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 Post subject: Disk Brakes and Rotor Replacement Procedure
PostPosted: Wed Jan 30, 2008 11:41 pm 
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Joined: Wed Mar 14, 2007 2:30 am
Posts: 155
Location: Pocono Mts, PA
Edit 03 March 2009: It upsets me that I had to do this repair again so soon, but when you fail inspection, you got to do it. So now we're benifiting from it by the addition of pictures...

Well, I just finished changing the rear disc brakes on my 03 Astro. Disc brakes are pretty basic to most folks here, but I'm posting for the benefit of those who have never had the pleasure. I didn't think to take photos being this was supposed to be an hour job for both sides, that turned into a nightmare; next time I do work, I take will take photos.

Pad Change:
1: Take a huge C-Clamp, and fit the bottom over the back of the caliper. Fit the top of the clamp over the center of the exposed back of the pad. Tighten the clamp as much as possible by hand, then remove it.
Image

2: Using a 12 mm wrench, loosen, but DO NOT REMOVE the top caliber mounting bolt. Remove the bottom caliber mounting bolt. Note: On the front of late model vans, you'll be using a T-155 Torx Bit. On earlier vans (like my previous 1998) it will be an allen--I forget the size of that one.
Top One: Image Bottom One: Image

3: Swing the caliper up, and wedge a stick or something under it to hold it up. The GM service manual recommends tying with wire, and that should work too.
Image

4: Using a screwdriver and hammer, tap the brake pads loose from the tops. If you must, gingerly use the screwdriver to pry them loose on each end, but be careful not to damage the rotor--those are over $50 a piece at Advance. If you can't get them off, see below. But trust me, you want to get them loose at this point if at all possible.

5: You've probably already done this. Inspect the rotors for any damage. If they are not smooth, you'll want to replace them or have them lathed. It's worthwhile to find a shop that lathes rotors, as the one near me will do it for $12. (See below if damaged)

6: The new brake pads go in much the same way the old ones came out.

7: Replace caliper, re-install bolt, remember to tighten top bolt. You're done.

Caliper Bracket Removal, Rotor Replacement
This part of the job is not fun. And GM intended it that way. From looking at it, you'll note that it seems straightforward The two bolts you're looking for are the big ones behind the rotor. They are torqued to 148 lbs. And the top one is a !%!@% to remove.

1: Spray the bolts with some penetrating oil to make your life easier (WD-40, PB, etc). Edit: First use a blowtorch on the bolt head, then spray it with the PB Blaster. If you have a really good impact wrench, try it on the bottom one first... Repeat these steps a couple more times. Here are the bolts I'm talking about:
Top One: Image

Bottom One: Image

2: Using an 18 mm socket and an impact wrench, if you have one, remove the bottom bolt holding the bracket. The first time around on this job my compressor was a pancake style unit, this didn't work out too well for me. If you find yourself in this boat, use a breaker bar and fit a 1.5 inch steel pipe over the back end. With the right amount of leverage it'll come off. Use a long enough pipe and you can just step on it from the back of the van.

3: Using an 18 mm wrench, preferably with a 6 point back instead of a 12, remove the top bolt holding the bracket. You'll end up hitting it with a hammer to get the bolt to move. Alternatively, fit a shorter length of 2 inch steel pipe over the wrench for some leverage. Do not use a socket and rachet to remove this bolt. I tried that with a 3/8" drive socket and rachet, and the top bolt backed the rachet into a bracket holding the leaf springs to the axle. A universal won't work either. There's too much torque and locking compound on those bolts... Edit: Don't be afraid to re-apply the blowtorch and PB Blaster a couple times when you hit sticking points.

Note: Don't just let the whole assembly drop as you remove the bracket. You could damage the brake line to the caliber if you do. The GM manual says to tie it to something, but I find that putting the caliper assembly on the leaf spring works just as well...
Image

4. Pull the old rotor off and replace it. Note, you may need to hit it front and back repeatedly with a mallet--it may be stuck. Also, others have indicated that a blowtorch applied to the base of the rotor, where it mounts to the hub, can be helpful here as well...
Old Rotor Off: Image New Rotor On: Image

4: Replace the bracket the same way you removed it. If you feel strongly that you need to torque the bolts holding the bracket to 148 lbs, let me know how that works out for you with the top one ](*,)

_________________

Previous Vans: 1998 Astro, AWD, 138K mi; traded on 2003 Chevy Astro, AWD, 125K mi; traded on
2009 Chevy Silverado 1500 WT, 4x4, ext, long box
2007 Chevy Cobalt
1998 Maza MPV (180K mi and in need of PA inspection--only paid $500!)

