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Discussion Starter #1
I am on the verge of going of the deep end. I had an earlier post regarding brake drag on passenger side. LS1 caliper/Drum spindle.

I replaced both calipers (warranty) a couple of weeks ago turn pass side rotor on the hub. Assembled and everything seemed good limited(normal drag). I had to again replace the pass caliper due to leakage. The new replacement had a ton of drag, one piston is sticking out further than the other.

Two more calipers later, the last one a different brand-(MAJOR Drag )on the pass side. Still Dragging Hardcore!

I since replumbed the hard lines, checked and changed flexible front lines. New pads to make sure they were square-(caliper floats freely on well lubed abuttments).

I just removed my power MC and Booster and replaced it with a 7/8 bore wilwood MC going to manual. Bled the system and its just as bad if not worse. I knew the MC wasn't the issue this was just to improve pressure and modulation.

I can't believe that three different calipers could be defective, the drag on the pass side has always been excessive, but now it is ridiculous. I zero up the caliper bracket to the back side of the rotor with dial indicator and ended up having to move the lower caliper mounting point out .007".

Could the caliper be too far of center due to alignment and applying pressure to the pads?

The only thing left-possible alignment issue; if the caliper floats how is it apply so much pressure to the pads on the one side? I cannot figure it out!


I am at a total loss. The next thing is replace the spindles with Un-touched factory originals and buy and bracket kit from Kore 3. I am not convinced this would remedy the issue!

Please help, I am just about ready to give up!

Thanks, in advance SS.
 

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If i remember correctly when i had with Willwoods they have a shim on the back side of the caliper and mounting bracket.. It may be worth the shot to first check clearance from the piston closed to the rotor and compare it to the other, you may have to shim it to move the caliper farther from the rotor. Also ive used a spring kit on the pins between the pads to keep them from the slightest drag.
 

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It is the design of the piston seal that pulls the piston back a few thou to release the pads
If these are working, which sounds like they are...there is drag rather than locked on...
then either
the slides are not sliding correct...jambing the front or rear pads on
Or the sliders are out of alignment doing the same as above
Or the caliper mounts are bent out of alignment.

Or the actuating pin in ther back of the master cylinder is a few thou to long...not allowing enough fliud to return to the mc.
An easy check for this is back off the mounting bolts on the MC drop a spacer in then try...it so adjust the length of the pin
How to is in several older posts.
 

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Discussion Starter #4 (Edited)
Must be the caliper mount, I just dial indicated again removed the shim thinking this was adding some slight pressure on the back of the caliper. I removed some more material from the upper bolt boss and difference is .004". The steel caliper brackets were laser cut but they are not flat.

I guess I will throw some additional part$ at it (New bracket ) and new/old spindles in an effort to eliminate by process.

Anyone know of a LS1 Brake Bracket Manufacturer? Not sure if the Kore 3 will work being the c5 rotor hat is more shallow.

If if was the MC pressure wouldn't I have residual pressure on both sides?
SS
 

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Discussion Starter #6
Yes I talked to Tobin, he recommended the MC, said it could be abuttment binding (but they move freely) until I pedal it and then pass side gets tight.

Before I throw anymore parts at it, I would really like to figure out what the heck the deal is. There has to be a simple solution. The pistons seem to be out fairly evenly on the caliper in question. To change brackets I will have to change spindles as well, with no Guarantee of solving the issue.
 

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If if was the MC pressure wouldn't I have residual pressure on both sides?
9 times out of 10 yes...I have seen the issue 2x times where the MC pin is just long enough to hold 1 disc on slightly....
If there is slack of a few thoiu it is not your problem..I suggested to recheck because that is the simplest thing to do
I do tend towards bent or out of alignment mounts.
 

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Discussion Starter #9
I presume you are talking about shim(washer) between the abuttment bracket and caliper bracket? I added some today(pass side) with no difference.

With the rears 93-7z28 I shimed the abbuttment to center on the rotor.

Or am I missing something?

If I compress the pistons with a c clamp and the abbuttement floats freely, go to the pedal and apply pressure- and pistons extend to the pt where are gap is taken up and still are applying slight pressure (which is enough to cause major drag).

I guess this could be misalignment but it is not obvious by sight. It acts as if residual pressure exists, but I have removed the flexible line during and it doesn't release.

The gaps of the abuttment to the rotor seem adequate front and back, shims appeared to make it better visibly more aligned, but yielded no difference.
 

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By "abutment shims" I meant these, that help the pads slide accurately in the abutments. (you probably have them)



Have you tried swapping just the abutments from side to side? (they're identical) Possibly one of those is tweaked causing it to bind on the pins.
 

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Discussion Starter #11
Yes thanks, I thought about that might be what you ment after I posted. I have tried at least 2-3 pairs since I have had 3 calipers in the past 2 weeks and new pads with supposedly premium (shim pack). I am tempted to swap caliper brackets from side to side, however the spindle machining is suspect.

With a floating caliper should .004-.005 make that much of a difference?

That is what I get with dial on a sweep between upper and lower holes (setting zero in the center). However, the middle is off and so are the ends (thats why I say the bracket is not flat). Seems funny that I am the only one to run into this with as many people who have done the swap and ground the bolt bosses by hand (a shop did mine).

I really appreciate the help, SS.
 

