pony up for the M5 box, but youre probably right, we had probably put in both parts of the 265 but i honestly can't remember anymore.

  • mw

    June 9, 2011 2:34 p.m. mw HalfDork

    Why nit use a flipped vw transaxle?

  • ransom

    June 9, 2011 2:43 p.m. ransom Reader

    In reply to mw:

    That's what I was thinking when I contacted Kennedy, since they do a lot of adapters for that transaxle.

    Without a preexisting adapter available for input via driveshaft, the 944 unit (or the Corvette arrangement) would seem to be the easiest route, leaving me only to sort out the engine/clutch end of things.

    BTW, I head back from Kennedy, but apparently I wasn't clear enough about what I was asking, as they just said that they don't adapt to the 944 transaxle and directed me to Renegade. I've clarified that I was only using the 944 as an example of the layout, but I think it's probably moot.

  • GameboyRMH

    June 9, 2011 2:48 p.m. GameboyRMH SuperDork

    If you're going for Frankenstein options, a modded Impreza transaxle is probably your best bet. You'd have to custom build a torque tube to connect whatever clutch you're using to the input shaft.

  • ransom

    June 9, 2011 2:54 p.m. ransom Reader

    In reply to GameboyRMH:

    Why would you pick the Impreza unit over some of the others mentioned? I'd have to remove the rear output, and like the VW (but unlike the 944 or C5) would have to build a cover plate/bearing mount.

    Is it price, availability, weight, differential options, ???

  • RossD

    June 9, 2011 2:58 p.m. RossD SuperDork

    How about just tuck the engine back into the fire wall into you get the weight distribution you're looking for?

  • ransom

    June 9, 2011 3:17 p.m. ransom Reader

    In reply to RossD:

    I can go back about 1 7/8".

    I suppose you may be talking about larger changes to the firewall. Hmm... I think I'm more afraid of the reworking of the heat/defrost/dash/etc and other repercussions of hacking that up than the aftermath of moving the gearbox.

    I'm not sure I'm right, but I'm less afraid of the mechanical/subframe/minor sheetmetal changes of the gearbox move. I should give it some thought, though.

    I think I effectively make a bigger shift by moving 70 pounds (?) of gearbox back four feet or so than I'm going to make by moving the engine a few inches, which in turn would mean moving the footwells back, the seats back... All doable, but I think these impinge more on what it's like to be in this car than I want to do.

  • DrBoost

    June 9, 2011 3:23 p.m. DrBoost SuperDork

    The Prowler used a front engine, rear transaxle. The beauty is, the engine and trans are both just Vision, Intrepid and concord bits. Then have a torque tube built and....

  • NOHOME

    June 9, 2011 3:38 p.m. NOHOME Reader

    You really need to look at Corvette Drivetrains.

    Kust cut the bit in the middle and drop it under the 2002 with some LSx goodness. And since it has already been well established on this board that "Box Flairs Make Everything Better", you are good to go in that respect.

  • mad_machine

    June 9, 2011 6:42 p.m. mad_machine SuperDork

    ^^^ just needs a seat, some pedals, and a steering wheel for fun times

  • Taiden

    June 9, 2011 7:16 p.m. Taiden HalfDork

    C5 t56

  • GameboyRMH

    June 10, 2011 9:19 a.m. GameboyRMH SuperDork

    ransom wrote:

    In reply to GameboyRMH:

    Why would you pick the Impreza unit over some of the others mentioned? I'd have to remove the rear output, and like the VW (but unlike the 944 or C5) would have to build a cover plate/bearing mount.

    Is it price, availability, weight, differential options, ???

    Price and availability. There are plenty of diff options with the others but your options for the Impreza box should be more affordable.

 
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