SFBD and IRS info

I have searched and searched and cant seem to find any info on a mazda SFBD. Trying to get a plan together for my truck. Any links would be great.

Also have an RX7 IRS that I was on the fence about using. Mainly concerned with rear camber. Is there enough neg camber with the RX7 to make it worthwhile? The straight axle will be a much easier build but rear camber is so sexy.

SFBD is the Short Fat Bed

The SFBD is difficult to do on a Mazda. From the pinch to the floorboard is approx. 3 1/4". This leaves very little room for the frame. My roadster has a SFBD frame built by Bio Kustoms in Hemet, CA. We used a Toyota front suspension and rear axel. Everything was custom fabricated with 3"x2" tube steel from the frame horns back. This allows the truck to lay pinch only. Having one, I think the expense is not worth it. Consider that my other Mazda lays frame and is less than 3" from the pinch on a stock frame. I would recommend a 3 1/2" traditional body drop. This should lay flat rocker and be a lot less money.



As far as IRS is concernd, I think it is easier to set up an IRS than a live axel if you are doing a custom frame anyway. You don't have to worry about changing pinion angles and you can set the ride height when the frame is mocked up. The only thing you should keep in mind is the distance between the wheels. Make sure the rear you choose is not wider than the bed. IRS can be a real bear to narrow and maintain the proper amout of travel with the half shafts. As far as negative camber is concerned, I think you would have what you are looking for with that RX-7 rear set up. I would remove the springs from the rear assembly and put the center on a jack. cycle the suspension as if it were on bags already. See if it binds or what the limits are. Also determine what your ride height is going to be. This will tell you how high up in the frame the rear chunk will be.

First off, sick truck. I hope mine turns out as nice one day. Frame turned out real nice but wouldnt expect anything else from Max. I dont mind putting in the work for the SFBD. To be honest untill last week I was going to send the truck to the scrap yard. The wife actually convinced me not to. It has been sitting tore down in my back yard for about 4 years now. In that time I have lost and forgot all the research that I had in the past for the BD. Fabrication is something that I absolutly love to do so I really dont mind putting in the work. The frame is what has got me pumped about this truck again. Have the scrap sitting around to build the frame jig.

Going to build the frame from 2x3x1/4" and probably use the IRS. I paid for it so I might as well use it. I was on the fence because I love rear camber but didnt know what to expect out of the Rx7 IRS vs. like a supra which has a different mount style. I also like the clean simplicity of a solid axle though.

The motor went to the junk yard years ago so a 350 is the plan but also started looking into the Rx7 motor last night. Rx7 would match up nicely to the IRS also.

anyone else have any links or pictures. Looking for anything I can get.