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Ways to Strengthen the AWD Drivetrain?

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    Ways to Strengthen the AWD Drivetrain?

    Hello! I'm new to modifying older cars (the previous project was a 2017 Mustang GT) and even newer to this group; I just purchased my first E30 (1988 325iX) as a project car and want to add around 200 more horsepower to it. I'm essentially looking at turbocharging as it stands right now, I've already researched what ill need to do to the engine to strengthen it for 400 hp thanks to this great community. However, I have come across issues regarding the lack of information on strengthening the AWD system. Does anyone have any knowledge on ways I can improve the strength of the drivetrain without forfeiting the AWD system?

    Sorry in advance for the newbie question. I'm still very new to forums and how they work.

    #2
    nando would know for sure
    5 series IX was sold in Europe.. 525IX I think
    I BUY/SELL REFURBISHED CM5907s & CM5908s

    HOWTOs:
    DB vert plastic bumpers
    OEM Keys
    MTech1 docs

    88 ix Lach/Card
    91 ic Calypso 3.1
    86 Cosmo 2.7

    OEM+ or bust!


    reelizmpro: I will always be an e30 guy.. I still do all of my own labor
    TrentW: There's just something so right about a well-built M20 in an E30
    e30m3s54turbo: I save my money for tuner parts.

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      #3
      The only real weak link is the front diff. There's no easy solution there - maybe you can fabricate something from another AWD BMW. but the ix also has unique final drive ratios, which complicates things.

      400hp is probably fine anyway, it's torque that breaks stuff, not power. but don't expect to do hard drag race launches a bunch of times without breaking the front diff. At the same time, I kind of question if 400hp is really needed in the E30 at all - 300 would still be plenty fast (these cars are not heavy) and it'll be easier to attain and easier on all the components.
      Build thread

      Bimmerlabs

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        #4
        Originally posted by nando View Post
        The only real weak link is the front diff. There's no easy solution there - maybe you can fabricate something from another AWD BMW. but the ix also has unique final drive ratios, which complicates things.

        400hp is probably fine anyway, it's torque that breaks stuff, not power. but don't expect to do hard drag race launches a bunch of times without breaking the front diff. At the same time, I kind of question if 400hp is really needed in the E30 at all - 300 would still be plenty fast (these cars are not heavy) and it'll be easier to attain and easier on all the components.
        okay thank you for the information, im glad to know the AWD system is alot stronger than most actually give it credit for!! the reasoning for wanting 400hp instead of 300hp is because i want a really exhilarating ride. I make almost 300hp in my STI, i want my e30 to stand out above it every time i floor it essentially. Not doing any drag races or anything like that, just a fun weekend car i can put the hammer down with on the track. but again thanks for the quick and detailed response, im glad this community has alot more support and knowledge than the mustang one i was in prior. haha

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          #5
          The E30 is lighter than an STI. the gearing is also going to be shorter. It probably won't have the same top speed regardless, but off the line I think it would surprise you even with "only" 300hp.
          Build thread

          Bimmerlabs

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            #6
            Do the front driveshaft modification to get more spline depth into the female part in the transfer case. X5 parts and guibo? Keep the front shaft splines lubed once a year. Should be good. Torque is the issue. You will be already underway by the time the 400 ponies kick in.

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              #7
              Second opinion, I think there are 2 main issues: Front driveshaft and front diff.

              Front driveshaft issue is spline engagement into the transfer case, plus ~30 years of likely poor maintenance (No grease). Fixes for this are things like the X5 pilot and guibo, spacers, or jute91 's spline extension/replacement if he still makes them.

              Front diff is 3 separate issues:

              Low fluid volume - when it leaks, there's not much reserve and it runs dry. One of my diffs was like this and has the spider gears chewed up badly.
              IMO the only way to deal with it is to preemptively reseal it and monitor it.

              Weak spider gears - these tend to explode when shock loaded with high power. Could choose to avoid hard launches, excessive wheel speed when transitioning from dirt/snow to pave.
              Some people like mw255 have added 2 more spider gears harvested from another diff, welding sections into the diff pumpkin to support it, but that's probably overkill for 400whp.

              Front ring & pinion is small so similar issue to the spider gears, but seems to be pretty rare. Just for info though, e30 iX came with 3.64, 3.73, 3.91, 4.10 diff options. The taller the ratio, the larger (and stronger) the pinion. All US/Canada iX are 3.91 for manuals and 4.10 for autos, some (all?) Euro cars have the taller diffs (It's been a while, someone correct me if I have that wrong).
              Again, I wouldn't worry about this for 400whp, but it's worth having in the back of your head if you ever want more.


              Other front diff stuff: E34 525iX seems to retrofit onto the front of the e30 iX in some combination.
              Look for Nisse Järnet 's thread on this, but the E34 iX wasn't sold in NA, and was very low production so parts are probably very hard to find.
              Originally posted by priapism
              My girl don't know shit, but she bakes a mean cupcake.
              Originally posted by shameson
              Usually it's best not to know how much money you have into your e30

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                #8
                E34 IX can be made to fit, but it requires fabrication, the parts are hard to find, and also really expensive. A guy here has the DCT M20 Turbo ix with the E34 parts I sent to him. You also need the E34 front CV shafts, which need to be modified, and they are also rare & expensive. probably not worth it IMO. it was expensive when I collected those parts 10 years ago, and it's only going to be worse now.
                Build thread

                Bimmerlabs

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