Needed: a Gen 2 Astro project vehicle...


Last edited by chemist on Wed Mar 04, 2009 6:41 am, edited 2 times in total.

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 Post subject: Re: Rear Disk Brakes--Standard for Late Model Vans
PostPosted: Sun Feb 03, 2008 12:54 am 
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Joined: Sun Jan 13, 2008 5:23 am
Posts: 217
Thanks for the good write up on the rear disc pads.

I have a 2003 AWD Astro with rear disc brakes and your info will come in handy when I need to do brake work.

Does your parking brake work properly? I guess the rear parking brake has a small set of brake shoes inside the rotor assembly.

I had some trouble with the parking brake on mine Astro. I finally turned the adjusting nut and got it correct. then to prevent it from slipping, I used strong cable ties to secure the adjustment nut to the cable.

Astrophyshics


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 Post subject: Re: Rear Disk Brakes--Standard for Late Model Vans
PostPosted: Sun Feb 03, 2008 2:47 am 
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Location: Lost Angels, Sovern KarlyFornia.
What diameter are those rear disks?...... jus` curious?

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A British Wanker living in So KarlyFornia.
My Astro tows my toys to Glamis sand dunes http://www.youtube.com/watch?v=jp2pqjQtpso
First ever canal jump at Glamis http://www.youtube.com/watch?v=oXZjM84x_Xc


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 Post subject: Re: Rear Disk Brakes--Standard for Late Model Vans
PostPosted: Thu Feb 26, 2009 6:29 am 
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I finally get the smurf thing

Joined: Wed Mar 14, 2007 2:30 am
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Location: Pocono Mts, PA
Note: for front disc brakes you'll need to used a 155 torx bit instead of a wrench...

It my be necessary to use a good antisieze and/or heat from a torch to get the bollts to looosen...

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Previous Vans: 1998 Astro, AWD, 138K mi; traded on 2003 Chevy Astro, AWD, 125K mi; traded on
2009 Chevy Silverado 1500 WT, 4x4, ext, long box
2007 Chevy Cobalt
1998 Maza MPV (180K mi and in need of PA inspection--only paid $500!)

Needed: a Gen 2 Astro project vehicle...


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 Post subject: Re: Rear Disk Brakes--Standard for Late Model Vans
PostPosted: Fri Feb 27, 2009 3:08 am 
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Location: Lost Angels, Sovern KarlyFornia.
I would recommend loosening the bleed nipple and attach a piece of vacuum line into a catch bottle, before prying back the caliper pistons (which will move much easier).This dumps out the fluid from the caliper which sometimes contains rust deposits or water contamination, rather than pushing it back into the hydraulic system.

Dark brown or black brake fluid is not good also, and will lead to a softer/ spongy brake pedal feel underfoot. Pressure bleeding your entire hydraulic brake system and replacing all that bad fluid with new, will certainly make your brakes perform better.

_________________
`86 V8 Lowered Cargo, extensively modified, shaved bald, wearing the shortest, sluttyest white primer dress....

A British Wanker living in So KarlyFornia.
My Astro tows my toys to Glamis sand dunes http://www.youtube.com/watch?v=jp2pqjQtpso
First ever canal jump at Glamis http://www.youtube.com/watch?v=oXZjM84x_Xc


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 Post subject: Re: Rear Disk Brakes--Standard for Late Model Vans
PostPosted: Fri Feb 27, 2009 3:14 am 
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Location: Lost Angels, Sovern KarlyFornia.
Ooops, do a search for Pressure Bleeder for info on how you can build your own.

_________________
`86 V8 Lowered Cargo, extensively modified, shaved bald, wearing the shortest, sluttyest white primer dress....

A British Wanker living in So KarlyFornia.
My Astro tows my toys to Glamis sand dunes http://www.youtube.com/watch?v=jp2pqjQtpso
First ever canal jump at Glamis http://www.youtube.com/watch?v=oXZjM84x_Xc


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 Post subject: Re: Disk Brakes and Rotor Replacement
PostPosted: Wed Mar 04, 2009 6:37 am 
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I finally get the smurf thing

Joined: Wed Mar 14, 2007 2:30 am
Posts: 155
Location: Pocono Mts, PA
Bumping this one. I've updated the original post to include pictures, new tips and to also include instructions for front brakes on this model and earlier models so it reads like a real procedure. Should it stay here or go in general procedures?

_________________

Previous Vans: 1998 Astro, AWD, 138K mi; traded on 2003 Chevy Astro, AWD, 125K mi; traded on
2009 Chevy Silverado 1500 WT, 4x4, ext, long box
2007 Chevy Cobalt
1998 Maza MPV (180K mi and in need of PA inspection--only paid $500!)

