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Old 05-03-2022, 10:08 PM
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Default disc vs. drum axle shafts

Are rear axles the same for drum brake rear ends and disc brake?
My parts book shows two different part numbers and I get conflicting info if they are the same or not when searching for an answer.
Something about they are the same but the height of the wheel centering hub is slightly taller for the rear disc equipped rears.

Need to replace an axle in a disc brake rear and was wondering if a drum brake axle is ok to use.

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Old 05-04-2022, 01:20 AM
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I believe they will interchange...but carried a different P/N....due to the rear disc part using a slightly longer axle stud to accommodate the extra thickness of rotor..

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Old 05-04-2022, 09:38 AM
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Longer studs and a longer brake center pilot(0.700) for the thicker rotor. Otherwise your hubcentric wheels won't center.

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Old 05-04-2022, 12:36 PM
ekancler ekancler is offline
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I'd have to assume that drum to disc conversion kits take care of this. If you're converting from drum to disc, you can't just buy the disc parts, you need the kit for adaptation purposes.

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Old 05-04-2022, 07:47 PM
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Quote:
Originally Posted by ekancler View Post
I'd have to assume that drum to disc conversion kits take care of this. If you're converting from drum to disc, you can't just buy the disc parts, you need the kit for adaptation purposes.
Not converting, I am replacing a bad axle on a factory disc car.

The height of the wheel centering hub on my disc axle is 11/16"..........it's approx 9/16" on a drum brake axle. Not too much of a difference but want to be sure before buying a used axle from a drum brake car then having issues mounting the wheel.
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Old 05-04-2022, 08:00 PM
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I may have a couple of extra factory not sure what shape they are in . Pulled 2 out of my 78 and I think one out of the 81 that was still decent in bearing area.

Dutchman was the only axle company that would custom make the pilot longer. Scarebird uses some steel rings machined and tack welded on. What I did with some Mosers.

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1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
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Old 05-04-2022, 08:14 PM
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Quote:
Originally Posted by abefromen View Post
Not converting, I am replacing a bad axle on a factory disc car.

The height of the wheel centering hub on my disc axle is 11/16"..........it's approx 9/16" on a drum brake axle. Not too much of a difference but want to be sure before buying a used axle from a drum brake car then having issues mounting the wheel.
Whoops. Read that a bit too quickly.

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Old 05-04-2022, 08:40 PM
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Quote:
Originally Posted by Skip Fix View Post
I may have a couple of extra factory not sure what shape they are in . Pulled 2 out of my 78 and I think one out of the 81 that was still decent in bearing area.
I definitely need one if it has the longer hub, or if I know that I can safely mount the wheel on a shorter hub drum brake axle........still doin research on that.

I have the factory turbo wheels on the car............I guess the easier question would be are they hub or lug centric?


Last edited by abefromen; 05-04-2022 at 08:51 PM.
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Old 05-04-2022, 11:23 PM
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Quote:
Originally Posted by abefromen View Post
I definitely need one if it has the longer hub, or if I know that I can safely mount the wheel on a shorter hub drum brake axle........still doin research on that.

I have the factory turbo wheels on the car............I guess the easier question would be are they hub or lug centric?
I would think that the lugs would have a pretty big influence on that......with that cone behind the washer flange...

Also....if an aftermarket wheel was used....there is no guarantee that it would match axle hub diameter.

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Old 05-05-2022, 09:29 AM
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Factory snowflake and Turbo wheels are hub centric. Lug nuts .710ish, holes .750

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1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever!
1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand
1965 GTO 4 barrel 3 speed project
2004 GTO Pulse Red stock motor computer tune 13.43@103.4
1964 Impala SS 409/470ci 600 HP stroker project
1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs
  #11  
Old 05-05-2022, 11:23 AM
'ol Pinion head 'ol Pinion head is offline
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Have pulled quite a few disc rears out of own partscars & pulled in well over a dozen more as loose rears. Parted nearly of out, as needed the S spring posi cores to rebuild/use. Have sold off most rear disc small parts & coming up on easily 1/2 of stock original disc axles. More nice ones in the racks. Need a disc axle, can set up a F-body housing on the bench w/ a disc caliper bracket & ck run out on the axle flange. One thing learned decades ago, if there is more than .007 runout on the disc axle flange, can get some slight noise out the caliper area, not good.

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Old 05-06-2022, 09:46 PM
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Quote:
Originally Posted by 'ol Pinion head View Post
Have pulled quite a few disc rears out of own partscars & pulled in well over a dozen more as loose rears. Parted nearly of out, as needed the S spring posi cores to rebuild/use. Have sold off most rear disc small parts & coming up on easily 1/2 of stock original disc axles. More nice ones in the racks. Need a disc axle, can set up a F-body housing on the bench w/ a disc caliper bracket & ck run out on the axle flange. One thing learned decades ago, if there is more than .007 runout on the disc axle flange, can get some slight noise out the caliper area, not good.
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