NBS/Astro knuckle brake upgrade.

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99bluetahoe

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I believe the PPV tahoe brakes are the same as that performance brake system but with uncoated calipers. If you search the part numbers, you can get the calipers for 400 each and 70 bucks each for the rotors. Not bad for 15" rotors and 6 piston brembos around $1000 for everything.
 

Lowrado09

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How much shorter were the 2wd Astro spindles than the gmt400 ones? The pictures are not showing anymore
 

Shwa Kid

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How much shorter were the 2wd Astro spindles than the gmt400 ones? The pictures are not showing anymore
I'm not sure what happened to the old photos, I think I had uploaded to the forum, maybe they just expire or something.

Here's the spindles side by side, sorry I can't remember the dimensions
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I can't remember what other photos I uploaded so here's a couple more.

Full compression (spring removed), wheel turned. Wheel is a stock 2020ish 17" x 8" with a 275/55R17 tire, fender is rolled.
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A few installed pics:
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Evan Wyatt

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I'm not sure what happened to the old photos, I think I had uploaded to the forum, maybe they just expire or something.

Here's the spindles side by side, sorry I can't remember the dimensions
You must be registered for see images attach

I can't remember what other photos I uploaded so here's a couple more.

Full compression (spring removed), wheel turned. Wheel is a stock 2020ish 17" x 8" with a 275/55R17 tire, fender is rolled.
You must be registered for see images attach

A few installed pics:
I noticed the 2011 Durango runs the 5x127 like the 2wd OBS trucks and looks like it will bolt up to the knuckle.
 

andremora71

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What size tapered reamer did you use for the tie rod hole ? Since I need to flip it?
 

Schurkey

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I have been wanting to do this swap for years and finally the local self serve yard got a 6 lug awd astro van in. When gm upgraded the brakes on the astro van they made a knuckle with gmt800+ style brakes that bolts in place of a gmt400 style knuckle(what the astro previously used). So for $54 and an hours work I was ready to upgrade my suburban.

The old setup:
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The new setup:
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Side by side:
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Everything bolts right in with a few exeptions.
Old thread, old post. But what the hell.

The original GMT400 brakes appear to be JB5 or perhaps JB6, both of which are the same in front. They have low-drag calipers needing a 3-chamber (Quick Take-Up) master cylinder. The Astro calipers are not low-drag, and use a conventional 2-chamber master cylinder.

What are you doing with the master cylinder? Have you checked the bore sizes of the original calipers vs. the new calipers to see what the Master-Slave cylinder ratio is? How about the rear brakes? Can the Astro master cylinder properly supply the rear brakes on the GMT400s?

Seems to me that the master cylinder compatibility has been ignored/forgotten on this swap.

Wild Guess: Using a 3-chamber master cylinder on calipers that don't need them is way better than using 2-chamber master cylinder on calipers that need a 3-chamber master. But I've got no personal experience with that.
 
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