Rear Disk Brake Conversion Parts

W

william hubert

New member
May 17, 1999
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I have seen a number of posts about rear disk brake conversions. I am
trying to determine just what kinds of parts are required. What is the
vehicle application or part numbers. I have seen several sites with lots
of pictures but not the basic part info.

Also I saw a reference to running 60 mm cyl on the rear but waiting for
Caddy backing plates to go to 80 mm on rear.

Finally what kind of rotors are used? How are they fitted/adapted to the
GMC hub.

Any and all response would be greatly appreciated.

Bill Hubert
Glens Falls NY

78 Royale ( Turned 21 last month )
 
Bill:

Did you get a response to this yet???

Paul Bartz

From: William Hubert [mailto:whubert]
Sent: Thursday, May 27, 1999 7:57 AM
Subject: Re: GMC: Rear Disk Brake Conversion Parts

I have seen a number of posts about rear disk brake conversions. I am
trying to determine just what kinds of parts are required. What is the
vehicle application or part numbers. I have seen several sites with lots of
pictures but not the basic part info.
Also I saw a reference to running 60 mm cyl on the rear but waiting for
Caddy backing plates to go to 80 mm on rear.
Finally what kind of rotors are used? How are they fitted/adapted to the GMC
hub.
Any and all response would be greatly appreciated.
 
No I have not received any response but surewould like one or more!

Thanks

Bill Hubert

>Bill:
>
>Did you get a response to this yet???
>
> Paul Bartz
>
>From: William Hubert [mailto:whubert]
>Sent: Thursday, May 27, 1999 7:57 AM
>Subject: Re: GMC: Rear Disk Brake Conversion Parts
>
>I have seen a number of posts about rear disk brake conversions. I am
>trying to determine just what kinds of parts are required. What is the
>vehicle application or part numbers. I have seen several sites with lots of
>pictures but not the basic part info.
>Also I saw a reference to running 60 mm cyl on the rear but waiting for
>Caddy backing plates to go to 80 mm on rear.
>Finally what kind of rotors are used? How are they fitted/adapted to the GMC
>hub.
>Any and all response would be greatly appreciated.
>
>
 
>Bill:
>
>Did you get a response to this yet???
>
> Paul Bartz
>
>From: William Hubert [mailto:whubert]
>Sent: Thursday, May 27, 1999 7:57 AM
>Subject: Re: GMC: Rear Disk Brake Conversion Parts
>
>I have seen a number of posts about rear disk brake conversions. I am
>trying to determine just what kinds of parts are required. What is the
>vehicle application or part numbers. I have seen several sites with lots of
>pictures but not the basic part info.
>Also I saw a reference to running 60 mm cyl on the rear but waiting for
>Caddy backing plates to go to 80 mm on rear.
>Finally what kind of rotors are used? How are they fitted/adapted to the GMC
>hub.
>Any and all response would be greatly appreciated.
>
>
 
Bill:

We previously corresponded May 19th on the 80 mm caliper upgrade parts for
the front wheels. Some updates to that list of AutoZone parts are: caliper
bolt p/n H5004 @ $1.79 and master cylinder p/n 10-1668.

One option for converting to rear disc brakes is using 76-78 Cadillac El
Dorado rear wheel backing plates as the basis to mount the caliper's.
Enlarging the center hole (2.250" with a 45 degree by 1/16" chamfer on the
back side) and elimination of the dust shield on the backing plate is
required, as well as a slight notching of the backing plate to clear the
swing arm.

The rotor requires locating and drilling three new holes (same size as
existing) for the mounting bolts.

Additional parts, from Autozone (price does not include tax), you'll need to
change over to rear disc brakes on the rear wheels are:
2 ea Banjo bolt, p/n 313940, $1.99
1 ea Caliper, left front rear axle, p/n 90185, $12.99 + core
charge ($17.00)
1 ea right front rear axle, p/n 90184, price same as
above
1 ea Caliper, left rear rear axle, p/n 90557, $73.94 + core
charge ($70.00)
1 ea right rear rear axle, p/n 90553, $73.94 + core
charge ($70.00)
8 ea mounting bolt, p/n H5002, $3.39
1 ea Brake pad set (front rear axle), p/n 0524, $26.99 (these are
Performance Friction carbon metallic pads)
1 ea Brake pad set (rear rear axle), p/n 25265, $6.49 (these are
not Performance Friction carbon metallic pads)
4 ea Flexible hose, p/n 77226, $9.99
2 ea bracket, left side p/n 3757443, $8.20
2 ea bracket, right side, p/n 10257203, $8.20
4 ea bracket clip, p/n H1457, $1.29
4 ea jam nut (don't have AutoZone number for
this)
4 ea Brake line, 3/16 x 20", p/n H320, $2.49

