Rotor replacement
Thread Starter
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Rotor replacement
I am getting ready to replace the rotors on the LT4. I bought a set from a forum member off a 3500 mi LT4. They're in perfect shape and ready for install.
As I understand, it's pretty straight forward. Once the wheel is off, remove the two caliper bracket bolts on the knuckle, clean out the threads, put on the rotors and tighten them down, I believe 137 ft lbs.
The recommendation is to replace the bolts w/ new ones from Chevrolet which have thread adhesive on them. But have read that cleaning the old ones and using blue thread locker is good enough.
Is there anything I'm missing or should know about? I want this to be right the first time as this is my only car and won't be able to make a "parts run" and also, well, brakes are a good thing have working properly.
As I understand, it's pretty straight forward. Once the wheel is off, remove the two caliper bracket bolts on the knuckle, clean out the threads, put on the rotors and tighten them down, I believe 137 ft lbs.
The recommendation is to replace the bolts w/ new ones from Chevrolet which have thread adhesive on them. But have read that cleaning the old ones and using blue thread locker is good enough.
Is there anything I'm missing or should know about? I want this to be right the first time as this is my only car and won't be able to make a "parts run" and also, well, brakes are a good thing have working properly.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
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If the bolts' thread is in good shape, re-use them (i did). I used red thread lock.
Check the FSM, I think they tight to 156 ft-lbs
Check the FSM, I think they tight to 156 ft-lbs
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
You've got it! Don't be shocked if you have to use a large cheater bar to break them (caliper mounting bolts) loose the first time.
The torque is lower for the rears tho I think it's in the 80's range.
Recheck the caliper mounting bolts for proper torque at each oil change and lube. It only takes a minute.
The torque is lower for the rears tho I think it's in the 80's range.
Recheck the caliper mounting bolts for proper torque at each oil change and lube. It only takes a minute.
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
You've got it! Don't be shocked if you have to use a large cheater bar to break them (caliper mounting bolts) loose the first time.
The torque is lower for the rears tho I think it's in the 80's range.
Recheck the caliper mounting bolts for proper torque at each oil change and lube. It only takes a minute.
The torque is lower for the rears tho I think it's in the 80's range.
Recheck the caliper mounting bolts for proper torque at each oil change and lube. It only takes a minute.
I had to use a wrench with an 18" pipe for leverage to break the bolts free.
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
Use the blue loctite. Red is stronger (permanent) and will make it very hard to remove in the future. I replace rotors very often as mine is track driven and crack frequently; I reuse the bolts and never use Loctite(but I examine the bolts regularly.)
Le Mans Master
Joined: Sep 2003
Posts: 5,874
Likes: 0
From: Littleton CO
I didn't need a breaker bar for mine, but I do have a flex-head ratchet with a slightly longer handle. Other than on the exhaust, I really haven't had trouble with any of the typically stubborn fasteners yet.
If I remember correctly, the parking brake cable isn't slackened, but the self-adjuster is locked at the handle. It doesn't seem to be a big deal for this job anyway, in my experience. I've had the rear rotors on & off at least twice without fussing with it, and the parking brake still holds well on my sloped driveway. Just leave the cable attached to the caliper. I will probably follow the FSM in this regard when I remove the calipers entirely for a rebuild & repaint. (One of these days... some of you may have seen me say that a long time ago. :o)
I actually went to a local dealer service department to ask about re-use of the fasteners, and that's what they do. If it's good enough for them with the risk of litigation, then I'm OK with it too. I use the blue loctite.
Make sure you have all the right socket sizes. The fronts were larger than in my set, and one of the rears is an allen head. Luckily, we have another car, so acquiring tools as I go is a mere annoyance.
If I remember correctly, the parking brake cable isn't slackened, but the self-adjuster is locked at the handle. It doesn't seem to be a big deal for this job anyway, in my experience. I've had the rear rotors on & off at least twice without fussing with it, and the parking brake still holds well on my sloped driveway. Just leave the cable attached to the caliper. I will probably follow the FSM in this regard when I remove the calipers entirely for a rebuild & repaint. (One of these days... some of you may have seen me say that a long time ago. :o)
I actually went to a local dealer service department to ask about re-use of the fasteners, and that's what they do. If it's good enough for them with the risk of litigation, then I'm OK with it too. I use the blue loctite.
Make sure you have all the right socket sizes. The fronts were larger than in my set, and one of the rears is an allen head. Luckily, we have another car, so acquiring tools as I go is a mere annoyance.
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Le Mans Master
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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Mine are off and on so much that locktite would be a waste. I go a max of 2 events before they are off and on again.
FOr street car - USE THE BLUE!
Thread Starter
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Yeah, so I get the "new" rotor on. Get the caliper back on. Give it a spin to test. It goes about 1/3 turn and comes to screaching halt. Okay, so perhaps I need to push the piston back to reset the clearance, right. Well I keep the bracket on, and decide to put the lugs on all five, tighten them by hand plus about 1/4. Give the rotor a spin and this thing looks like one of those kiddie rides at the carnival. All kinds of warp in this S.O.B. 
Thought it might be dirt or debris, or install issue as it didn't want to come off at first. But the old one went back on w/o problem.
Oh well, I really wanted slotted/drilled rotors anyway.
Thought it might be dirt or debris, or install issue as it didn't want to come off at first. But the old one went back on w/o problem.
Oh well, I really wanted slotted/drilled rotors anyway.
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
There was a long post a few years ago, including lots of testing which confirmed the torque in the FSM is INCORRECT and too high (causing stretching and breakage).
