Keep Or Scrap 8" Rear

Discussion in '1965 - 1973 Classic Mustangs -General/Talk-' started by Randy'65, Jun 3, 2014.

  1. Back when my 65 was a daily driver, I had a problem with the rear tires wearing on the inside. Took it to a body/frame shop, they initially said that a PO was probably hit on the side, tweaking the diff tubes a little bit. When they started measuring, they found that the housing had somehow bent slightly, just enough to cause the tire wear but not affect operation. Their solution was to chain down the ends and jack up the center section until the flanges were parallel. Drove it fine for another 5 years before I took it off the road.

    My question for you guys is should I waste resources building this rear (want to go posi), or should I just buy a new one from Currie or somebody like that? I was thinking of going with a 9", but not sure it's necessary. I'm probably going to shoot for around 400 hp with the engine, thinking I could get a strong center section for the 8" to handle that with no problems.

  2. If you primarily plan on driving/cruising the car then the 8" will be sufficient. If you plan to use sticky tires or drag race the car then look towards upgrading. It's not so much the hp that is the problem here it's a matter of the load on the differential with a set of tires that is not spinning when you apply a lot of power ( ie slicks or drag radials )
  3. Not planning on drag racing. So I shouldn't be concerned with the history of the housing? I'm trying to get the brake drum off now so I can pull the axles to check for pitting at the seals, that may be another issue I have to deal with.
  4. I still have my 8", but have a Currie billet side cover and Currie 4 spider TSD. Its lasted for about 15 years through nitrous, a blower and now the turbo.
  5. build the 8" it will handle the power you intend to make.
  6. I looked at Currie's website for the billet side cover but couldn't find it. Could you elaborate on this piece?
  7. Billet bearing caps possibly ? 8 inch and 9 inch share the same axle size and bearings ,they both have a small 28 spline and a large 28 spline axle You can tell the small axle when you see it ,it looks like something from a go cart . the 9 inch 31 spline is very tough but you would not need something that strong . The 8 inch third member is basicalley as tough as a 9 inch Except for a 4 spider 9 inch. I have never broke one .
  8. As far as the history of the housing, If it's straight then rock and roll. I've fixed many of bent housings and never had any issues
  9. I guess they don't make them anymore, but its the cover that the bolt go through to the ring gear. It was supposed to be stronger then the cast piece.