Paul Bartz

From: William Hubert [mailto:whubert]
Sent: Wednesday, June 02, 1999 11:17 PM
Subject: RE: GMC: Rear Disk Brake Conversion Parts

No I have not received any response but sure would like one or more!

Thanks

Bill Hubert

>Bill:
>
>Did you get a response to this yet???
>
> Paul Bartz
>
>From: William Hubert [mailto:whubert]
>Sent: Thursday, May 27, 1999 7:57 AM
>Subject: Re: GMC: Rear Disk Brake Conversion Parts
>
>I have seen a number of posts about rear disk brake conversions. I am
>trying to determine just what kinds of parts are required. What is the
>vehicle application or part numbers. I have seen several sites with lots
of
>pictures but not the basic part info.
>Also I saw a reference to running 60 mm cyl on the rear but waiting for
>Caddy backing plates to go to 80 mm on rear.
>Finally what kind of rotors are used? How are they fitted/adapted to the
GMC
>hub.
>Any and all response would be greatly appreciated.
>
>
 
Paul,

Thank you very much for the detailed list of parts. I do have a few
questions that would help me clarify things:

>Some updates to that list of AutoZone parts are: caliper
>bolt p/n H5004 @ $1.79

Is this new number for the H5002 bolt referred to below?

>and master cylinder p/n 10-1668.

Is this the P-30 master cylinder?

>.... 76-78 Cadillac El
>Dorado rear wheel backing plates .... Enlarging the center
>hole (2.250" with a 45 degree by 1/16" chamfer on the
>back side) ....

Do the backing plate mounting bolt holes need to be enlarged or moved?

>The rotor requires locating and drilling three new holes (same size as
>existing) for the mounting bolts.

What is the part number or application for the rotor?

> 8 ea mounting bolt, p/n H5002, $3.39

Is this the Caliper mounting bolt? Is this the one that is replaced by the
H5004 part?

> 2 ea bracket, left side p/n 3757443, $8.20
> 2 ea bracket, right side, p/n 10257203, $8.20
> 4 ea bracket clip, p/n H1457, $1.29

What are these brackets used for?

> 4 ea jam nut (don't have AutoZone number for

What is the jam nut used for?

> 4 ea Brake line, 3/16 x 20", p/n H320, $2.49

Where is the brake line used?

Sorry for all the questions but I am trying to visualize how it all fits
together.

Dave
73 Sequoia
 
Paul
Thanks so much for the response. Now I'll search for parts.
By the way the front parts seem to all work out fine,

>Bill:
>
>We previously corresponded May 19th on the 80 mm caliper upgrade parts for
>the front wheels. Some updates to that list of AutoZone parts are: caliper
>bolt p/n H5004 @ $1.79 and master cylinder p/n 10-1668.
>
>One option for converting to rear disc brakes is using 76-78 Cadillac El
>Dorado rear wheel backing plates as the basis to mount the caliper's.
>Enlarging the center hole (2.250" with a 45 degree by 1/16" chamfer on the
>back side) and elimination of the dust shield on the backing plate is
>required, as well as a slight notching of the backing plate to clear the
>swing arm.
>
>The rotor requires locating and drilling three new holes (same size as
>existing) for the mounting bolts.
>
>Additional parts, from Autozone (price does not include tax), you'll need to
>change over to rear disc brakes on the rear wheels are:
> 2 ea Banjo bolt, p/n 313940, $1.99
> 1 ea Caliper, left front rear axle, p/n 90185, $12.99 + core
>charge ($17.00)
> 1 ea right front rear axle, p/n 90184, price same as
>above
> 1 ea Caliper, left rear rear axle, p/n 90557, $73.94 + core
>charge ($70.00)
> 1 ea right rear rear axle, p/n 90553, $73.94 + core
>charge ($70.00)
> 8 ea mounting bolt, p/n H5002, $3.39
> 1 ea Brake pad set (front rear axle), p/n 0524, $26.99 (these are
>Performance Friction carbon metallic pads)
> 1 ea Brake pad set (rear rear axle), p/n 25265, $6.49 (these are
>not Performance Friction carbon metallic pads)
> 4 ea Flexible hose, p/n 77226, $9.99
> 2 ea bracket, left side p/n 3757443, $8.20
> 2 ea bracket, right side, p/n 10257203, $8.20
> 4 ea bracket clip, p/n H1457, $1.29
> 4 ea jam nut (don't have AutoZone number for
>this)
> 4 ea Brake line, 3/16 x 20", p/n H320, $2.49
>
> Paul Bartz
>
>From: William Hubert [mailto:whubert]
>Sent: Wednesday, June 02, 1999 11:17 PM
>Subject: RE: GMC: Rear Disk Brake Conversion Parts
>
>No I have not received any response but sure would like one or more!
>
>Thanks
>
>Bill Hubert

