Common Questions Starting your e9x LS Swap

The e9x swap is becoming more and more documented everyday.  Between social media groups and forum posts a lot of information is being shared.  But after being around and quite involved for years now, here are some of the most common questions we get about the swap:

  1. What is the cost to do a complete swap?

    The truth is, no matter what, no one can just give you a number.  Yes, it is possible to give a "ROUGH" figure for the swap but it is only accurate if you follow and source the parts IDENTICAL to that person.  The best advice we can offer referring to cost, whatever you think your final parts list cost will be add 10-20% as unallocated funds.  Anyone who has completed a swap will tell you that time and time again through the build you will have forgotten something, run into an unexpected issue, or just changed your mind on how you want something done.  A lot of times this money is spent on small purchases but after several $100 parts orders it begins to add up quick.

  2. What transmission should I use?

    Again, it is hard for anyone to tell you this since it is based of use, preference, budget, etc.  Won't go into much detail on selection since it is discussed often online.  The best answer is first ask yourself what is my transmission budget? After that start making decisions like auto vs manual.  Your horsepower goal needs to play a large part in the decision making process as well. It is extremely disheartening to complete your build and in the first few weeks destroy the transmission and the car be down for months from not having a complementing engine/transmission package.

  3. Can I run the stock rearend?

    Yes, but the real question is how long will it last?  Depending on the model being swapped determines how go of an idea this is.  Also horsepower plays a large role too.  The third factor that seams to always be overlooked is rear tires.  It makes a HUGE difference running everyday street tread 9" tires vs 11" drag radials.  Torque that sticks vs spins will apply much more stress to the diff and axles.  Just weigh your options and cost of each to decide.  Some go with M3 differentials from u-pull part lots to save money, which can be a great choice depending on your application.  Hands down the best but most expensive option currently available is Ford 8.8 IRS swap paired with aftermarket axles.  

  4. Electronics, what do I need?

    We will be going over this entirely on its own post.  Please check it out for more info.

  5. Driveshaft, what is best vs what is cheapest?

    This has to be one of the top three issues we come across people having after starting the swap.  We will start with cheapest, this is reworking the stock two piece driveshaft to have a coupling for the transmission (assuming use of a stock rear end) you chose to use.  Before going deeper, we need to debunk the main issue going this route.  First, issue is it will be a weak shaft for potential horsepower of an LS engine.  Second, in all the builds we have priced or helped others with it is almost as expensive as just having a one piece driveshaft made.  Front side driveshaft failures can be very damaging and dangerous.  The second route (preferred for many reasons) is having a one piece driveshaft made by a reputable local shop.  A steel 3.5" 1350 shaft can be made, dependent on your area, for $350-$550 on average in our experience.  We have seen many people charged $300 (before any shipping costs) to rework the BMW two piece driveshaft.  It is money well spent.


This is just the first of many guides we will be writing to help everyone along the way on LS swapping the e9x chassis.  We would love to hear from you on topics you want to see discussed in detail!

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