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BMWGURU Rear Vette Upgrade by MstangsBware
Started on: 11-21-2013 04:50 PM
Replies: 11 (529 views)
Last post by: MstangsBware on 11-24-2013 06:58 AM
MstangsBware
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Report this Post11-21-2013 04:50 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
Working on installing BMWGURUs 12 inch Vette upgrade on a local car. I have ran into the issue of the pads locking down the rotor once everything is tight. Unsure if I am over looking something or I have other issues. Anyone else install his rear 12 inch brake upgrade yet?
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MstangsBware
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Report this Post11-21-2013 05:17 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by MstangsBware:

Working on installing BMWGURUs 12 inch Vette upgrade on a local car. I have ran into the issue of the pads locking down the rotor once everything is tight. Unsure if I am over looking something or I have other issues. Anyone else install his rear 12 inch brake upgrade yet?




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bmwguru
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Report this Post11-21-2013 05:24 PM Click Here to See the Profile for bmwguruClick Here to visit bmwguru's HomePageClick Here to Email bmwguruSend a Private Message to bmwguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Install looks correct. Check rotor application. Should be 1988 Corvette non HD REAR rotors. Is it possible that the suspension has changed the hub or bearing offset?

Dave
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fieroguru
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Report this Post11-21-2013 05:42 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
If only the outboard pad is dragging, check close between the caliper slider bosses (aluminum part around the sliders) and the weld at the bracket for interference. It looks like there is still room on the sliders for the caliper to move outboard some to free up the outer pad.

If the inboard pad or both pads are dragging, remove the parking brake lever and back the piston in further.
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MstangsBware
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Report this Post11-21-2013 05:58 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

If only the outboard pad is dragging, check close between the caliper slider bosses (aluminum part around the sliders) and the weld at the bracket for interference. It looks like there is still room on the sliders for the caliper to move outboard some to free up the outer pad.

If the inboard pad or both pads are dragging, remove the parking brake lever and back the piston in further.


They r both dragging...Pretty sure I gave the piston bottomed out. Here is a picture of piston

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fieroguru
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Report this Post11-21-2013 06:39 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here is a picture of one fully bottomed out. It protrudes about .210" from the bridge mounting surface.


Another area to check is the outboard pad. The backside need to only have 2 protruding rivets and those rivets tend to bottom out on the bridge before the pad is fully seated. I normally grind the rivet heads down about 1/2 way or take an air tool to the pocket on the bridge. You also need to make sure there isn't any rust build up in the corners that could keep the pad from fully seating to the side of the bridge:

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MstangsBware
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Report this Post11-21-2013 11:48 PM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
Had no luck figuring out the issue today as every thing looks good. The amount thats left before tighteneing the bridge down is a good amount. Owner is checking to make sure he ordered the correct rotors. I used a brake tool to crank the piston in as far as it will go. Calipers r rebuilds from calipers on line..

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TXOPIE
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Report this Post11-22-2013 12:30 AM Click Here to See the Profile for TXOPIEClick Here to visit TXOPIE's HomePageClick Here to Email TXOPIESend a Private Message to TXOPIEEdit/Delete MessageReply w/QuoteDirect Link to This Post
BMWguru what thickness should the rotors be?

Want to verify that I have something weird with the rotors.

If I know that, then I can get Fieroguru to sell me a set for the rear with the correct drilling. ...thank God my other two Fieros are 88s and will just get Fieroguru's 13" upgrade kits

Help please...getting so close...we finally fired up the engine tonight and she sounds great with a smooth idle.

Thanks Mr. Poe for all your help!

[This message has been edited by TXOPIE (edited 11-22-2013).]

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fieroguru
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Report this Post11-22-2013 06:42 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The advertized thickness is .790"

Its quite difficult to use the wrong rotor.
The Early (Pre 88) C4 rotors were only 11.5" in diameter, so the caliper pads would be in the wrong place with a bracket for a 12" kit.
The 12" 88+ C4 front rotors are too deep and won't even fit the rear 84-87 uprights.
The heavy duty 88+ C4 rotors are only different for the front rotors and those are 13" OD and 1.10" thick so the 88 calipers won't fit over them.

If you can loosen the caliper mounting bolts and spin the
I would check the areas on the upright that were cut/ground down to make sure the upright isn't interfering with the back side of the rotor. You can bolt the rotor to the wheel bearing and spin it to make sure (with the caliper removed).
Also check to make sure the rotor clears the caliper bridge as it passes over the rotor.
With the rotor bolted to the wheel bearing and the caliper bolts loosened up, if you can easily spin the rotor, then isn't not a caliper piston issue as there is adequate clearance. If that's the case, then check the caliper brackets for being parallel to the wheel bearing flange by clamping a small piece of steel to it and measuring from the caliper bracket at all 4 corners to the piece of steel - they should all be the same dimension.

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TXOPIE
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Report this Post11-22-2013 03:09 PM Click Here to See the Profile for TXOPIEClick Here to visit TXOPIE's HomePageClick Here to Email TXOPIESend a Private Message to TXOPIEEdit/Delete MessageReply w/QuoteDirect Link to This Post
fieroguru...thanks for your input! We will review all the these things and see what we can figure out.

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bmwguru
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Report this Post11-24-2013 06:21 AM Click Here to See the Profile for bmwguruClick Here to visit bmwguru's HomePageClick Here to Email bmwguruSend a Private Message to bmwguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
If the rotor measures in spec, my thoughts are that the main part of the bracket is too thick. That is a copy of my kit and when you sent it to me to have the ears welded, we didn't measure it. I assume it is correct if you used my CAD files. The only other variable from the kits I ran off is the knuckle you sent me to make a jig. If there was an issue with the knuckle, then it may be causing the issue.
We didn't test fit your kit like I did with the others because after we ran off the last of my kits, the jigs and test components were scrapped.
Is it doing this on both sides of the car or did you just try to put on one side so far? Maybe there is an issue with the caliper.
Dave
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MstangsBware
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Report this Post11-24-2013 06:58 AM Click Here to See the Profile for MstangsBwareClick Here to Email MstangsBwareSend a Private Message to MstangsBwareEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by bmwguru:

If the rotor measures in spec, my thoughts are that the main part of the bracket is too thick. That is a copy of my kit and when you sent it to me to have the ears welded, we didn't measure it. I assume it is correct if you used my CAD files. The only other variable from the kits I ran off is the knuckle you sent me to make a jig. If there was an issue with the knuckle, then it may be causing the issue.
We didn't test fit your kit like I did with the others because after we ran off the last of my kits, the jigs and test components were scrapped.
Is it doing this on both sides of the car or did you just try to put on one side so far? Maybe there is an issue with the caliper.
Dave


I only tries fitting the Pass side of the car....Will try DRV side next time I go over to work on the car. Will taje calipers to take measurements of brackets then compare to CAD files...Something isnt right or is being over looked. Hope to figure it out soon...
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