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Thread: Cheap 99-00 chassis bracing upgrade

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    Thumbs up Cheap 99-00 chassis bracing upgrade

    I made a discovery last night while flipping through the shop manual... it says that the rear crossmember support bracket was added in 2001. In otherwords, 99-00s don't have this!

    I just can't imagine not having this cheap, but crucial part (it came with my 2001, of course). It sits between the bottom of the floor and the center portion of the rear crossmember. Its purpose is to reduce the rear crossmember flex in order to stabilize the rear suspension geometry under load. As with all chassis bracing, that is it's main purpose; to maintain suspension geometry in order to provide stable, predictable handling.

    So for many of you 99-00 owners who weren't fortunate enough to have the Autoexe chassis braces, this is the next best thing. Here in the US, it's a mere $20 part, so you might be able to find one from the junk yard for next to nothing!

    Here is what the part looks like:

    There are also 5 bolts that goes with it

    It goes here (the red Autoexe piece you see replaces it; I didn't bother taking pics of my stock one on the car):

    Installation is very easy.
    First, remove the 4 bolts for the rear crossmember, and lower it with everything still attached. Do NOT touch the lateral link bolts if you don't want to get an alignment done again.
    Afterwards, bolt the support bracket into the bottom of the floor with 3 bolts. The opening side where you can insert the bolts are towards the fuel tank.
    Finally, just raise the crossmember back up with a jack or with help of another person very slowly/carefully, then bolt the crossmember back on the car and bolt the bottom side of the support bracket through the openings at the bottom of the crossmember. There are 2 alignment/centering pins on each side where the crossmember bolts to the car, so its position will practically be the same as before.

    If you installed the MSP sway bar kit on your 99-00, YOU NEED THIS in order for you to get the full potential from your suspension upgrades!!

    Any of you who want to just buy this cheap part new, the part number is B30D-28-8C0. You will need 5 bolts, in which the part number is 9078-60-820.

    Interestingly, Mazda chose to use a stronger support bracket for the Protege5 in the US. I don't have pics of it, but it is a US only part. Part number is BN5V-28-8C0A. It is a little more expensive.

    Other chassis stiffening improvements Mazda put in 2001 was the front strut tower stiffeners (the black metal plates that sits on top of the strut towers) but not worth mentioning because a strut bar does a lot more, and the lower tie brace in the front crossmember (the GT spec 4 point ladder brace replaces this). Installation of the OEM lower tie brace or GT spec ladder brace requires changing the front crossmember out completely because the mounting holes are not there in the 99-00! Do this only when you install a bigger sway bar or swap engines, otherwise, it's not even worth your time.
    Last edited by TheMAN; 04-09-2012 at 05:46 AM.

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