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Help! Rear drum brake questions
https://slantsix.org/forum/viewtopic.php?t=3931
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Author:  Patrick Devlin [ Sat Jul 20, 2002 1:10 pm ]
Post subject:  Help! Rear drum brake questions

Hi everybody,

I have an 8 3/4" rear end with small bolt axles that I'm putting in my '68 Dodge Dart. Unfortunately, I don't have the rear drum backing plates for the 10x1 3/4" drums.

These seem hard to find around here. Can I use the B/E body 10" rear drums if I also use the B/E body backing plates? Of course, I would have to have the drums re-drilled to 5x4" bolt pattern. I want to keep the small bolt pattern axles, especially since I got new ones. I also don't want to replace all of my wheels, since I finally got ones that I like.

Any suggestions on what other rear drums will fit with my axles and the 8 3/4" rear would be appreciated. I already tried drilling the backing plates on my 9" drums, but ran into a snag since the bearings on the 8 3/4" axles won't fit through the centering hole (I don't really want to re-drill this).

pwd22@drexel.edu

Author:  bud L. [ Sat Jul 20, 2002 4:29 pm ]
Post subject:  Re: Help! Rear drum brake questions

Quote:
: Hi everybody,
:
: I have an 8 3/4" rear end with small bolt
: axles that I'm putting in my '68 Dodge Dart.
: Unfortunately, I don't have the rear drum
: backing plates for the 10x1 3/4" drums.
:
: These seem hard to find around here. Can I use
: the B/E body 10" rear drums if I also
: use the B/E body backing plates? Of course,
: I would have to have the drums re-drilled to
: 5x4" bolt pattern. I want to keep the
: small bolt pattern axles, especially since I
: got new ones. I also don't want to replace
: all of my wheels, since I finally got ones
: that I like.
:
: Any suggestions on what other rear drums will
: fit with my axles and the 8 3/4" rear
: would be appreciated. I already tried
: drilling the backing plates on my 9"
: drums, but ran into a snag since the
: bearings on the 8 3/4" axles won't fit
: through the centering hole (I don't really
: want to re-drill this).


I am not absolutely positive about your idea but I think it might work. I do know that I swapped axles, backing plates and drums(11" x 2 1/2") from a B-body wagon onto an A-body 8 3/4" axle housing. All I remember having to do is shorten and respline the axles and swap emergency cables.

fglmopar@aol.com

Author:  Patrick Devlin [ Sat Jul 20, 2002 9:14 pm ]
Post subject:  Rear brake...found the answer

Crap! Looks like I'm out of luck with my B-body brake idea. I found the following information on the bigblockdart.com site (also posted elsewhere on the Internet):

"Section 2: Flange Axle Taper and Flange Differences

Besides the obvious bolt circle lug pattern difference
between the A-body 4" BC axle and all other passenger
car 4.5" BC axles, there is a sometimes unexpected
difference in the flange that tends to cause confusion.
The distance from the axle housing flange to the wheel
flange of the axle is 1/4" smaller on A-body axles than
on the standard 4.5" passenger car axle. On an A-body
axle this measures 2", on 4.5" BC axles its 2.25".

This slight difference will cause problems when one
attempts to adapt brake systems (drum and backing
plate together), or a brake drum from a 4.5" BC axle to
a 4" BC axle. If you are using original A-body axles,
regardless of what BC is may have been redrilled for,
you can only use the original 10x1.75" drums (redrill
the drums as well)."

Man, I wish I ordered different axles, or picked up the backing plates when I was at Carlisle! I'm still asking around locally for 10x1.75" brake backing plates/hardware, but I've had no luck so far. This is getting frustrating, since my Dart is my only car.
Quote:
:
: I am not absolutely positive about your idea
: but I think it might work. I do know that I
: swapped axles, backing plates and
: drums(11" x 2 1/2") from a B-body
: wagon onto an A-body 8 3/4" axle
: housing. All I remember having to do is
: shorten and respline the axles and swap
: emergency cables.



pwd22@drexel.edu

Author:  bud L. [ Sat Jul 20, 2002 10:36 pm ]
Post subject:  Re: Rear brake...found the answer

Quote:
: Crap! Looks like I'm out of luck with my B-body
: brake idea. I found the following
: information on the bigblockdart.com site
: (also posted elsewhere on the Internet):
: "Section 2: Flange Axle Taper and
: Flange Differences
:
: Besides the obvious bolt circle lug pattern
: difference
: between the A-body 4" BC axle and all
: other passenger
: car 4.5" BC axles, there is a sometimes
: unexpected
: difference in the flange that tends to cause
: confusion.
: The distance from the axle housing flange to
: the wheel
: flange of the axle is 1/4" smaller on
: A-body axles than
: on the standard 4.5" passenger car axle.
: On an A-body
: axle this measures 2", on 4.5" BC
: axles its 2.25".
:
: This slight difference will cause problems when
: one
: attempts to adapt brake systems (drum and
: backing
: plate together), or a brake drum from a
: 4.5" BC axle to
: a 4" BC axle. If you are using original
: A-body axles,
: regardless of what BC is may have been
: redrilled for,
: you can only use the original 10x1.75"
: drums (redrill
: the drums as well)."
:
: Man, I wish I ordered different axles, or
: picked up the backing plates when I was at
: Carlisle! I'm still asking around locally
: for 10x1.75" brake backing
: plates/hardware, but I've had no luck so
: far. This is getting frustrating, since my
: Dart is my only car.


That's too bad. I was going to suggest you make a 1/4" spacer for the axle bearing retainer, but then you couldn't adjust the end play. You can either go the route I went, or keep looking for 10" SBP backing plates. It may end up being easier just buying a complete axle ass'y.

fglmopar@aol.com

Author:  Dart270 [ Mon Jul 22, 2002 10:16 am ]
Post subject:  Re: Rear brake...found the answer

Quote:
: That's too bad. I was going to suggest you make
: a 1/4" spacer for the axle bearing
: retainer, but then you couldn't adjust the
: end play. You can either go the route I
: went, or keep looking for 10" SBP
: backing plates. It may end up being easier
: just buying a complete axle ass'y.


If you have a little extra bread, you can go to rear discs ($400 w/o park brake, 550-600 with). Check out <A HREF="http://www.tsmmfg.com">www.tsmmfg.com</A>. I have these on my '64 Dart and they are a noticeable step up from 10" drums...

Lou

Author:  Patrick Devlin [ Mon Jul 22, 2002 4:05 pm ]
Post subject:  Re: Rear brake...found the answer

Hey Lou!

Thanks for the information. Are the brakes you have on your '64 Dart small bolt pattern?

Patrick Devlin
Quote:
:
: If you have a little extra bread, you can go to
: rear discs ($400 w/o park brake, 550-600
: with). Check out <A HREF="http://www.tsmmfg.com">www.tsmmfg.com</A> . I have
: these on my '64 Dart and they are a
: noticeable step up from 10" drums...
:
: Lou



pwd22@drexel.edu

Author:  kesteb [ Mon Jul 22, 2002 5:52 pm ]
Post subject:  Re: Rear brake...found the answer

The brake drums and backing plates from a 5x4" 7 1/4" axle with the 10" drums will bolt on. This should widen the search.


klesteb@aol.com

Author:  Dart270 [ Tue Jul 23, 2002 6:50 am ]
Post subject:  Re: Rear brake...found the answer

Quote:
: Hey Lou!
:
: Thanks for the information. Are the brakes you
: have on your '64 Dart small bolt pattern?
:
: Patrick Devlin


Nope, big bolt.

Lou

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