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but I have removed the flexible line during and it doesn't release.
OK that means the MC is not the issue, and you have replaced the flex lines so they dont have crap in acting as a valve...
It just leaves that the pistons are not pulling back on the O rings enough to clear the discs
Have you driven the car and bedded the pads in yet....if they are at a slight angle to the disc and not bedded then the O rings cant pull the pistons back enough....
The pads most proberly just need bedding in.

Put some engineers blue on the disc, turn the wheel after applting brakes, remove the pads and see where the blue is on the pads...then file that 'high' spot/cnr down a little.
Sort of bedding the pads by hand.

just how much drag do u have?
 

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Discussion Starter #13
I did drive it last week with the old pads and (different caliper) go figure! I tried to re-bed the old pads with multiple hard stops (although a short drive). Came home jacked up the pass side tire and drag hadn't changed.

Since then changed pads, caliper, abbuttments, clips, MC, tried a different flexible line, and removed more material from upper boss based on dial indicator readings, and tried shimming the caliper outward with thin washers.-No difference-noting the difference between all changes one at a time.

With the caliper body off and just the abuttment and pads on-it takes very little pressure (tried by hand) to create substantial drag.

To put in perspective with everything assembled: If you install wheel and try spinning by hand, tire doesn't quite make a full rotation. The other side same effort 1.5-1.75 rotations.

Currently the pistons seem almost even in outward displacement, the last reman calipers one piston was sticking out farther.

I have not driven it in its current form since I didn't want to cook the pad/rotor since both are a fresh surface. The other side spins free as ever with new pads and clips etc...

SS
 

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With the caliper body off and just the abuttment and pads on-it takes very little pressure (tried by hand) to create substantial drag.


SS
Not sure I understand? Do you mean just pinching the pads to the rotor with your hand creates drag?

When you drove the car was there a pull to the right, both braking and just driving?

It almost sounds it could be as simple as a wheel bearing on one side either failing or being tighter than the other side.
 

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To put in perspective with everything assembled: If you install wheel and try spinning by hand, tire doesn't quite make a full rotation. The other side same effort 1.5-1.75 rotations.
It almost sounds it could be as simple as a wheel bearing on one side either failing or being tighter than the other side.
That is what I thought also
When doing up the castle nut, tighten firm to seat the bearings then back off till loose and put the slpit pin thru the nearest resess on the nut...DO NOT have it up tight.
This doesnt apply to ALL cars...ie older cars that have machined spacers inside the hub where the spacer takes the 'pressure' of the castle nut but dosent put pressure on the bearings.
And to bed the pads heavy braking does stuff all...meduim brake pressure over 100yds will bed the pads/shoes far better.
 

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Discussion Starter #16 (Edited)
I repacked both sides recently, and the pass side spins freely with the pistons compressed.

I pulled the cal bracket off and checked with T square and it appears flat. I think the issue is the spindle upper bolt boss being machined a a different angle then the lower. But I am not sure(hard to explain)

This swap required the machining of the upper bolt boss down to be parallel with the lower.

I think the only way to be sure is swap spindles, and use same brackets, etc... and see if drag persists.

It didn't pull without brake application and after I pseudo re-bedded the old pads it went pretty straight upon braking.

I don't know how it will behave with new pads etc...but I don't really want to cook them.

The spindle seems to be the outlier, but it is a PITA experiment, but at least it doesn't cost $.
 

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Maybe this will make you feel better (I hope!)

My car is up on stands for a winter project. I have similar brakes to yours (C6 - same basic deal)

After applying the brakes, I spun each wheel by hand as hard as I could. Result: Pass side 6 complete revolutions Driver's side 3 complete revolutions

I'm not concerned about it. The brakes have been on the car for several thousand miles and work perfectly. There are no pulls at all, and the pads and rotors are wearing evenly. I frequently put my fingers to the brakes after driving to check for an excessively hot rotor and have never found a problem.

For a simple test, I'd suggest this. Loosen the castle nuts on each side and torque the bearings to the same value - 12 lbs/ft for example, and don't install a cotter pin. Then do your spin test and see what you get.
 

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Discussion Starter #18
swapped the spindles, no difference! so the mount is not the issue.

The original replacement raybestos caliper did not have drag that was on there 2 weeks ago, except it leaked.

I replaced it with a centric rebuild the drag issue surfaced, and tried another centric, and bought another wagner.

the nut on the wheel bearing is fingertight, the caliper is just grabbing?

I even cracked the bleeder open for several minutes and no noticeable change!

It seems that alignment and residual pressure have been eliminated, whats left?

SS
 

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The brake ssytem is one of the most simple hydrolic systems around
If no residual pressure , no alighnment issue, no wheel bearing issue, that only leaves the piston seal...it is the design of the seal that dropps the piston back a tiny bit...the pads still touch the disc, unlike drums...
All it leaves is
the new pad(s) are a bit higher and not quite level....the engineers blue and file above post
Or
Similar the pads need to be beded in..take it for a 10 mile spin around town lots of interections.
 

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Discussion Starter #20
One piston is sticking out .100" compared to the other. Causing the pad to drag? question is, why?

Unequal pressure in the caliper-(not sure how that could occur)

poor QA/QC on reman parts (x3 different cals) or, somehow the caliper is shifting in the abbuttment and not remaining centered and parallel to the rotor. Looking at the abuttment it is pretty darn square relative to the rotor.

Going to try a few more experiments, but I think I am TSOL!
 
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