Brakes: Drum Fun with Fairborn Axles WITH interchange part numbers!!

[AKAchamptrucking]

I recently bought a tapered axle sans brake drums and a Fairborn axle kit. The Fairborn Axle Kit is sweet! After the axle install and differential swap in my Lark I thought I could use the flanged axle rear drums I already had off my old axle. The center hole in my drums were too small to register on the Fairborn axles. I believe the Fairborn Kit is designed to work with the drums off of a TAPERED AXLE so do not assume (!) like I did flanged drums will automatically fit. I started out increasing the center hole with a burr bit but soon realized I was actually removing the fish mouthed edge of the center hole rather than increasing the actual inside diameter. So I ground the fish mouth off smooth on the drum and then gently snuck up on the inside diameter so it actually fits the axle register. (See picture below)

Yesterday I had enlarged one drum too much being impatient with the bit. Forgetting I had a spare drum in stock I did a little research online and found a reference from the old NG about a Jeep brake drum that would fit FLANGED AXLE model 44's. It is AIMCO # 8838, and is designed for a 84 - 85 JEEP Cherokee with a screaming 2.7 Litre power house. I purchased a pair from my FLAP'S but they are available thru Autogroan, I mean Autozone. My FLAP's part number is Ctek (Centrex?)123.63014. Use the Aimco number and let your FLAPOs figure it out. So I installed these drums on the Fairborn axles and snugged down some lug nuts. One axle would turn and the other was bound up. After looking inside the drum,one brake surface was machined 2.5 inches wide and one was machined 2.25 inches wide. A quarter inch difference!! WTH?? The narrower machined surface had a nice shoulder that rubbed on the brake shoes preventing the axle from turning when the lug nuts were tightened!!!

THEN I remembered the spare drum I had in the parts stash so I did the grinder boogie on it and I now have a pair of drums that actually fit. The AIMCO replacement drums match up well with a stock flanged axle drum I have off my other Stude (see other pic below,rusty drum is stock,new is AIMCO) and would appear to work on a STOCK FLANGED AXLE since the stock flanged axle drum's machined surface is 2.25 inches. Maybe I will pull a wheel off the second Stude and see. IF you choose to buy a new pair of AIMCO drums for your Fairborn Axle swap look inside and make sure they are 2.5 inches wide or prepare to have them machined by a friend with a brake lathe.
Hopefully by posting this I can save someone some drum stress!!!! Take care.

[StudeRich]

The studs look like a loose fit in the Drum, without a tight fit I don't see how the drum could center.

[swvalcon]

THE CENTRIC NUMBER YOU LISTED ROCKAUTO HAS FOR $27.79 EA. They show it also fit 78 amx,74 javlin, and pacers plus a lot of others.

[AKAchamptrucking]

The studs look like a loose fit in the Drum, without a tight fit I don't see how the drum could center.

On my old drums THEY ARE too loose,thats why I was worried about the center hole being too big to register on the axle after I ground the center hole too big.

And after a few test drives my brakes work extremely well without drama,like they should.

- - - Updated - - -

THE CENTRIC NUMBER YOU LISTED ROCKAUTO HAS FOR $27.79 EA. They show it also fit 78 amx,74 javlin, and pacers plus a lot of others.

Cool addition to the post. Thanks!!

[Skybolt]

If anyone read my post, which I deleted I'm sorry. I had a brain fart. I never enlarged the hole in the brake drums. My mistake. Again, sorry.

Len

[JoeHall]

The studs look like a loose fit in the Drum, without a tight fit I don't see how the drum could center.

The large, center hole will keep it centered, and if it were not centered, you'd know it the first time you hit the brakes, since it would likely shudder at speed.

However, the excess clearance around the studs will allow the drum to shift back and forth, when going forward to reverse, to forward. Biggest initial problem may be the lug nuts working loose, and eventually the wheel holes may begin to oblong, and/or wear into the studs. That would probably take several thousand miles though. I'd just run it, and keep an eye on the lug nuts.

[bezhawk]

There are many stock "lug centric" based drums and rotors running millions and millions of miles with no problems.

[JoeHall]

There are many stock "lug centric" based drums and rotors running millions and millions of miles with no problems.

Bez,
Sure there are, as are OEM Stude drums. But the only thing centering the subject hubs, is the center hole. The lugs are free-floating, around .100" smaller than the holes in the hubs. The studs are missing the shoulders that come up into the drums, as on OEM Stude setups. The wheels will be lug centric, but the hubs will shift back and forth as the brakes are applied, forward to reverse, to forward. That is why I suggested keeping an eye on the lug nuts, to insure they don't work themselves loose. Look closer at the pix, and I think you'll see what I mean.
Joe

[Treblig]

The easiest way to grind (enlarge) the center hole and still have the hole concentric with the center of the axle is to put the rear end of the car up on some good solid jack stands. Then put some nuts on the lug bolts leaving only 1/2" of the stud exposed. Install the brake drum onto the lug bolts and put some nuts on the studs basically trapping the drum between the nuts. With the drum "standing off" from it's normal position you have ample space to grind. With a little adjustment (on the nuts you can get the drum running pretty straight when you start the engine and put the car in gear. Once you get the drum running straight you can raise the idle (idle screw) and grind the inner hole as the drum spins. You have to approach the inside diameter very slowly and keep even pressure on the ID as you grind. Doing it this way will allow you to remove metal in such a way that it keeps the hole concentric with the axle center line. As a machinist I've done things like this many times by hand. As you get close to the correct hole size you can remove the drum and using a cheapy pair of harbor freight vernier calipers you can measure the distance from each lug hole to the edge of the center hole. This will tell you how centered the hole is . If the measurements are off by a few thousanths of an inch you can mark that area re-install the drum and gently remove metal in the marked area. Anytime you spin the object you're cutting it greatly increases the chances of making the hole round and concentric. Once all the lug hole to center hole measurements are all the same and the center hole is the correct size your drum should fit perfectly snug (like millions of other cars) and it should run perfectly straight!!


Don't know if this helps but I couldn't help passing on tricks I've used in the past!!
treblig

[doofus]

From your pix it looks like their is a different offset on the new drums, will this work out? curios CASO's want to know. Doofus