>>Bill:
>>
>>Did you get a response to this yet???
>>
>> Paul Bartz
>>
>>From: William Hubert [mailto:whubert]
>>Sent: Thursday, May 27, 1999 7:57 AM
>>Subject: Re: GMC: Rear Disk Brake Conversion Parts
>>
>>I have seen a number of posts about rear disk brake conversions. I am
>>trying to determine just what kinds of parts are required. What is the
>>vehicle application or part numbers. I have seen several sites with lots
>of
>>pictures but not the basic part info.
>>Also I saw a reference to running 60 mm cyl on the rear but waiting for
>>Caddy backing plates to go to 80 mm on rear.
>>Finally what kind of rotors are used? How are they fitted/adapted to the
>GMC
>>hub.
>>Any and all response would be greatly appreciated.
>>
>>
>
>
 
Dave:

Answers to your questions:

1. Yes it is.
2. Yes it is.
3. No they don't. Machining is only required to allow the backing
plate to fit over the axle shaft.
4. Sorry, I overlooked listing the rotor. It is AutoZone p/n 5512,
$36.94.
5. Yes it is.
6. The bracket restrains the flexible hose where it joins the steel
line.
7. Jam nut secures the flexible hose to the bracket.
8. Brake line goes from the T hose, mounted on top of the rear wheel
center casting, to the flexible hose connection.

If interested in saving a little money, when you obtain your backing plates
also get the calipers. They can be turned in when purchasing caliper's and
eliminate the core charge.

If the rotors are in decent shape and within tolerance, get them also. They
can be cleaned up and used in lieu of purchasing new one's. I'm told that
"aged" rotor's have a hardness greater than new one's.

Paul Bartz

From: Dave [mailto:DGMDGM]
Sent: Thursday, June 03, 1999 5:49 PM
Subject: RE: GMC: Rear Disk Brake Conversion Parts

Paul,

Thank you very much for the detailed list of parts. I do have a few
questions that would help me clarify things:

Some updates to that list of AutoZone parts are: caliper bolt p/n
H5004 @ $1.79

Is this new number for the H5002 bolt referred to below?
and master cylinder p/n 10-1668.

Is this the P-30 master cylinder?
.... 76-78 Cadillac El Dorado rear wheel backing plates ....
Enlarging the center hole (2.250" with a 45 degree by 1/16" chamfer on the
back side) ....

Do the backing plate mounting bolt holes need to be enlarged or moved?
The rotor requires locating and drilling three new holes (same
size as existing) for the mounting bolts.

What is the part number or application for the rotor?
8 ea mounting bolt, p/n H5002, $3.39

Is this the Caliper mounting bolt? Is this the one that is replaced by the
H5004 part?
> 2 ea bracket, left side p/n 3757443,
$8.20
> 2 ea bracket, right side, p/n 10257203,
$8.20
> 4 ea bracket clip, p/n H1457, $1.29

What are these brackets used for?
> 4 ea jam nut (don't have AutoZone
number for

What is the jam nut used for?
> 4 ea Brake line, 3/16 x 20", p/n H320, $2.49

Where is the brake line used?
Sorry for all the questions but I am trying to visualize how it all fits
together.
 
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