Hub replacement with front brake upgrade
Schurkey
10-19-2022, 02:37 AM
FINALLY got around to swapping the larger-diameter rotors and brackets from my "Parts" Trailblazer EXT to my daily-driver Trailblazer. This is a cheap and easy brake upgrade if your GMT360 has 17" wheels. The only parts needed for the brake upgrade are the long-wheelbase GMT370 rotors, and the matching GMT370 caliper brackets, and MAYBE the dust-shields (I forgot to measure them.). All else stays the same. (Going all the way to the "Trailblazer SS" front brakes requires the SS rotors (more cooling fins, but same diameter and thickness as GMT370), SS calipers (bigger pistons, iron body instead of aluminum) and brackets, SS master cylinder (larger diameter bore to match the larger caliper pistons.))
This was prompted by a failing RF hub/bearing assembly, along with a worn-out right outer tie rod end. Which led me to discover that the brake pads are wiped-out AGAIN. All these parts were scavenged from the Trailblazer EXT and transferred to the daily-driver. The worn-out parts were reinstalled on the EXT so that it's still mobile with four wheels and steering.
Jacked-up and secured both vehicles. Removed wheel, brake caliper, brake caliper bracket, rotor, and tie-rod stud nut from both vehicles. Smacked the tie rod studs down with a hammer to separate them from the tapered-holes in the steering knuckles. I counted the turns needed to unscrew the outer tie rod ends from the vehicle--20 turns on one and 21 on the other. I also measured the installed distance to the steering knuckle, and made sure to get the installed measurement as close to the original measurement as possible. I may need to have the vehicle aligned--we'll see. Removed CV shaft nut with 36mm socket and impact wrench. With the tie rod end separated from the knuckle, the knuckle turns side-to-side making access to the three hub bolts easy, especially if the CV shaft is pushed "in" a little. Security clip removed from ABS connector, then connector unbuckled, and the various harness clamps were released so the ABS harness hung free.
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A 18mm swivel impact socket and a 1/2" air impact wrench made short work of the three hub bolts on each vehicle. This was a refreshing change from the hub bolts on my '97 K2500 8-lug, which had 13mm heads, fought me all the way, and which were all rounded-off (ruined) by the time they came out. Both Trailblazer hubs practically fell out of the steering knuckle, not rusted in place like the K2500. The three hub bolts got cleaned-up, and I reapplied "Blue" 242 Loctite thread locker for reassembly and torquing.
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I wire-brushed loose rust off of...everything. Paid particular attention to the rotor- and wheel-mounting surface of the hubs and rotors, the inside of the rotor, and where the hubs mount to the steering knuckles. This left a rusty-brown color, but no big chunks or flakes. Hub and ABS cable, and tie rod end reinstalled and torqued.
At that point I compared rotors and caliper brackets. Note the rusted braking surface of the bigger rotor, which will be dealt with later.
(Thumbnail 4)
Yup, the bigger rotors are bigger...but not much bigger.
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Then got busy cutting (remachining) the braking surface of the larger rotors. This is pretty-much a "lost art" because by the time a person pays the labor and shop fees to have the rotors remachined, you're about half-way to the cost of brand-new rotors, and with no clean-up of rust like I went through--and likely a better surface finish. But I happen to own an ancient Bear rotor-and-drum lathe set. It's nearly as old as I am. The bigger Trailblazer rotors are at the absolute limit of the lathe's capacity; in fact I had to cut the outer 1/8 inch by turning the feed handle manually; the self-feed was "done". Modern brake lathes make a big deal out of cutting a rotor in one pass. But I favor making multiple passes, each with a relatively light cut. I know for certain that I'm not removing more metal than absolutely needed. I spend a lot more time cutting each rotor in several operations; but I don't have to pay for my labor.
The Bear rotor lathe, with the Trailblazer rotor mounted:
(Thumbnail 8)
After a couple passes, I still had a major gouge on the front surface. Rear surface (not shown) looked really good--just a "shadow" of un-cut metal.
