Pros and Cons of going with the Ford 9"

[TwoLaneBlackTop]

have been needing to freshen up my cars rear end for awhile and was looking at going with either moser or strange 33 spline axles, full spool, and c-clip eliminators (and hope they don’t leak), The car will be raced a lot, and I put less then 3000 miles on the car in a year so I can get over the annoying problems with running a spool on the street. I think this set up would be more then enough for the car but I have started to look at a Ford 9"

I might be able to get a Ford 9" all ready setup for a G body car with 33 spline axles, and a full spool that has not even been used yet and get it for about what the parts for the 8.5" will run me!

I like the idea of the ford 9" strength and the parts for the 9” if something ever does go wrong are cheaper, I don't like the idea of the extra power loss or weight.

So, here are my questions.

1. How much power loss can you expect from a ford 9" apposed to a GM 8.5”

2. How much more does a typical Ford 9" set up for our cars weigh in comparison to the GM 8.5"

 

[Reginald West]

I have been running a ford 9 inch for about 5 years. I can't tell you what the weight difference exactly but it does weigh more and I have been told that it takes about 25 more horse power to turn it. It works great on the street and strip the only problem I have had was the pinion support broke and I had to replace that.

 

[Ormand]

My guess on the horsepower would be more like 5 hp than 25. Think about it. How does it "use" horsepower? The pinion angle is a little steeper, which makes it a little less efficient, so it turns horsepower into heat. But we're talking about just a couple of a percent, max. If the GM rear is 98% efficient, and the Ford is 96% efficient, you would get a 20 hp difference if you were using 1000 hp. How long can you use that kind of power, unless you're driving at Taledega, or Indy? That kind of heat requires a rear end cooler, and except the NASCAR boys, and the Silver State road racers, who has one of those? I'm just using these numbers as examples, don't really think there is that much of a diff between the two rear ends, probably only one percent, but the range for hypoids is generally accepted as 96 to 98 percent. Using synthetic gear oil will cut down the losses by a little bit.

 

[49-blues]

Mark Williams Enterprizes has been working on a center section for the 9" ford rear which would raise the pinion angle about 2" and would be able to use GM 12 bolt gears which would reduce the driveline friction. This is the route i opted for. i already have the 9" w/350 posi center section.