My Alpina B2 powered 3.0CS

Discussion in 'E9 Projects and Restorations' started by JamesE30, Oct 10, 2018.

  1. Ohmess

    Ohmess I wanna DRIVE! Site Donor

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    How do the German rules deal with incorporating parts from later BMWs? By way of example, many US e9 owners have changed our starters to use the starter from an e24 because the fixed magnet starters are much more efficient in actually starting the engine. Obviously, this is a BMW part that was an improvement BMW made to its line of M30 engines.

    Would this type of change need approval, and listing in the paperwork with the car?
     
  2. JamesE30

    JamesE30 Member

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    Honestly I couldn’t say with any real authority as I’m not doing the metalwork myself, but as the floors all need to be aligned and welded to the rocker structure, I would say it’s save to assume it would make sense to do the rockers first. Especially on my car where they were so far gone already.

    Funny I was just looking at that upgrade just the other day. Unfortunately the Bosch SR441X which everyone seems to use appears to only be available in America. Can’t find one anywhere in Europe...

    I think generally speaking oem replacement parts are not considered aftermarket upgrades as they already have some form of oem certification. Certainly something like a starter motor is never going to be noticed by any inspection.
     
  3. Ohmess

    Ohmess I wanna DRIVE! Site Donor

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    Quoting Chris Macha: "SR71x, SR440x, SR441x, they all work, be sure they have the small case and permanent magnet."
     
  4. eriknetherlands

    eriknetherlands Active Member

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    Markos,
    If your floors are really bad, your sill (rocker) is usually bad as well, and the other way around. So it normally makes sense to do both. (i'm not taking about (dry) cars with floors that just have small holes that can be patched)

    Doing the floors first works better; after you finish the floors, you open up the sill , asses it's state, replace or fix, and then weld the new floor to the fixed sill, treating the welds on both sides: grinding, clean and paint 'em.
    Doing the sill first, keeping the old floor in, and closing the sill up completely before your weld in the floor gives you the problem that once you do the floor, that you'll end up with untreated welds inside your fresh sill. Wax won't prevent rust, it'll just delay it.

    So in my view, the floor is replaced first, and the weld to the inner sill is made after the inner sill is opened up and replaced or fixed-up.

    The question that defines the amount of work is however not what order to choose but: Do I replace the inner sill, or fix it up? .

    If i'd (ever again..) tackle another E9, I'd first check the condition of the inner sill and decide to renew or freshen-up. Once it is solid again, i'd build up the other sill layers only after the floor is in, welded to the inner sill, cleaned the welds up inside, and then continue with the intermediate sills, the A/B/C pillars, the outer layer and lastly the skins.

    - If a little rust, you can leave the inner sill in place, perhaps replacing only some rusty sections (usually front, back and/or some bottom edge). Just drill some location holes for Cleco's /screws prior to dissecting the spot welds, clean up/patch the rough edges of the parts, and tack it all back together in the right place. Doing so, you have the advantage that you can keep alignment of subsequent layers perfect as the location of the A, B and C pillar reinforcements and the under-seat reinforcements will not change. You don't want to weld them in 2 mm off in X/Y/Z.
    Second advantage is that with the sill reduced to only the inner layer + the floor out, you can access both sides of that sill to clean it up or replace. Then weld in the floor; still having the ability to clean the welds and coat both sides of the welds. Once finished, there will be no rust left in the seam where the panels meet. It is what I choose on my car.

    - If your inner rocker is gone beyond saving, as in the case of James above, then no solid alternative exists other then to replace the complete inner rocker. Keeping the old floor in for a while helps to locate the new inner rocker using the position of the old floor. I'd stiffen up the old floor with an additional temporary welded bar prior to removing the last sill layer to keep the floor's shape (front to rear); prevent it from sagging. Once the new inner sill is in, you can mark the height of the old floor to the fresh sill, and then proceed to cut& replace the floor sections and tack / spot weld them to the inner sill. Once finished, there will be no rust left in the seam where the panels meet. Disadvantage is that you have lost the reference for your A/B/C pillar locations, so you must engineer other ways to relocate them.

    regards, Erik.
     
    Last edited: Apr 18, 2019 at 3:42 AM
    Belgiumbarry and Gransin like this.
  5. Markos

    Markos Well-Known Rust Staff Member Site Donor $$

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    Amazing details Erik. I will definitely leverage your insights! Sorry to hi jack your thread @JamesE30!
     

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