Narrowing a Ford 9 - Few Questions

[67rstbkt]

So like the title states, I'm about to get into the task of chopping up a Ford 9 to fit my Firebird. I wanted to make sure of a few things before I make the cuts. I have the original rear end out of the car and have lined up the two housings with axles installed. I lined up the center of the pinion on each to the other. What I get with this one side of the Ford will need a small amount removed, maybe around 1/2 to 3/4 of an inch. The other end needs probably 4 or so inches chopped off.

Any issues with cutting it this way so that the centers of both are the same? This will make the originally longer/shorter axles in the Ford housing much closer to equal sized, any issues with that?

I already borrowed the alignment jig from a friend and bought myself the measurement tool to determine axle length afterwords. I'm using Moser Ford 9 (big bearing) ends with a GM bolt pattern for the brakes and will do a few tack welds to hold it together and then have another friend tig it for me.

So, is my method sound? One side will lose more than the other, no issues? Any other pointers before I make the cuts? Any tips, tricks, or advice would be greatly appreciated.

[ammoyer]

The 9" has a pinion offset of approximately 1" and I think the 10/12 bolt GM axles are 1/2". Decide if you want the pinion or the housing centered and go from there. If your car is really low and there is no modifications to the tunnel, centering the pinion may be a better option.

Once you've got the length of each side of the housing determined, cut the axle tubes. 4.5" cut-off wheel in an angle grinder works pretty well. Leave 'em a bit long (1/16"-18"). Set up the narrowing fixture with the dummy bearings in a 3rd member, bolt it to the housing and slide the alignment bar in. Mate a new housing end to the outer bearing collar of the alignment fixture and slide that assembly on the bar and check the squareness of the cut tube end. Grind the tube end until the correct length and squareness are achieved. Repeat for the other side.

Chamfer the outer edge of the tube to allow for good weld penetration. Tack your ends on and double check your alignment.

Once the ends are welded on and all the suspension brackets are welded on, recheck your alignment. You may be surprised how much the alignment will be off. You can true up the housing with a torch and some spot shrinking. This is how I've done shortened several Ford 9" housings, when I was fabricating. YMMV.

[67rstbkt]

The 9" has a pinion offset of approximately 1" and I think the 10/12 bolt GM axles are 1/2". Decide if you want the pinion or the housing centered and go from there. If your car is really low and there is no modifications to the tunnel, centering the pinion may be a better option.

Once you've got the length of each side of the housing determined, cut the axle tubes. 4.5" cut-off wheel in an angle grinder works pretty well. Leave 'em a bit long (1/16"-18"). Set up the narrowing fixture with the dummy bearings in a 3rd member, bolt it to the housing and slide the alignment bar in. Mate a new housing end to the outer bearing collar of the alignment fixture and slide that assembly on the bar and check the squareness of the cut tube end. Grind the tube end until the correct length and squareness are achieved. Repeat for the other side.

Chamfer the outer edge of the tube to allow for good weld penetration. Tack your ends on and double check your alignment.

Once the ends are welded on and all the suspension brackets are welded on, recheck your alignment. You may be surprised how much the alignment will be off. You can true up the housing with a torch and some spot shrinking. This is how I've done shortened several Ford 9" housings, when I was fabricating. YMMV.


Thanks for the tips!

[67rstbkt]

Well, started on the narrowing process and I could use some advice here. This is the first time I've done this; I've measured a bunch of times and have the length where it needs to be. The main issues I ran into is that the new ends do not seem to line up exactly with the axle tubes. They are off a little bit, almost like the housing tubes are a bit out of alignment. I have not welded on this yet, escept for the tacks holding the ends on.

As it sits right now, the new ends are lined up with the alignment slugs in the center chunk, so basically the rod going through the 4 slugs is straight while the new ends are tacked on slightly off. Is it ok to weld them on like this? I can't see how the alignment of the axles could be off, unless it was like that to begin with?

I assume the axles being centered to the carrier is the most important thing? If not, can someone help me out with the "spot shrinking" concept? How much heat, location to apply heat?

Thanks

[dontlifttoshift]

Weld them up. Trust your alignment bar. I don't think I have ever seen tubes that were perfectly straight.

[67rstbkt]

Weld them up. Trust your alignment bar. I don't think I have ever seen tubes that were perfectly straight.

Awesome, thanks!!