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Discussion Starter · #1 ·
I am dismantling and cleaning front and rear calipers and replacing with the BOE pistons in the front. Normally I wouldn't separate caliper halves because of internal plumbing but the front AP's have an external pipe bridging the halves, so I did break the halves apart for cleaning and ease of piston replacement. I will torque and Loctite blue the halves together after rebuilding.

Hopefully there are no problems doing this. Anyone have any input?

I was going to paint the halves while the calipers are dismantled because I don't want to paint the fixing bolts, but think the stock calipers in front look just fine silver. Maybe I will paint the back calipers silver to match. They look black right now, but maybe that's just brake dust. I realize that the rear caliper disassembly will be slightly more complicated, but I have the link to a tear down.

Any advice is appreciated ....
 

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There is no bleed port on the inner half...bleeding that will be a bitch. One way of bleeding the inner piston is to turn the caliper up-side-down and crack open the cross-over-tube. If you "blue" Lok-Tite it, that is no more an option. I think the best option is to send your caliper halves to BOE, and have them machine bleed port on the inner halves. An other option is to lay down the caliper with a disc in it and crack open the banjo bolt... all but the BOE option requires removing the brake assembly and doing something stupid to bleed it.
 

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Discussion Starter · #5 · (Edited)
There is no bleed port on the inner half...bleeding that will be a bitch. One way of bleeding the inner piston is to turn the caliper up-side-down and crack open the cross-over-tube. If you "blue" Lok-Tite it, that is no more an option. I think the best option is to send your caliper halves to BOE, and have them machine bleed port on the inner halves. An other option is to lay down the caliper with a disc in it and crack open the banjo bolt... all but the BOE option requires removing the brake assembly and doing something stupid to bleed it.
Thanks for your input. Yup I did consider sending them to BOE but I already have their braided brake hose (not yet installed) for front and rear factory lengths. I wonder if the one that comes in their regular line replacement kit will work with the inner caliper port they machine in.... Looks to need about the same length. Maybe they will trade it in for me. I'll try to call them tomorrow. Looks like having the inner bleed screw will make a good bleed job more likely.

I was going to flip the caliper and pressure bleed, then turn it over when oil starts coming out of the factory outboard bleed screw.

The Loctite was just for the four bolts that fix the caliper halves and not for the banjo bolts. I didn't know it was required there, but I will consult the manual on reassembly. I just ordered new seals for the front and rear rebuild kits, so I'm waiting on those now.
 

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Thanks for your input. Yup I did consider sending them to BOE but I already have their braided brake hose (not yet installed) for front and rear factory lengths. I wonder if the one that comes in their regular line replacement kit will work with the inner caliper port they machine in.... Looks to need about the same length. Maybe they will trade it in for me. I'll try to call them tomorrow. Looks like having the inner bleed screw will make a good bleed job more likely.

I was going to flip the caliper and pressure bleed, then turn it over when oil starts coming out of the factory outboard bleed screw.

The Loctite was just for the four bolts that fix the caliper halves and not for the banjo bolts. I didn't know it was required there, but I will consult the manual on reassembly. I just ordered new seals for the front and rear rebuild kits, so I'm waiting on those now.
Just a FYI- the front lines are totally different for the modification... If they're unused, we can swap you lines. Just include with the calipers...

Thanks,

Phil
 

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So I'm under the impression that flipping the calipers to bleed is a perfectly ok way to get air out of the fronts (if a little time consuming). Am I missing something here? (Asking because I'm actually going to do this procedure in the next day two)
 

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So I'm under the impression that flipping the calipers to bleed is a perfectly ok way to get air out of the fronts (if a little time consuming). Am I missing something here? (Asking because I'm actually going to do this procedure in the next day two)
Correct, tapping on the body and the cross over tube to help the air bubbles along will help as well. Rotate the caliper to taste when bleeding.
 

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Discussion Starter · #10 ·
BOE's modification just makes it less of a pain in the a$$. If you are bleeding brakes frequently it is another step to take the caliper off.
 

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BOE's modification just makes it less of a pain in the a$$. If you are bleeding brakes frequently it is another step to take the caliper off.
There's no need to take the caliper off every time as far as I can tell. Once their are no air bubbles in the line they aren't going to magically appear. I bleed my brakes fairly often and have no regular practice of taking the caliper off.

Doing some recent brake work I disconnected the line into the front caliper, thus introducing air into the system... now I need to spend the extra time flipping the caliper. Since I don't plan to disconnect the front line very often, seems like there is little need to spend money saving time here. :shrug:
 

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FWIW- There are excellent reasons high performance calipers have a bleeder for each bank of piston(s). Faster, more complete, and efficient fluid bleeding are among them.

