Changing the bolt pattern on Ford 9" axles

[Movin/on]

I've go quite a few 31 spline 9" axles with the 5.5 bolt pattern. They are cheap and plentiful. But I want to change them to the Ford-Chrysler 5X4.5 BP.
I've got a drill press and some of the adapters to put 5.5 BP wheels on the 4.5 axles. So my thought is to use the adapter for a pattern and drill the axle flanges thru the holes.
2 questions
1: I'll need a way to center the pilot holes (thinking a lug nut to fit the taper of the adapter) is there another way?
2: What type of drill bit is recommended?
I may make a pattern jig so I don't ruin the aluminum adapter drilling that many axles

Has anyone done this. Don't want to spend a lot of money and ship the axles
I do have at least 16 axles to drill.

Richard >>> Movin/on

 

[The Cobbler]

your results in a drill press with an adapter will be poor results I think
there is a company that makes a jig for drilling holes , there was a post on here a few years ago about it.
Depending on the end use, if it is for road use, and you're selling them, IMO, the proper way to do it would be on a mill with a dividing head

 

[The Cobbler]

something like this , but I don't know the accuracy , but it will be better than using an adaptor I think https://www.hellsgatehotrods.com/product-category/drill-guides/

 

[u2slow]

I found a hex nut that slip-fit into the lug hole of a wheel spacer. Then I used a transfer punch that slip-fit into the nut. Punched the points, and pilot drilled. Worked ok I think- never tried that before.

Then I realized when I open up the holes to full size, the hole would land partway into the unmachined backside of the axle flange.

So now I have to pull the axles, and machine the backside a little to land the studs on flat surface.

(My axle is from a '00-ish grand cherokee, 5x5" pattern.)

 

[Wrench97]

Is the center hub the same size as the wheel?

 

[rsanter]

Not worth it IMO
You can buy a new pair of axles for $250

 

[kabinenroller]

I've go quite a few 31 spline 9" axles with the 5.5 bolt pattern. They are cheap and plentiful. But I want to change them to the Ford-Chrysler 5X4.5 BP.
I've got a drill press and some of the adapters to put 5.5 BP wheels on the 4.5 axles. So my thought is to use the adapter for a pattern and drill the axle flanges thru the holes.
2 questions
1: I'll need a way to center the pilot holes (thinking a lug nut to fit the taper of the adapter) is there another way?
2: What type of drill bit is recommended?
I may make a pattern jig so I don't ruin the aluminum adapter drilling that many axles

Has anyone done this. Don't want to spend a lot of money and ship the axles
I do have at least 16 axles to drill.

Richard >>> Movin/on

The only correct way to put a new bolt pattern in an axle flange is to have a jig that pilots off the centering hub of the axle with a long alignment tube for the drill to follow.( after a pilot hole is drilled using the alignment tube as a guide) I recommend not using a drill press instead use a mill, the axle flange must be perfectly horizontal otherwise the hole will not be straight and the lug stud will not be able to be installed correctly. A few thousands off at the flange will make the end of the stud even worse. The overall diameter of the 5 on 5 axles might limit what brakes you will be able to use.
Just my opinion.

 

[evintho]

Rotten Leonard's drill jig is the way to go especially if you're drilling 16 axles! It's proven itself over the years in the hot rod community.

 

[toplessHO]

wish they had this for 6 lug to 5

 

[gorilla]

Re drilling an axle flange on a vertical mill is not a simple task. You need to build a fixture plate to hold the axle off the edge of the table and then move the head off center to reach the axle. The set up takes longer than drilling the holes. For 16 axle's the drill jig is the way to go.

 

[superduty1]

Not worth it IMO
You can buy a new pair of axles for $250

I think I am in this camp as well. Why do you need 16 axles? Are they OEM? If you are breaking them, stepping up to an aftermarket shaft will definitely help. If you can, step up to 35 spline and be done with breakage (unless you are really pounding on your vehicle). I have run Currie 35 spline shafts in my offroad vehicles for the last 25 years with zero issues.

 

[Kevin54]

Don't do it in a drill press. The stud holes need to be exactly centered with the axle and the stud holes need to be exactly parallel to the axle shaft. If not, then you will have balance problems, or will wear out your stud holes in your wheels. Someone with a mill that knows what they are doing can easily do it.