(Thumbnail 9)
Another couple of passes, and the outer surface is as nice as I can make it. It's not as nice as "new".
(Thumbnail 10)
That's as far as I've gotten. Need to cut one more rotor, and measure it. This one is still nicely thicker than the machining limit, well above the "discard" thickness. And then install the rotors, caliper brackets, pads, calipers, and wheels.
Then it's time for "test-abuse".
This was prompted by a failing RF hub/bearing assembly, along with a worn-out right outer tie rod end. Which led me to discover that the brake pads are wiped-out AGAIN. All these parts were scavenged from the Trailblazer EXT and transferred to the daily-driver. The worn-out parts were reinstalled on the EXT so that it's still mobile with four wheels and steering.
Jacked-up and secured both vehicles. Removed wheel, brake caliper, brake caliper bracket, rotor, and tie-rod stud nut from both vehicles. Smacked the tie rod studs down with a hammer to separate them from the tapered-holes in the steering knuckles. I counted the turns needed to unscrew the outer tie rod ends from the vehicle--20 turns on one and 21 on the other. I also measured the installed distance to the steering knuckle, and made sure to get the installed measurement as close to the original measurement as possible. I may need to have the vehicle aligned--we'll see. Removed CV shaft nut with 36mm socket and impact wrench. With the tie rod end separated from the knuckle, the knuckle turns side-to-side making access to the three hub bolts easy, especially if the CV shaft is pushed "in" a little. Security clip removed from ABS connector, then connector unbuckled, and the various harness clamps were released so the ABS harness hung free.
(Thumbnail 1)
(Thumbnail 2)
A 18mm swivel impact socket and a 1/2" air impact wrench made short work of the three hub bolts on each vehicle. This was a refreshing change from the hub bolts on my '97 K2500 8-lug, which had 13mm heads, fought me all the way, and which were all rounded-off (ruined) by the time they came out. Both Trailblazer hubs practically fell out of the steering knuckle, not rusted in place like the K2500. The three hub bolts got cleaned-up, and I reapplied "Blue" 242 Loctite thread locker for reassembly and torquing.
(Thumbnail 3)
I wire-brushed loose rust off of...everything. Paid particular attention to the rotor- and wheel-mounting surface of the hubs and rotors, the inside of the rotor, and where the hubs mount to the steering knuckles. This left a rusty-brown color, but no big chunks or flakes. Hub and ABS cable, and tie rod end reinstalled and torqued.
At that point I compared rotors and caliper brackets. Note the rusted braking surface of the bigger rotor, which will be dealt with later.
(Thumbnail 4)
Yup, the bigger rotors are bigger...but not much bigger.
(Thumbnail 5)
(Thumbnail 6)
(Thumbnail 7)
Then got busy cutting (remachining) the braking surface of the larger rotors. This is pretty-much a "lost art" because by the time a person pays the labor and shop fees to have the rotors remachined, you're about half-way to the cost of brand-new rotors, and with no clean-up of rust like I went through--and likely a better surface finish. But I happen to own an ancient Bear rotor-and-drum lathe set. It's nearly as old as I am. The bigger Trailblazer rotors are at the absolute limit of the lathe's capacity; in fact I had to cut the outer 1/8 inch by turning the feed handle manually; the self-feed was "done". Modern brake lathes make a big deal out of cutting a rotor in one pass. But I favor making multiple passes, each with a relatively light cut. I know for certain that I'm not removing more metal than absolutely needed. I spend a lot more time cutting each rotor in several operations; but I don't have to pay for my labor.
The Bear rotor lathe, with the Trailblazer rotor mounted:
(Thumbnail 8)
After a couple passes, I still had a major gouge on the front surface. Rear surface (not shown) looked really good--just a "shadow" of un-cut metal.
(Thumbnail 9)
Another couple of passes, and the outer surface is as nice as I can make it. It's not as nice as "new".