AP's original intent for these calipers was to have dual bleeders. Have to ask the intern at Lotus who spec'd them out with only one why he/she did it. I'm assuming that person was an intern, because no reasonable person with any experience would have done it that way on purpose :facepalm :D

I didn't invent the process. Just offering it up as a service for those that don't want to hunt down their own resources for doing it. We made the jig and line spec/fittings for our own cars, so happy to offer that time invested to others as well...

-Phil



 

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so one last question for people without the boe style... is there some kind of test you guys to perform to confirm all the air is out? Wish I would have driven it before i did something that needs this procedure, as now i'm not 100% certain I've gotten all the air out! Put plenty of fluid through it though...

And might as well ask the question to Phil. With your mod you don't ever do any funky bleeding techniques to get all the air out? Caliper rebuilds are easy peasy? If it turns out that it is quite a pain to get the air out, sometime i've got to do SS lines and will be more willing to do what it takes to save time.
 

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Discussion Starter · #14 ·
so one last question for people without the boe style... is there some kind of test you guys to perform to confirm all the air is out? Wish I would have driven it before i did something that needs this procedure, as now i'm not 100% certain I've gotten all the air out! Put plenty of fluid through it though...

And might as well ask the question to Phil. With your mod you don't ever do any funky bleeding techniques to get all the air out? Caliper rebuilds are easy peasy? If it turns out that it is quite a pain to get the air out, sometime i've got to do SS lines and will be more willing to do what it takes to save time.
I can't speak for Phil, but I will try. With the caliper mod, the added step of removing two caliper fixing bolts to flip the caliper over is removed. If you want to be sure you have all the air out without the mod, you will have to flip the caliper over and bleed it first upside down, then continue to bleed with it right side up. With the mod, you bleed inside first, then outside to make sure all the air is out of the banjo connecting tube also. No need to turn the caliper, which can also stress the brake hose and fittings if you're not careful.

I thought that dismantling and reassembling the front calipers was easy.

The rear calipers are proving to be much more difficult. They are technically not supposed to be serviceable but there are rebuild kits with new seals. I'm currently stuck on the reassembly. I can't get the damn locking ring seated in the piston. Maybe I need to push the inner assembly in harder, but man I don't want to mess up the bearings.
 

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dipan, I did this recently and found that even a hydraulic press would not seat the assembly well enough to engage the snap ring. I think the slightest misalignment makes it bind.

I was able to use the technique of screwing the piston and worm screw together while compressing the spring. (Hint #3 in the SELOC wiki) You need to compress the spring very hard while you do this so there will be friction between the piston and cone disc. Quickly and carefully slip the assembly into the cylinder and then screw the piston further in (I used the ol' needle-nose pliers) while pressing down very hard on the piston. You'll hear the ring snap into place.
 

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Discussion Starter · #16 ·
dipan, I did this recently and found that even a hydraulic press would not seat the assembly well enough to engage the snap ring. I think the slightest misalignment makes it bind.

I was able to use the technique of screwing the piston and worm screw together while compressing the spring. (Hint #3 in the SELOC wiki) You need to compress the spring very hard while you do this so there will be friction between the piston and cone disc. Quickly and carefully slip the assembly into the cylinder and then screw the piston further in (I used the ol' needle-nose pliers) while pressing down very hard on the piston. You'll hear the ring snap into place.
Thanks, I was going to work my way through those tips, but I tried this one first and it worked...
 

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FWIW- There are excellent reasons high performance calipers have a bleeder for each bank of piston(s). Faster, more complete, and efficient fluid bleeding are among them.

AP's original intent for these calipers was to have dual bleeders. Have to ask the intern at Lotus who spec'd them out with only one why he/she did it. I'm assuming that person was an intern, because no reasonable person with any experience would have done it that way on purpose :facepalm :D
I seriously doubt that any intern is that stupid...

Have you considered that a bean counter could have demanded that "cost savings"? :shrug:
 

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Discussion Starter · #18 ·
Finally got one side reinstalled but now the Carbonne Lorraine RC6 pads I got from S111 won't fit! They're too thick! Anyone ever heard of that? A few mm is all that it looks like it needs. I'm guessing I shouldn't or couldn't grind them down...
 

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As I have yet to replace my pads, I am taking away something from the Michael Sands video on Rear Brake Pad Replacement where he is "screwing-in" the brake caliper piston with a pair of needle nose pliers for lack of the "Lotus" brake caliper compression tool. I am reminded of this as I'm about to replace the rear brake pads on my VW GTI which appears to require the same/similar tool. I found/saw this set at Sears.com.
Sears.com
Does any one have this kind of "Euro-brake-piston" compression tool?
Apparently my days of brake piston compression with a wood clamp are over!
 
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