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 Post subject: 2003+ Brake upgrade thoughts?
PostPosted: Wed Jun 28, 2017 10:00 pm 
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So as my rig gets more and more built up... she's been gaining weight. As such, she doesn't stop that well these days. I'll keep up with the stock hardware and maintenance as best as I can, but I feel like eventually a brake upgrade might be in order. I've done pretty well with the General's parts bin thus far, so I want to keep on that track if I can.

Looking at the Silverado, I see that the early V6 and some V8 1500s up to ~2005 (depending on engine) share the same 12" front brake rotor and caliper as the 2003-2005 Astro/Safari.
From ~2005 (again depending on engine) forward, though, they get a 13" rotor.

I'm still trying to piece through the interchange info to figure out whether it's just the caliper bracket and rotor that change, or what, but I think there's a strong possibility that there's a low-buck upgrade to a larger rotor that might work for the 6-lug vans. This would almost certainly dictate 17" wheels, which is a bummer for those of us who like a lot of sidewall in our tires, but it might be worth it to be able to stop well.

If anybody knows a better part-interchange research website, please let me know.

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2003 Astro AWD Astrolander/ZMB - GTRV Top Transplant, 4" OLV Lift, NP233 T-case, evolving interior
1995 Safari GTRV Organ donor - gutted and gone.
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 Post subject: Re: 2003+ Brake upgrade thoughts?
PostPosted: Wed Jun 28, 2017 10:33 pm 
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Referencing a lot of info from this thread:
http://z71tahoe-suburban.com/iboard/ind ... 28846&st=0

Seems like I'm on the right track. The only thing I find confusing is that the above thread indicates brackets AND calipers (and I see references elsewhere to upgraded twin-piston calipers), but several of the interchange sites I'm looking at show same part# for reman'd calipers for 2003-2005 Astro and 1999-2007 Silverados (for a variety of packages, but it's hard to nail that down)

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"My minivan is cooler than your bro-truck"
2003 Astro AWD Astrolander/ZMB - GTRV Top Transplant, 4" OLV Lift, NP233 T-case, evolving interior
1995 Safari GTRV Organ donor - gutted and gone.
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 Post subject: Re: 2003+ Brake upgrade thoughts?
PostPosted: Thu Jun 29, 2017 5:03 pm 
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Herbie, what are you running now for your brake setup?

Even fully loaded with motorcycle(s) and track gear, tools, equipment, etc I've never felt the van was marginal on stopping power?

I run OE rotors with Hawk LTS and a reasonably decent brake fluid like Castrol GT LMA or whatever it's called now. The pads dust but they don't fade, have excellent initial bite with great stopping power and feel so maybe give the Hawk LTS or HPS front/rear a try first as a cheaper option.

If I remember correctly, you've done auto track stuff in the past and you're a smart guy so I'm not telling you anything you don't already know but with our vans being almost 15 years old now, the rest of the brake system could surely use a refresh - lines, calipers/hardware, perhaps even master cylinder rebuild/replacement.

That being said, if you do decide to upgrade the brakes, especially if all the above needs to be done anyway then it might be a worthwhile venture and I'll be following along. You've got me headed over to Rock Auto to check parts and cross-references. :cheers:

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 Post subject: Re: 2003+ Brake upgrade thoughts?
PostPosted: Thu Jun 29, 2017 5:34 pm 
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I didn't read thread linked above but after quick glance on RA, it looks like the Silverado 1500 front calipers for the 13" rotors are for the rear drum brake equipped models hence the reason for larger front rotors.

Comparing the Silverado 1500 calipers that are the same as on our 2003-2005 Astro vans to the Silverado 1500 front calipers for the 13" rotors, the calipers look the same/very similar but the mounting brackets are slightly different with different mounting hole location which is most likely to push out the calipers the 1/2" necessary for the 1" larger diameter rotors. I do wonder now if these bolt onto the same knuckles without issue.

I guess one way to find out would be to pick up a cheap reman caliper at local auto parts store to test fit but you'd probably have to pay a core charge or find one in a salvage yard, Ebay, etc. You could then see if your 16" wheel would clear which I'm doubtful of but worth a try or see if wheel spacers would help clearance by moving the wheel drop center out away from the caliper. I did this on a Subaru when went from 17" to 15" wheels and while they cleared the calipers with no spacers, I went with 25mm hubcentric spacer adapters not only to give a bit more caliper clearance but the additional track width since I lifted it and the Subaru stock offset has the wheels located very inboard.

Astro front caliper (note the mounting location on both)

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Silverado 1500 front caliper for 13" rotor

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 Post subject: Re: 2003+ Brake upgrade thoughts?
PostPosted: Thu Jun 29, 2017 5:53 pm 
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Here's the difference in front brake pads which shows a nice, slight increase in pad surface area.

2003-2005 Astro:

http://www.hawkperformance.com/performance-street/pads/hb323y724-1329

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2005 Silverado 1500 with 13" front rotors:

http://www.hawkperformance.com/performance-street/pads/hb561y710-693

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 Post subject: Re: 2003+ Brake upgrade thoughts?
PostPosted: Thu Jun 29, 2017 10:29 pm 
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All good info.

Currently running (I think) the Napa Premium pads. Fluid is relatively fresh, but Master cylinder and lines are original.

Yeah, I'm definitely running off to buy parts yet, it's just my thing to start researching possibilities early. (Check my history, I started asking questions about transfer case swaps about six years before I did mine!) At this point, I'll definitely be doing a refresh on the stock system very soon (doing interior work this month, but have a trip in September I need to be ready for), but I'm adding a few notes to my running list about checking out GMT900 brake hardware the next time I'm at the pick-n-pull.

Thanks for the Rx on the Hawk pads, I'll make sure those are what go on next, along with starting to replace all the aging rubber bits...

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"My minivan is cooler than your bro-truck"
2003 Astro AWD Astrolander/ZMB - GTRV Top Transplant, 4" OLV Lift, NP233 T-case, evolving interior
1995 Safari GTRV Organ donor - gutted and gone.
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