(Thumbnail 10)
That's as far as I've gotten. Need to cut one more rotor, and measure it. This one is still nicely thicker than the machining limit, well above the "discard" thickness. And then install the rotors, caliper brackets, pads, calipers, and wheels.
Then it's time for "test-abuse".
Blue Bowtie
10-19-2022, 08:57 AM
Good documentation of the project. That's going to be useful down the road.
Schurkey
10-28-2022, 01:49 PM
Minor update. Yes, the larger rotors should be used with the larger dust-shields. The dust shields are as much bigger as the rotors are; keeping the dust shield proportional to the rotor size.
My rotors, caliper brackets, and dust-shields all came from a donor vehicle; I don't know if the dust shields are available from GM or the aftermarket. God bless the Treasure Yards. [Edit:] Part numbers for dust shields, posted below.)
The hub has to be removed to change dust shields. But since I didn't remove the second hub, I've still got the smaller dust-shield on one side.
My rotors, caliper brackets, and dust-shields all came from a donor vehicle; I don't know if the dust shields are available from GM or the aftermarket. God bless the Treasure Yards. [Edit:] Part numbers for dust shields, posted below.)
The hub has to be removed to change dust shields. But since I didn't remove the second hub, I've still got the smaller dust-shield on one side.
Blue Bowtie
10-29-2022, 12:20 PM
As of about 15 months ago, the rear dust shields were still available. I haven't looked again since buying them at that time.
http://www.wwdsltd.com/files/EnvoyOEMBrakeBackingPlate.jpg
http://www.wwdsltd.com/files/EnvoyOEMBrakeBackingPlate.jpg
Schurkey
11-03-2022, 10:50 PM
Update to the update.
APPARENTLY, the left side hub got jealous of the right side hub. I drove the vehicle for about one day, and then the left hub started making noise. Not as bad as the right side, but that hub clearly wants to retire like her sister.
At least I'll be able to install the larger splash-shield now. New hub should be here in a few days.
Also--thanks for the tip on the rear dust shields. Ordered 15158972 (left) and 15158973 (right) from Amazon; about forty dollars with tax. Strangely, one was priced lower than the other by about four dollars. Apparently, made in Thailand. Thanks, gm
https://www.amazon.com/ACDelco-15158972-Original-Equipment-Driver/dp/B00496JPP2
https://www.amazon.com/ACDelco-15158973-Original-Equipment-Passenger/dp/B00496NG3Y
Front Right shield for EXT/larger diameter rotor:
https://www.amazon.com/ACDelco-15753012-Original-Equipment-Passenger/dp/B0055AA4TM ($64)
Front Left shield for EXT/larger diameter rotor:
https://www.amazon.com/ACDelco-15753011-Original-Equipment-Driver/dp/B0055AA3PC ($22)
Both front dust shields are listed as "Made in China", why one is three times the price of the other I do not understand.
APPARENTLY, the left side hub got jealous of the right side hub. I drove the vehicle for about one day, and then the left hub started making noise. Not as bad as the right side, but that hub clearly wants to retire like her sister.
At least I'll be able to install the larger splash-shield now. New hub should be here in a few days.
Also--thanks for the tip on the rear dust shields. Ordered 15158972 (left) and 15158973 (right) from Amazon; about forty dollars with tax. Strangely, one was priced lower than the other by about four dollars. Apparently, made in Thailand. Thanks, gm
https://www.amazon.com/ACDelco-15158972-Original-Equipment-Driver/dp/B00496JPP2
https://www.amazon.com/ACDelco-15158973-Original-Equipment-Passenger/dp/B00496NG3Y
Front Right shield for EXT/larger diameter rotor:
https://www.amazon.com/ACDelco-15753012-Original-Equipment-Passenger/dp/B0055AA4TM ($64)
Front Left shield for EXT/larger diameter rotor:
https://www.amazon.com/ACDelco-15753011-Original-Equipment-Driver/dp/B0055AA3PC ($22)
Both front dust shields are listed as "Made in China", why one is three times the price of the other I do not understand.
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