So last week as my brother is following me in my dads 04 Jetta GLI (im in my wife's 97 Miata) we sit at a stop light and BOOM, BOOM, BOOM the car behid my brother gets rearended, smacked them into him and he then barely tapped me. You can hardly telll that there is any cosmetic damage to the car. it bent the rear finish panel forward a little and the trunk won't close. But other than that no suspension or any other serious damage, other than the differential housing being cracked. I can't figuire out how this happened. The car was tapped very lightly and I had released the brakes by the time I realized I was about to be hit. The only thing I can think is that the diff just swung forward on the mounts and cracked.

I just figuired I would ask if this is fairly common. I have seen these housings cracked in the same place before but never payed attention to why they were broken.

 

Is it on the arm? There is a thin spot there, made to be the weakest link.

 

Extremely common. The insurance company will probably pay you for an entire diff, but you can just replace the housing.

 

Housings are $100, you can do the replacement in your garage. No special tools required.

 

Yeah, this is an easy one. If you examine the other side, you'll see that the mounting arms actually have a weak spot cut into them, as if Mazda intended for the arm to break in order to protect the rest of it.

I got a good deal on my Torsen because it had a broken wing. Bought an unbroken cover off an open diff and swapped 'em in the garage. No special tools needed, just a wrench, a big hammer, a chisel or flat screwdriver, and some sealant for re-assembly.

 

Good time to do the FC NA RX7 housing swap

 

So if one is to grind away the relief, what drawbacks will there be? I mean, would it have caused more damage to his car if the mounting arm didn't break?

 

I bought mine broken, works the very best now.

I've heard a good welder could weld it back together as well.... but housings are cheap enough

 

Only one arm is designed to break away. It's the driver's side if memory serves me.

 

 

I'd clean that broken housing out and cook in it next time you camp.

 

Beings that its cast metal, It can be welded, but its not that strong.

 

Panicmotorsport is just down the road from me and he has the rx-7 housing. Are the rx-7 housings a drop in fit? I know you can swap the internals but I thought the housing needs modification to work. Depending on what the insurance company payes out I might just see if I can get a torsen though. It has an open diff right now.
I have also debated welding it, I have two people I can take it too, but I just don't want it to be weaker than it apparently already is.
Thanks for the info guys.

 

RX7 housing will fit, you will need miata specific bushings though

This is the procedure I copied for the conversion
2. 86-88 RX7 assembly conversion:

Parts:
86-88 RX7 NON-TURBO differential assembly
94-95 Miata stub shafts or RX7 stub shafts and 94-95 Miata half-shafts
or 96-05 Miata axles (no stubs needed)
94-05 Miata driveshaft
Miata Ring and Pinion
Miata Pinion housing (pumpkin) (find at RX7 performance shops)
Miata Diff. Bushings

Procedure:
Open the RX7 assembly. Bolt the miata ring gear to the RX7 LSD. Swap the LSD to the miata pinion housing. Set the backlash and assemble the miata pinion housing to the RX7 carrier. Drill out the RX7 diff bushings and push in miata specific bushings. Install as normal.

 

Thanks. I will have to look into that.

 

Our salvage '01 had a busted one, it's the passenger side.

 

is passenger side Ben, you slippin'?

 

Got a salvaged 97 with a broken pass side.

 

where can i buy a differential housing for $100? am in long beach

 

Holy ****, is it 2013 already?

Sorry, but while one day shy of three years is certainly a commendable effort, it's by no means a record.

Here's a good place to start: http://car-part.com/