Needed: a Gen 2 Astro project vehicle...


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Mon Apr 20, 2009 5:02 pm 
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Joined: Mon Jan 07, 2008 12:40 pm
Posts: 294
Location: Columbia, MO
I have a question related to rear disks for my project van. I wanted to convert the rear drums (94 AWD with Hydro boost) to the 11" drum or aftermarket (such as SSB) rear disk. I have new 4.10 gears for the front and rear. The gears for the front are installed now but I haven't installed the rear gears yet. The rear end is really rusted and requires sandblasting and rust treatment. I have upgraded the fronts to 1 ton calipers with the larger pads. I do have the full HD metal leave springs form Overlands. Plan is 31" tires.

What would be the best option for the rear end upgrade?

    Junkyard axel with disks from an AWD? Will my taller gear fit in the new rear end?
    SSB upgrade $$$'s
    11" drums

Remember the project truck does not have the weight like a normal van as it has been chopped down (glass and seats). It has a HO 383 CI v8 in the front and has 4" lift tubes on the sub-frame. My object is performance type breaking and not necessarily for a daily driver.

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1994 AWD GMC Safari, V8 truck van project
1998 2WD Astro
1999 AWD Astro


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Mon Apr 20, 2009 5:13 pm 
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The bolt pattern will be different on the newer rear end. Comments?

SSBC
http://www.ssbrakes.com/commerce/detail/index.cfm?nPID=8648

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1994 AWD GMC Safari, V8 truck van project
1998 2WD Astro
1999 AWD Astro


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Mon Apr 20, 2009 11:53 pm 
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One avenue you might research is using earlier 5 bolt axles. If they are the same length and the bearings are the same they should work. You would have to redrill the rotors but that's no biggie. Rear rotors should last nearly a lifetime. \:D/

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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Tue Apr 21, 2009 12:08 pm 
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So are you saying there was a stock rear disk five lug offered for the Astro/Safari? What years? and can the calipers be upgraded?

The SSBC kit to convert is $735.00 which is a bunch of cash. I would rather do the junk yard thing and have stock style because of the cost.

Either way, I’m sure there will be some proportioning work that needs to be done. Where do I go for info on that subject?
Thanks-
j

oh- new pictures on the Tran build posted.

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The Tran man http://jayjensen.shutterfly.com/action/

1994 AWD GMC Safari, V8 truck van project
1998 2WD Astro
1999 AWD Astro


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Tue Apr 21, 2009 12:23 pm 
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I don't know if there was a 5 bolt disc rear. What I suggested was using 5 bolt axles in the 6 bolt housing. Lots cheaper than using an aftermarket conversion. \:D/

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1996 Safari SLX Hotair balloon transport vehicle


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Tue Apr 21, 2009 4:33 pm 
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Location: Columbia, MO
Got'cha! :bounce:

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1994 AWD GMC Safari, V8 truck van project
1998 2WD Astro
1999 AWD Astro


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Thu Apr 23, 2009 12:56 am 
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Location: Rochester,NY
Jinmajay wrote:
So are you saying there was a stock rear disk five lug offered for the Astro/Safari? What years? and can the calipers be upgraded?

The SSBC kit to convert is $735.00 which is a bunch of cash. I would rather do the junk yard thing and have stock style because of the cost.

Either way, I’m sure there will be some proportioning work that needs to be done. Where do I go for info on that subject?
Thanks-
j

oh- new pictures on the Tran build posted.


Jim-here is some ref info:

http://www.stoptech.com/tech_info/wp_pr ... lves.shtml

http://www.wilwood.com/PDF/ds488.pdf

http://www.chevyhiperformance.com/techa ... index.html

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1985 Astro-"Ole Yellar"
1994 LT Astro
1981 Winnebago-"Baby"
12'dual axle enclosed trailer
The vendor trailer


Lead with my heart & take the hits because of it like a man.


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 Post subject: Re: Disk Brakes and Rotor Replacement Procedure
PostPosted: Thu Apr 23, 2009 12:08 pm 
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I sleep in my van
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Joined: Mon Jan 07, 2008 12:40 pm
Posts: 294
Location: Columbia, MO
Thanks for the info Gary! The first link is explains the concept very good! I need to dig into my factory service manual to see what and how the Hydro boost braking system controls. If it is like most topics (FSM) they generally said "see same year truck manual..." and never get into the topic you want. Then it's off to the library to search the complete set.

Thanks again. \:D/

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The Tran man http://jayjensen.shutterfly.com/action/

1994 AWD GMC Safari, V8 truck van project
1998 2WD Astro
1999 AWD Astro


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