Brake specs

MAY03LT

Original poster
Member
Nov 18, 2011
3,422
Delmarva
02-05

Front rotors:

-nominal thickness - 1.140"
-discard thickness - 1.080"
-max allowable thickness variation - .001"
-max allowable lateral runout - .002"

Rear rotors:

-nominal thickness - .787"
-discard thickness - .728"
-allowable thickness variation - .001"
-max allowable lateral runout - .002"

Torque specs:

Front caliper bracket bolts - 118 ft/lbs
Front caliper bolts - 31 ft/lbs
Front brake hose bolt - 30 ft/lbs
Front brake bleeder screw - 110 INCH/lbs

Rear caliper bracket bolts - 148 ft/lbs OR 89 ft/lbs, see note below
Rear caliper bolts - 23 ft/lbs
Rear brake hose bolt - 40 ft/lbs
Rear brake bleeder screw - 110 INCH/lbs
Rear backing plate nuts - 100 ft/lbs

Wheel nut torque:

103 ft/lbs

Brake fluid:

DOT 3

Source: MOTOR Brake specifications guide, 2011

Note - There has been conflicting torque specs for the rear caliper bracket bolts. GMSI and Motor show 148ft lbs, while a Helms book shows 89ft/lbs. At the time of this edit, the official answer is unknown. I'll update this as soon as we know the real toque spec. Credit to meerschm and billzie for pointing this out.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
As to the lug nut torque: My 2003 Envoy owners manual calls for 100 ft. lbs. And I've seen other posts calling for 106 ft. lbs.
 

MAY03LT

Original poster
Member
Nov 18, 2011
3,422
Delmarva
Wooluf1952 said:
As to the lug nut torque: My 2003 Envoy owners manual calls for 100 ft. lbs. And I've seen other posts calling for 106 ft. lbs.

To make things even more confusing, one of my references listed 105 ft/lbs!:crazy:

103ft/lbs was listed in more then one source, so I went with it.
 

Mark20

Member
Dec 6, 2011
1,630
All those values are probably within the tolerences of the torque wrench.
 

tblazerdude

Member
Dec 4, 2011
321
rear caliper bracket bolts to 148 ft/lb; that's nuts. I put maybe 115 ft/lb on front and rear. Does anyone know why the rear would be higher?
 

meerschm

Member
Aug 26, 2012
1,079
My Helm service manual (for trailblazer, and EXT) for the 03 has different specs for torque than May03 found.

View attachment 30815

sorry it is a bit fuzzy.

I do not see any separate figures for the EXT related to brakes.

looks like there are some differences in the part numbers for front brake parts between the short and long wheelbase, but no torque differences I can see
 

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billzie

Member
Aug 20, 2012
86
Athens, OH
Not sure about some of the specs May03LT posted. I just did the rear brakes on my 03 EXT. Maybe I'm just a big wuss nowadays, but with truck jacked up just enough to remove tires and me sitting/laying down doing the work, I was never able to acheive that 148 ft/lb mark and I've never though of myself on the weak side of wrenching. So I pulled out my GM dealer service manual and sure enough only lists 89 ft/lbs. I didn't double check the other specs that were listed but meerschm posted a pic that appears to be the same page I have in my manual (he says it's Helm?).
Anyway, thanks for this forum!
Bill.
 

MAY03LT

Original poster
Member
Nov 18, 2011
3,422
Delmarva
Good looking out. For the most part, the motor specs are spot on. I'll investigate and revise as needed.

FWIW I can't get a torque wrench on the rear caliper bracket bolts so I didn't try it myself.:redface:

Update with attachment, straight out of the GMSI.
 

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misterhyde

Member
Oct 14, 2012
34
How about brake fluid needed for complete drain and refill. Knowing that I'll probably use more, but would like an idea?
 

MAY03LT

Original poster
Member
Nov 18, 2011
3,422
Delmarva
Good question - I'm not seeing a published capacity.

If anyone who has done the flush wants to post up how much fluid they used, I'll update the post.
 

DanD

Member
Mar 23, 2014
46
Hewitt, WI
I know this is an old thread, but I'll comment anyway due to the importance of the issue. There have been sources (including the Helm manual shown above and my Haynes manual) that list the torque for the front caliper guide pin bolts at 85 ft. lbs. I was just tightening these last night on my Trailblazer and thought to myself, "Self, that seems like too much torque for that little bolt. Must be some special hard stuff." Anyway, before it got tight, I could feel the bolt starting to give way, so I just finished the twisting off job to get it over with. The scary part is, I have tightened those bolts in the past and would have used the specs in my Haynes manual. Been driving for a few years with the bolts way over tightened. So, my point is, be sure to change the spec in any books you have to the proper 31 foot pound level and if you have over tightened them already, maybe consider stopping by the parts store and getting new pins and bolts. I see online that a pair is $10 and change at Napa and $9 and change at Oreilly.
 
Nov 21, 2021
150
Sanford, Maine
Hey all. Took my truck in for inspection and it failed, one thing was a missing rear caliper mounting bolt! Looking around online and got a torque spec of 33 ft. lbs. Ending up torquing them to 35 after replacing the bolt with some blue locktite. Another post I saw after said 24. Should I worry about that? Should I pull the wheel again and adjust the torque or is it ok to leave it at 35? Didn't seem to stretch at all but don't want to over torque it too much.
 

Blckshdw

Moderator
Nov 20, 2011
10,697
Tampa Bay Area, FL
Hey all. Took my truck in for inspection and it failed, one thing was a missing rear caliper mounting bolt! Looking around online and got a torque spec of 33 ft. lbs. Ending up torquing them to 35 after replacing the bolt with some blue locktite. Another post I saw after said 24. Should I worry about that? Should I pull the wheel again and adjust the torque or is it ok to leave it at 35? Didn't seem to stretch at all but don't want to over torque it too much.

Assuming you're talking about the bolts for the guide pins and not the mounting bracket... Could that 33 number you got, be referring to the front guide pins, and not the rears? :undecided: You could also check the torque on the bolts on the other caliper, and see where they are at for comparison. :twocents:

From the first post...

Front caliper bracket bolts - 118 ft/lbs
Front caliper bolts - 31 ft/lbs
Front brake hose bolt - 30 ft/lbs
Front brake bleeder screw - 110 INCH/lbs

Rear caliper bracket bolts - 148 ft/lbs OR 89 ft/lbs, see note below
Rear caliper bolts - 23 ft/lbs

Rear brake hose bolt - 40 ft/lbs
Rear brake bleeder screw - 110 INCH/lbs
Rear backing plate nuts - 100 ft/lbs
 

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