The conclusion was that 137 ft lb is max front caliper mounting bolt torque.
Also regarding the re-use of the bolts, one concern is that IF the bolts had been previously torqued to the FSM torque amount, reuse (even with blue locktite) could be dangerous.
Given a lack of knowledge of what the PO has done, would recommend buying new bolts this time, but if needed, reuse later on -- is it really worth a few dollars for the damage (or death) which could result otherwise if the caliper bracket where to come loose !!
P.S. if you were to disagree with the old post of the torque being too high in the FSM -- and want to believe the FSM is correct, then by default you would also need to believe the FSM specifing to REPLACE the bolts is ALSO correct -- as the two things are directly related...
Last edited by theadmiral94; Jul 31, 2009 at 10:44 AM.
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
Yeah, so I get the "new" rotor on. Get the caliper back on. Give it a spin to test. It goes about 1/3 turn and comes to screaching halt. Okay, so perhaps I need to push the piston back to reset the clearance, right. Well I keep the bracket on, and decide to put the lugs on all five, tighten them by hand plus about 1/4. Give the rotor a spin and this thing looks like one of those kiddie rides at the carnival. All kinds of warp in this S.O.B.
Thought it might be dirt or debris, or install issue as it didn't want to come off at first. But the old one went back on w/o problem.
Oh well, I really wanted slotted/drilled rotors anyway.
Thought it might be dirt or debris, or install issue as it didn't want to come off at first. But the old one went back on w/o problem.
Oh well, I really wanted slotted/drilled rotors anyway.
Thread Starter
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
Sorry, but on torque,
There was a long post a few years ago, including lots of testing which confirmed the torque in the FSM is INCORRECT and too high (causing stretching and breakage).
The conclusion was that 137 ft lb is max front caliper mounting bolt torque.
Also regarding the re-use of the bolts, one concern is that IF the bolts had been previously torqued to the FSM torque amount, reuse (even with blue locktite) could be dangerous.
Given a lack of knowledge of what the PO has done, would recommend buying new bolts this time, but if needed, reuse later on -- is it really worth a few dollars for the damage (or death) which could result otherwise if the caliper bracket where to come loose !!
P.S. if you were to disagree with the old post of the torque being too high in the FSM -- and want to believe the FSM is correct, then by default you would also need to believe the FSM specifing to REPLACE the bolts is ALSO correct -- as the two things are directly related...
There was a long post a few years ago, including lots of testing which confirmed the torque in the FSM is INCORRECT and too high (causing stretching and breakage).
The conclusion was that 137 ft lb is max front caliper mounting bolt torque.
Also regarding the re-use of the bolts, one concern is that IF the bolts had been previously torqued to the FSM torque amount, reuse (even with blue locktite) could be dangerous.
Given a lack of knowledge of what the PO has done, would recommend buying new bolts this time, but if needed, reuse later on -- is it really worth a few dollars for the damage (or death) which could result otherwise if the caliper bracket where to come loose !!
P.S. if you were to disagree with the old post of the torque being too high in the FSM -- and want to believe the FSM is correct, then by default you would also need to believe the FSM specifing to REPLACE the bolts is ALSO correct -- as the two things are directly related...
Thread Starter
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
The lug nuts have to be tightened onto the rotor for the "spin test" or to properly seat the pads during their installation. I very much doubt the rotors are warped; that a wives tale. Put it back together, tighten the lugnuts, give the brakes a stab,do the spin test and repost the outcome.
Instructor
Joined: Apr 2006
Posts: 215
Likes: 0
From: Conway AR
Non climate controlled area? How about the 1000s of vettes parked outside, North, South, reckon they sit thru some "non climate controlled areas"?
Take your old rotors and get them turned, cost $4 here (arkansas) then they will be true.
Good start.
bill
Take your old rotors and get them turned, cost $4 here (arkansas) then they will be true.
Good start.
bill
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
Presume you know this but just in case...
be sure to wire-brush the center spindle and area around the lugs and the back of the rotor and the back of the rim (and can always 'index' (rotate the rotor 1/2 way around on the lugs) to try and reduce the runout--
I recently did this on our 2000 TA and was able to reduce run-out and pedal pulsation (even though they 'looked' clean).
Also, the metal of the rotors is soft enough that you cannot get the 100 ft lb of torque required to properly set the rotor -- best way is with the wheel installed, but then you can't get to the outer edge of the rotor with a run-out gauge, so ideal is with a spacer plate over the lug bolts or maybe just the center of a rim or just do the back-side of the rotor...
be sure to wire-brush the center spindle and area around the lugs and the back of the rotor and the back of the rim (and can always 'index' (rotate the rotor 1/2 way around on the lugs) to try and reduce the runout--
I recently did this on our 2000 TA and was able to reduce run-out and pedal pulsation (even though they 'looked' clean).
Also, the metal of the rotors is soft enough that you cannot get the 100 ft lb of torque required to properly set the rotor -- best way is with the wheel installed, but then you can't get to the outer edge of the rotor with a run-out gauge, so ideal is with a spacer plate over the lug bolts or maybe just the center of a rim or just do the back-side of the rotor...
Le Mans Master
Joined: Apr 2005
Posts: 6,413
Likes: 9
From: The Old Dominion
If you have stock sliding calipers and you seated the pistons fully, I would think the rotors would have to be insanely warped to drag on used pads...
That said, I'm not sure I'd put used rotors on a car unless in a pinch.
That said, I'm not sure I'd put used rotors on a car unless in a pinch.
Thread Starter
Le Mans Master
Joined: Dec 2006
Posts: 5,139
Likes: 482
From: H-Town Texas
